University of Calgary

PRISM: University of Calgary's Digital Repository

Graduate Studies Legacy Theses

1997

Controls on the chemistry of the Bow River, southern

Alberta, Canada

Grasby, Stephen E.

Grasby, S. E. (1997). Controls on the chemistry of the Bow River, southern Alberta, Canada

(Unpublished doctoral thesis). University of Calgary, Calgary, AB. doi:10.11575/PRISM/15509

http://hdl.handle.net/1880/26620

doctoral thesis

University of Calgary graduate students retain copyright ownership and moral rights for their

thesis. You may use this material in any way that is permitted by the Copyright Act or through

licensing that has been assigned to the document. For uses that are not allowable under

copyright legislation or licensing, you are required to seek permission.

Downloaded from PRISM: https://prism.ucalgary.ca

THE UNIVERISTY OF CALGARY

Controls on the chernistry of the

Bow River, southern Alberta, Canada

by

Stephen E. Grasby

A DISSERTATION

SUBMlTTED TO THE FACULTY OF GRADUATE STUDIES

IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE

DEGREE OF =OR OF PHlLOSOPHY

Department of Geology and Geophysics

Calgary, Alberta

March, 1997

O Stephen E. Grasby 1997

Acquisitions and Acquisitions et Bibliographie SemMces - s e ~ k e s bibiiograptiiques

The author has granted a non- exclusive licence allowing the National Library of Canada to reproduce, loan, distniute or sell copies of M e r thesis by any means and in any fonn or format, malQng this thesis avaiiable to interested persons.

The author retains ownership of the copyright in M e r thesis. Neither the thesis nor substantial extracts fkom it may be printed or otherwise reproduced with the author's permission.

L'auteur a accordé une licence non

Bibliothèque nationale du Canada de reprod&, prêter, distri'buer ou vendre des copies de sa thése & quelque d e t e a sous quelque forme qye ce soit pour mettre des exemplaires de ce~te thèse à la disposition des personnes intéressées.

L'auteur caoserve la propriété du droit d'auteur qui protège sa thèse. Ni la théSe ni des extraits substantiels de ceile-ci ne doivent être imprimés ou autrement reproduits sans son

ABSTRACT

Integrated chernical and stable isotope analyses were used to defhe the controls on the

dissolved inorganic load in the Bow River, and thereby eiucidate the chernical and

hydrologie dynamics of the nver.

The dominant sources of ions in the nver are amiospheric deposition and rock

weathering. The input by weathe~g is largely controiied by dissolution of carbonate and

evaporite minerais. Calgary is the most significant point source input dong the river-

Effluent fiom the sewage treatment plants loads Na, K, and Cl to the nver. Cation activity

ratios are strongiy controiied by exchange on smectite. Smectite is absent in the nver,

suggesting that activity ratios are an iaherited signature of ground water.

Stable isotope data indicate that discharge in the fail and winter is fed by groundwater.

The high discharge event in the spring is a mixture of snowmelt and displaced

groundwater. Summer discharge is fed by rainfall. Despite seasonal variations in the TDS

load, element ratios are constant, suggesting that the chemistry of snowmelt and r a i d " are

altered by the same processes controiling groundwater chemistry. This suggests snowmelt

and rab faU must pass through the ground before becoming discharge. S1*O,, data

indicates dissolved sulfate undergoes a complex redox history before reaching the river,

implying that the water transporting the sulfate passes through the anoxic zone before

becoming discharge. Therefore, the Bow River is largely fed by ground water.

The chernical denudation rate for the Bow River at Banff is 678 kg/ha/y. The

denudation rate for the basin as a whole is 340 kg/ha&. Loading fiom Calgary accounts

for 8 to 9 2 of the mass flux out of the basin in the spring and f d and 25% of the mass

flux in the summer.

1 am gratefiil to my s u p e ~ s o r Ian Hutcheon, and to Roy Krouse, who were both

encouraging and supportive of my work. They were never too busy to sit down and talk

about my research. Funding for this pmject was provided by research grants to 1.

Hutcheon and H.R. Krouse.

This work was assisted by the cooperation of several agencies. Chernical data for the

Bow River at Lake Louise and Ban€f was supplied by the Water QwLty Branch of the

Water Survey of Canada. The Wakr Survey of Canada and Trans-Alta Utilities provided

discharge data for the Bow River and tributaries. Aiberta Environment provided

precipitation chemistry. Parks Canada provided groundwater data for Banff National Park.

Several people at the University of Calgary helped me complete this project. 1 am

gratehil to Maria Miehailescue, Jesusa Pontoy-Overend, and Nenita Lozano for teaching

me how to nui the mass spectrometers, as weii as for feeding me. Maurice Shevaiier not

only helped in the lab, but also solved ali my computer problems. Pat Michad ran cation

andysis. The 'Pudes" provided many hours of stimulahg arguments about geochemistry.

matched by many hours of playing Doorn. Marian Johuson assisted in collecting water

samples, as well as distracthg me with ski trips.

Once again, thanks to Teresa for her support and patience.

TABLE OF CONTENTS

ABSTRAa ACENOWLEDGEMENTS TABLE OF CONTENTS LIST OF TABLES LIST OF FIGURES

CHAPTER 1 Introduction

BACKGROUND PROJECT DEFINITION

OBJEcmms FIELD AND LABORATORY METHODS

CEIAPTER 2 Overview of the Bow River Basin

GEOGRAPHY CLIMATE GEOLOGY ANTaROPOGENIC WATER USE

CHAPTER 3 Meteonc verms groundwater inputs to the Bow River

INTRODUCTION O AND H ISOTOPE COMPOSI'MONS OF PRECIPITATION AND

GROUNDWATER O AND H ISOTOPE COMPOSITIONS OF WATERS IN THE

BOW m R BASIN VARIATION IN THE SCABLE ISCJIDPE COMPOSlTlON OFTRlBUTARlES - THE '-" CONïTNENTALEFFmT CATIONS FOR PALEO-CWMATE STUDIES

6180 AND 6D OF THE BoW RIVER - THE SOURCE OF DWHARCX

~ W N S I R E A M VARIATION IN 6D CONCLUSIONS

CHAP'iZR 4 Chemical weathering of the Rocky Mountains

INTRODUCTION METHODS CONTROLS ON THE CHEMISTRY OF THE BOW RIVER

CORRKIWG IQR NON-WEATHEWG COWNENTS WEATHERING REACIIONS C O ~ O L L I N G RIVER CHEMISIRY THERMODYNAMICCONIROLS ONFWERCHEMISTRY -CAL DENUDATiON RATE

CONCLUSIONS

CEAPTER 5 Chernical dynamics of the Bow River

INTRODUCTION CHEMICAL CaARACTERISTICS OF POINT SOURCE INPUTS CHEMICAL CHARACTERISTICS OF TEIE BOW RIVER CONTROLS ON TBE MAJOR ION CHEMISTRY OF TBE BOW RIVER

CHLmcDE SODIUM SULFUR CALCIUM AND MAGNESIUM BICARBONATE

CHEMICAL DENUDATION RATE SUMMARY IMPLICATIONS FOR BASIN HYDROLOGY

CaAPFER 6 Tracing anomalous TDS in Nose Creek

INTRODUCTION TBE NOSE CREEK BASIN RESULTS AND DBCUSSION

SOURCE OF NOSE CREEK WA'IER INORGANE C H E M ~ ~ ~ R Y OF NOSE CREEK WATER OXUGEN AND HYDROGEN SOTO OPE conmsmo~s OF NOSE CREM WATER SOURCES OF SULFATE

CONCLUSIONS

CEiAPTER 7 Conclusions

REFERENCES APPENDIX 1 Sâmple Locations APPENDIX 2 Chernical and stable isotope data for the Bow River APPENDLX 3 Chcmical data for springs and shallow ground water APPENDIX 4 Chernical and stable isotope data for Nose Creek

Table 2-1

Table 2.2

Table 3.1

Table 4- 1

Table 4.2

Table 4.3

Table 4.4

Table 4.5

Table 4.6

Table 4.7

Table 5.1

Table 5.2

Table 5.3

Table 6.1

Average annual flow for the Bow River and major aibutaries.

Licensed and actual water use for the Bow River for 1991.

Isotope &ta for spcings in the Bow Basin.

Chioride normaliseci eqyivalents ratios for precipitation.

Mean m u a l wet and dry deposition rates for the Bow Basin.

Dominant weathering reactiom anticipated for the Bow Basin.

Ca and Mg bearing minerals that may occur in sedimentary rocks

Calculated beidellite activities for smectite in equilibrium with Bow River water at Banff and Lake Louise.

Long term denudation rate for the Bow Basin.

Chernical deaudation rates for world rivers, and world average rate.

Chemisüy of storm sewer discharge, sewage effluent, and irrigation return flow.

Calculated beidellite activities for mectite in equiliirium Bow River water at Banff.

Total monthly discharge and flux of TDS for the Bow River at Banff, Carseland, and Hays.

Flow data for Nose Creek.

LIST OF FIGURES

Figure 1.1

Figure 1.2

Figure 2.1

Figure 2.2

Figure 2.3

Figure 2.4

Figure 2.5

Figure 2.6

Figure 2.7

Figure 3.1

Figure 3.2

Figure 3.3

Figure 3.4

Figure 3.5

Figure 3.6

Figure 3.7

Figure 3.8

Figure 3.9

Figure 3.10

Figure 4.1

Figure 4.2

Location of study area and sampling locations.

Discharge for the Bow River at Calgary, showing sampling periods.

~ a j o r weather systems for the Bow River Basin.

Physiographic Regions of the Bow River Basin.

Mean annual precipitation and evapotmnspiration for the Bow River Basin.

Composite monthly discharge for the Bow River at Batlff.

Monthly average mual precipitation for Calgary.

Geology of the Bow River Basin.

Dowmtream variation in discharge of the Bow River.

Variation in the stable isotope composition of precipitation from the five main weather systems that bring moisture to the Calgary area

m> and 6"O of tributaries versus the distance of their confluence dong Bow River.

6D and Sf8O of tributaries versus distance of the headwaters of the tributaries h m the Great Divide.

Schematic illustration of mixing relationship of westerly and easterly winds over the Rocky Mountains.

Plot of SD versus 6% for ail samples coilected dong the Bow River.

Plot of 6D versus 6 1 8 ~ .

Plot of m> versus 6180 best fit iines for each sample set from the Bow River.

Discharge versus temperature, measured at Banff.

Plot of 6D versus 6180 for the tributaries dong the Bow River.

Downstream variation in 6D.

Geology in the headwaters of the Bow River basin.

Discharge venus TDS for the Bow River at Banff, 1978 - 1995.

VlIl

Figure 4.3 Composite plot of monthly TDS measurements at Banff, 1978 - 38 1995.

Figure 4.4

Figure 4.5

Figure 4.6

Figure 4.7

Figure 4.8

Figure 4.9

Figure 4-10

Figure 4.1 1

Figure 4.1 2

Figure 4.13

Figure 4.14

Figure 4.15

Figure 5.1

Figure 5.2

Figure 5.3

Figure 5.4

Figure 5.5

Figure 5.6

Figure 5.7

Figure 5.8

T e m q diagram showing major cation and mion composition of the Bow River at Lake Louise and B d .

Cumulative plot of mon- Cl concentrations at Banff and Lake Louise.

Na+K vs. Cl for Banff.

Major ion composition of the Bow River and rivers draining a variety of Lithologies throughout the world.

Ca+Mg vs. HCO,.

Ca+Mg vs. HCO, + SO,.

Discharge vs. SO,/total anions.

Plot of log a ~ a l a ( ~ ) ~ versus log a ~ g / a ( ~ ) ~ for Bow River water.

Plot of log aCa/a(W2 venus log aMg/a(H)' for Bow River water with calculated phases boundaries superimposed.

Plot of log aNa/H versus log aKM-

Plot of a) log a ~ a / a ( ~ ) ~ versus log a ~ g / a ( ~ ) ~ , and b) log a N f l versus log aK/H for groundwater.

Instantaneous M y flux versus a) discharge and b)cumulative instantaneous flux, measuted at Banff.

Temary diagram, in equivalents, showing major ion composition of tributaries, storm sewer discharge and effluent from waste water treatment plants.

TDS of tributaries to the Bow River.

Total dissolved solids load versus distance dong the Bow River.

Temary diagram of major cations and anions of Bow River water.

Dowstream variation in CI concentrations for the Bow River.

Dowstream variation in Na concentrations for the Bow River.

Downstream variation in the Na+KICa+Mg equivalence ratio.

Na + K versus Cl for the Bow River and tributaries.

Figure 5.9 Na-K activity plot for the Bow River.

Figure 5-10 63S of potential inputs of S to the Bow River.

Figure 5.1 1

Figure 5.12

Figure 5.13

Figure 5.14

Figure 5.15

Figure 5.1 6

Figure 5.17

Figure 5.18

Figure 5.19

Figure 5.20

Figure 5.2 1

Figure 6.1

Figure 6.2

Figure 6.3

Figure 6.4

Figure 6.5

Figure 6.6

Downstream variation in the concentration of SO, and PS, for the Bow River.

6YS versus 1/S04.

Dowllstream variation in 6% aud 8180 in SO,.

Downstream variation in a) Ca and b) Mg for each season.

Ca + Mg versus totai ak for the Bow River and tributaries.

Ca + Mg versus alk + SO, for the Bow River and tributaries.

Ca-Mg activity plot, a) f d , b) winter, c) spring, and dl mmmer-

Sources of DIC and their associated 6I3c values (after Pawellek and Veizer, 1992).

Variation in pC0, dong the length of the Bow River.

613c of DIC vernis calculated pCO, for the Bow River.

Nose Creek basin, showing sample locations

Ternary plot of major ions for Nose Creek

Variation in major dissoived ions dong the length of Nose Creek.

Plot of m> versus 6180 for Nose Creek.

kf80 in sulfate verses ~ " 0 of water for Nose Creek.

6% venus suUate concentration for Nose Creek.

When the well's dry, we know the worth of water Benjamin Franklin

CHAPTER 1 Introduction

BACKGROUND

Each year 40,000 km3 of water from the continents to the oceans. Of this

approximately 20,000 km3 are available for human (Clarke, 1993). This representr the

global resource of renewable fiesh water. This resource is becoming increasingly stressed

due to population growth; our per capita renewable water mpply has decreased by one third

since 1970, due to the addition of 1.8 billion people to the Earth since then (Postel, 1993).

As water supplies becorne stressed, maintahhg water quality becomes increasingly

important. In order to niaintain water quality, it is necessary to understand contmls on the

chemistry of fiesh water systems.

River systems are perhaps the most dEcuit fresh water system to examine due to their

dynamic nature. Chemical analyses alone are often not sunicient to elucidate the sources

of, and controls on, the inorganic chemistry of nver water. Chemical analyses are

pdcularly limited when tracing non point-source inputs to river systems. Stable isotope

analyses can enhance our understanding of the geochemistry of nver systems as they offer

the potential to distinguish sources of dissolved inorganics in surface water, particularly

sulfate and catbon.

Stable isotopes of sulfate have k e n used to irace both naturai and antbropogenic inputs

of suifur into the environment (e.g. Krouse and Grinenko, 199 1; Hendry et al., 1986;

Norman and Krouse, 1992; k m e u et al., 1994; van Donkelaar et al., 1995; Eden, 1996).

These studies have focused on tracing industriai emissions into the atmosphere, lakes,

groundwaier, soils, and vegetation. A number of workea have also used sulfiu isotopes

to trace non-point source inputs into river systems (e.g. Hitchon and Krouse, 1972;

Rabinvich and Grinenko, 1979; Ivanov, 1983; Longinelli and Edmond, 1983;

Trembaczowski and Halas, 1993). These investigations served to identify naairal sources

of sulfate, such as dûsolution of evaporites or oxidation of suifide minerals.

Stable isotopes of carbon have also k e n used to examine controls on the carbon cycle

in river systems. The riverine carbon cycle is complex due to the various sources and

interactions dong the fiow path. Stable isotopes of carbon have been used to examine the

role of organic matter in the generation of CO, overpressure in riven (e-g. Richey et al.

1988; Buhl et al., 1991), and atmospheric buffering of pCO, in river systems with long

residence times (Yang et al., 1996; Pawellek and Veizer, 1994). The role of algd

photosynthetic activity in controliing p C 4 was also examined by Pawellek and Veizer

(1994).

Hydrograph separation is another important appiication of stable isotopes analysis in

river snidies (e.g. Fritz et al., 1976; Sklash and Farvolden, 1979; M d e c , et al., 1974).

By exarnining the stable isotope composition of H and 0, it is possible to test models of

runoff generation (e.g Horton, 1933; Hewlett and Hibbert 1967; Dunne and Black, 1970).

The basic problem these models try to address is how do snowmelt and rainfd reach a

Stream. By understanding the pathway water follows to the river, we can better understand

the factors that innuence the chemimy of that water.

PRO JECT DEFINITION

This study examines controls on the chemistry of the Bow River in southem Alberta. The

Bow River is quickly reaching it's sustainable Limit as a water resome for local

inhabitants. Currently, 88% of the average annual fiow of the Bow River is licensed for

use and up to 39% is consurned (Table 2.2). The Bow River is the largest of three rivers

that feed the South Saskatchewan River. Future increase in consumption of the Bow River

is Limited by interprovincial agreements to maintain 5090 of the average annual discharge of

the South Saskatchewan River.

Despite heavy use, there are o d y a few water quality saidies of the Bow River; the

most complete data sets are in the pristine headwaters. Block md W(1988) and Block et

al. (1993a,b) examined inorganic, organic, and trace elernent data of the Bow River in

Banff National Park. Cross et al. (1986) and Charlton et al. (1986) examined nutrient

levels down stmrn of Calgary. The Bow River Water Council (1994) provides a good

summary of the state of the Bow River, cumnt water use, and an overview of the natural

and anthropogenic environment of the basin. They note a general decrease in water quality

dong the length of the river. Unforninately, the down Stream areas, with the highest

potential for anthropogenic impacts, have the lean background data. The most noticeable

detenoration of water quality is high levels of nutrients, fecal coliCorms and benthic aigae,

ail of which increase downstream of Calgary.

Objectives

The primary goal of this study is to use the integrated anaiysis of major ions and stable

isotopes to identify the source and controls on dissolved inorganic loads, and thereby

c o n t n i e to the c m n t understanding of the chemical and hydrologic dynamics of river

systems. To achieve this goal, the objectives of this work were to:

1) Characterise the hydrologic cycle of the Bow River Basin in tenns of relative inputs

of ground and meteonc water.

2) Mode1 controls on the river chemistry in ternis of weathering and equilibrium

exchange reactions.

3) D e t e d e the chemical denudation rate of the Bow River in the pristine headwaten,

and the basin as a whole.

4) Distinguish natural from anthropogenic sources of sulfur and iheû relative inputs to

the Bow River-

5) Examine the riverine carbon cycle.

Nose Creek, a minor tributary to the Bow River, was also examined to &temine if the

anomalously high total dissolved solids (TDS) load is the resd.t of naaual phenornena or

anthropogenic activity in the Nose Creek basin.

FIELD AND LABORATORY METHODS

There are two primary sources of data in this study. Discharge data dong the Bow River

and triiutaries, and long term data sets of chemical analyses in the headwaters of the River,

were obtained nom Environment Canada. In order to examine the chemical dynafnics

along the length of the river, samples were collected along the Bow River and at the mouths

of the main tributaries. These samples were analysed for major ion composition, and stable

isotope measurements of SD and PO in &O, 6°C in HC03, and 6% and 8''O in SO,.

Four sample sets, fiom spring of 1993 to fall of 1994 were coiiected along the Bow

River and its major tributaries (Fig. 1.1, AppendU. 1). These sample sets represent a range

fkorn baseflow to highflow conditions (Fig 1.2). Each sample set was cokted over a

p e n d of 4 to 7 days. To avoid sampling storm events, s p ~ g and summer samples were

coilected at least 7 days after the last rainfd. A sample set includes 15 samples nom dong

the Bow River, and 8 samples nom tributaries. The mean annuai discharge at the mouth of

the Bow River (from 1965 to 1990) is 2.8 1 km3 (Environment Canada, 1990). The 1993

and 1994 discharge was 44% greater than and 23% less than average respectively. The

1993 and 1994 tlow does not appear as extreme when compared to the longer term flow

data at Calgary (191 1 to 1990). Here the 1993 and 1994 discharge was 3% greater than

and 12% las than average respectively. Data at Calgary are a more diable mesure of the

variabilïty in the river flow as there are no irrigation developments upstream of the city.

Figure 1.1 Location of study area and samphg locations. BR = Bow River, BT = Bow tributary. Sample locations are given in Appendix 1.

Sample collection and bottle cleaning foilowed procedures defhed by Envirocment

Canada (1983). Grab samples were collected in mid-stream, either fiom the upstream side

of bridges, or by wadiag. Tnbutary samples were collected near their confluence with the

Bow River. Unstable parameters (pH and temperature) were meanired on-site. For the

remaining analyses, the water was passed through a 0.45 pm fdter. Samples for cation

analysis were acidïfied to pH Q with ultrapure HNO,. Samples for anion analysis were

untreated and stored at 4 O C . For stable isotope analysis, dissolved sulfate was precipitated

in the field as barium sulfate, by the addition of BaCl,. The water was then acidified to pH

6

4 2 in order to dissolve any BaC03. For measurement of 613c in HCOi, water was

extracteci h m the sample bottie by syringe and then passed through a syringe nIter into a

h t g l a s boctle. The sample was preserved by poisoning with HgC4, and storage at 4

OC. In the lab, CO, was exsolved by addition of phosphoric acid in vacuo. Chernical and

stable isotope analyses were conducted at the University of Calgary. Alkalinity was

determined within 24 hours of sample collection using an Onon 960 auto-titrator. Anions

were measured by ion liquid chromatography and cation concentrations were measured by

atomic absorption. Analytical emr was estimated to be less than 2%. Samples with

charge balance greater than 5% were rem.

