Light, Secchi, Weather and Miscellaneous Comments

Liz Ely, Ira Smith, and

Margaret Soulman

secchi depth for varous lakes

0

5

10

15

Lakes

De

pth

(m

)

Arbutus

Deer

Wolf

Green

Skaneateles

Onondaga

Oneida

ARBUTUS & ONEIDA LAKES

0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

5

0 50 100 150 200 250 300 350 400 450

LIGHT

DE

PT

H(m

) DECK ARBUTUS

SPHERICAL ARBUTUS

DECK ONEIDA

SPHERICAL ONEIDA

GREEN LAKE

0

5

10

15

20

25

0 200 400 600 800 1000 1200 1400

LIGHT

DE

PT

H (

m)

DECK

SPHERICAL

SKANEATELES LAKE

0

10

20

30

40

50

60

0 200 400 600 800 1000 1200 1400 1600

LIGHT

DE

PT

H(m

)

DECK

SPHERICAL

DEER LAKE

0

0.5

1

1.5

2

2.5

3

3.5

0 100 200 300 400 500 600 700

LIGHT

DE

PT

H (

m)

DECK

SPHERICAL

Wolf Lake - Deck Cell Correction Example

Light Intensity (moles of quanta m-2 sec-1)

0 200 400 600 800 1000 1200 1400 1600 1800 2000

Dep

th (

met

ers)

0

2

4

6

8

10

DECK vs DEPTH SPHERICAL vs DEPTH corrected spherical vs DEPTH

Green Lake Light Extinction Calculation

0

5

10

0 5 10 15 20 25

Depth

Ln (l

ight

)

r2=0.88

Arbutus Light Extinction Calculation

0

2

4

6

0 1 2 3 4 5

Depth

Ln

(Lig

ht)

r2=0.999

Light Extinction Coefficient

0

0.2

0.4

0.60.8

1

1.2

1.4

Arbut

usDee

r

Green

Oneida

Onond

aga

Skane

ateles W

olf

Lake

Lig

ht

Ex

tin

cti

on

Co

eff

icie

nt

(light extinction coefficients fixed now)

Secchi and Light Extinction Coefficient Comparison

Onondaga Oneida Deer Arbutus Wolf Green Skaneateles

Y D

ata

0

2

4

6

8

10

12

Light Extinction Secchi

Secchi versus Light Extinction

Secchi Depth

0 2 4 6 8 10 12

Lig

ht

Ext

inct

ion

Co

effi

cien

t

0

1

2

r2=0.90

YSI Group

Chris Hotaling

Nicole Hotaling

Rosa

YSI data

• Five parameters:– Depth, temp., pH, conductivity,

dissolved oxygen

• Measured on multiprobe• Graphed actual data (adjusted depth)

YSI Parameters

• Depth – Basin morphometry: nutrients, chemistry, heat

balance, productivity, habitat

• Temperature– stratification, organism distribution

• pH – measure of H+ concentration– chemical forms, organism response

YSI Parameters

• Conductivity – measure of ability to carry an electric current– Indicates ionic content, basin geology

• Dissolved Oxygen – Respiration, chemical form

Temperature (C)

0

5

10

15

20

25

30

35

40

45

50

5 7 9 11 13 15 17 19

dept

h (m

)

Deer

Wolf

Arbutus

Onon

Oneida

Green

Skan02

pH

0

5

10

15

20

25

30

35

40

45

50

6 6.5 7 7.5 8 8.5 9 9.5 10

dept

h (m

)

Deer

Wolf

Arbutus

Onon

Oneida

Green

Skan02

Conductivity (uS/cm)

0

5

10

15

20

25

30

35

40

45

50

0 10 20 30

dept

h (m

) Deer

Wolf

Arbutus

Oneida

Conductivity (uS/cm)

0

5

10

15

20

25

30

35

40

45

50

1400 1500 1600 1700 1800 1900 2000 2100 2200

dept

h (m

)

Onon

Green

DO (mg/L)

0

5

10

15

20

25

30

35

40

45

50

0 5 10 15 20

dept

h (m

)

Deer

Wolf

Arbutus

Onon

Green

Skan02

%DO

0

5

10

15

20

25

30

35

40

45

50

0 20 40 60 80 100 120 140 160 180 200

dept

h (m

)

Deer

Wolf

Arbutus

Oneida

Green

Whole Lake

• Adirondack lakes – shallow, lower pH (but not acidic), low conductivity, moderate DO

• Green, Skaneateles – deep, pH/cond reflects watershed geology

• Onondaga, Oneida – productive, pH/cond reflect different geology

What else?

• Could measure:– Specific conductance, salinity, redox potential,

recent weather patterns

• Error?– Zero depth, Onon/Oneida depths

Nutrients

Sampling techniques:

• strata depths were determined from temperature profile

• water samples were obtained using Kimmerer bottle

• three 1 L bottles were filled (1 each from epi, meta, hypo)

Analysis:

• phosphorus, nitrogen, silica

• dissolved nutrients is target, but acid-digestion in P and Si analyses may release nutrients from particles if sample is not filtered, leading to over-estimate of dissolved concentration

Phosphorous• The key controlling nutrient in freshwater systems

• Adding Phosphorous to a system increasing its productivity

• Deeper lakes will dilute Phosphorous

• In the presence of oxygen Fe3+ binds with and ‘traps’ phosphate

• If the hypolimnion is anoxic phosphorous will be released

• Rooted aquatic macrophytes take phosphorous up from sediments and releases it into water

Sources of Phosphorous

• Precipitation (dust in the air)

• Groundwater (small) adsorbs to soil particulates

• Surface runoff

• Weathering of calcium phosphate minerals (e.g.. Apatite)

- slow process

Anthropogenic Sources

• Point Source – sewage, industry, faulty septic systems, urban runoff

• Non-point Source – agriculture, animal waste

Phosphorous

>100Hypereutrophic

30-100Eutrophic

10-30Mesotrophic

5-10Oligotrophic

<5Ultra-Oligotrophic

Total Phosphorous ( g/L)

Lake Productivity

Eutrophication – increased growth of biota of lakes and the rate of productivity is higher than would have occurredwithout any disturbances.

