2

A study on the seasonal variation of uranium in groundwater of hard rock

terrain in south India

Prof. S. ChidambaramDepartment of Earth Sciences

Annamalai University

The element uranium (U) is distributed throughout the crust of the earth in trace quantities in all the rock types.

It is rich in acid igneous rocks like granites, syenites etc. while depleted in basic and ultra-basic rocks.

The average concentration of U in Earth crust is 2.7 ppm (Siegel and Bryan 2004).

In nature, U generally occurs in tetravalent state as insoluble species and hexavalent state as highly soluble species.

Uranium concentrations in most of the groundwaters are generally low, typically in the range of 0.1 to1 ppb, but it can reach several tens to hundreds of ppb when it reacts with U rich minerals in the aquifers.

Uranium concentration in groundwater is important in understanding the radiological impact valuation to secure the standard of life.

No. Types Typical examples % of total deposits

% of totaluranium resources

1 Quartz-Pebble-Conglomerate type

Witwatersrand area, South Africa 3.8 13.0

Elliot Lake region, Canada

2 Unconformity related Athabasca basin, Canada 4.0 33.0

Alligator river basin, Australia

3 Vein type (hydrothermal or disseminations)-structurally controlled / stratabound

Beverlodge, Uranium City, Canada 23.7 9.0

Massif central, France

Schwatzwalder, USA

4 Sandstone type Oklo, Gabon 42.8 18.0

Grants, USA

Niger

Kazakhstan

5 Breccia complex Olympic Dam, Australia 0.2 17

6 Intrussive Rossing, Namibia 2.2 10.0

Bancroft, Canada

7 Volcanic Jiang Xi, China 7.4

Michelin, Canada

8 Metasomatites Ross Adams, USA 2.1

Kriverozhsky-Zheltye, Ukraine

9 Collapse breccia type Orphan lode and Hack Canyon, Arizona, USA

1.7

10 Phosphorite Montpelier, USA 1.7

11 Black shale Chattanooga, USA 1.5

Ranstad, Sweden

12 Lignite Slim Buttes, South Western Williston Basin, USA

3.8

Czech Republic

13 Surficial / Fluvial valley fill Yeelerie, Australia 2.7

14 Metamorophic Forstau, Austria 2.4

15 Others  

A simplified list of different uranium deposits with examples along with the share of such deposit types in the uranium inventory (after Dhalkamp, 1993

and IAEA, 1996)

Time bound characteristics of Uranium deposits (Modified after Simov 1979)

Uranium exploration, spanning over 50 years within the 3.28 million square km area in the Indian shield has brought out the presence of uranium deposits of all major types in different geological settings.

Distribution of Indian Uranium resources

S.No Country Range of Uranium

concentration in water

(µg/L)

Average

value

(µg/L)

Reference

1 Ontario, Canada 0.05-4.21 0.40 OMEE (1996), Moss et al. (1983)

and Moss (1985)

2 New York, USA 0.03-0.08 - Fissene and Welford (1986)

3 USA - 2.55 US EPA (1900,1991)

4 Argentina 0.04-11.0 1.3 Bomben et al. (1996)

5 Japan - 0.0009 Nozaki et al. (1970)

6 Norway 18% samples had U

concentration

in excess of 20 ppb

-- Frengstad et al. (2002)

7 New Mexico >20 ppb - Hakonson-Hayes et al. (2002)

8 Central Australia >20ppb - Hostetler et al. (1998)

9 Jordan 0.04-1400 2.4 Gedeon et al. (1994) and Smith et

al. (2000)

10 Kuwait 0.02-2.48 - Bou-Rabee (1995)

11 United States 0.01-652 - Drury et al. (1981), Edgington(1965) and

Cothern and Lappenbusch (1983)

12 South Greenland 0.5-1.0 - Brown et al. (1983)

13 Turkey 0.24-17.65 - Kumru (1995)

14 India 0.08-471.27 - Talukdar et al. (1983), Bansal et al. (1985,1988),

Singh et al.(1993,2003) and Mehra et al. (2007)