~[FIOW Data at Calgary

Figure 1.2 Discharge data for the Bow River at Calgary, showing periods of sample coiIection.

34 Stable isotope compositions ('0, D, S, and I 3 c ) are expressed using the usual 6

notation:

8 @O) = [(R sample - &tandard) 1 ktandard x 105 (1-1)

were R is-the abundance ratio of heavy to Light isotopes. The standards used are VSMOW

for oxygen and hydrogen, Caiion Diablo Troilite (VCDT) for sulfur. and V-PDB for

carbon. For 6% analyses, S 0 2 was prepared using the rnethod of Yanapisawa and Sakai

(1983); SI~O,,, was measured with CO2 prepared by graphite reduction of BaSO,

(Shakur. 1982); was rneasured on CO, isotopicaIIy equilibrated with (Epstein

and Mayeda, 1953); and m) was measured using H, produced by the Zn-reduction method

of Coleman et al. (1982). Combined sampling and analyticd errors for isotope data were 18 18

estimated to be f0.2%0 for 6 O (H201 and fi, and f l%o for 6D and 6 O,,, Precision of

isotope measwements of carbon is high. f0.3%0, however erron induced by sarnpling and

filtering increase erroa to tl%.

CHAPTER 2 Overview of the Bow River Basin

GEOGRAPKY

The Bow River fiows wt h m the Canadian Rocky Mountains into the interior plains of

western Canada (Figs. 2.1.2.2). The river originates at Bow Sumrnit, 2063 m a.s.1.. and

flows 619 km to join the Oldman River 1260 mm lower than i origin. to form the

South Saskatchewan River that evenrualiy discharges into Hudson Bay. The river drains

an area of 25,300 krd, and has an average muai discharge near its mouth of 2.8 1 km3

(Environment Canada, 1990). Variation in flow dong the river. and the relative inputs of

major triiitaries, are given in Table 2.1. The river reaches it peak discharge at Calgary.

Water Loss downstream of Calgary is related to extensive irrigation developments.

Figure 2.1 Map of western Canada showing the Bow River Basin aad schematicaliy illustrating the two major weather systems that bting the majonty of precipitation to the basin. The high pressure sytern in Idaho is marked "W.

Table 2.1 Average annual flow data for the Bow River and major tributaries, arranged ftom the headwaters to the confïuence with the Oldman River. Tniutaries are placed in the relative position of theV confluence with the Bow. Locations are hdicated in Figure 2.2. Discharge data nom Enviromnent Canada (1990).

- -

Location Tributary Bow River Index discharge discharqe

Bow River Tributaries (Fig. 2-21 x 106 m3 x 106 m

Upstceam Lake Louise Pipes tone Brewster Redearth Baker

Banff spray Cascade

Kananaskis Seebee

Ghost Ghost Reservoir

Bearspaw Cdgary

Carseland Bassano Confluence with Oldman River

Jumping Pound

Elbow Nose Highwood

The Bow River Basin can be divided into three main physiographic units: 1) the Rocky

Mountains. 2) the foothills, and 3) the prairies (Fig. 2.2). The Rocky Mountains are

characterised by vaiieys covered by coniferous forests that are surrounded by steep

mountains with exposed bedrock. The foothills are characterised by rolling hills covered in

mked deciduous and coniferous forests that open eastward into grasslands. The eastem

~uo-thirds of the basin is covered by praine grasslands that have been converted withia the

1st 100 years to agricuitural use (mostiy cereal grains and canola crops). The major

tniutaries to the Bow River al l have kir headwaters in the &ont and main ranges of the

Roclcy Mountains, whereas some minor tributaries have theû headwaters in the prairies

/ Bow River Basin

Figure 2.2 Physiographic Regions of the Bow River Basin and sample locations (BR = Bow River, BT = Bow Tributary). Numbered locations are discharge measurement stations cable 2.1).

CLIMATE The Bow River Basin has a cold temperate climate. Average annual temperanires

reported by Environment Canada Vary h m -0.4 OC in the momtains (at Banff) to 5.5 OC

in the prairies (at Calgary). Average precipitation exceeds evapompiration in the

11

mountains (600 and 250 mm/yr respectively), whereas in the prairies evapotranspiration

exceeds precipitation (450 and 300 d y r respectively) (Fig. 2.3 a and b). In parts of the

eastem basin, potential evapotranspiration c m exceed 600mm/y. On average, 50% of the

precipitation in the mountains is snowfd. In the prairies this drops to 25%, most of which

is evaporated by Chinook winds. The dominant hydroogic event in the basin is the

melting of the winter snow pack. This lasts about 40 days, beginning in May, with the

highest discharge occuning in June (Fig. 2.4).

There are two main weather systems that b ~ g the majority of precipitation to the Bow

River Basin (Reinalt, 1970) (Fig. 2.1). The dominant source of precipitation is westerly

winds that bring precipitation to the basin in the faii and winter. In spring and summer

precipitation is denved largely fkom winds that swing no& around a high pressure system

in Idaho. Although both systems derive precipitation £kom the Pacinc Ocean, the moisture

in the westerlies onginates nom higher latitudes. In the winter months the Rockies have a

strong min shadow effect on the westerly flow, creating progressively drier conditions

fÎom West to east. In the spring and nunmer this affect is reversed, as air systems from

Idaho rise orographicaily against the eastem dopes of the Rocky Mountains, creating

progressively dner conditions from east to West (Rehalt, 1970). Moisture derived from

Idaho can account for up to 45% of the annual precipitation in the eastem Rockies.

Overall, the most precipitation fds during the summer months (Fig. 2.5), with the majority

of precipitation falling in the Rocky Mountains. Based on Figure 2.3, the average annual

raidail for the Bow River Basin is calculated to be 13 km3. In coatmt the average annual

flow of the river at its mouth is approximately 2.8 km3. Using an estimated additional 1

km3 consumed by irrigation, the nuioff ratio for the Bow River is 0.3 1, less than the world

average of 0.46 (Berner and Berner, 1987), and consistent with the dry nature of the basin.

precip. z evap \ avap > precip.

Figure 2.3 Mean annual a) precipitation, and b) evapotranspiration for the Bow River Basin in m m . (after Atlas of Alberta, 1969).

I F M A M J J A S O N D

Figure 2.4 Composite monthly discharge for the Bow River at Banff for 1978 to 1995,

from Environment Canada (1990).

Figure 2.5 Monthly average anoual precipitation for Calgary (from Klivokiotis and Thomson, 1986)

14

GEOLOGY

Figure 2.6 iuustrates the geology of the Bow River B d . The basin is underlain entkely

by sedimntary rocks. For simplicity, the basin can be divided into 4 main LithoIogic

groups. The western most part of the basin, upstnam of Lake Louise, is dominated by

clastic rocks of the Miette and Gog groups. The Miette Group is dominantiy low-grade

peiites and grits (feldspathic pebble conglomerates). The Gog Group is dominantly

quartzite. The area between Lake Louise and B d is underlain dorninantly by Cambrian

carbonates and interùedded cdcareous shdes. From Banff to Morely, the basin is

dominated by Devonian carbonates and calcareous shales. The Cambrian sequence was

deposited in an open maxine setting, whereas Devonian carbonates were deposited in a

resmcted sea (Mossop and Shetsen, 1994). As a consequence, the Devonian carbonates

have a higher evaporite mineral content. The eastem two thirds of the basin are underlain

by Cretaceous to Paleocene saadstones and shales.

Wkù the exception of the exposed cWs in the Rocky Mountains, and dong the river

valIey, the entire Bow Basin is overlain by tin and glacial lake deposits. The till can be

divided into a western and eastem unit based on lithology (Moran, 1986). The western till

is derived fiom the Cordillerian ice sheet, and consequently is dominated by carbonate

clasts. The eastem till was deposited by the continental ice sheet and is characterîsed by

igneous and metamorphic rocks derived fiom the Canadian shield. The boundary between

the two tills runs through the eastem edge of Calgary (Fig. 2.6).

ANTHROPOGENIC WATER USE

Table 2.2 details the water use and consumption in the Bow Basin for 1991. Domestic use

accounts for ody 11 % of water use in the basin. in cornparison, imgation accounts for

8595, or 46% of the average annual flow. Figure 2.7 illustrates variations in discharge

dong the length of the river. Heavy irrigation use in the summer reduces the river

discharge at Bassano below levels in the head waters at Lake Louise. Total iicensed

withdrawal h m the river is 88% of the long term annuai flow. with total consumption

estimated at 39%. The comption estimate is high as t includes loss to ground water,

which wodd evennially be returned to the river.

There is one instream storage reservoir on the Bow River, the Ghost Reservoir upstream

of Calgary (Fig. 2.7). The net effect of operating this resewoir decreases the naturai fiow

of the Bow River during the summer and inmases it in the fdl and winter. In addition to

the Ghost Reservoir, there is a large diversion development at Bassano downstream of

Calgary. Here the river Ievel is raised h m April to October to allow diversion to a series

of off-stream storage reservoirs. Through the f a and winter the river flows free. In

addition to storage reservoirs, there are several "nui of the river" hydropower

developments and weirs that alter the fiow on a daily basis.

Table 2.2 Licensed and actual water use for the Bow River for 199 1 (after Bow River

Water Quality Council. 1994)

User Group

Irrigation Agriculture Industrial Others Total % of total annual flow* (inStream1

Licensed Withdrawa

*based on Environment Canada (1990) value for long term average fiow of 28 10 m3 x 106 rather than the Bow River Water Council's nported value of 4lûû m3 x 106

Amount m3 x i06

490 1894

8.9 !

60.8 16

2469.7

% total 19.8 76.7 0.4 2.5 0.6

100.0

i Withdrawn Consumed Amount m3 x 106

166.6 1296.6

8 -5 30.6 15.3

1517.6

Amount m3 x 106

10.2 1050.9

8.5 13.6 15.3

1098.5

% total 11.0 85.4 0.6 2.0 1 .O

100.0

% total

0.9 95.7 0.8 1.2 1.4

100.0

Lake Louise Ghost Dam. Carseland Weir Banff Bearspaw Dam 8assano Dam

600 4 1 0 fall ,*--,, O winter . . -- -,

'Oo - 0 --9

O spring .

0 -9

I 0 -9- .

8 A summer . 400 &**..O ---+y'

distance (km) from confluence with the Oldman River

Figure 2.7 Dowostream variation in Bow River discharge for fd, winter, spring and summer (after Environment Canada, 1990).

Assessing seasonal variation in meteoric versus groundwater inputs to the Bow River using 6% and 6D

INTRODUCTION

Ultimately, most mof f originates fiom precipitation. However, the pathways precipitation

follows to reach streams are often unclear. By understandhg thes pathways, we can gain a

clearer understanding of the hydrology of the basin, and the factors that Muence the

chemistry of surface water. The stable isotope composition of the Bow River was

examined to discern the relative inputs of meteoric and ground water to the river system.

and how they Vary seasondy. By gaining a better understanding of the hydraulic cycle of

the Bow River, it will be easier to examine the controls on the chemishy of the Bow River.

In order to quantify the isotope composition of meteoric input, it is necessary to examine

the "reversecl" continental effect observed by Yonge et al. (1989). Most models of the

isotope composition of precipitation are based on Rayleigh htionation mechanisms; as

precipitation is progressively ~leased from clouds the remaining vapour becomes

progressively depleted in the heavy isotopes D and "O. This OCCUIS as weather systems

move inland, and is often referred to as the continental effkct (Dansgaard, 1964). The

continental effect is often expressed as a progressive inland depletion in the heavy isotopes

of surface water. B is more pronounced over mountainous areas where orographie uplifc

enhances precipitation and also superimposes a minor bctionation due to the drop in

temperature related to lifhng of the air mas. In a reconnaissance study of western Canada,

Yonge et al. (1989) sarnpled surface water across southwestern Canada, fiom the Pacific

Coast, across the Great Divide, and into the Canadian Prairies. They note that from the

Pacinc Coast to the Great Divide the 6D and 6'*0 of water bodies foiiow a typicd Rayleigh

distiüation pattern. However, ihis trend abmptiy changes east of the divide to a trend of

increasing 6D inland. Standard modek of evapotranspiration (e.g. Salati et al., 1979;

Rozanski et al., 1982; Ingraham and Taylor, 1986) do not explain such a trend. Yonge et

al. (1989) suggest, but do not demonstrate, that the "reversed" continental effect observed

east of the Great Divide is related to either recycling of moisture fiom evapotranspiration or

mixllrg of precipitation h m dinerent sources.

O AND H ISOTOPE COMPOSITIONS OF PRECIPITATION

AND GROUNDWATER

in order to examine relative inputs of ground water and meteonc water to the river it is

necessary to characterise the isotope composition of these two sources. The isotope

composition of precipitation in Calgary varies widely, with extremes in 6''0 rangkg fiOm

-5.0480 to -44.W00 and m) fiom -48.5 to -333960 (C.Yonge, unpublished &ra; Fig. 3.1).

The heaviest precipitation is associated with spring and summer raios denved nom Idaho,

whereas the iightest is associated with weather systems derived fiom Arctic fronts. The

average isotope composition of precipitation derived h m Idaho is &"O = -15%0, 6D = - 112%0, whereas westerly winds cany precipitation with lighter isotope compositions, 6180

= -20qO0. 6D = -155%~~ Calgary precipitation has a weighted average local meteoric water

iine (LMWL) expressed by the equation (C. Yonge, unpublished data):

similar to the global MWL defiued by Craig (196 1).

0 Idaho 1 O

TOC

Figure 3.1 6"0 versus temperature, showing the variation in the stable isotope composition of precipitation from the five main weather systems that bring moisture to the Calgary ana (after Yonge, unpublished data).

Results h m stable isotope analyses of nine springs dong the Bow River are presented

in Table 3.1. Ground water samp1es f d on a best fit line defined by:

Since both ground water and precipitation have well dehed relationships between 6%

and 6D we can assess their relative contri'bution to the river.

Table 3.1 Isotope data for springs in the Bow Basin

Location 6~ % amo %O

Vermilian Lake Canmore Creek Many Springs Mount Yarrianuska Big Hiil Springs Silver Springs A Silver Springs B HW 1A

O AND H ISOTOPE COMPOSITIONS OF WATERS IN THE

BOW RIVER BASIN

Variation in the stable isotope composition of tributaries - The ccreversed" continental effect

Results from stable isotope analysis are presented in Appendur 2. Figure 3.2 shows the

variation in m) and S180 of tn'butaries; 6D and 6180 are plotted vs. distance dong the river

where the tributaries enter the river. For each season there is a trend of increasing m) and

6'6 with distance. This trend is similar to that observed by Yonge et al. (1989) and is

contrary to a simple single-source Rayleigh hctionation mode1 that pcedicts a progressive

inland depletion in the heavy isotopes. Nomally, when waters becom enriched in D and

'b, it is interpreted to be due to evaporation. However, two feahires suggest that although

evaporation occurs, it is not the primary control on the observed e~chment . Fust, the

spring samples show the greatest increase in 8D and 6I8O with distance. However, this is

when evapotranspiration would be relatively low. Second, the Elbow (ER) and Highwood

(HR) nven have 6D and 8'0 values that are very negative compared to the trend of

e ~ c h m e n t in heavy isotopes east of the Great Divide, as defmed by the other tributaries.

If the and 6180 of the tributaries are plotted against the distance of their headwaten fiom

the Great Divide (Fig. 3.3), then the Elbow and Highwood rivers fit the observed trend of

inland e~chment in heavy isotopes. This suggests that the stable isotope composition of

Uibutaries is a function of theïr source area rather than evaporation.

As discussed in Chapter 2, the Bow River Basin receives the mjority of precipitation

nom two sources, westerlies and weather systems originating in Idaho. The stable isotope

composition of precipitation derived h m Idaho is more enriched in heavy isotopes than

precipitation derived h m the westetly winds (Fg. 3.1). Due to the reveaing min shadow

efSect over the Rocky Mountains, precipitation h m these two weather systems mix, with

moisnire derived nom Idaho fonning a larger proportion of the total precipitation eastward

in the Bow River Basin (Fig. 3.4). The rnixing effect appears greatest in the spring, when

the of triiutaries is observed to increase at a rate of 3mJ100 km away fiom the Great

Divide (Fig. 3.3). This is coincident with the time when weather from Idaho is a

significant source of precipitation in the eastem ranges of the Rocky Mountains, and the

western Ranges are adding significant fluxes of snow melt (denved h m westerly flows)

to the triiutaries drainhg the Rwky Mountains. In the fall, mixing appears less significant

as the observed increase in m) of tniutaries is ody 6%d100 km. This is coincident with

the season when westerlies are the dominant source of precipitation in the basin. Thus, the

fact that the trend of increasing 6D eastward of the Great Divide is greatest when input fkom

the two different weather systems is greatest, and potential evapotranspiration is low,

indicates that this trend is related to the rnixing of weather fronts. rather than evaporation

effects.

a faIl

O winter

O spring

a) distance (km) along Bow River b) distance (km) along Bow River of the tributaries confluence of the tributaries confluence

Figure 3.2 Plot of a) 6D and b) 8'0 of tniutaries versus the distance of their confluence along Bow River. PR = Pipestone River, SR = Spray River, KR = Kananaskis River, GR = Ghost River, JC = Jumpingpound Creek, ER = Elbow River, NC = Nose Creek, HR = H i g h w d River.

a) distance (km) of heaûwaters from the Great Diide

Figure 3.3 Plot of a) 6D and b) 8'0 of tn'butaries vernis distance of the headwaten of the tn'butaries from the Gnat Divide. Letter codes are the same as in Figure 3.2.

distance h m Great DMde

Figure 3.4 Schematic diagram illustrating mixing relatioaship over the Rocky Mountains of weather systems derived fiom westerly winds and nom high pressure systems in Idaho, and the resdtant surface water composition.

Implications for paleo-climate studks

The above data indicate caution should be used in paleoclimate studies of continental

interion. As stated by von Grafenstein et al. (1996) "The temporal GL80-temperature

relatiomhip is the foundation of many attempts to reconstruct paleo temperatures ..." However, as they indicate, this relationship is generally only calibrated for the modem day.

Although von Grafenstein et al. (1996) show that #'O in pmipitation is related to

temperature changes for the 1s t 200 years in southern Gemiany, other worken have

demonstrated that historical variations in 6 ' b are relateci to changes in atmospheric

circulation patterns (Amundson et al., 1996). In a seaing Lüre the Bow River basin, a shift

in circulation pattems could cause a sipnincant shift in the PO composition of net

precipitation. For example, if easterlies bmught less precipitation to the Bow Basin. the net

8'0 at any particular point east of the Great Divide would decrease, whereas if they

brought more precipitation the net 6180 would increase. Ushg the temperature effect of

Dansgaard (1964), a decrease in 6I8O would be wrongly interpreted as a net decease in

mean temperature, where as an increase in 8'0 would be interpreted as a net inc~a~e.

Although variations in weather pattern do represent ciimatic changes, the isotope record

can not always be used as a simple proxy for temperature: east of the Rocky Mountains.

However, if properly calibrated (e.g. Amundson et al., 1996), historïcal variations in VO

could be used to examine temporal changes in circulation pattems in this part of North

America

6"O and 6D of the Bow River - The source of dikcharge

A key question hydrologists seek to answer is "how is rainfd or snowmelt over a

catchment aansfonned into stream moff?" Rodhe and Killingtveit (1997). Stable isotope

data can be used to distinguish whether melting snow enters stream networks directly by

overland flow, or indirectly by seepage through the ground (e.g. Martinec et al. 1974;

Krouse et al., 1978; Sklash and Famolden, 1979 ). If snow melt was translated directly to

the river by overland flow, the river would show a meteoric water signature coincident with

the rise in stage. If seepage displaces e x i s ~ g gmundwater into streams, the rise in stage

will not be accompanied by a significant shift in the isotope composition of the stream

water. Dincer, et al. (1970) show that in a mountainous carbonate terrain, similar to the

ROC@ Mountains, only one-third of the snow melt becomes direct surface moff, the other

two-thirds displaces groundwater into surface streams.

The 6'*0 and 6D isotope composition of the Bow River was examhed in order to better

define runoff generation in the Bow River Basin. The 6% and 6D values of the Bow

River samples are plotted in Figure 3.5. The best fit Iùle is defined by:

The low r value shows there is no simple relatiombip in the isotope composition of the

nver through the course of the year. However, when samples h m each season are plotted

separately, seasonal variations in the isotope composition arr evident (Fig. 3.6).

Figure 3.5 Plot of 6D versus SmO for ail samples collected dong the Bow River.

Figure 3.7 illustrates the best fit lines for each season, as well as the LMWL and the best

fit line for groumi water (GWL). The best fit line for samples coilected in the fd is

coiocident with the groundwater he, suggesting groundwater is the primary source of

river water during this season. The f d and winter represent low stage flow of the nver

when groundwater input is maximum (020ray and Bames, 1977). This is evident in

Figure 1.2 as the background 50 km3/s discharge, and Figure 4.2b where TDS of the nver

is highest during low stage flow. Presurnably the winter samples, when the ground

surface and most of the nver is fiozen, would exhibit the greatest groundwater input of any

of the simple sets. However, this sample set is biased by upstream samples which may

explain the best fit Line having a dope pater than the GWL.

1 d) summer h

Figure 3.6 Plot of m> versus 6% for a) f a , b) winter, c) spring, and d) summer.