Phosphorous – Total Phosphorous

Total Phosphorus

0

5

10

15

20

25

30

0 2 4 6 8 10 12 14 16

Concentration (umol/L)

Dep

th (

m)

Green

Onondaga

Oneida

Wolf

Arbutus

Deer

Phosphorous – Total Phosphorous

Lower Values of Total Phosphorus

0

2

4

6

8

10

0 1 2 3 4 5 6

Concentration (umol/L)

Dep

th (

m)

Green

Onondaga

Oneida

Wolf

Arbutus

Deer

Phosphorous – Total Dissolved Phosphorous

Total Dissolved Phosphorus

0

5

10

15

20

25

30

0 1 2 3 4 5

Concentration (umol/L)

Dep

th (

m)

Green

Onondaga

Oneida

Wolf

Arbutus

Deer

Phosphorous – Total Dissolved Phosphorous

Lower Values of Total Dissolved Phosphorus

0

2

4

6

8

10

0 0.2 0.4 0.6 0.8 1

Concentration (umol/L)

De

pth

(m

)

Green

Onondaga

Oneida

Wolf

Arbutus

Deer

Phosphorous Conclusions• Onondaga Lake considered hypereutrophic and had a

much higher phosphorous content than the other lakes contributing to noxious algal blooms

• Oneida has been eutrophic for over 350 years and is the next highest phosphorous values next to Onondaga Lake although there is a very large gap

• Wolf Lake is oligotrophic with plenty of oxygen throughout, this allows the phosphorous to be trapped by Fe3+ in the hypolimnion

Phosphorous Conclusions• Arbutus Lake near oligotrophic, and followed expected

pattern for P

• Deer Lake - P values seem to do the opposite of expected - possibly due to errors in sampling, such as brushing bottom sediments during sampling

• Green Lake is very oligotrophic, although the phosphorous concentrations follow those of a lake with anoxic bottom waters due to it being meromictic. Nutrients are entrained in bottom layers, so little in upper layers.

Lake Comparisons: Chemistry

Nitrogen

Sources of Nitrogen in the Water

• Inorganic nitrogen– Nitrate– Ammonia

• Organic nitrogen– Organisms– Dissolved Organic

General Nitrogen Distribution Within Water Column

• Surface waters– Increased organic nitrogen

• Buildup of phytoplankton– Decrease inorganic nitrogen

• Assimilated by phytoplankton

• Bottom waters – Increased organic and inorganic

• Lack of phytoplankton to assimilate inorganic• Settling of organic material• However, denitrification can convert inorganic to N gas

Total Nitrogen

0

5

10

15

20

25

30

0 20 40 60 80 100 120 140 160

Concentration (umol/L)

De

pth

(m

) Green

Onondaga

Oneida

Wolf

Arbutus

Deer

Lower Values of Total Nitrogen

0

2

4

6

8

10

0 5 10 15 20 25 30

Concentration (umol/L)

De

pth

(m

) Green

Onondaga

Oneida

Wolf

Arbutus

Deer

Total Dissolved Nitrogen

0

5

10

15

20

25

30

0 25 50 75 100 125 150 175

Concentration (umol/L)

De

pth

(m

)

Green

Onondaga

Oneida

Wolf

Arbutus

Deer

Lower Values for Total Dissolved Nitrogen

0

1

2

3

4

5

6

7

8

9

10

10 12 14 16 18 20 22 24

Concentration (umol/L)

De

pth

(m

)

Green

Onondaga

Oneida

Wolf

Arbutus

Deer

Nitrogen Conclusions

• Lakes show different nitrogen distributions– Cyanobacteria: present or absent?

• Nitrogen fixers– Elevate organic nitrogen levels

» Epilimnion or metalimnion (stratification effects)

– Turnover• Nitrogen levels tend toward uniform

– Denitrification in bottom waters• Due to low oxygen in bottom waters (Eutrophic?)

Silica in the Water Column

Dissolved:- silicic acids

Particulate:- diatoms- organic complexes- adhered to inorganic particles

Silica in the Water Column

Major source: - degraded alumino-silicate minerals

Solubility:- increased by humic compounds

Typical Profile:- biogenic reduction of dissolved silica in the epilimnion during early summer, and low epilimnetic silica maintained throughout summer

Cause: - intensive assimilation of silica by diatoms, and a greater rate of diatom sedimentation than rate of silica replenishment from sources

Expected silica profile (Wetzel)E

Silica

0

5

10

15

20

25

30

0 10 20 30 40 50 60 70

Concentration (umol/L)

Dep

th (

m)

Green

Onondaga

Wolf

Arbutus

Deer

DISSOLVED SILICA: Sep-Oct, 2003

Annual Cycle:

Lake inDenmark(Wetzel)

Why Opposite of Expected Silica Trends?

• Possible explanations?

- diatom bloom in epilimnion after turnover?

- samples were not sufficiently filtered, so [Si] reflects acid-dissolved diatoms as well as dissolved silica?

- runoff after rains from soils high in siliceaous materials

- or, data were recorded in reverse order