Worldwide Uranium concentration in water

Geological map of India (GSI 1995) showing Uranium deposits/occurrences

Study area map with classification of blocks (CGWB 2007)

Era Age Formation LithologyQuaternary Recent Alluvium,

LateriteSand, Clay, Silt, Kankar pebbles and laterite

UNCONFORMITYAzoic Granites with Pegmatites and

Quartzites, Granite, Charnockite and complex gneisses

The geological succession of the study area

Lithology map of the study area

Lineament map of the study area

Drainage map of the study area

Water level map of the study area (amsl)

Landuse map of the study area

Flow chart for methodology

Maximum, Minimum and Average of the Chemical constituents in groundwater representing all four sampling seasons (All Values in mgl-1 except EC in

μscm-1 and pH)Statistics

PRM

SWM

NEM

POM

Parameters Max Min Avg Max Min Avg Max Min Avg Max Min Avg

pH 8.20 6.60 7.45 8.00 5.20 7.03 8.50 6.20 7.11 7.83 6.12 7.21

TDS 1855.43 281.70 640.16 3223.00 96.40 980.40 3500.00 78.90 1001.46 3340.00 68.90 998.50

EC 2900.00 441.00 1000.64 5033.00 130.90 1532.98 6850.00 132.40 1815.00 5218.75 107.66 1630.02

Ca 276.00 20.00 77.13 552.00 12.00 122.99 156.00 8.00 42.27 294.00 32.00 80.20

Mg 98.40 1.20 18.45 214.00 9.60 46.30 216.00 2.40 38.82 131.00 10.00 33.77

Na 312.00 18.00 106.31 412.00 18.00 123.96 716.00 19.00 145.34 654.00 19.00 132.81

K 147.20 2.40 40.87 162.00 6.00 30.29 137.00 3.00 25.59 98.90 3.70 25.63

F 1.96 0.17 0.52 2.17 0.14 0.68 2.12 0.10 0.73 2.68 0.12 0.62

Cl 925.00 35.00 181.18 2144.73 35.45 371.92 1843.40 17.73 332.79 1637.71 35.30 294.69

HCO3 439.20 109.80 269.05 475.80 73.20 341.04 390.40 12.20 157.70 435.13 120.53 256.13

NO3 372.50 1.90 100.42 377.50 0.20 114.31 261.25 0.01 60.59 322.50 0.85 96.89

PO4 3.50 BDL 0.29 2.30 0.01 0.26 12.50 BDL 0.73 4.98 0.03 0.41

SO4 100.00 12.00 30.98 40.20 0.00 10.76 17.50 2.50 5.57 38.07 6.52 15.50

H4SiO4 72.00 2.50 46.57 172.00 2.00 84.33 129.50 8.00 114.35 113.33 4.17 81.71

U 113.00 0.20 6.21 156.84 0.56 7.39 46.70 1.17 6.72 116.32 1.28 8.21

222Rn 123.00 BDL 9.15 59.95 BDL 7.81 211.60 BDL 10.17 98.26 BDL 8.18

Zn 13.38 BDL 0.50 0.71 BDL 0.05 0.41 BDL 0.02 4.47 BDL 0.27

Cd 0.18 BDL 0.03 0.81 BDL 0.07 5.03 BDL 0.54 1.16 BDL 0.07

pb 0.00 BDL 0.00 2.13 BDL 0.10 0.48 BDL 0.03 1.02 BDL 0.07

Cu 1.92 BDL 0.12 0.52 BDL 0.05 3.15 BDL 0.21 0.83 BDL 0.04

(a) (b)

(c) (d)

Spatial distribution of EC (µs/cm) for a)PRM, b)SWM, c)NEM and d) POM with sampling points