Figure 3.7 Best fit lines for each sample set, with the LMWL and GWL, and the average isotope composition of precipitation derived nom westerlies and the

Idaho High.

Spring high discharge (Fig. 1.2) is related to the melt of the winter snow pack,

however, the scattered data in Figure 3.7 suggests that water feeding the river is fiom a

variety of sources. The low slope of the best fit iine defined by the stable isotope data (Fig.

3.7) suggests there is sipnincant groundwater input to the river at this tirne. Varying

mixtures of gromdwater and melt water would explain the observed scatter of data.

Temperature profiles of the river support this. If snow melt reached the river as overland

fiow, then the temperattue of the water entering the river would pnsumable be close to zen,

untii the snow pack was melted. However, the initiation of s p ~ g high discharge is

associated with a jump in water temperatures, h m near zero, to 5 to 10 'C as measured at

Banff (Fig. 3.8). Thus, similar to the study by Dincer, et al. (1970), the spriag ml t in the

Bow Basin is interpreted to displace Large amounts of groundwater into the river.

The summer sarnples plot on a best fit line that has a slope close to the LMWX.,. This

indicates üiat the dominant source of the summer discharge is meteoric water. This is

consistent with the summer king the weaest part of the year (Fig. 2.4), with a large

meteoric water input h m weather systems derived h m Idaho.

discharge m3/s

Figure 3.8 Temperature versus discharge, measured at B d (Environment Canada, 1990).

Timing of groundwater recharge can be estimated based on stable isotope data presented

above. The GWL, and the best fit line for the fall sample set, intercept the LMWL close to

the average value for precipitation derived fkom westerly winds. Whereas the best fit Line

for summer discharge has a less negative intercept with the LMWL, closer to average

composition of precipitation from Idaho. This suggests that groundwater is dominantly

recharged by precipitation nom the westerly air masses. Westedies are dominant in the

winter months, suggesting that spring mit of the winter snow pack is the domhant source

of groundwater recharge in the basin. This is consistent with the above interpretation that

spring w l t displaces pre-existing groundwater into the river.

The 6180 and 6D values for tniutaries have a sîmiIar relation as the Bow River (Fig.

3.9). Samples h m the spring and nunmer plot close to the LMWL, whereas the samples

fiom fall and winter define slopes of 3.8 and 4.6 mpectively. This indicates that, like the

Bow River, ground water is the major source of tn'butary water in the fd and winter,

whereas meteonc water is the primary source in spring and sumrner. As well, the

intercepts of the best fit lines with the UifWL show seasonal variations. The s p ~ g anci

summer samples have a less negative intercept with the LMWL, relating to pmcipitation

derived fiom Idaho. In cornparison, the fall and winter sampies have intercepts close to the

average values for precipitation denved fiom westeriies. Again, this suggests that the

dominant source of groundwater recharge is spring melt of the winter snow pack.

Given the above data, the question as to "how is tainfidl or snowmelt over a catchment

transformed into Stream runoff?" can be addressed to some extent for the Bow River. If

we make the simple assumption that 50 m3/s is the average groundwater discharge into the

Bow River (based on falywinter discharge data in Figure 1.2 and isotope data present

above), then groundwater accounts for a maximum of 40% of the average annual discharge

of the Bow River. However, the grotmdwater contriibution is likdy greater because the

spring melt appears to have a significant component of displaced groundwater.. In order to

quantq this input, and thus better define gmund water contriution to the river, it would

be necessary to c o k t detailed tirne-series samples of surface, ground, and snow melt

waters during the spring melt. The implications these data have on the hydrologie cycle of

the Bow Basin are discussed m e r , in relation to chernical data, in Chapter 5.

Figure 3.9 Plot of 6D versus 6180 for the trioutaries dong the Bow River, with best fit h e s for each sample set and the LMWL and GWL, and average isotope composition of precipitation deriveci 6rom westerlies and the Idaho High.

Downstream variation in 6D

The variation in 6D dong the length of the Bow River is plotted in Figure 3.10. Each

season has a general trend of increasing 6D fkom the headwaters to the confluence with the

Highwood River. This is largely a function of addition of tri'butiuy water progressively

enriched in D as discussed above; there are no major tnibutaries downstream of the

Highwood River confluence. In the f d samples, the isotope composition of the Bow

River is relatively constant dowmtream of the Highwood confiuence. This suggests there

is littie input of "new" water, and that there are no insiream processes affecting the isotope

composition (e-g. instream evaporation). Due to ice cover, samples downstream of

Calgary were not collected in the winter. The 6D values of spring samples show enatic

variations. This is Wrely related to mUing of multiple sources of water along the river.

S p ~ g represents the highest discharge in the river due to melt of the mountain snowpack,

as weiI as relatively hi@ rain fail. To accommodate melt, resemoirs along the river are

lowered, thereby adding stored water h m the previous year to the s p ~ g flow. Thus the

isotope composition of the river water will be a fiinction of muiag of these various sources

along the river.

Summer samples show a progressive increase in m) downstream of the Highwood

confluence. This observed enrichment in D is unWrely related to evaporation, as

evaporated water tends to plot to the right of the LMWL. Table 2.1 and Figure 2.7 show

an increase in discharge of the Bow River, unaccounted for by major tributaries,

downstream of Bassano. This added water is iikely from ephemeral tributaries and

irrigation r e m flow dong this portion of the river.

distance (km)

-la-

-145 a O

g -150- tO

-156 - -1 60

@ïiEëmcI

d", * , Figure 3.10 Downstream variation in

- -1 ôD, for a) fd , b) winter, c) spring, -135 -

and d) summer. -140 -

s a -145- ce

-150 - -156 - -16Q , i

CONCLUSIONS

The anomalous trend of increashg 6D inland, observed by Yonge et al. (1989), is ~lated

to the rain shadow effect east of the Great Divide, and the d t i n g east-west mixing of

precipitation fiom the two predominant weather systems (westerly flow, and weather

systems derived nDm Idaho). Thus, caution shouid be used in applying Rayleigh type

fhctionation modeis to interpreting trends in the stable isotope composition of surface

waters. Lt is important to quanti.@ whether more than one weather system is bringing

moisturc! to a basin, and how mixing of Merent weather systems can create apparent

hctionation trends. More importantly, these data indicate caution should be used in

paleoclimatic studies of continental intenors as a shifi in circulation patterns could cause a

significant shift in the 6"O composition of net precipitation. If tùis is the case, variations

in the stable isotope composition of a historical record would be wrongly interpreted as

changes in mean temperature. Although variations in weather patterns do represent climatic

changes, the isotope record can not always be used as a simple proroxy for mean temperatme

east of the Rocky Mountains. However it may be possible to use bistoncal variations in

6180 to examine temporal changes in climate patterns.

Stable isotope data indicate that ground water is an important input to the Bow River,

accounting for at least 40% of total mual discharge. Groundwater feeds the river in fd

and winter, whereas rain water feeds the river in the summer. The spring discharge is a

combination of grouudwater displaced by snowmelt and snowmelt itself. Seasonal pattems

in the stable isotope composition of the Bow River suggest that spring melt of the winter

snow pack recharges gromdwater systems in the basin. while at the same tirne displaciag

older pundwater into the river system.

CHAPTER 4 Chernical Weathering of the Rocky Mountains

INTRODUCTION

Environment Canada has monitored the chemistry of the Bow River at Lake Louise and the

B a Park gate (Fig. 4.1) since 1978 (Block et ai., 1992). In addition, discharge is

monitored daily at the toms of Banff and Lake Louise. These data offer an opportunity to

examine weathering rates, and controls on river chemistry, in a near pristine, cold-

temperate climate carbonate-basin. These long tenn data sets are necessary for weathering

rate calcdations, as they reduce the influence of short-term climatic and biotic fluctuations

that may cause yearly variations in river chemistry (Bluth and Kump, 1994).

The two Environment Canada stations represent a 35 km reach of the river, nom Bow

Lake to Lake Louise, and a 80 km reach fiom Lake Louise to the Banff Park gates.

Upstream of Lake Louise, the basin is an undeveloped wilderness area. Between Lake

Louise and Banff the basin is largely undeveloped except for the two t o m sites. The basin

has weU defined geology (Rice and Mountjoy. 1972% 19724 1978, 1979). Upstream of

Lake Louise, the basin is dominated by clastic rocks of the Mietîe and Gog groups, and

Cambrian carbonates (Fig. 4.1). The Miette Group is dominantly low-grade pelites and

grits (feldspathic pebble conglornerates), and the Gog Group is dominantiy quartzite.

Between Lake Louise and Banff, the basin is underlain by Paleozoic carbonates with

interbedded units of calcareous shales. The vaiiey bottoms are covered by giaciolacustrian

deposits.

Lake 2 Louise

âi iarge & chernistry

Banff

Figure 4.1 Geology in the headwaters of the Bow River basin. Sarnple coilection sites and discharge measurement stations are indicated.

METHODS

The data malysed in this chapter were collectecl by the Water Survey of Canada. Cheniical

data h m 1978 to 199 1 are published in Block et al. (1993a,b). Daily average discharge

data for the Bow River and tributaries, h m 1901 to 1990, are published by Environment

Canada (1990). Additional unpublished cbemicd and discharge &ta for 1990 through to

December 1995 were provided by the Water Survey of Canada. At Lake Louise, discharge

is measured at the same location samples are coilected for chemicai analyses. However, for

Banff, discharge is measured 15 km upstceam fiom the sampling site (Fig. 4.1). The data

sets were culled for samples with an inorgaaic charge balance greater than 5%. Trend

analyses by Block et al. (1993a) do not show any long tem antbmpogenic impact on this

portion of the Bow.

CONTROLS ON THE CHEMISTRY OF THE BOW RIVER

Typical of most rivers, discharge is the major control on the chemistry of die Bow River

(Fig. 4.2). n ie TDS load is highest during winter base flow conditions, vaqing between

95 to LOS mg/i at Lake Louise and 175 to 200 mgll at Banff (Fig. 4.3). During spring melt

of the snow pack, there is a significant drop in TDS (approximately 50% of winter

maximum), foiiowed by a steady increase through nimmer and faii as discharge returns to

base flow conditions.

Aithough the TDS load is largely related to runoff, the chemistry of most unpolluted

rivers is controlled by weathering of bedrock mever, 1988; Meybeck, 1987). Despite

large seasonal variations in TDS of the Bow River, the aonnalised composition of the river

is nearly constant and distinct fkom that of precipitation (Fig. 4.4). Element ratios of the

Bow River are characteriseci by a fixed WMg ratio, low Na, a slightly variable AWSO,

ratio, and low Cl. The consistent nature of the normalised composition of the water, both

seasonaily and for the 18 years of measurement, suggests there are fundamenial control(s)

on element ratios. Processes controlling the major element ratios must be operating within

the basin as the chemistry of precipitation is altered before the water entea the river (Fig.

4.4).

As a first approach to determùiing controls on the river chemistry, the abundance and

relative proportions of dissolved ions in surface water can be modeled usiag a mass balance

approach in terms of chemical weathering of the common rock forming xninerals in the

basin (e-g. Garrels and MacKenie, 1967). However, in order to examuie the role

weathering reactions play in coatrolling river chemistry, it is necessary to correct the

measured water chemistry for the non-weathering components (e.g. Stailard and Edmond.

198 1 ; White and Blum, 1995).

discharge m3/s

1 b) Banff b

discharge m3/s

Figure 4.2 Discharge versus TDS for the Bow River at a) Lake Louise, and b) Banff, 1978 - 1995.

J F M A M J J A S O N 0

1 1 b) Banff

F M A M

Figure 4.3 Composite plot of monthly TDS measurements ai a) Lake Louise, and b) Banff, 1978 - 1995.

Louise

rn Na+K Alk

Figure 4.4 Temary diagram, in equivalents, for major cation and anions for Lake Louise and Banff.

Correcting for non-weathering components

The chernical dynamics of a river system can be summarised using the relation given by

White and Blum (1995):

Where F- represents the annual flux of material fiom weathering of bedrock and till,

F,, is the measured river Bux, F,, and F,, represent atmosphenc loading, F,, ,,, represents the net flux of dissolved solids h m ion exchange sites in clay miaerals, and F,,

represents the net flux of dissolved solids due to changes in biomass. Equation 4.1

assumes that there is no significant net ground water flux into the basin. In order to

quantify this relationship it is necessary to define each component of the flux of dissolved

inorganics to the river.

1) Atmospheric loading

h order to examine the role of chernid weathe~g, it is important to fkst correct for

atmospheric loading, both wet and dry f d , of major dissolved ions (e.g. Hoiland, 1978;

Stiùlard and Edmond, 1981). Typically, corrections for atmosphenc loading are doue

using methods outlined by S tallard and Edmond ( 198 1 ), where they separate atmospheric

flux into a marine and terrestriai component. They use only the marine component to

correct for atmosphenc loading, as the terresaial component is assumed to be derived fiom

within the basin. This is a reasonable assumption for a basin where weather systems move

inland in an upstream direction. However, the geographic settkg of the Bow River basin

is signxcantly dinerent. Here the dominant weather systems move 800 km overland

before reaching the headwaters of the Bow basin. Thus atmospheric loading in the basin

should have a signincant tenestriai component tbat is derived from outside of the basin.

This is readily observed on the westem margin of the basin, where precipitation is heavily

enriched in Ca, Mg, and SO, relative to costal min (Table 4.1). As the majority of Bow

River water onginates in the western part of the basin, the most reasonable way to correct

41

for cyclic sait input in the Bow River is to use the average annual loadhg rates for wet and

dry f d in the headwaters of the basin. Annuai wet and dry deposition rates were taken

fiom Legge's (1988) region 9. This region represeats the integrated deposition h m the

western margin of the basin to Calgary. Tbe contribution of the atmosphenc load to the

river can be calculated by averaping the annual wet and dry deposition over the yearly

discharge. Table 4.2 illustrates that atmosphenc loading is a signif'ant source of some

ions in the river (50% of K, 17% of SO, and 16% of Cl). In contrast, dissolved NO, in

the river accounts for only 4% of atmosphenc NO,. Nitrate is generdy thought to be lost

from basins by denitrification reactious in the soi1 zone (Schlesinger, 199 1).

Table 4.1 Chloride normalised equivalent ratios for average concentratiom in precipitation. h m West (Kananaskis) to east (Suffield), from Myric (1992). and world average coastal, from Berner and Berner (1987).

element Kananaskis Calgary Suffeld Coastal Rain

2) Ion exchange and biologic uptake

Ion exchange reactions are much more rapid than chernical weathering reactions

(Cresser and Edwards, 1987) so the net flux fiom ion exchanges processes should be

minimal for basins where there hasn' t k e n any sipnincant change in input, or the basin

environment (e.g. acid rain, or anthropogenic activity). Similarly, if the net biomass in the

basin has remained relatively constant through the, then the flux related to biomass should

be minimal. Since the headwaten are in a protected park, anthropogenic impact has been

42

minimal. There have been no major fkes in BMNational Park or Kananaskis since 1940

due to fire suppression (Whh. 1985). leading to the deveiopment of a stable biomass. As

weîl, the pH of precipitation has remauied relatively constant at 5.5 over the 1st 18 years

(Lau and Dass, 1985; Myric, 1992). Given the above, changes in both ion exchange and

biologic uptake should k minimal during the p e n d analysed. ln addition, carbonate

weathering rates are bigh enough that the weathering flux wouid overwhelm any flux h m

ion exchange and biologic upstake @river, 1997).

Table 4.2 Mean annual wet and dry deposition rate (kg/ha/y) averaged over the head waters of the Bow River (fkom the Great Divide to Calgary), from Legge (1988), and calculated atmospheric component of major ions in river water

at Banff (annual atmospheric loading averaged over annual discharge).

Bow River atmospheric Species wet rate dry rate total component 5%

kg/hd~ ~ W Y kg/hd~ mgfl mg/l atmospheric

3) Anthropogenic Input

Visitor use in Banff National Park appears to have minimal impact on the water

chemistry of the Bow River. The two most notable effects on the inorganic chemisüy are

elevated phosphorus levels related to sewage input (Block and ZaU, 1988), and a 0.2 m u

increase in minimum Na concentrations during the 1980's, attributed to road salting and

water sofieners (Block et al., 1993a).

Weathering reactions conîroIting river chemistry

Given the above, equation 4.1 can be simplified by dropphg the terms F,, Fion -hs, and

F-=, reducing it to:

The two basic implications of equation 4.2 are th& 1) the measured river chemistry only

needs to be comcted for atmosphenc input, and 2) despite the various inorganic and

organic systems operating in the basin, the dissolved load of the river can be modeled in

terms of primary weathering reactions anticipated for the geohgy of the basin (Table 4.3).

Table 4.3 Dominant weathering reactions anticipated for the Bow River basin, based on relative weathering rates of doahant minerds (Lasaga et al., 1994).

- -

Ca CO, + &CO3 * Ca + 2HC0, (1)

CaMg(CO3, + 2H$03 - Ca + Mg + 4HC03 (2)

C a S O p Ca + SO, (3)

NaCl --. Na + Cl (4)

2FeS, + 4 q O + 60, FqO, + 8H + 40, (5)

&SO, + 2CaC03 * 2Ca + SO, + 2HC0, (6)

2H,CO, + 9H20 + 2NaAiSi,O, iUS~05(OH), + 2Na + 2HC0, + 4H,Si04 (7)

44

Of these reactions, the dissolution of NaCl is the easiest to quantify becaux Cl ôehaves

consematively in surface water. Sewage effluent at Ban£€ has less than 1 mg/l Cl (Block

and Zall, 1988). thus al1 Ci after correction for atmsopheric hput can be assumed to be

denved from dissolution of evaporite rninerals. Cumulative Cl concentrations. h m 1978

to 1995. are plotted for Lake Louise and Ba& in Figure 4.5. Overail. Cl concentrations

are lower at Lake Louise than downstream at Banff. For Banff, the Cl concentrations are

rdatively high in winter and close to zero during spring and summer. This cm be related to

groundwater hput king diiuted during spring and summer by snow melt and precipitation.

An interesting feature at Lake Louise is that there is a slight increase in Q in early spring,

before the majority of the snowpack has begun to melt. A possible explination could be

initiai melting of the snow pack at low elevations. where snow almg the Icefields Parkway

(HW 93) would contriiute Cl fiom winter road salting.

If Na and K were only denved fiom dissolution of evaporite minerais, then (Na+K)

should balance Cl. A plot of (NatK) and Cl (Fig. 4.6) illustrates that (Na+K) is in excess.

On average, 90% of (Na+K) is accounted for by dissolution of halite. One potentiai source

of excess Na is weathe~g of detntal albite in the Miette Group (reaction 7 in Table 4.3).

The abundant carbonate rock in the basin, and the rapid weathering rate of carbonate

mllierals, suggest that dissolution of carbonate miaerals wül add signincant amounts of Ca

and Mg to the river. As would be expected, the Bow River plots among rivers draining

carbonate terrains, aad well away Born rivers draining silicate rocks (Fig. 4.7). The most

common weathering reaction for carbonates is simple dissolution (Drever, l988), reactions

1 and 2 in Table 4.3, givhg a (Ca + Mg):HCO, equiiivance ratio of 1:l. For Banff,

(Ca+Mg) balances alkalinity at low concentrations (Fig. 4.8), however, (Ca+Mg)

progressively deviates h m the 1: 1 Lure as alkalinity increases.

a)- buse 33

J F M A M J J A S O N 0 8 J F M A M J J A S O N D

Figure 4.5 Cumulative plot of monthly Cl concentrations at a) Lake Louise and b) Banff, corrected for atmosphenc input.

Figure 4.6 Na+K vs. Cl for a) Lake Louise, and b) Banff.

46

Two possible sources of additional Ca+Mg are oxidation of sulphides (cornbined

reactions 5 and 6). or dissolution of gypsum and anhydrite (miction 3). These two sources

can not be disthguished solely based on stochiometry, since both reactiom require tbat

(Ca+Mg) be baianceci by (HCO, + SOJ, flabIe 4.3, Figure 4.9). The stable isotope

composition of SO, can be used to distinguish SO, derived from evaporite minerals and

oxidized sulphide minerals. Stable isotope data presented in Chapter 5 indicate that the

major@ of SO, measured at Banff is derived nom dissolution of evaporites. m e n plotted

against discharge (Fig. 4-10), the SO,:(SO, + Alk) ratio at Banff is highest during low

flow, when groundwater discharge is the dominant source of the river. This could be a

function of evaponte minerals being leached out in the near surface, andor grouadwater

having a longer residence tirne dowing more dissolution.

The deviation from the 1: 1 Ca+Mg:Ak is not sipificant at Lake Louise. As well, there

is no seasonal variation in the S04:(S04 + AUc) ratio as seen in Banff, suggesting

evaporites are not as common. This is consistent with the local geology; evaporites are

scarce in the Cambrian carbonates upstream of Lake Louise, where as they are more

common in the Devonian carbonates exposed between Banff and Lake Louise (Mossop and

Shetsen, 1994).

In su-, the major elemnt chemistry of the Bow River, after correction for

atmospheric input, is dominated by dissolution of carbonate minerals. Additionai Ca and

Mg, as weil as SO, is added to the river downstream of Lake Louise by dissolution of

gypsum and anhydrite. This is more signiticant during base flow when ground water is the

major source of water in the river. Na and K are largely derived fiom dissolution of

evaponte minerals. Again, this is more sipnincaut downstream of Lake Louise. Excess

(Na+K) is likely derived fkom weathe~g of feldspars. At Lake Louise, the rise of Cl in

April may be related to inital melting of snow near the Icefields Padovay.

O carbonate O shale O sanelstone I gneiss A granite A volcanic + Bow River

Figure 4.7 Temary diagram of major ion composition of the Bow River and rives draining a varieîy of lithologies throughout the world (after Meybeck and Helmer, 1989).

Figure 4.8 Ca+Mg vs. HCO, for a) Lake Louise. and b) Banff.

Figure 4.9 Ca+Mg vs. HCO, + SO, for a) Lake Louise, and b)Banff.

a)Lake Louise L

O 20 40 60 80 O 100 200 300

discharge m3/ s discharge ma/ s

Figure 4.10 Discharge vs. SO,/totai anions for a) Lake Louise, and b) Banff.

Examuiing the major ion stoichiomeûy provides information on weathering reactions

controiiing the input of ions to the river system, in contrast, thermodynamic analyses on

help illustrate equiliirium rractions controlling the water chemisw There are limited

snidies that examine equiltirium feactions of river water. Norton (1974), examining the

Rio Tama River in Puerto Rico, used activity ratios to suggest that wea the~g

stoicâiometry was the primary control of river chemistry. However Drever (1988)

reinterpreted Norton's (1974) data, and suggested tbat cation exchaage between m a -

smectite and Wg-smectite is the dominant control. Similarly, in examining numerous

rivers draining basaltic terrains, Bluth and Kump (1994) note that cation activity ratios

always plot on trends paralieling smectite exchange boundaries. In their words, "if river

chemistry depended only on bedrock composition and weathe~g stoichiometry, we would

expect a much pater variation amoag the cation activity ratios". Bluth and Kump (1994)

conclude that the major cation ratios are likely controiIed by smectite exchange reactions.

The role equili'brium reactions play in controlling the chemisay of the Bow River is

investigated by coastructing activity-activity diagrams. Activities of major ions are

calculated using the geochemical modeling package SOLMINEQ.88 PUSHEU. (Wiwchar,

et al., 1988). Ca and Mg activity ratios plotted in Figure 4.1 1 &fine a iine with a dope of

1 (9 = 1). The strong correlation of measwed activities to a slope of 1 suggests a 1: 1 Ca-

Mg exchange reaction is contmlling the element ratios in the river. In order to identify

potentiai exchange reactions, minerai stability boundaries were calculated at 5 OC by the

program PTA (Brown, et al., 1988), for the system: Ca, Mg, Al, Si, C, 0, and H. The

range of possible actions was resûicted by only considering common minerals in

sediment. rocks (Table 4.4). Of over 7000 stable and meta-stable reactions possible,

only 2 have a 1: 1 Ca-Mg exchange boudary in the range of activities measured in the Bow

River:

Calcite + Mg = Dolomite + Ca

Recipitation of dolomite is rare in modem environxnents, iadicating the only potentiai

reaction controiling the major ion ratio of the Bow River is equation 4.3.

Table 4.4 Ca and Mg bearing mine& potentiaily found in sedirnentary rocks.

Anorthite Brucite

Clinochlore Gibbsite

Kaolinite Wairakite

Ca-beideIIite Mg-beidellite

Heuiandite Calcite

Dolomite

The C a M g exchange reaction in equation 4.3 is investigated fiutber using methods

outlined in Abercrombie (1989). Smectite is rnodeiied as a mixtue of Ca-, Mg-, Na-. and

K-beideihte end member components. The activities of these components are unknown,

but can be caicuiated for an individual water sample ifequil'briwn is assumed. The sum of

activites of the individual smectite components would equal 1:

Three indepentant cation exchange reactiom can be written, with their equiliirium

constants defked as:

Equüirium constants for these reactions are cdcdated using EQCALB, a version of the

program EQCALC (Flowers, 1986) modified to use thermodynamic propeaies of minerals

tabulated by Bernian et al. (1985). Thus, Equations 4.4 through 4.7 can be solved

simdataneously to obtain the activites of the four beidellite components in equili'brium with

a given water sample. Activities of the beidellite components were calculated for samples

80/04/23 fkom Banff and 79/06/06 from Lake Louise flable 4.5). The calculateci activties

iodicate that smectite in equilibirum with the river water would be dominantiy Ca- and Mg-

beideilite, with subordhant Na- and K-beidellite.

Using the calculated activity of the smectite components, miueral stability boundaries

are caicuiated by the program FTA (Brown, et al., 1988). Because samples 79/06/06 for

Lake Louise, and 80/04/23 for Banff, were used to calculate the activities of the sxnectite

components, they must faIl on the caiculated exchange-reaction boundary . However, the

location of the other river samples are independent of the calcuiated boundaries. If the

activities nom water analyses cluster dong a phase boundary, it suggests that the water

52

may be in equiliirium with the exchange reaction (Hutcheon, 1989). Water samples are

plotted on the calcuiated phase diagrams in Figure 4.12. The measured activy ratios of Ca

and M g show a stmng comIation with the calulated exchange boundary, arguing that

exchange between Ca- and Mg-beideilite is contmiling the Ca/Mg activity d o . .

Table 4.5 Caicuiated beideIlîte activities for smectite in equiliïrium with samples 79/06/06 for Lake Louise and 80/04/23 for Banff.

Smectite Lake Louise Banff component (79~06106) (8W04/23)

%-kidci~ia 0.4955 0.4955

For Na and K. the activity &ta are more scattered, but they do cluster around the

caiculated Na-K beidellite exchange boundary (Fig. 4.13). Again, this suggests

e q u i l i i exchange between Na- and K-beiâellite is controUing the NaK activity ratio in

the river.

l ai Lake Louise

12 13 14

log a MgM2 log a Mg/H2

Figure 4.11 Plot of log aCa/a(H)2 versus log aMg!a(~)~ for Lake Louise and BauK

a) Lake Louise l5

5

log a Mg/H*

Figare 4.12 Plot of log aCa/a(H)' versus log aMg/a(H)2 as in Figure 4.1 1. with calculated reaction boundaries at t bar and 5 O C .

La)- Louise

O a

Figure4.13 Plot of log aNa/H versus log aK/H for a) Lake Louise, and b) Banff- Reaction boudaries are calculated at I bar and 5 O C .

10 11 12 13 14 15

log a MgMa

Figure 4.14 Plot of a) log aCa/a(~)' venus log aMg/a(H)', and b) log aNaM venus log aKRI for ground water (closed circle). Open circles represent high and low values for the Bow River data at Banff. Reaction bomdaries are for Banff, calculated at 1 bar and 5 O C ,

55

An important issue to address is: are equiiiiwn exchange reactions occwiag within the

river, or are we obsenring an inherited signature of groundwater chemisûy? For the

reactions to be occuring within the river, smectite wouid have to be present as suspended

sediment. Given the cationexchange capacity of smectite (80 - 150 mq1100g; Drever,

1988). and an average Ca concentration of 19 meqll. 1.3 - 2.4 g/i of suspended smectite is

required. This is significantly higher than the average total suspended load of 5.5 mg. In

addition. suspended and bottom sediments h m the river were analysed by XRD, and

smectite is only a trace component This suggests that activity ratios observed in the river

water represent hhented signatures of equilibrium reactions occurrjng in the soii and

ground water zones. This is supported by the fact that activity ratios calculated for shallow

ground water samples collected by Park Canada (Appendix 3), upstrearn of the Banff

town site, have the same range of activity ratios as river water (Fig. 4.14). If we are

observing an inherited signature of groundwater chemistry, then smectite must be present

in the basin. Smectite is commonly associted with volcanic ash layers in Crrtacous shales

in the basin. There are few studies on the clay minedogy of older units in the basin,

however, ash layers have been observed in the Banff and Exshaw formations (G. Davies,

pen. communication, 1997). The presence of smctite bearing units supports the

interpretation that the activity ratios observed in the river are an inherited gromdwater

signature. The implications of river chemistry being an inherited signahue of groundwater

chemistry is discussed in relation to basin hydrology in Chapter 5.

Chernical denudation mte

The river chemistry discussed above only provides infomtion on weathering processes,

not on weathering rates and mass tramfer fiom the basin. By combining chexnical data

with discharge information, chemicai denudation rates in the Rocky Mountains can be

56

caicuiated Annuai denudation rates are caiculateA by nomaiking the weighted average

annual flux (C, x Q ) over the basin area (421 kmt above Lake Louise and 22 10 kmZ

above Banff Padc gate). Where weighted average aunual concenaaiion (C,) is defieci as

the average of the monthly samples (Zemm, 1978; White and Blum, 1995):

where C, is the concentration of the individual Stream sample, is the discharge during

the sampling interval j to j-1, and Q is the total mual discharge. htantaneous flux is

defmed as (Ca x Q), where Q is the daily discharge.

Figure 4.15 Uidicates instantaneous flux is a function of discharge, consistant with

most world rivers (Berner and Bemer, 1987). Figure 4.15 also shows that the majonty of

the dissolved ioad, approximately 75%, is transported during the summer months, when

concentrations are lowest.

The weighted average chemical &nu&tion rate (CDR) for the Roclues upstream of

Banff, after conecting for atmosphenc loading, is 997 kghaly. If reaction I in Table 4.3 is

the dominant meam of carbonate weatherins, then only one half the HCO, in the river is

from rock weathering. This reduces the CDR to 678 kgha& or 1.5 x ld kg of rock

removed as dissolved load each year flable 4.6). This falls in the typical range for

carbonate basins (Table 4.7). The denudation rate above Lake Louise is ody slightly lower

at 804 kgmaly, or 516 kgha& after correction for HCO,. The lower denudation rate

upstream of Lake Louise is iikely related to the large exposures of silisiclastic rocks in that

part of the basin. The Bow River is unusual in that the suspended load is much less than

the dissolved load. The non-nlterable residue (NFR) measund by Environement Canada at

Banff averages 2 mgll, w hich translates to an additional 1 1 kgmaly , or 1.1 % of the to ta1

57

load ID conûast, the North Amencan average suspended Ioad comprises 70% of the total

load (Schiesinger, 1991), and carbonate basins in the Himalayas have ~ p e n d e d loads that

are 90% of the total Ioad (Sarin et al., 1989; Berner and Bemer, 1987). The iow

suspended solids load may be reiated to the fact the vaüey flwrs of the basin are heavily

forested, Ibducing the amount of loose sediment that cm mach the river.

0 0 0 0 0 0 0 V ) o V ) o V ) o

J F M A M J J A S O N D r - CU CU m

discharge m3/s mont hs

Figure 4.15 Iostantaneous daily mix versus a) discharge and b) cummunulative instantaneous flux, measured at Banff.

Table 4.6 Weighted average long term denudation rate (kg/ha/y) for the Bow River at Banff and Lake Louise (total flux - atmosphenc input).

K -5 .9 so4 33 106 HCO, 575 638 SiO, 15 18 cl 2 4 CDR 804 997 CDR - corrected 5 16 678 for HCO,

Table 4.7 Chemical denudation rates (CDR) for world nvers, and world average rate.

CDR River Basin Type k d w ~ Re ference

Yamunu Carbonate 1430 Sarh et al. (1989)

Indus Yagtze Hwangho Brahmaputra Meykong Zaire Amau>n World

1 Ming-hui et al. (1982) 1 1 Edmond (1982) 1 1 3 1 Berner and Berner (1987)

59

CONCLUSIONS

Discharge is the dominant control on the TDS load of the Bow River. Spring melt and

summer raias inmase discharge and düute groundwater input to the river. Although

discharge is the dominant contrd on concentration, the source of ions in the river is

controlled by atmospheric deposition and water/rock interaction. Atmospheric Ioadbg oui

be a signincant source of some ions in the pristine headwaters of the river (e.g. 50% of JC,

17% of SO,, 16% of Cl). In terms of water/mk interaction, the input of ions to the river

is largely controiled by dissolution of carbonate and evaponie miner&.

Cation exchange reactions exert a strong control on element ratios in the river. The

WMg activity ratio is strongiy controlied by exchange between Ca- and Mg- beidellite.

NaK activity ratios are controUed to a lesser & p e by exchange between Na- and K-

beidellite. These activity ratios appear to be ïnherited signatures of ground water. The

fixed element ratios in the river suggest that that both snowmelt and rainfall mut pass

through the ground before reaching the river.

The chernical denudation rate for the Bow River at Banff is 678 kg/ha/y, or 1.5 x 108

kg of rock that is removed as dissolved load each year, consistant with CDR of other

carbonate basins. Up to an additional 11 kg/ha/y are removed as nispended load. Ushg a

density for ibnestone of 2.75 @cm3 (Daly, et al. 1961). this weathe~g rate represents a

rock volume, carried by the Bow River each year, of 54,545 m3.

CHAPTER 5 Chernical dynamics of the Bow River

INTRODUCTION

Chapter 4 examined geochemical coatrols on water chemistry in the pristine headwaters

of the Bow River. This chapter examines variations in the chemical and stable isotope

composition dong the length of the nver, eom the headwatea above Lake Louise to the

confiuence with the Oldman River. Characterishg controls on the chemistry of the river

is more complex than in Chapter 4 because the basin is less homogenous, and there is

more anthropogenic activity downstrearn of Banff National Park. An integrated chemical

and stable isotope approach is used to trace point and non-point source inputs to the river-

Four sample sets, representing fail, winter, spring, and summer, were collected to

characterise the chemicai variation along the length of the river. Main tributaries to the

nver were also sampled. Sample locations are shown in Figure 1.1. The basin can be

subdivided into four main segments. The Bow River, ftom Lake Louise to Morely

(sample stations BR1 to BR4, Fig. 1.1) drains the near pristine Rocky Mountains. The

foothills area between the Rocky Mountains and Calgary (BR4 to BR6) is largely used

for ranching, but is otherwise undeveloped. Calgary, the only large urban centre in the

basin. lies within stations BR6 to BRIO. The city has numerous storm sewer out falls

along the river, and two outlets for treated domestic sewage fiom the Bonny Brook and

Fish Creek treatment plants. Effluent fiom the plants enters the river between sample

stations B R9 and BR10 (Fig. 1.1, Appendix 1). Downstream of Calgary, agriculture is

the dominant land use (mostly cereal grains and canola crops).

Before examinhg the chemical dynamics of the Bow River itself, it is necessary to

characterise the chemistry of major point source inputs dong the river.

61

CHEMICAL CHARACTERISTICS OF POINT SOURCE INPUTS The main point source inputs to the Bow River are tniutaries, Storm sewer outlets,

treated domestic sewage, and irrigation retum ffow dong the river. The main tributaries

to the Bow River ali have headwaters in largely undeveloped basins in the Rocky

Mountains (Fig. 1.1). The aibutaries have Ca-Mg-HCO,SO, type waters, simiiar to the

Bow River in its headwaters (Chapter 4). With the exception of Nose Creek, the cation

ratios of tributary waters are characterised by a fixed CalMg ratio and low Na (Fig. 5.1).

Cation ratios of triiutary waten are similar to each other and the headwaters of the Bow

River (Chapter 4). This is consistent with the fact that tributaries are drainhg essentially

the same rock units as the Bow River in the headwaters. Anion ratios of tributary waten

are characterised by low CI, and S0,fA.k ratios that have similar seasonal variations as

the Bow River at Banff (Chapter 4). With the exception of Nose Creek, the total

dissolved solids (TDS) loads of tributaries are also in the same range as the Bow River

(Fig. 5.2). Because tributaries have the same chemical makeup and variability as the

Bow River, the addition of tributary water wiU not greatly affect the chemical

characteristics of the river, although tributaries will affect mass balance calculations

(discussed below). Nose Creek has anomalously high TDS, and a significantly difterent

chemicai makeup compared to the Bow River and other tributaries (Fig. 5.1). However

the volume of Nose Creek is too small to alter the Bow River composition (Table 2.1).

Factors controlling the chemistry of Nose Creek are addressed separately in Chapter 6.

0 storm sewer 0 effuient @ irrigation return 0 Bow River aver. B aroundwater - .

Na+K Alk [ O spring water

Figure 5.1 Temary diagram, in equivalents, showing major ion composition of

tributaries to the Bow River, as weil as storm sewer discharge and effluent fiom waste water treatment plants in Calgary. Tniutary samples emïched in Na+K and Cl are from Nose Creek (NC).

The major ion composition of storm sewer discharge in Calgary is similas to Bow

River water (Table 5.1, Fig. 5.1). and has a simiiar range in TDS (160 mgll in the summer

to 300 mgA in the winter). Thus, like the tributaries, storm sewer discharge wili not

greatly affect the major ion chemistry of the river, although they may dilute the river in

the summer. In contrast, effluent from water treatment plants in Calgary has significantly

higher TDS (575 to 875 mgll) and is enriched in Na, Cl and SO, compared to the Bow

River (Table 5.1, Fig. 5.1). Irrigation return flows have TDS levels within the range of

the Bow River (280 mg/l) and are e ~ c h e d in Na compared to the river. Return flows

generdy discharge water to the river during summer irrigation.

Figure 5 2

Table 5.1

Range of TûS for the Bow River

TDS of tributaries to the Bow River.

Chemistry of storm sewer discharge (this work), effluent from the Bomy Brook and Fish Creek sewage matment plants, and average composition of Mgation retum flow (fkom Sosiak, 1996).

storm sewer Bonny Brook Fish Creek irrigation ion average effluent* effluent* retumflow*

( m m mgm (mp;li) (md) Ca 44 55 70 35 M g 13 25 33 17 Na 2.7 82 118 15 K 0.8 16 10.5 2.0 HCO, 148 185 325 153 SO4 28 142 165 54 Cl 2.3 68.4 133 5.7 *h Sosiak (1996)

64

CHEMICAL CHARACTERISTICS OF THE BOW RlVER

Waters nom the Bow River are dominantly Ca-Mg-Alk-SO,. The TDS load of the river

varies seasonally, as weU as dong the river. The highest TDS values are observed duriog

baseflow conditions in the id and winter, where as the lowest TDS levels are observed

during the summer rainy season Fig. 5.3). Intermediate levels are observed during peak

discharge related-to spring snowmelt. The following dowmtream variations in TDS are

observed in all four sample sets (Fig. 5.3): 1) the lowea TDS values are observed in the

headwatea, 2) there is a general trend of increasing TDS as the river fiows through the

foothills to Calgary, 3) TDS drops as the river flows through the City of Calgary,

particularly in spring and summer, and 4) downstream of the sewage treatment plants in

Calgary there is a noticeable increase in TDS. In the fd , TDS remains constant through

the agriculnual areas downstream of Calgary, whereas in spring and summer TDS

A summer 50 I

I I I I

8 8 in 8 n 8 8 CI( 8 O

Distance from the Oldman canfiuenœ (km)

Figure 5.3 Total dissolved solids load versus distance dong the Bow River for faii, winter, spring, and summer.

65

The variations in TDS as the Bow River fiows through Calgary are consistent with

point source loading h m Storm sewers and efnuent fkom treatment plants. Storm sewer

discharge, with relatively low TDS, would dilute the river as it flows through the city.

This is most noticeable during the rainy season in spriag and summer Fig. 5.3). In

contrast, loading h m waste water treatment plants increases the TDS levels of the nver

above those upstream of Calgary. Despite variations in TDS dong the length of the river,

element ratios are relatively fixed (Figure 5.4). The Ca/Mg ratio of Bow River water is

nearly constant. However, waters from upstream and downstream of Calgary plot in iwo

distinct clusters, where waters downstream of Calgary are more enriched in Na+K. In

order to examine controls on the observed seasonal and downstream variations in the

nver chemistry, individual ion chemistry is discussed below.

Mg Na+K Alk

Figure 5.4 Temary diagram, in equivaleats, of major cations and anions of Bow River water for di four seasons.

CONTROLS ON THE MAJOR ION CHEMISTRY OF THE BOW RIVER

Chloride is the easiest ion to account for because of its conservative nature and limited

sources. The main sources of Cl in rivers are sea sdt (fiom tain fall), weathering of

halite, and pollution (Berner and Berner, 1987). The downstream variations of Cl

concentrations in the Bow River are plotted for each season in Figure 5.5 (distances are

measured fiom the confluence with the Oldman River, the end of the Bow River). Cl

concentrations are Iow (around 0.5 meq/l) and slightly variable upstream of Calgary.

Concentrations are within the range observed at Banff in Chapter 4, and thus represent

cornbined atmospheric loading and evaporite dissolution. There is no loading of Cl

between Banff and Calgary. In contrast, the concentration of Cl increases nearly 4x as

the river flows through Calgary (the Calgary city limit starts at Bearspaw reservoù in

Figure 5.5). Cl is a common pollutant from municipalities, denved fiom domestic

sewage and road salt. The most significant increase in Calgary occurs between the hua

sampling stations that bracket the outlets for the Bomy Brook and Fish Creek sewage

treatment plants. Effluent waters are significantly e ~ c h e d in Cl compared to the Bow

River (Table 5.1, Fig. S. 1).

As the river flows through agricultural land downstream of Calgary, there is no

additionai loading of CI. There are two spikes in Cl concentrations downstream of

Calgary in the spring and summer. It would be difocult for Cl concentration to decrease

as rapidly as observed without significant amounts of dilute water king added to the

river. What these spikes likely represent is effluent from the sewage treatment plant that

has not been M y mixed with the river. Cross et al. (1986) estimate that the mixing zone

for the effluent is over 20 km long.

distance f m Oldman cmfiueme (km)

Figure 5.5 Dowstream variation in Cl concentratiom for the Bow River.

Sodium

The downstream variations of Na concentrations in the Bow River are ploned for each

season in Figure 5.6. Like Cl, Na concentrations are low upstream of Calgary, and

increase signincaatly as the river passes the outfall for the Bomy Brook and Fish Creek

sewage treatment plants. The most common sources of Na fiom municipalities are NaCl,

N%C03, NaSO,, Na-borate, and other Na salts used in industry (Bemer and Berner,

1987). As weii, Na is commonly derived fiom Na,C03 and Na-zeolite used as domestic

water softeners.

diitance from Oldman duence (km)

Figure 5.6 Dowstream variation in Na concentrations for the Bow River.

Loading of Na fkom Calgary causes a significant shift in the (Na+K):(Ca+Mg) ratio

of the river (Fig. 5.7), resuiting in the two data clusters observed in Figure 5.4. The

(Na+K):(Ca+Mg) ratio continues to rise as the river flows through agricultural areas

downstream of Calgary, particularly in the s p ~ g and summet* This increase is solely

due to loading of Na+K, as Ca and Mg concentrations remain relatively constant

downstrram of Calgary (Appendix 2). Although both Na and the (Na+K):(Ca+Mg) ratio

increase progressively through the agricultural areas downstream of Calgary, Cl

concentrations nmain constant (Figs. 5.5.5.8). This d e s out road salt or other fonns of

NaCl as the source of Na. The progressive increase in Na concentrations is coincident

with a progressive e ~ c h m e n t in 6D observed in Figure 3.10. As was indicated in

Chapter 3, this shift in 6D is related to addition of water relatively e ~ c h e d in D to the

Bow River. The coincident increase in Na implies that the added water must also be

eariched in Na relative to the Bow River. The most obvious source of this water is

irrigation return flow. This is consistent with the observations that 1) Na is king loaded

progressively dong the river, and 2) Na is oaly king loaded in the spring and Nmmer

when irrigation retum canals discharge to the river.

distance from Oldman confluence (km)

Figure 5.7 Dowmtream variation in the Na+K/Ca+Mg equivaience ratio.

Figure 5.8 Na + K versus Cl for the Bow River (open circles) and tributaries (closed circles) for a) f d , b) winter, c) spring, and d) summer.

The role smectite exchange reactions play in controllhg Na and K ratios dong the

length of the river is investigated hen using methodology outlined in Chapter 4. The

activities of individual beidellite components were calculated assuming equilibrium with

the Banff sample for each season. Smectite in equilibrium with river water at Banff

71

wodd be dominantly Ca- and Mg- beidellite. with subordinate Na- and K-beideiiite

(Table 5.2). Because the Banff samples were used to calculate activities of the beideilite

components they must f a on the calculated exchange reaction boundary (Abercrombie,

1988). However, the location of other water samples are independent of the cdculated

boundaries. Water samples nom the river and main tributaries cluster around the

calculated phase boundary (Fig. 5.9), suggesting that the Na-K activity ratio in the river is

hxed by smectite exchange reactions.

Table 5.2 Caicdated beideiiite ac tivities for smectite in equilibrium with samples colIected at Banff for each season.

Smectite component fall winter s p r i . summer

%kidcilie 0.4929 0.4939 0.49 19 0.4956

NaBd + K = KBd + Na

2 3 4 5 6 7

log a WH

b) winter -/

2 3 4 5 6 7

log a WH

Figure 5.9 Na-K activity plot for samples dong the Iength of the Bow River (open circles), and main tributaries (closed circles), for: a) f a , b) winter, c) spring, and d) summer.

Sulfate in river systems can be derived from a variety of sources such as: the dissolution

of sulfate minerais, oxidation of pyrite or other reduced forms of sulfur, and

anthropogenic input fiom fenüizer, industrial emissions fkom sour gas processing, or

34 32 municipal effluent. If any of these potential sources have an unique ratio of SI S, then

73

it is possible to use the 6% vaiue of dissolved d a t e in the river to trace S input. Figure

5.10 illustrates the 6 3 4 ~ values of potentid S sources in the Bow River Basin.

Background values for precipitation in the basin are +5 to +IO%, but nach + 23%0 near

Sour gas plants (Norman, 1991). However, SO, in precipitation is not a sipnincant source

of SO, in the river, it comprises at most 17% of the S flux (Chapter 4). Sulfate h m tills

in the basin is largely derived nom reduced S, and thus has negative 6 3 4 ~ values in the

range of -8 to -12 %O (Hendry et al, 1986; 1989; Ferne& 1994). The 6% of S-based

fertilizer sold in the basin was measured to be +14%0, S-based fertiIizer is not commonly

used as soils in the ana generally have sufficient S for most crop plants (Aiberta Wheat

Pool - personal communication). Sour gas processing plants emit S with approximately

the same range of 6% values as evaporite minerais in Devonian carbonate rocks in the

basin. Springs discharging from Devonian carbonates in the Rocky Mountains (the

dominant source of evaporite minerals) bave 6MS, values ranging b m +17 to +25%0.

- till effluent from sewage - treatrnent plants

evaporite minerals 1-1

precipitation - spnngs 1-1

Figure 5.10 6% of potentid inputs of S to the Bow River.

Downstream variations in sulfate concentration and 6Y~,,, are plotted for each

season in Figure 5.1 1. Sulfate concentrations vary nom 2 mgn in the headwaters, to 50

mgA near the confiuence with the Oldman River at Hays. 6M~,, varies inversely,

decreasing fiom +2(%0 in the headwatea to 5%0 at Hays. In the winter, both sulfate

concentrations and the 6 % ~ ~ remain relatively constant along the river. Loading fkom

the sewage trcatment plants at Calgary is ody significant in the f a and winter, when

discharge in the river is low. Sulfate concentrations remain relatively constant through

the agricultural areas downstream of Calgary in the fd, but increase in spring and

surnmer.

The inverse relationship between SO, and 6 Y ~ s o 4 along the length of the river

indicates that two or more sources of SO, with different SYsS, values are mixing dong

the length of the river. By plotthg the inverse of SO, concentration veaus YS,,, it is

possible to determine the 6US,value of S04 king added to the river if simple mixing of

two or three end rnembers is taking place. For the f d , s p ~ g and summer sample sets, a

minimum three component mixing is indicated (Fig. 5.12). Samples fiom Lake Louise

have Ps, values fiom +17 to +2M~, in the typical range for evaporite minerais. There

is a significant increase in SO, concentration from Lake Louise to Banff, with a

concurrent shift in the 6%&,. From Banff to Calgary, concentrations of SO, and the

6%,, remain relatively constant. The best fit lines, from Lake Louise through the data

cluster representing Banff to Calgary, give intercepts of +8 to +1û%0. If simple mixing is

occuring, +8 to +1û% is the 6% of SO, king loaded to the river. A value of +lm0 is

consistent with SO, derived from soils. However, Mayer et al. (1995) show that forest

soils tend to be a s u h sink rather than a sulfur source. The more iikely origin of the

SO, is a mixture of the two dominant S sources in the bedrock, SO, denved from

evaporites and oxidized pyrite. Taking +19%0, the 6WSso4 value at Lake Louise

(Appendix 21, to represent the average composition of evaporites, and -10% as the

average value for pyrite (Hendry et al, 1986; 1989; Femeu, 1994), then oxidized pyrite

comprises approximately 3 1% of the SO, king loaded.

A second mixing relationship is apparent downstream of Calgary. The 6 % ~ ~

progressively decreases as the concentration of SO, increases. Best fit lines drawn for the

data downstrearn of Calgary have intercepts that indicate a FS, value of -10% for SO,

king loaded to the river in the fail and spring, and -2%0 in the summer. A value of - l M ~

is consistent with the range of values observed for SO, in tills in the basin (Hendry et al,

1986; 1989; Ferneil, 1994). The more positive vdue (-2%0) for the summer is not

consistent with any primary source of sulfùr in the basin. This Uely represents sulfate

fiom till that has mixed with a source more e ~ c h e d in "S. Sulfur derived fkom sour gas

operations is unlikely as the more positive 6U~,,4 values are ody observed in the

summer. Given that the summer represents the active fanning season in the basin, soi1

sulfate is a possible source. Unlike stablised forest soils that are sulfur sinks (Mayer et

al., 1995), tilled soils in the prairies may be a sulfur source due to oxidation of organic

sulfur. Taking -Ima as the tiü component, and +6%0 as the soi1 component, a -2% value

would represent a 1: 1 ratio of SO, denved £rom soils and till.

The winter samples suggest a single SO, source is king loaded to the river with a

6%,, value of +12%0. As interpreted above, this Likely represents the combined

signature of S from evaporites and oxidized pyrite.

8'0 in sulfate

The 6 ' 8 ~ in sulfate provides additional insight into the sulfur cycle in the basin. The

dowwtream variation in 6'8~,, and 6% is plotted in Figure 5.13. With the exception of

the winter samples, the PO, values are lowest at Lake Louise, and increase through to

Calgary. Downstream of Calgary the 6180,, values remain relatively constant. In the

winter, the 6'b, , values remain constant dong the river, similar to 6%.

Figure 5.11 Downstream variation in the concentration of SO, and 69, for the Bow River in a) fall, b)winter, c) spring, and d) summer.

Banff to Calgary

10

P * dow nstrearn -

Figure 5.12 P S versus l/SO,for a) fall, b) winter, c) spring, and s) summer.

distance h m Oldman confluence (km) d i n œ from Oldman confluence (km)

Figure 5.13 Downstream variation in 8% and 6180 in SO, for a) fall, b) winter, c) spring, and d) summer.

The 6'b, is plotted versus 6'b,,, in Figure 5.14- 6'b, has a narrow range,

between +6 and -6%0, and varies independently of S"O,,,. The O in SO, is depleted in

180 compared to the typical range for evaporite minerals (6f80, = +10 to +i6%0,

Claypool et ai., 1980). Exchange reactions between water and sulfate c m not be invoked 18

to explain the depleted 6 O,,, because the SO, - $0 exchange is extremely slow at

temperatme and pH conditions comparable to the Bow River (Lloyd, 1968). As well, the

6'8~, values are not consistent with oxidation of reduced sulfur, with the exception of

samples from Lake Louis, as waters fiom the Bow River plot outside of the theoretical

sulfide oxidation field of Van Stempvoort and Krouse (1993) (Fig. 5.14). The lower

boundary of the sulfide oxidation field represents 1006 conmiution of oxygen in SO, from H20,

The upper bounâary is derived from num&ous experiments (e.g. Taylor et al., 1984) of sulfide

oxidation and represents the minimm contribution of oxygen from H,O (approxirnately 62% of O

in SOJ. Thus the sulfide oxidation field dehes the range of 6'8~,, possible when suifide is

oxidized in the presence of water with a given S'b,,.

There are two possible explanations for the observed 6'8~,,, in the Bow River L) a

mixture of sulfate fiom evaporite rninerals and oxidized sulfides, and 2) bacterial

32 16 moderated sulfate reduction which preferentially reduces S O (Vao Stempvoort and

Krouse, 1993), leaving the remaining 6'*0,,) e ~ c h e d in "O. A mixture of sulfate nom

evaporite minerals and oxidized sulndes does not secm possible given the downstream

variation in 6''0[,, (Fig 5.13). At Lake Louise, the 634S indicates SO, is derived from

dissolution of evaponte minerals, whereas the 6180, plots in the suEde oxidatioa field

(Fig. 5.14). This implies that most of the sulfate derived fiom dissolution of evaporite

minerals is reduced to sulfide, and then reoxidized in the presence of groundwater before

reaching the river. As well, as discussed above, the 6% indicates that SO, king loaded

to the river downstream of Calgary is largely from a reduced sulfur source (oxidized

pyrite and organic matter in tus). When sulfides are oxidized to SO,, the 6"0,, should

plot in the suKde oxidation field. Although there is gypsum preseat in the eastern tiil,

the 6 3 4 ~ (-13%~ Fenneu, 1994) indicates it is derived from oxidized pyrite, and thus can

80

not be the source of the high values. The fact the St80, plots welî above the

sulfide oxidation field suggests that the 6%, of the newly formed SO, has been

e ~ c h e d by sulfate ~duction. Similar e~chments in the 6'9, relative to the suitide

oxidation field have been observed in tills in Saskatchewan (Van Stempvoort et al., 1994)

and streams in Italy (Schwarn and Cortecci, 1974).

0" 0 spring rn .- = O

Figure 5.14 #'O in SO, versus S1'O in H,O.

The basic implication of these data is that SO, in the river goes through a complex

history of redox conditions before entering the river. This in tum supports previous

arguments in Chapter 3 and 4 about the flow path of water feeding the river. Sulfate

derived nom precipitation contributes at most 17% of sulfate in the river. Thus the vast

majority of SO, in the river is denved nom some form of rock weathering. The 6%

value of sulfate in the head waters of the river indicate that dissolution of marine

evaporites is the dominant source of this sulfate. The 8180,,,, indicates that once

dissolved in the water, this sulfate must be reduced and then reoxidized before entering

the river. As well, S king Ioaded in the prairie regions must onginate as oxidued

sudes , pass through the anoxic zone, and finally be added to the river. This implies that

the water transporthg this S must move fkom the surface, through the anoxic zone, and

then to the river, indicating that the river is largely gmundwater fed

Cakium and Magnesiuin

In most riven calcium and magnesium are derived dominantiy from rock w e a t h e ~ g ;

they are not a common poiiutant (Berner and Berner, 1987). This is evident in the Bow

River, where uniike the other major ions, calcium and magnesium are not king loaded

by CaIgary (Fig. 5.15). The loading of Ca and Mg to the river is consistent with the local

geology. Ca and Mg behave similarly, with concentrations increasing from the

headwatea to Calgary. This trend occurs in the western part of the basin that is largely

underlain by carbonate rock, and covered by the carbonate dominated Cordilleran till.

Where as downstream of Calgary, where the boundary between the Cordilleran till and

the igneous and metamorphic dorninated eastem tili occurs (Fig. 2.6), Ca and Mg

concentration remain relatively constant.

As stated above, calcium and magnesium are dominantly derived from rock

weathering. The most common weathering reaction for weathering of carbonates is

simple dissolution (Drever, 1988). reaction 1 in Table 4.3, giving a (Ca + Mg):HCO,

equivalence ratio of 1 : 1. Figure 5.16 iliustrates that (Ca+Mg) is in excess of alkaluüty by

up to 25%. where as it is balanced by (alk + SOJ (Fig. 5.17). As discwed in Chapter 4,

excess (Ca+Mg) c m be denved nom oxidation of sulfides or dissolution of gypsum and

anhydrite. Both processes require Ca+Mg to be balanced by Alk + SO,. Based on stable

82

isotope evidence discussed above, at least 7046 of the SO, king loaded upstream of

Calgary is derïved from evaponte dissolution.

distance (km) from the confluence with the Oiârnan

- - --

0 fall Q winter O spnng A surnmer

Figure 5.15 Downstream variation in a) Ca and b) Mg for each season.

1 2 3 4 5

alk meq/l

1 2 3 4 5

alk meqll

Figure 5.16 Ca + Mg versus total ak for the Bow River (open circles) and tributaries

(closed circles) for a) fail, b) winter, c) spring, and d) summer.

2 3 4

alk + m4 meqll

2 3 4

alk + 93, meqll

Figure 5.17 Ca + Mg versus a1.k + SO, for the Bow River (open circles) and tributaries (closed circles) for a) f d , b) winter, c) spring, and d) Sumner.

Phase diagrams were used to examine the role smectite exchange reactions play in

controlling the Ca:Mg activity ratio of the river. As above, phase boundaries were

calculated assuming equilibrium with the nver water at Banff. Bow River waters show a

strong correlation with the calculated exchange boundary, suggesting that Ca-Mg

exchange reactions exert a strong coatrol on the river chemistry (Fig. 5.18).

As in Chapter 4, it is important to examine whether Ca-Mg exchange reactions, and

those controliing the Na:K activity ratios, are instream processes or inherited

groundwater signatures. A number of factors argue that these equilibrium exchange

reactions are an inhented ground water signature: 1) As calculated in Chapter 4. 1.3 to

2.4 g/l of suspended smectite is required to exert the observed conaols on activity ratios

in the river. However, non-filterable residue, a measure of total suspended solids, is too

Low along the length of the river (5 to 20 mgll) for there to be sunicieut smectite, 2) XRD

analyses of suspended sediment along the river indicates that smectite is a trace

component. 3) Activity ratios observed in the river are similar to those measured for

discharge nom springs dong the river (Fig. 4.14). The basic implication of this is that

the chemistry of the majority of water entering the river is controiled by waterlrock

interaction. In hm, this indicates that, as previously discussed, the majority of water in

the river must have passed ihrough the groundwater zone before reaching the nver.

log a MgM2 log a MgH2

Figure 5.18 Ca-Mg activity plot, a) f d , b) winter, c) spring, and d) summer.

Bicarbonate

The carbon cycle in riven is complex due of the various sources and interactions dong

the flow path. Most rivers in the world are characterised by large overpressures in pCO,,

10 to 15x equilibrium with atmospheric CO, (Pawellek and Veizer, 1994; Stallard and

Edmond, 198 1, 1983; Buhl et al. 199 1). Carbon isotope studies of these riven attribute

overpressures of CO, to oxidation of organic matter, generaliy attributed to enhanced

organic productivity related to nutrient poilution (Richey et al. 1988; Buhl et al., 1991).

In contrast. river systems that have natural interfluvial lakes (e.g. the St. Lawrence) or

extensive impoundments (e.g. the Danube) tend to have pC02 values near, or below,

equilibrium with ahwspheric CO, ( Yang et ai., 1996, Paweliek and Veizer, 1994). In

these cases the long residence time dows pCO, to equilibrate with annosphecic

pressures, and this in tum ailows partial isotopic equilibration with atmosphenc CO,. In

the case of the Danube River, intense algal photosynthetic activity causes a significant

&op in p C 4 during the summer with a concurrent enrichment in 6°C due to preferential

withdrawal of "C by algae. These shldies demonstrate that by examining the stable

isotope composition of DIC, it is possible to elucidate the controls on the riverine carbon

cycle. In order to do this, it is necessary to first d e h e the 6I3c values of potential carbon

sources.

Pawellek and Veizer (1994) sllmmarise the various sources of dissolved inorganic

carbon @IC) and their expected S13C values (Fig. 5.19). DIC can be derived from

extemal sources via uptake of atmospheric CO,(-~XG), or carbon derived from

dissolution of carbonate minerais (-5 to +2%0). DIC may ais0 be generated within the

river by oxidation of organic matter (-24 to -31%) and respiration of aquatic plants. It is

important to note that the isotope composition of these potential sources of DIC are

altered on entering solution. Under equiiibrium conditions. the enrichment factor

between DIC and atmospheric CO, is expressed as:

where T is in OK (Mook et al., 1974). Based on observed water temperahues, and 613c of

atmospheric CO, of -7%0. the 6I3C of DIC in equilibrium with atmospheric CO, would be

+3%0. The 8°C of DIC derived from CO2 from oxidation of organic matter wïU be in

the range -14 to -24%. Carbonate rock is typically weathered by carbonic acid produced

in the soil zone (Drever, 1988; reaction 1 in Table 4.3). The resultaat composition of

CO, h m the soil zone and rock weathering would be -7 to -12%~. DIC may be lost nom

the river by degassing to the atmosphere or photosyuthetic activity.

(PBD) r I I I 1 I 1 I 1

-35 -25 -1 5 -5 +5 - soi1 organic matter

CO2 in soi1 water - carbonate rock

DIC derived from bicarbonate - acid dissolution of carbonate rocks

= atmospheric CO2 dissolved in water atrnospheric CO2 I

Figure5.19 Sources of DIC and their associated 613c values (after Pawellek and

Veizer, 1992).

Variation Ut pCO, of the Bow River

The pCO, for Bow River waters were calculated using Solmin88 (Wiwchar. et al., 1988)

and are presented in Fig. 5.20. Overall, the pCO, of the Bow River is relatively low

compared to larger river systems. This may be due to the turbulent nature of the river.

particularly in the upper reaches, ailowing excess CO2 to escape to the atmosphere. in

the summer and fd pCO, values are generaliy the same order of magnitude as expected

for equilibrium with the atmosphere (350 ppm). The winter samples have erratic

variations in p C 4 dong the river, varying nom highly overpressured to near equilibrium

values. The erratic variations in p C 4 are likely related to ice cover on the river. During

the winter, the river is mainly fed by groundwater (Chapter 3) which genetally has high

pCO, compared to atmospheric values. Due to intermittent ice cover dong its length, the

river is oniy able to release this excess CO, in ice fm portions. The variations in pCO,

dong the river would then refîect the degree tbat water has been able to degas. In the

spring pCO, is near equilibrium with atmospheric pressures fiom the headwaters to

Calgary, and steadily increases dowostream of Calgary. The observed high pCO, values

in the river downsaarn of Calgary may be related to either instream production or the

introduction of groundwater with high pCO, to the river.

Laice Louise Banff Bearspaw ûonny Bmok Bassano Dam

O fall o winter O spring A sumrner

distance from Oldman confluence (km)

Fip* 5.20 Variation in pCO, dong the length of the Bow River.

Figure 5.2 1 illustrates the variation of pCO, with 6°C. The most noticeable trend is

in the spring, where low pCO, values tend to be associated with higher 6 " ~ values,

90

whereas high pCO, vaiues trend towards a S13C of -8%0 (withui the range expected for

carbonate minerais). The river itseif wodd aot be able to generate the overpressures in

CO, by carbonate weathering, implying that high pCO, values in the river are associated

with groundwater discharge. In the spring, lower pCO, values trend towards Waa,

suggesting that as pCO, reaches e q u i l i i with atmospheric pressures there is also a

partial isotope equilibrium of DIC with atmosphenc CO2. This is similar to relations

observed in the Danube by PawelIeck and Veizer (1994). The high pCO, value observed

downstream of the Bassano Dam in the spring (Fig. 5.20) is associated with a much lower

613c value than typicd (Fig. 5.21). This concurrent increase in p C 4 and decrease in

8l3c must be related to oxidation of organic matter. The high spring discharge may be

fiushing out organic material fiom the Bassano resewoir that is then oxidized in the water

O downstream

Eo of Bassano O fall O winter e spring A summer I

pCO2 ( P P ~ )

Figure 5.21 613C of DIC versus calcuiated pCO, for the Bow River.

91

CEEMICAL DENUDAION RAIE

Foilowing methods ouilioed in Chapter 4, the mass tlux and chemical denudation rate for

the Bow River Basin c m be estimated. Mass flux is calculated at three stations dong the

river: Banff (BR2). Caneland (BR1 l), and Hays (BRIS). These stations represent the

headwaters of the river (Banff), a midpoint downstream of Calgary (Carseland), and the

end of the river at the conîiuence with the Oldman River (Hays). Mass flux can be

calculated using a modified version of Equation 4.2, where the term Fmk,,, is

included.

The majority of water that feeds the Bow River onginates within the Rocky

Mountains (Table 2. l), therefore atmospheric loading rates used in Chapter 4 (Table 4.2)

can be used for the temis Fm,, and FM* The only anthropogenic input of major ions

EnthmPogenic ) identifïed is the city of Calgary. Given the average TDS of effluent (Table

5.1) and the average discharge at Bomy Brook and Fish Creek (5 and 2 m3/s

respectively), then the mass flux fiom Calgary is approximately 4 x l d kglday .

Using total discharge for the months samples were collected, mass flux for the Bow

River was calculated for each station (Table 5.3). There is a large increase in mass flux

nom Banff to Carseland. mainly due to the addition of tributary water. Mass flux from

the basin is highest during the spring and lowest during the summer. The low rnass flux

during the summer is related to heavy use of the river for irrigation. This is readiiy

observable in Table 5.3, where the flux at Hays is oniy 40% of the flux upstream at

Carseland. Outside the irrigation season, the mass flux fiom Carseland to Hays remains

relatively constant. Loading from Calgary accounts for 8 to 9% of the mass flux out of

the basin in the spring and f d . In contrast Calgary accounts for 25% of the mass flux in

the summer, when both concentrations and water volumes of the Bow River are relatively

low. Averaged over the year, the flux at the mouth of the Bow River (near Hays) is 1,112

x 1 o6 kg. After comcting for non-weathering components this gives a chemicai

denudation rate of 340 kghdy, close to the world average (Table 4.6).

Table 5.3 Total monthiy discharge (x 1o6 m') and flux (x 106 kg) of TDS for the

Bow River at Banff, Carseland, and Hays for the four seasons sampled.

Location

Banff Carseland Hays

SUMMARY

Seasonaüy, the main variation in the chemistry of the Bow River is in the TDS load; TDS

is mainiy a hinction of discharge. Element ratios remain relatively constant through the

year. Upstream of Calgary, then are no point source inputs that affect the major ion

chemistry of the Bow River. The chernical makeup of the river is identical to that of the

Bow River in its pristine headwaters. The source of ions in this section of the river are

interpreted to be atmospheric loading and waterhck interaction. Sulfate is dominantly

derived fiom dissolution of evaporite minerais, with up to 30% denved from oxidation of

sulfides. Once dissolved, sulfate under goes a complex redox history before reaching the

10/93

~ O W ~ U X

x10 m3 x106kg

69.6 13.6

325.0 99.2 320.0 110.2

OU94

~ O W ~ U X

x10m3 d06 kg

26.4 7.0

n.a. n.a 157.0 n.a.

06/94

~ O W flux x10 m3 x106 kg

282.0 47.5

553.0 148.0 481.0 148.9

08/94

~ O W ~ U X

x10 mJ xlo6 kg

145.0 22.9

216.0 47.8

78.1 18.8

river, implying that the water transport@ sulfate to the river passes through the anoxic

zone before becoming discharge.

Calgary is the most significant point source input dong the river. Effluent fiom the

sewage treatment plants loads a significant amount of Na, K, and CL to the river, and

minor arnounts of SO,. Downstream of Calgary, Na and SO, is loaded to the nver by

irrigation nuioff. Sulfate fkom this part of the basin is largely derived from oxidized

sulfides in the local till. In the summer, sulfate derived fiom soils can be a signü'icant

component of sulfate being added to the nver (up to 50%). As observed upstream of

Calgary, sulfate has a complex redox history before reaching the river. 6180 data

suggests that after sulfides are oxidued, they are partialiy reduced before reachuig the

nver. Again, this indicates that water transporthg this sulfate must pass through the

ground before becomuig discharge.

DLC in the river is largely derived from the weathering of carbonate rock by soil CO,

The p C 4 of the Bow River is generaliy near equilibrium with atmospheric pressures,

particularly in the turbulent headwaters. High p C 4 values are associated with

groundwater discharge. In the s p ~ g there is a partial isotope equilibrium of DIC with

atmospheric CO,, as pCO, reaches equiliirium with atmospheric values.

Cation exchange reactions exert a strong control on cation activity ratios in the river.

The CalMg and N a K activity ratios are controlled by exchange reactions with smectite.

These activity ratios appear to be inherited signatures of ground water as smectite is

absent in the suspended and bottom load.

Mass flux from the Bow River Basin is highest during the spring and lowest during

the summer. The low mass flux during the summer is related to heavy irrigation use of

the river. Loading from Calgary accounts for 8 to 9 8 of the mass flux out of the basin in

the spring and faii and 25% of the mass flux in the summer. The chernical denudation

rate of the Bow River, 340 kg/ha/y, is close to the world average.

94

IMPLICATIONS FOR BASIN HYDROLOGY

In Chapter 3, the question was posed: "how is rainfail or snowmelt over a catchent

transformed into stream runoff?" One of the earliest attempt to address this was by

Horton (1933). In Horton's model (Hortoaian overland flow) stream mnoff is generated

when raiafall intensity exceeds the infiltration capacity of soil. Water in excess of the

infiltration capacity reaches the stream by overland flow. In this model, runoff is the sum

of slowly changiog groundwater discharge and rapidly changing direct nuioff. Later

models are based on the observation that rainfall intensity does not normaIly exceed soil

infiitration capacity. Still, these models differ in the relative importance of overland and

subsurface flow (e.g. Dunne and Black, 1970; Hewlett and Hibbert, 1967). Recent

studies using stable isotope techniques have tried to test these models (e.g. Maainec et al.

1974; Krouse et al., 1978; Skiash and Famolden, 1979, Dincer, et ai., 1970) What these

studies show is that in high discharge events, whether generated by snow melt or rainfaii,

the 'new* water being added to the basin displaces pre-existing groundwater into the

river. So that high discharge in comprised of a mixture of displaced groundwater, and

'new* water. Although the stable isotope signature can be used to quantify the relative

proportions of groundwater and 'new' water in stream discharge (hydrograph separation)

it stül does not provide any information of the pathway that the 'new* water takes to

reach the stream (i.e. as overland flow or subsurface flow). Some recent studies have

suggested that the chemistry of snowmelt is altered by reactions in soil and groundwater

before it becomes stream discharge (e.g. Williams et al., 1993; Campbell et al., 1995;

Williams et al.. 1995), implying that the 'new' water must foiiow a subsurface path to the

river. Several lines of evidence fiom this study provide further insight into the processes

of runoff generation. with particular reference to the Bow River basin; they are

surnmarised below :

1) In Chapter 3, discharge in the fail and winter is shown to be fed by groundwater.

In contrast, the high discharge event in the spring is a mixture of 'new' snowmelt and

groundwater displaced h t o the river. Summer discharge is fed by summer rainfall.

These data indicate that at least 40% of the river is fed by groundwater (Le. water that has

had sufficieut residence time for isotope exchange reactions with rock fonning minerals

to occur). The remainder of the discharge is comprïsed of 'new' water (water with a

short residence time). Although these data belp determine the relative proportion of 'old'

water (Le groundwater) and 'new' water feeding the river, they do not provide

information on the flowpath of 'new' water to the river.

2) Chernical data in Chapter 4 show that the TDS of the river varies with discharge.

The spring and summer high discharge events are more dilute than groundwater fed

baseflow in the fa11 and winter. If snowmelt and rainfall were diluthg groundwater, a

simple mixing relationship between the groundwater and precipitation end members

would be expected. This can be tested using a mass balance calculation. Taking the

average TDS of precipitation (7.4 mg/l), winter discharge (190 mgA) and summer

discharge (100 mg/l) (Chapter 4), and the average discharge in winter (10m3/s) and

summer (1 10 m3/s), then summer discharge caries four time the mass bat would be

expected for simple dilution of groundwater. This indicates that precipitation generating

the high spring and summer discharge undergoes some degree of water/mck interaction.

The observation that summer discharge has nearly identicai chernical composition as

baseflow, and quite distinct from that of precipitation (Figs. 4.2 and 4.4)' suggests that

precipitation undergoes similar water/rock interaction as groundwater. This is supported

by themodynamic models that show equilibrium exchange reactions on smectites are

controlling the activity ratios of major cations in the river water, although smectite is

absent from the river. The interpretatîon that this is an inberited groundwater signahm is

supported by the similarity of activity ratios for river water and groundwater in the basin.

Therefore, contrary to common opinion, the relationship of discharge to TDS is not one

of dilution, but rather, the controlling variable is the relative residence tirne of the water

in the ground. During high discharge events, related to snowmelt and heavy rainfall,

there would be a large flux of water through the ground. This would reduce the time

available for water-rock interaction dong the flow path, and thus the TDS of water.

For this mode1 to work, snow melt must be able to enter the ground during a

period when it would presumably be frozen (Le. during the spring melt). Work by Harris

(1986) indicates that the relatively high snowfall in the headwatea of the Bow Basin

thermally insulates the ground, making the p e d o s t iine anomalously high compared

to areas north and south. As well, mass balance calculations (S. Harris, persona1

commun., 1997) indicate that melt water h m the winter snow pack in the Bow Basin is

transferred to the groundwater zone as early as mid-February. In addition, the

headwaters of the Bow River basin are domhated by carbonate rock, which tends to have

a high permeability.

3) The 6'8~, indicates that after evaporite minerals are dissolved, sulfate goes

through a complex redox history &fore entering the river. Similarly, after oxidation

sulfides show evidence of partial reduction before entering the river. This complex

history of redox conditions implies that the water transporthg this S must move fiom the

surface, through the anoxic zone, and then to the river.

In summary, the above data al l support the conclusion that the Bow River is almost

entirely fed by groundwater input. Snowmelt and rainfail flushes groundwater into the

river. The seasonal variations in TDS of the river is not a function of dilution, but rather

97

hydrology is a dynamic system, where the majority of water feeding the river flushes

through the groundwater system seasonaiiy. Care should be taken in applying these

results to runoff generation models. The basin geology, and anomaiously high

permafrost line, ailow snowmelt to enter the ground, reducing surface runoff. It is likely

that riven draining dinerent other lithologies may not be dominated by groundwater

discharge. However, a survey of basins with Merent lithologies, using a combined

stable isotope and geochemicai approach, would help resolve the process of runoff

generation.

CHAPTER 6 Tradng anomalous TDS in Nose Creek

INTRODUCTION

Nose Creek was examined as part of the Bow River Basin study (Fig. 1.1). It was chosen

for a more deiailed study because the total dissolved solids load (TDS) is significantly

higher than the Bow River or its other tniutaries. These high concentrations must be the

result of either natural phenomena or anthropogenic activity in the basin. This study

combines both chernical and stable isotope anaiysis to determine the origin of the high

dissolved load in Nose Creek.

Samples nom Nose Creek representing two flow regimes, fa base flow conditions

and spring/summer high discharge, were couected. The f d samples were coiIected dong

Nose Creek over a two day period (October 30 to 31, 1993). Spring samples were

coiiected on June 5, 1996. For each set, seven samples were collected dong Nose Creek,

and one from West Nose Creek (Fig. 6.1). s

THE NOSE CREEK BASIN

Nose Creek is located in southem Alberta, Canada (Fig. 6.1), in an area dominated by

prairie grassland. The basin has a dry-subhumid ciimate, with annuai precipitation of 400

mm, and potential evapotranspiration of 530 mm (Ozoray and Bames, 1977).

Precipitation is concentrated in the spring and summer, with a dry fall and winter (Fig.

6.2). Nose Creek extends 45 km f ~ o m its confluence with the Bow River to its head

waters north of the town of Crossfield (Fig. 6.1). The creek drains a 986 km2 area, and

has an average annual fiow of 0.73 m3/s (Environment Canada, 1990). The creek has one

main tributary (West Nose Creek) and several ephemeral tributaries. The basin lies

99

outside of any of the Bow River irrigation districts, so groundwater and precipitation are

tbe only sources of water in the creek. Discharge in the creek is relatively high during

spring and early summer, and low in the f d and wintet.

The Nose Creek basin is underlain by up to 15 m of Balzac Till, a silty to sandy till

with abundant blocks of limestone and quartzite, and rare blocks of granite and gneiss

(Moran, 1986). The Porcupine Hills Formation, a non-marine, fme graine4 calcareous,

cherty sandstone, forms the bedrock of the basin (Green. 1972). The dominant land use

in the north part of the basin is agricultural (mostly cereal grains and canola crops). In

addition, there are two natural gas processing facilities that extract sulfur, one at

Crossfield and one at Balzac. The southernmost part of the basin lies within the northeast

section of the City of Calgary. This section of the city is dominated by residential

housing, the Calgary International Airport, and some light industry.

Figure 6.1 Nose Creek basin, showing sample locations and the Bearspaw Reservoir.

Sample stations dong Nose Creek have the prehx NC and those on the Bow River, the

prefix BR (Fig. 6.1, Appendur 2,4). An important feature to note is that although station

NC5 Iies within the City of Calgary, the surroundhg area is undeveloped agricultural

land. Stations NC6 and 7 lie withïn the developed part of the city.

RESULTS AND DISCUSSION

Source of Nose Creek Woirr

For the fall samples, precipitation and surface mnoff can be eliminated as major

contributors to Nose Creek, as only 9 mm of precipitation were recorded in the 2 months

preceding sampling. The ody water that municipalities pipe directly into Nose Creek is

storm water runoff, and aLl of the storm sewers observed during sampling were dry.

Therefore, groundwater must be the primary source of water in Nose Creek in the f a .

This is consistent with Ozoray and Bames (1977) who indicate that in the fail,

groundwater is the principal source of surface water in large parts of southem Alberta. In

contras t, during spring sampling storm sewea draining paved streets were observed

discharging into Nose Creek. Environment Canada recorded 78 mm of precipitation in

the 2 months preceding the spring sampling.

Inorganic chemistry of Nose Creek water

Chernical data for Nose Creek are presented in Appendix 4. Two features distinguish

Nose Creek water from the other tributaries: 1) concentrations of inorganic ions are

anomalously high, and 2) the dominant ions in Nose Creek are Na-SO, - H C 4 whereas

aIi other tributaries to the Bow River are Ca-HC03 waters (Fig. 6.2). Precipitation can

not be a major source of the dissolved load because it is relatively dilute (north Calgary

precipitation has an average TDS of 4 ma). Therefore, the high TDS load of Nose

101

Creek can only be explained by either natumi controls (e-g. wea the~g of till andlor

bedrock, evaporation, etc.). or anthropogenic activity in the basin.

Figure 6.2 Ternary plot of major ions for Nose Creek (open circles) and other tributaries to the Bow River (closed circles).

Figure 6.3 illustrates the variation in major ion concentrations dong the length of Nose

Creek for spring and fd. For the spring samples, the most important features to note are

that: 1) upstream of Airdrie, in the headwaters of Nose Creek, concentrations are high

cornparrd to other tributaries of the Bow River, and 2) Nose Creek is diluted where the

creek flows through the cities of Airdrie and Calgary. For the fa11 samples,

concentrations of Na and SO, are generally higher. the cities of Airdrie and Calgary cause

more significant dilution, and concentrations of major ions (particularly Na and SO,)

increase steadily as the creek flows through agriculhiral land between Aircirie and

Calgary. These spatial relations imply that municipalities act as point source inputs of

relatively dilute water, and that in the fd l either a dispersed source, or a

physicaVchemica1 process, significantly increases the TDS of Nose Cree k within the

102

agricultural areas of the basin. In the spring, the major ion chemistry is relatively

consistent dong the creek. althwgh the concentration of SO, does increase through the

Airdrie 1

distance fmm Bow River confience ()an)

Airdrie . Calgary

12.5

1 0

7 -5

5

2 -5

I

b) distance from Bow River confluence (km)

Figure 6.3 Variation in major dissolved ions dong the length of Nose Creek for a)

spring, and b) fall runoff. Note that the Land between the Calgary City Limits and 'tuban Calgary" is undeveloped agricultural land.

Of the dissolved solids, chloride is the easiest to account for because of its

conservative nature and Limited numbers of potential sources. There are no naturai

sources of Cl in the Nose Creek Basin, the concentration of Cl in precipitation is Low

(0.165 mgil), and neither the bedrock nor the till in the basin contain evaporites. This

103

implies that Cl is derived fiom an antbropogenic source. The most Likely source of the Ci

is road salt used to melt winter ice on Highway (HW) 2 and other secondary roads (Fig.

6.1). Road salt used by Aiberta Transportatioa is typically 95% NaCl, with the

remainder king K, Ca, and M g chlorides. Accepting that road salt is the major source of

Cl, it only accounts for 10 - 20 % of the cations in Nose Creek, and does not account for

the significant Levels of sulfate. The steady increase in major ion concentrations dong

the length of Nose Creek between Airdrie and Calgary, pdcularly in the f d (Fig. 6.3),

makes it dïffkult to define a source based on chemûtry aione. It is unlikely that in-

stream evaporation could account for the observed increase. Thus, there must be addition

fiom non point-source(s) dong the length of the creek. Stable isotopes of water and

sulfate were used to trace the source(s).

Oxygen and hydrogen isotope compositio~~~ of Nose Creek water

Stable isotope data for Nose Creek are presented in Appendix 4. On a plot of 6~ vs PO

(Fig. 6.4), the data for the s p ~ g samples plot in a relatively tight cluster, with 6D of -120

to 125960 and 6% of -15%0. The data falis just off the local meteoric water Line

(LMWL), suggesting precipitation is the dominant source of creek water. This is

consistent with the buik of precipitation occurring during the spring (Fig. 2.5). If

groundwater is king added to the'creek, the consistency of the isotope composition dong

the creek suggests that the proportion of groundwater to rain water is nearly constant.

In the fali, Nose Creek water becornes relatively depleted in the heavy isotopes of O

and H in the downstream direction, 6"O decreases nom -12.5 to -19.0470. On a plot of

6D vs 6"O (Fig. 6.4), the faii samples d e h e a best fit line with a dope of 5.4 (8- .92),

as compared to a slope of 8 for the local meteonc water line ( L m ) . Data defining on

a dope lower than the LMWL represents either evaporation or mixing. In a small creek,

evaporation dong the flow path would be unlikely. If it did occur, the 6D and 6"0

104

values would progressively increase downstream, opposite to what is obsewed. The

progressive dowustream decrease in 6D and 6"0 in the fall sample set can only be

explained by addition of water relatively depleted in D and '*O.

a Bow R h r a Nose Creek -1 00

between Airclrie

within Calgary 4-1 Bow River

downstream of Bearspaw

-1 60

Figure 6.4 Plot of 6D versw S"O for a) spring and b) f d , aad the Bow River below

the Bearspaw Reservoir (square). The local meteoric waterline @D =

8PO + 6) is given for reference.

The isotope data for the f a samples in Figure 6.4 plot in three clusters, with each

cluster representing a separate reach of Nose Creek: 1) upstream of Airdne, 2) between

Calgary and Aiidrie, and 3) within Calgary. The higher #'O values upstream of Airdrie

(relative to the LMWL) are consistent Mth groundwater king the principal source of the

head waters of Nose Creek (Ozoray and Bames, 1977). The best fit h e defined by Nose

Creek water passes through Bow River water sampled downstream of the Bearspaw

Reservoir (Figs. 6.1,6.4; Bowness sample in Appendix 2). Normally, such a relationship

would be interpreted as miung between two end members (i.e. the head waters of Nose

105

Creek and the Bow River). Because Nose Creek is a tributary of the Bow River, it seems

impossible that Nose Creek water is mixing with Bow River water dong the length of

Nose Creek. However, it is important to note that the stable isotope composition of Nose

Creek water only changes as it flows through the two cities (Airdrie and Calgary). This

suggests that the cities are adding signincant amounts of water to the creek, consistent

with the observed dilution (Fig. 6.3). Cities c m add water to a creek directly via storm

sewer discharge and sewage outlets, or indirectly from leaking pipes via groundwater

(curent estimates by the City of Calgary put water loss from Calgary pipes at 15%).

Although lawn watering can add additional water, it is minor relative to water loss from

pipes. Tliere was no storm sewer discharge observed during sampling, and residential or

industrial sewage is not discharged into Nose Creek. Therefore, the water king added to

the creek by Airdrie and Calgary must be derived ftom groundwater. Both Airdrie and

north Calgary draw their water supply fkom the same source, the Bearspaw Reservoir on

the Bow River, consistent with the mUing relationship observed in Figure 6.4. Thus, the

observed dilution and increased flow of Nose Creek is a result of addition of municipal

water, denved from the Bearspaw Reservoir, and added to Nose Creek via groundwater

infiltration.

Assuming the relationship in Figure 6.4 represents perfect mixiag, an isotope balance

approach can be used to caiculate the amount of Bearspaw Reservoir water king added

to Nose Creek at Airdrie and Calgary in the fd. These calculations suggest that the fiow

of Nose Creek increases by a factor of 1.6 as it fîows through Airdrie and 3.8 as it fiows

through Calgary. There are iimited Stream flow data to compare with these results.

Environment Canada operated two gauging stations on Nose Creek fiom 1980 to 1986,

one below the confluence with West Nose Creek, just south of station NC5, and one at

the same location as station NC7 flable 6.1). Excluding the high flow year of 1986, the

flow between the two stations increases an average of 4.5 times (n=4), in good agreement

106

with the 3.8 fold increase in flow calculated nom the isotope data. Given the average

flow for October of 0.33 m3/s, a 3.8 fold increase in flow implies Calgary is adding

approximately 22 MVday to Nose Creek, or 10% of the 220 MV &y that are piped into

north Calgary h m the Bearspaw reservoir. This is reasonable when compared to the

estimated 15% water loss through lealry pipes Ïn Calgary.

Table 6.1 - Environment Canada (1990) flow data for Nose Creek flow data south

of NCS' flow data at NO Increase in flow

Envimument Canada stations 'OSBH003 and ' 0 5 ~ ~ 9 0 1

In surnmary, m) and 6"O data indicatc that in a dry climate, municipalities can add

signifcant amounts of water to local water bodies. During base flow conditions, water

nom the head waters of Nose Creek is mïxed with two pulses of "Bow River" water

added via leaky pipes in the cities of AUdrie and Calgary, increasing the creek discharge

approximately 4 fold. It should be noted that the town of Baizac apparentiy does not alter

the isotope composition of Nose Creek water. The smail population of Baizac (250), as

compared to Calgary (700,000) and Aircirie (25,000), would not introduce as much

municipal water into the basin. The volume of water added to the creek by spring rains

(3 times bwflow conditions) appears to overwhelm any isotope signature of municipal

water king added to the creek. Municipal water use in the city is relatively constant,

summer consumption is 10-15% greater than winter (Engineering and Environmentai

SeMces, The City of Calgary). Thus, we can assume the addition of muncipal water

107

calcuiated for October (22MVday), is consistent through the year. Taking the

Enviroment Canada (1990) average discharge for Nose Creek of 11,500 Ml, fiom May

to October, municipal water accounts for 35% of discharge during this time. Whereas

during low fiow in October, municipal water accounts for 77% of discharge. Flow data is

not available for wintet months, however flow conditions would be similar to, if not less

Sources of su@te

Evaporation can not account for the observed increases in major ion concentrations

between Airdrie and Calgary. This impiies that a dispened source(s) adds inorganic

solutes dong this reach. The S and O stable isotope compositions of sulfate cm serve to

identify these source(s). Dissolved sulfate can be derived fiom the dissolution of sulfate

minerals, the oxidation of pyrite and other forms of reduced s u , and anthropogeaic

inputs (e.g. fertiluer, industrial emissions from natural gas facilities that process s u h ,

etc.). Given the typical concentration of sulfate in Calgary rain (1.5 mg/l), atmosphenc

sulfate can not be a major contributor of sulfate to Nose Creek. Soils in southem Alberta

generally have sufticient suifur content for rnost crop plants, so that S-based fertilïzer is

not commonly used (Hendry et ai., 1986). Even where used in parts of the eastern Bow

Basin, Hendry et al. (1986) noted that the application of S-based fertiher did not affect

the groundwater chemistry. The only plausible origin(s) of sulfate in Nose Creek are 1)

weathering of till andlor bedrock, or 2) anthropogenic input. The oxygen isotope

composition of sulfate was used to determine if the sulfate was denved fiom a primary

source (e-g. sulfate minerals), or the oxidation of reduced sulhu.

The 6"0 of sulfate and water are plotted in Figure 6.5. The fall samples have a

relatively wide distribution with 6180,,,,, ranging from +7 to -7460, and a positive

correlation with 8*0,,,,. In contrast the spring samples only have a 5 % ~ variation in

108

6'80,, and 6"Om, is constant. Overaii, the 6180, values of ai l samples are depleted

cornparrd to evaporite minerais; the 6'80, compositions of evaporites range nom +10

to +16%0 (Claypool et al. 1980). Exchange reactions between water and sulfate can not

be invoked to explain the depkted 6%- because the SO, - H,O exchange is extremely

slow at temperature and pH conditions comparable to Nose Creek (Lloyd, 1968).

However, when reduced S is oxidized, 50 to LOO% of the oxygen is derived from water

(Van Stempvoort and Krouse, 1994). Therefore, the positive correlation between

6180,s,, and 6'80,,, in the fail samples suggests SO, is derived nom oxidation of a

reduced sulfur source. The unifonn 81800,,,, in the spring samples makes a correlation

impossible. The s p ~ g rains would Wtely be washing out soluble salts built up in the

soil, so a correlation between 6'8~~0,,,,, and 6'8~,H20) would not even be expected.

However, as in the fail, the depleted 6"0,, values suggest at least some of the sulfate

was derived fkom a reduced sulfur source*

Figure 6.5 8'0 in sulfate verses 6"O of water for spring (open cirlces) and fd (closed

circles).

The stable isotope composition of sulfur in sulfate was examined in an attempt to

identify the sources(s) of sulfur. The 6% valws are plotted against sulfate concentrations

in Figure 6.6. For the fklI samples, these data plot in clusters as in Figure 6.4,

representing the three reaches of Nose Creek: 1) upstream of Airdrie, 2) between Airdrie

and Calgary, and 3) withh Calgary. Unlike Figure 6.4, these data do not defme a muciog

h e , but rather, each mach of the creek has a different source of sulfate. There is ody

one data point upstream of Airdne so it is difficdt to Say if it represents a unique source.

However, the 6% composition of +l% is weli above values typical of surface water in

southem Alberta, but consistent with S 4 emissions during processing of Sour gas.

Emissioas h m the Crossfield gas plant have g4s values near +25%0 (Norman and

Krouse, 1992). Between Airdrie and urban Calgary, the sulfate concentration increases 34

almost Linearly with distance, however the 6 S,, remains relatively constant i t +5%.

This indicates that a single. but uniformly dispersed source of sulfate, is being added

between the two cities during the f d . This source is likely related to the dominant land

use, agriculture. Fertilizer application can be d e d out because it is not common, and the

6% valw of S-based fertilizer sold in this area was determined to be +14%0, higher than

that observed. One possible source is oxidation of organic S in soils. Samples were

collected in the last part of October, near the end of the local harvest. During this time

soils are loose and uncovered. making them susceptible to wind erosion. The high

suspended solid load and brown colour of Nose Creek are consistent with large amounts . of particdates king added. Fennell(1994) examined an area 25 km NW of the Nose

Creek basin that is underlain by the Balzac Till. In this area A-horizon soils typically

have S'~S values in the range of +3 to + 10%~~ The SUs of the sulfate added to Nose

Creek between Airdrie and Calgary (+ 5%) f d s within this range.

t between Airdrie snd Qlgmy a a

e . a between Aiidrie and Caigary

Figure 6.6 6 * ~ versus sulfate concentration for a) spring and 6) fd.

In the f d , the 6% value of sulfate in Nose Creek is -7.7% in Calgary. Using the

calculated increase in volume of Nose Creek as it fiows through Calgary, a combined

mass and isotope balance can be used to calculate the 6% composition of the sulfate

source within Calgary needed to cause the observed change in the 6%- of Nose Creek.

These calculations yield a 6% value of -14.6460 and a sulfate concentration of 4.3 meqA

for water king added from Calgary. The calculated concentration of SO, is significantly

higher than that of the Bow River (Appendix 2). The excess sulfate must be denved fiom

the till and/or bedrock that the groundwater fiows through. The calculated value of the

sulfate (-14%0) is consistent with the average 6 3 4 ~ value of -12.5%0 @=IO) for total S

(pyrite + organic S) in the Balzac till (Fenneli, 1994). This implies that the large flux of

water king added by the City of Caigary is oxiduing reduced forms of sulfur in the till,

which is then mobilized as SO, and transported into Nose Creek via groundwater flow.

This is also observed by Hendry et ai. (1986, 1989) in the in the eastern Bow River B asin.

111

where groundwater in oxidized tüls has anomalously high suifate concentrations relative

to unoxidized tus , and has 6 3 4 ~ values of -9.2560. Hendry et al. (1986, 1989)

demonstrated that in this area, the high sulfate concentrations an related to oxidation of

organic matter in the till.

The s p ~ g samples show a simpler relationship between sulfate concentration and

6% The sample for F U S , upstnam of Air& was lost, so only the trend d o m stream

of Airdrie cm be analysed. There is a progressive decrease in the S4s value of dissolved

sulfate between Airdrie and Calgary, with a concurrent increase in sulfate concentration

(Fig. 6.6). This appears to be a simple mixing relation between a source with 6 3 4 ~ > +

12960 (possibly emissions nom the Crossfield naniral gas processing facility) and a

relatively depleted source. The 634s value of ciissolved sulfate approaches +5% as the

creek reaches Calgary, similar to the fdl samples. This may reflect soluble sulfate king

Ieached fiom soils by spring rains. The fs,, drops 5 % ~ where Nose Creek enters

urban Calgary. This observed çhift in the 6 3 4 ~ is likely the result of r.nixing of three

sources: 1) sulfate in the creek before it reaches the city, 2) sulfate in storm water, and 3)

oxidized sulhir fiom tills in the Calgary m a as observed in the fidl samples. The $s,,,

measured from storm sewer discharge is +13%0. There was no stomi water discharge in

the fall, so the addition in the spring of sulfate in storm sewer discharge, with a relatively 34

enriched isotope composition, would explain why the &op in 6 S, at Calgary is less

signiûcant than in the f d .

CONCLUSIONS

This study shows that in a dry climate. municipalities can add significant amounts of

water to local aquifers. During base flow conditions two pulses of Bow River water (the

municipal water supply) are added to Nose Creek via leaky pipes in the cities of Airdrie

and Calgary. This water increases discharge in the creek 4 fold during base flow, diluting

112

the dissolved inorganics, and thus enhancing water quality in Nose Creek. Munifipal

water accounts for 35% of spring and summer discharge, and up to 7796 of fd and

winter discharge in Nose Creek. In terms of basin scale water budgets, water fiom leaky

pipes has k e n recorded as lost 6rom the river system, however this study illustrates that

at least two thirds of this "lost watei' is eventually renirned to the Bow River via Nose

Creek.

The more positive 6% values above Airdrie suggests that the processing facility that

removes sulfur nom natural gas near Crossfield may be a major source of dissolved

sulfate in the headwaters of the creek. Significant loading of inorganic constituents

occurs in the agricultural area between Airdrie and Calgary. Stable isotope evidence

suggests that oxidation of orgaaic matter in soüs is the primary source of sulfate. Sulfate

relatively depleted in %S is added within Calgary through oxidation of reduced forms of

sulfur (pyrite + organic-S) in tills, by the anthropogenicaliy increased groundwater

recharge.

This study iilustrates how a combined chernical and stable isotope study c m help

elucidate processes controiiing surface water chemistry. However, this work wodd have

been m e r enhanced by measuring discharge at sample sites, thus aiiowing for more

accurate mass balance cdculations.

Conclusions

Controis on the chernistry of the Bow River

Although TDS is relateci to discharge, the source of ions in the headwaten of the nver is

controlled by atmospheric deposition and waterirock interaction. Amiosphenc loaduig can

be a signincant source of some ions in the headwaters of the river (e-g. 50% of K, 17% of

SO,, 1696 of Cl). In terms of water/rock interaction, the input of ions to the river is largely

controiled by dissolution of carbonate and evaporite minerals. Calgary is the most

significant point source input dong the nver. Effluent fiom the sewage treatment plants

loads a signincant amount of Na, K, and Cl to the nver, and minor amounts of SO,.

Dowastream of Calgary, Na and SO, is loaded to the river by ûrigation runoff.

In the headwaters of the basin, sulfate is dominantly denved kom dissolution of

evaporite minerals, with up to 30% derived nom oxidation of suifides. Once dissolved,

sulfate under goes a complex redox history before reaching the river, implying that the

water transporthg sulfate to the river passes through the anoxic zone before becoming

discharge. Downstream of Calgary, sulfate is largely derived h m oxidized sulfides in the

local till. In the summer, sulfate derived from soils cm be a signincant component of

sulfate king added to the river (up to 50%). As in the headwaters, sulfate undergoes a

complex redox history before reaching the nver. SL80 data suggests that after sulfides are

oxidized, they are partially reduced before reactiing the river. This indicates that water

transporthg this d a t e must p a s through the anoxic zone before becoming discharge.

The pCO, of the Bow River is generally eear equiliirium with atmospheric pressures,

particularly in the turbulent headwaters. High p C 4 values are associated with

groundwater discharge. DIC in the river is mainly denved from the weathering of

carbonate rock by soil CO,. As pC0, reaches equiliirium with atmospheric values there is

a partiai isotope equiiibrium of DIC with atmospheric CO,.

Cation exchange reactions exert a strong control on eiement ratios in the river. The

WMg activity ratio is strongly conmIIed by exchange between Ca- and Mg- beidellite.

NaK activity ratios are connolled to a lesser degree by exchange between Na- and K-

beidellite. These activity ratios appear to be inherited signatures of ground water. The

fked element ratios in the river suggest that that both snowmelt and rainfall must pass

through the ground before reaching the river.

The chernical denudation rate for the Bow River at Banff is 678 kghaly. The

denudation rate for the basin as a whole is 340 kgma/y. Loaduig fiom Calgaiy accounts

for 8 to 9% of the mass flux out of the basin in the spring and fall and 25% of the mass

flux in the summer.

Hydrology of the Bow River Basin

Discharge in the f d and winter is fed by groundwater. In contrast, the high discharge

event in the spring is a mixture of 'new' snowmelt and 'old' groundwater displaced into the

river. Summer discharge is fed by sumrner rainfall. Combined geochernical and stable

isotope data indicate that snowmelt and &&il Miow a subsurface path to the river,

flushing pre-existing groundwater into the river system. The groundwater residence time

durhg the spring and summer must be short, the matter of &YS or weeks.

Source of anomalous TDS in Nose Creek

This study shows that in a dry climate, municipalities c m add significant amounts of water

to local aquifers. hiring base flow conditions two pulses of Bow River water (the

municipal water supply) are added to Nose Creek via leaky pipes in the cities of Aircirie and

Calgary. This water increases discharge in the creek 4 fold during base flow. diluthg the

dissolved inorganics, and thus entisncing water quality in Nose Creek. Municipal water

accounts for 35% of spring and summer discharge, and up to 77% of f d and winter

discharge in Nose Creek. Significant loadiag of inorganic constituents occurs in the

agriculaurit m a between Airdrie and Calgary. Stable isotope evidence suggests thaî

oxidation of organic matter in soils is the primary source of sulfate. Sulfate relatively

depleted in 3 4 ~ is added within Calgary through oWdati011 of reduced forms of sulfur

(pyrite + organic-9) in tas, by the anthropogenically increased groundwater recharge.

FUTURE RESEARCH

Several avenues of future research have ken identified in this study. Stable isotope data in

Chapter 3 indicate that the discharge of the Bow River is a mixture of '018 and 'new'

water. By collecting detailed time-series samples of surface, ground, and snowmelt

waters, it would be possible to quant@ the seasonai variations in their relative

contributions to the river. Chapter 3 also indicates that the stable isotope composition of

surface water is a fwiction of rnixiog of two weather systems. By conducting detailed

sampling of surface water and precipitation, east of the Great Divide, it may be possible to

calibrate this relationship. This would make it possible to use temporal variations in 6180

records to examine historical variations in weather patterns in this part of North Amenca.

Chapter 4 examined chernical controls on the Bow River and weathering rates in the

headwaters of the basin. Several data sets, similar CO those used in this snidy, are available

for river basins north of the Bow River. As these basins are underlain by similar

lithologies, it is possible to do comparative studies, examining how colder ciimates m e r

north affect weathering rates.

Several Lines of evidence indicate that the Bow River is almost entirely fed by

groundwater discharge. The application of these results to modeis of runoff generation

need to be tested by conducthg a survey of basins with difterent Lithologies. This would

indicate if the Bow River is a special case due to the dominance of carbonate rock in the

headwaters.

REFERENCES

Abercrombie, H. J. (1989) Water-rock interaction during diagenesis and thermal

recovery, Cold Lake, Aiberta. W.D. thesis, Uaiv. of Calgary, Calgary, Alberta,

Canada, 183 pages.

Amundson, R., O. Chadwick, C. Kendall, Y. Wang, M. DeNiro, Isotopic evidence for

shifts in atmosphenc circulation patterns during the late Quaternary in mid-North

Amenca, Geolugy ,24,23-26,1996.

Atlas of Alberta (1969) University of Alberta Press, Edmonton Alberta, 158 pages.

Berman, R.G.; Brown, T.H. and Greenwd, H.J. (1985) A thermodynamic data base for

minerals in the system Na$-50-Cao-MgO-Fe0-Fe203-AI 203-Si0 22Ti02-H , M O 2 .

Atomic Energy Canada Ltd., Technical Report TR-377,70 pages.

Berner, E.K. and Bemer, R.A. (1987) The global water cycle. Prentice-Hall, New Jersey,

397 pages.

Block, H.; Crosley, R.; Shaw, P. and Donald, D. (1993a) Water quality monitoring in

Banff and Jasper National parks (1973 to 1991), Part 1: Interpretive Report.

Conservation and Rotection, Water Quality Branch, Environment Canada, 74 pages.

Block, H.; Crosley, R. and Shaw, P. (1993b) Water quality monitoring in Banff and

Jasper National parks (1973 to 1991), Part 2: Data Report. Conservation and

Protection, Water Quality Branc h, Envimnment Canada, 370 pages.

Block, H. and Zaal, F. (1988) An assessrnent of the Banff sewage lagoon and its effects

on the Bow River during February 1988. Conservation and Protection, Water Quality

Branch, Enviromnent Canada, 26 pages.

Bluth, G.J.S. and Klump, L.R. (1994) Lithologic and climatologie controls of river

chemistry . Geochimica et Cosmochhica Acta, 58,234 1-2359.

118

Bow River Water Quality Council(1994) Preserving our Iifeline: A report on the state of

the Bow River. Calgary, Alberta, October 1994,98 pages.

Brown, G.W.; Berman, R.G. and Perkins, E.H. (1988) GEO-CALC: A software package

for rapid calculation of stable pressure-tempature-activity phase diagrams using a [BM

or compatible personal cornputer. Cornputers and Geosciences, 14,279-289.

Buhl, D.; Neuser. R.D.; Richter, D.K; Riedel, D.; Roberts, B.; Strauss, H. and Veizer, J.

(1991) Nature and Nurture: Environmental Story of the River Rhine.

Naturwissenschaften ,78,3 37-346.

Campbell, D.H.; Clow, D.W.; Ingersoll, GR; Mast, M.A.; Spahr, NE. and Turk, J.T.

(1995) Processes controlling the chemistry of two snowmelt-dominated streams in the

Roc@ Mountains. Water Resources Research, 31,28 1 1-282 1.

Chariton, S.E.D.; Hamilton, H.R. and Cross, PM. (1986) The limological characteristics

of the Bow, Oldman, and South Saskatchewan nvers (1979-82). Part II, The Primary

Producers. Alberta Environment, Water Quaiity Control Branch, Edmonton, Alberta,

1 10 pages.

Clark, R. (1993) Water: the international crisis. MlT Press, Cambridge, 193 pages.

Claypool, G.E., Holser, W.T., Kaplan, I.R, Sakai, M. and Zak, 1. (1980) The age curves

of sulfûr and oxygen isotopes in marine sulfate and their mutuai interpretation.

Chernical Geology ,28,199-260.

Coleman, M.L.; Sheperd, T.I.; Durham, J.J.; Rouse, J.D. and Moore, G.R. (1982)

Reduction of water with zinc for hydrogen isotopes analysis. Analytical Chemistry,

54,993-995.

Craig, H. (196 1) Isotopic variations in meteoric waters. Science, 133, 1702- 1703.

Cresser, M. and Edwards, A. (1987) Acidification of freshwaters. Cambridge Univ. Ress.

Cross, PM; Hamilton, HB.; and Charlton, S.E.D. (1986) The limological characteristics

of the Bow, Oldman, and South Saskatchewan nvers (1979-82). Part 1, Nutrient and

water chemistry. Alberta Environment, Water Quality Control Branch, Edmonton,

Alberta, 182 pages.

Daly, R.A, Manger, G.E. and Clark, S.P. (1961) Density of rocks. in Handbook of

physicai constants, edited by S.P. Clark, The Geologicd Society of America Mernoir

97,19-26.

Dansgaard, W. (1964) Stable isotopes in precipitation. Tellus, 16,436-468.

Drever, I. 1. (1988) The geochemistry of natural waters, second edition. Prentice Hall,

New Jersey, 437 pages.

Drever, J.I. (1997) Catchent mass balance. in GeochemicaI processes, weathering and

groundwater recharge in catchments, edited by O.M. Saether and P. Caritat, A.A.

Balkema, Rotterdam, 400 pages.

Dincer, T., Payne, B K ; FLorkowski, T.; Martinet, I. and Tongiargi, E. (1970) Snowmelt

runoff from measurements of tritium and oxygen-18. Water Resources Research , 6,

110-124.

Dunne, T. and Black, R.D. (1970) Partial area contribution to storm runoff in a srnail

New England watershed. Water Resources Research, 6(5), 129613 1 1.

Eden, G.F. (1996) Sources of sulpbur in pst-indusmal sediments of Waterton Reservoir,

S.W. Alberta. M.Sc. thesis, University of Calgary, Canada, 147 pages.

Edmond, J.M. (1982) Major ion chemistry of some large chinese rivers. Nature, 298, p.

550-553.

Environment Canada (1990) Historical Streamflow Summary, Alberta. Inland Waters

Directorate, Water Resources Branch, Water Survey of Canada, Ottawa, Canada, 629

pages.

120

Environment Canada (1983) Sampling for water quality. Inland waters directorate,

Water resources branch, Water survey of Canada, Ottawa, Canada, 55 pages.

Epstein, S. and Mayeda, T.K. (1953) Variation of "0 content of waters fiom namal

sources. Geochimica Cosmochimica Acta, 4,2 13-224.

Ferne& J.W. (1994) Source and distribution of sulfate and associated organics at a sour

gas plant in southem Alberta. M.Sc. thesis, Univ. of Calgary, Calgary, Alberta,

Canada, 192 pages.

Fenneil, J.W.; Bentley, L.R.; Lyness, L.S. and Anderson, P. (1994) Source and

distn'bution of sulphate in groundwater near a sour gas plant in southem Aiberta 4th

Aanual Conference on groundwater and soil remediation, Sept. 21-23, Calgary, 529-

543.

Flowers, G.C. (1986) Computation of thermai dynamic propdes of reactions involving

rninerals and aqueous solutions with the aid of a personal cornputor. Cornputors and

Geosciences , 12,36 1-380.

Fritz, P.; Cherry, I.A.; Weyer, K.U. and Sklash, M. (1976) Storm runoff malyses ushg

environmental isotopes and major ions. in Interpretation of Environmental Isotope and

Hydrochemical Data in Ground Water Hydrology. Vienna: International Atornic

Energy Agency, Viema, 1 1 1 - 13 1.

Garrels, R.M. and MacKenzie, F.T. (1967) Ongin of the chexnical composition of some

springs and Iakes. in Equilibrium concepts in natural water systems. American

Chemical Society, Advances in chemistry series, 67,344~~.

Green, R. (1972) Geological map of Alberta. scaie 1:267,000, Alberta Geological

Survey, Nanual Resources Division.

Harris, S.A. (1986) Permafrost distribution, zonation and stability dong the eastem

ranges of the cordiliera of North Amenca. Arctic, 39,29-38.

121

Hendry, ML; Krouse, H.R. and S h a h , M.A. (1989) Interpretation of oxygen and sulfur

isotopes from dissolved sulphates in tas of southem Alberta, Canada. Water

Resources Research, 25(3), 567472.

Hendry, M.J.; Cherry, J.A. and Wallick, El. (1986) Origin and d i s t r i i o n of sulfate in

a fiactured tili in southem Alberta, Canada. Water Resources Research, 22(1), 45-6 1.

Hewlett, J.D. and Hibbert, A.R. (1967) Factors affécting the response of small watersheds

to precipitation in humid areas. in International Symposium on Forest Hydrology

1965 (W.E. Sopper and H.W. Ld, eds.), Pe~sylvania State University, Pergamon

Press, New York, 275-290.

Hitchon, B. and Krouse, H.R. (1972) Hydrogeochemistry of the surface waters of the

Mackenzie River drainage basin, Canada - III, Stable isotopes of oxygen, carbon and

sulphur. Geocliimica et Cosmuchimica Acta, 36,1337 - 1357.

Holland, H.D. (1978) The chemistry of the atmosphere and oceans. Wiley, New York.

Horton, R.E. (1933) The role of infiltration in the hydrologie cycle. Transactions

American Geophysical Union, 14,446460.

Hutcheon, LE. (1989) Application of chernical and isotopic analyses of fluids to

problems in sandstone diagenesis. in Short course in burial diagenesis handbook (LE.

Hutcheon, ed.), Mineralogicd Association of Canada, 15,279-306.

Ingraham, NL. and Taylor, BE. (1986) Hydrogen isotope study of large scale meteoric

water transport in northem Caüfornia and Nevada. Journal of Hydrology, 85, 183-

197.

Ivanov, M.V. (1983) The sulphur cycle in continental reservoirs. in The GLobal

Biogeochemical Sulphur Cycle, SCOPE Report 19, edited by M.V. Ivanov and J.R.

Freney, John Wiley, New York, 33 1-356.

122

KLivokiotis, P. and Thomson, R.B. (1986) The climate of Calgary. Climatological

Studies No. 38, The climate of Canadian cities No. 3, Environment Canada,

Atmosphenc Environment Service, Ottawa, Canada, 52 pp..

Krouse, H.R. and Grinenko, V.A. (1991) Stable Isotopes: Natural and Anthropogeoic

Suiphur in the Environment. SCOPE Report 43, John Wey and Sons, New York, 440

P%=-

Krouse, HP.; Holecek, G. and Steppuhn, H. (1978) Detecting snowmelt in streamfhw

by D/H and 160 abundances in two western Canadian basins. in Stable isotopes in

the Earth Sciences (ed. B.W. Robinson), DSIR Bulletin 220, New Zealand Department

of Scientific and Indusrrial Research, New Zealand.

Lasaga, A.C.; Soler, J.M.; Ganor, J.; Burch, T.E. and Nagy, K.L. (1994) Chernical

weathering rate laws and global geochemical cycles. Geochimica et Cosmochimica

Acta ,SB, 2361-2386-

Lau, Y.K. and Das, N.C. (1985) Precipitation quality monitoring in Alberta. PNWIS-

APCA 1985 &muai meeting, Calgary, Alberta, November 13- 15.

Legge, A.H. (1988) The present and potentiai effects of acidic and acidifjhg air

poilutants on Alberta's EnWoument. Crtical Point 1, 1988. Final Report. Prep. for the

Acid Deposition Research Program by the Biophysics Research Group, Kananaskis

Cenm for Enviroimental Research, The University of Calgary, Calgary, Alberta, 664

pages.

Lloyd, R.M. (1968) Oxygen isotope behavior in the sulfate water system. Journal of

Geophysical Research ,73,6099-6 1 10.

Longbelli, A. and Edmond, LM. (1983) Isotope geochemistry of the Amazon Basin: A

recomaissance, Journai of Geophysical Research, 88,3707-37 17.

123

Martinec, I.; Siengenthaier, U.; Oescbger, H. and Tongiorgi, E. (1974) New insights into

nuisff mechanism by environmental isotopes. in Isotope techniques in groundwater

hydrology, V1, Vienna: International Atomic Energy Agency, Vienna, 129-143.

Mayer, B.; Fritz, P.; Prietzel, J. and Krouse, H.R. (1995) The use of stable sulfur and

oxygen isotope ratios for uiterprethg the mobility of sulfate in aerobic forest soils.

Applied Geochemistry ,IO, 16 1- 173.

Meybeck, M. (1987) Global chemical weathering of surficial rocks estimated h m river

dissolved loads. American Journal of Science, 401-428.

Meybeck, M. and Helmer, R (1989) The Quaiity of Rivers: fkom pristhe stage to global

pollution. Palueogeography, Palaeoclimatology, Palaeoecology, 75,283-309.

Ming-hui, H; Siallard, R.F. and Edmond, J.M. (1982) Major ion chemistry of some large

Chinese rivers, Natute, 298,550-553.

Mook, W.G.; Bommerson, J.C. and Staverman, W.H. (1974) Carbon isotope

fractionation between dissolved bicarbonate and gaseous carbon dioxide. Eurth

Planet. Sci. Lett., 22, 169- 176.

Mossop, G.D. and Shetsen, 1. (compilers) (1994) Geological atlas of the Western Canada

Sedimentary Basin. Canadian Society of Peaoluem Geologis ts and Alberta Researc h

Council, 5 10 pages.

Moran, S.R. (1986) Su15cial geology of the Calgary urbao area. Alberta Research

Council, Terrain Sciences Department.

Myric, R.H. (1992) Summary of air quality moni to~g in Alberta 1992. Air assessrnent

section, Environmental Qualit. Monitoring Branch, Environement Assessrnent

Division, Alberta Environment Protection, 25 pages.

Norman, A. and Krouse, H.R. (1992) Stable isotope studies of atmospheric sulphur:

cornparison of Calgary, Canada and Bermuda. in Critical issues in the global

environment, vol. 2, Atmospheric Chemistry , Air and waste management association,

124

Pittsburgh, 16 pages.

Norton, D. (1974) Chernical mass transfer in the Rio Tanama system, west-central

Puerto-Rico. Geochmtica et Cornochimica Acta, 38,267-277

Ozoray, G.F. and Barnes, R. (1977) Hydroiogy of the Calgary-Golden are4 Alberta.

Aiberta Researçh Council Report 77-2,38 pages.

Pawellek, F. and Veizer, 1. (1994) Catbon cycle in the upper Danube and its tributaries:

6I3C,,, constraints . Isr. Journui of Earth Science, 43, 1 87- 194.

Postel, S. (1993) Facing water scarcity. in State of the world 1993, edited by L. Starke,

W. W. Norton and Company, New York, 22-4 1.

Pnce, R.A. and Mountjoy, E.W. (1972a) Banff (es t and West halves), 150,000 scale,

Geological S w e y of Canada, Maps No. l294A and 1295A.

Price, R.A. and Mountjoy, E.W. (1972b) Mount Eisenhower (east and West halves),

150,000 scale, Geological Survey of Canada, Maps No. 1296A and 1297A.

Price, R.A. and Mountjoy, E.W. (1978) Hector Lake (east and West halves), 150,000

scale, Geological Survey of Canada, Maps No. 1463A and 1464A.

Price, R.A. and Mountjoy, E.W. (1979) Lake Louise (east and West halves), 150,000

scale, Geological S w e y of Canada, Maps No. 1476A and 1477A-

Rabinovich, A.L. and Grinenko, V.A. (1979) Sulfate sulfur isotope ratios for USSR river

water. Geokhimja, No. 3,441-454.

Reinalt, E.R. (1970) On the role of orography in the precipitation regime of Alberta.

Albertan Geogmpher, 6,4548.

Richey, J.E.; Devol, A.H.; Wofsy, S C ; Victoria, R. and Riberio, M.N.G. (1988)

Biogenic gases and the oxidation and reduction of carbon in Amazon River floodplain

water, LimoL Oceanographer., 33,55 1-56 1.

Riley and Chester ( 197 1) Introduction to marine chemistry . Academica Press.

125

Rodhe, A. and Kilüngtveit, A (1997) Catchment hydolgy. in Geochemical processes,

w e a t h e ~ g and groundwater recharge in catchments, edited by OM. Saether and P.

Caritat, A.A. Badkema, Rotterdam, 400 pages.

Rozanski, K.; S o ~ t a g , C. and Munnich, K.O. (1982) Factors controlling the stable

isotope composition of Eumpean precipitation. Tellus, 34, 142-150.

Salati, E.; Dail"Olio, A.; Matsui, E. and Gat, J.R. (1979) Recycling of water in the

Amazon Basin: An isotopic study. Water Resources Research, 15, 1250- 1258.

Sarh, MM.; Krishnaswami, S.; Dilli, K.; Somayajuia, B.L.K. and Moore, W.S. (1989)

Major ion chemistry of the Ganga-Brahmaputra river system: Weathering processes

and fluxes to the Bay of Bengal. Geochimica et Cosmochmtica Acta, 53,997-1009.

Schlesinger, W.H. (199 1) Biogeochemistry - Aaalysis of global change. Academic Press,

New York, 443 pages.

Schwarcz, H.P. and Cortecci, G. (1974) Isotopic analyses of spring and Stream water

sulfate from the Italian Aipes and Apenoines. Chernical Geology, 13,285-294.

Shakur, A. (1982) 3 4 ~ and "O variations in terrestriai suiphates. Ph.D. thesis, Univ. of

Caigary, Calgary. Aiberta, Canada, 229 pages.

Sklash, M.G. and Farvolden, RN. (1979) The role of groundwater in storm runoff.

Joumai of Hydrology, 43,4565

Sosiak, A. (1996) Bow River synoptic surveys 1994-1995, preliminary evaluation of

resuits. Water Management Division, Alberta Environmentai Rotection, 103 pages.

Staiiard, R.F. and Edmund, JM. (1981) Geochemistry of the Amazon 1. Precipitation

chemistry and the marine contribution to the dissolved load at the time of peak

discharge. Journal of Geophysical Research, 86, No. C 10,9844-9858.

Staiiard, R.F., and Edmund, JM. (1983) Geochemistry of the Arnazon 2. The influence

of geology and weathering envkonemnt on the dissolved load. Journal of Geophysical

Reseurch ,88, No. C 14,967 1-9688.

126

Taylor, BE.; Wheeler, M.C. and Nordstrom, D.K. (1984) Stable isotope geochemistry of

acid mine drainage: Experimental oxidation of pyrite. Geochemica et Cosmochimica

A m T 48,2669-2678.

Trembaczowski, A. and Halas, S. (1993) Sulphur isotopes in sulphates in natural waters:

( 1) surface waters of relatively unpolluted terraios. Isotopenpr~~~'s, 28,2 15-228.

van Donkelaar, C.; Hutcheon, I.E. and Krouse, H R (1995) 6%. 8180, 8 D in shallow

groundwater: tracing anthropogenic sulfate and accompanyhg groundwaterlrock

interactions. Wuter, Air and Soi1 Pollution, 79,279-298.

Van Stempvoort, D.R.; Hendry, M.J.; Schoenau, J.J. and Krouse, H.R. (1994) Sources

and dynamics of sulfur in weathered till, western glaciated plains of North Arnerica.

Chernical Geology ,111,35-56.

Van Stempvoort, D.R.; and Krouse, H.R. (1994) Controls of 6180 in sulfate: Review of

experimental data and application to specific environrnents. in Environmental

geochemistry of sulfide oxidation, edited by C.N. Alpes and D.W. Biowes, ACS

Symposium Series 550,446480.

von Grafenstein, U.; Erlenkeuser, H.; Müller, I.; Trimborn, P. and Alefs, J. (1996) A 200

year mid-European air temperature record preserved in lake sediments: An extension

of the 6180p-air temperature relation into the past. Geochemica et Cornochimica Acta,

21,4025-4036.

White, C. (1985) Wildland fires in Banff National Park 1880- 1890. Occasional paper No.

3, National Parks Branch, Parks Canada, Environement Canada, 10 pages.

White, A.F., and Blum, A.E. (1995) Effects of chnate on chernical weathering in

watersheds. Geochemica et Cosmochimica Acta, 59, 172% 1747.

Williams, M.W.; Brown, A.D. and Melack, LM. (1993) Geochemical and hydrologie

controls on the composition of surface water in a high-elevation basin, Sierra Nevada,

127

California. Limnol. Oceanographer, 38,775-797.

Williams, M.W.; Yang, D.; Liu, F.; Tudc, I. and Melack, J.M. (1995) Controls on the

major ion chemistry of the Üriimqui River, Tian Shan, People's Repubiic of China.

Journal of Hydrdogy, 172,209-229.

Wiwchar, B.; Perkins, E.H. and Gunter, W.D. (1988) SOLMlNEQ.88 PCISHELL

manual. Alberta Research Council, Oil sands and hydrocarbon recovery department.

Yanagisawa, F. and Sakai, H. (1983) Precipitation of SO, for sulphur isotope ratio

measurements by thermal decomposition of BaS0,-V,O,SiO, mixtures. Anufytical

Chemistry, 55,9859987.

Yang, C.; Telmer, K. and Veizer, 3. (1996) Chemicai dynamics of the 'St. Lawrence"

nverine system: m), ,6 '6,, 6'3Ç,1c, 6% &. and dissolved ' ' ~ r / ~ ~ r . Geochemica

et Cosmachimica Acta, 60, 85 1-866.

Yonge, C.J.; Goldberg, L. and Krouse, H.R. (1989) An isotope study of water bodies

dong a traverse of southwestern Canada. Cunadian J. Hydrol., 106,245 - 255.

Zeman, L.I. (1978) Mass balance mode1 for calculation of ionic input loads in

atmospheric fdout and dishcarge from a mountainous basin. Hydrol. Sci Bull., 23,

103-1 17,

Sample locations

Distance Station Station Name Location h m Access

Number Comfluence (km)

Bow Rivet

BR1 Lake Louise Trans Canada Highway, West 575 wading of Lake Louis

BR2 Banff Banff townsite 510 bridge

BR3 Carmore Canmore bridge 486 bridge

BR4 Morely Morely bridge 435 bridge

BR5 Cochrane Highway 22 405 bridge

BR6 Bowness Nose Hill Drive, Calgary 378 bridge

BR7 Edworthy Pedestnan bridge at Edworthy 367 bridge Park, Calgary

BR8 LRT Pedestrian bridge below the 365 bridge noahwest LRT liae, Calgary

BR9 Bonny Ogden Road, Calgary 355 bridge

BR10 HW22X Highway 22X bidge 339 bridge

BR1 1 Carseland Highway 24 287 bridge

BR12 Cluny Highway 842 214 bridge

BR13 Bow City Highway 539 110 bridge

BR14 KW36 Highway 36 77 bridge

BR15 Hays Highway 875 41 bridge

Tributaries

BT1 Pipestone River Lake Louise townsite

B Spray River Banff golf course

BT3 Kananaskis River Highway 1

574

509 wading

459 bridge

Distance h m Access

Comfluence

BT4 Ghost River Highway 940 425 wading

BTS Jumping Pounnd Highway 1 407 wading Creek

BT6 Elbow River 9th Street bridge, Calgary 362 bridge

BT7 Nose Creek Calgary Zoo parking lot 360 wading

BT8 H i g h w d River Highway 552 3 15 bridge

Appendix 2 Chernical and stable isotope data for the Bow River (BR) and tributaries (BT)

Lake Louise Banff Canmore More1 y Cochrane Bowness Edworthy LRT Bonny HW22X Carsland Cluny Bow City HW36 Hays Pipestone River Spray River Kananaskis Ghost River Jumping Pound Elbow River Nose Creek Highwood River

4.0 4.3 6.6 8.3

1 1 *4 9.1

10.7 9.2 8.1 7.5 6.9

10.2 9.9 0.0

10.1 no sample

4.6 9.7 9.1 3.6

11.1 8.1 6.6

Appendix 2 (continued) Chernical and stable isotope data for the Bow River (BR) and tributaries (BT)

FaII 1993

Appendix 2 (continwd) Chernical and stable isotope data for the Bow River (BR) and tributaries (BT)

Winter 1994

Lake Louise Banff Canmore More1 y Cochrane Bowness Edworthy LRT Bonny HW22X Carsland Cluny Bow City HW36 Hays Pipestone River Spray River Kananaskis Ghost River Jumping Pound Elbow River Nose Creek Highwood River

0.0 0.0 2.2

no sample 0.5

-0.1 O. 1 0.5 0.6 0.2 0.6

no sample no sample no sample no sample no sample

0.0 2.1

no sample no sampie

0.4 no sample no sample

4.09 3.17 4.65

3.98 5.18

N.A. 3.62 3.81 3.50 3.77

8.64 2.53

NvA,

Appendix 2 (continueà) Chernical and stable isotope data for the Bow River (BR) and tributaries (BT)

Winter 1994

BR01 -1 0193 BR02-10193 BR03-10193 BR04-10193 BR05-10193 BR06-10193 BR07-10193 BROS-1 0193 BR09-10193 BR1 0-1 0193 BR1 1-10193 BR1 2-1 0193 BR1 MOI93 BR1 4-1 0193 BR1 5-1 OB3 BTOI -1 0193 BT02 - 1 0193 BT03 -1 0193 BT04 - 1 0193 BT05 -1 0193 BT06 - 1 0193 BT07 - 1 OB3 BTOB - t 0193

13.2 15.3 10.5

no sarnple 14.8 14.7 14.6 14.9 14.9 15.4 14.5

no sample no sample no sarnple no sampie no sample

18.7 t 0.5

no sarnple no sample

18.5 no sample no sample

Appendix 2 (continued) Chemical and stable isotope data for the Bow River (BR) and tributaries (BT)

Spring 1994

Appendix 2 (continuai) Chernical and stable isotope data for the Bow River (BR) and tributaries (BT)

Summer 1994

Lake Louise Banff Canmore Morel y Cochrane Bowness Edworthy LRT Bonny HW22X Carsland Cluny Bow City HW36 Hay s Pipestone River Spray River Kananaskis Ghost River Jumping Pound Elbow River Nose Creek Highwood River

-20.22 -3.80 19.92 -4.81 1.56 -1 7.48 -4.03 13.13 -1 .O4 2.22 -1 9.83 -7.88 13.74 5.26 2.67 -1 9.90 -3.65 13.41 3.07 IOS~

APPENDIX 3 Chernical data for springs and ground water

T Ca M g Na K HCO, S 0 4 Cl Location pH O C m@ mJI mg/l mfl m@i mpli mgll

- - - - - -- - - - -

Springs

Vermilian Lk 8.4 20.1 74.3 23.5 27.5 2.3 157 136.2 55.2

Canmore Ck 8.4 11.1 117 41.8 6.2 .9 252.4 213.6 2.1

Many Springs 8.6 1 1.4 77.4 24 1.3 -5 169.5 114.4 2.1

Yamanuska 6 67.4 15.9 13.9 1.2 292.1 7.2 5 -2

Big Hill 8.4 7.3 71.4 32-6 7.9 2 -9 369 a.a. 7-2

SiIverSprings 7.8 n.a. 78.6 49.2 45.4 3.1 469 82.2 15.3

Shallow groundwater in Banff National Park (from Parks Canada)

Appendix C Chernical and stable isotope data for Nose Creek (NC)

north Airdrie Airdrie North crossing South Crossing Country Hills 32nd Ave. NW C W Y Centre Street

Spring 19%

north Airdrie Airdrie North crossing South Crossing Country Hills 32nd Ave. NW Cakary Centre Street

~ ~ ~ g ~ w X ~ o m o r r n ~ c u - CU r r r r r r