Seasons Cations Anions

PRM Na+> Ca2+> K+> Mg2+ Cl-> HCO-3> NO-

3> SO2-4> PO3-

4> F-

SWM Ca2+> Na+>Mg2+> K+ Cl-> HCO-3> NO-

3> SO2-4> PO3-

4> F-

NEM Na+> Mg2+> Ca2+> K+ Cl-> HCO-3> NO-

3> SO2-4> PO3-

4> F-

POM Na+> Ca2+> Mg2+> K+ Cl-> HCO-3> NO-

3> SO2-4> PO3-

4> F-

The order of dominance of cations and anions in different seasons

Category Grade PRM SWM NEM POM Category Grade PRM SWM NEM POM Category PRM SWM NEM POMNa% Wilcox (1955) USGS Hardness TDS Classification(USSL,1954)

Excellent 0-20 5 13 5 4 Soft <75 3 4 2 3 <200 4 4 4 4

Good 20-40 7 19 6 12 Slightly Hard 75-150 16 0 19 2 200-500 21 10 12 11

Permissible 40-60 20 15 20 27Moderately

Hard 150-300 23 14 23 31 500-1500 27 35 32 29

Doubtful 60-80 21 7 23 11 Very Hard >300 12 36 10 8 1500-3000 2 3 4 7

Unsuitable >80 1 0 0 0 IBE Schoeller (1965) Cation Facies

Na% Eaton (1950)(Na+k)rock->Ca/Mg

g.w. 40 12 16 21 Ca-Mg Facies 1 6 2 0

Safe <60 32 47 31 43(Na+k)g.w.->Ca/Mg

rock 14 42 38 33 Ca-Na Facies 52 45 51 54Unsafe >60 22 7 23 11 Schoeller Classification (1967) Na-Ca Facies 1 3 1 0

S.A.R. Richards (1954) Type I 50 50 50 50 Na Facies 0 0 0 0Excellent 0-10 54 54 53 54 Type II 2 2 2 2 Anion facies

Good 10-18 0 0 1 0 Type III 2 2 2 2 HCO3 Facies 0 0 0 0

Fair 18-26 0 0 0 0 Type IV 0 0 0 0 HCO3-Cl-SO4 Facies 0 0 0 0

Poor >26 0 0 0 0 Corrosivity Ratio (Ryzner 1990) Cl-SO4-HCO3 Facies 47 47 34 47

R.S.C. Richards(1954) Safe <1 18 28 45 35 Cl- Facies 7 7 20 7

Good <1.25 37 48 49 48 Unsafe >1 36 26 9 19 Hardness Classification (Handa,1964)

Medium 1.25-2.5 9 0 1 2 Chloride Classification (Stuyfzand,1989) Permanent Hardness (NCH)

Bad >2.5 8 6 4 4 Extremely fresh 0 0 0 0 A1 8 18 5 7EC Wilcox (1955) Very fresh 0 0 1 0 A2 8 23 11 17

Excellent <250 4 4 4 4 Fresh 29 17 18 19 A3 7 6 22 16

Good 250-750 19 7 9 9 Fresh Brackish 21 15 17 21 Temporary Hardness (CH)

Permissible 750-2250 29 38 28 31 Brackish 4 20 16 12 B1 4 2 3 6

Doubtful 2250-5000 1 4 12 9 Brackish-salt 0 2 2 2 B2 17 2 2 2Unsuitable >5000 0 1 1 1 Salt 0 0 0 0 B3 8 3 11 5

Hyperhaline 0 0 0 0

Summary of Geochemical classification by WATCLAST Program for all four seasons (Chidambaram, et al 2003)

U (

pp

b)

Box Plot for U in groundwater samples in different seasons

PRM- Granite > Quartzite > Fissile hornblende biotite gneiss > Charnockite > Flood Plain

alluvium

SWM- Granite > Flood Plain Alluvium > Quartzite > Fissile hornblende biotite gneiss >

Charnockite

NEM- Granite > Flood Plain alluvium > Charnockite > Quartzite > Fissile hornblende biotite

gneiss

POM- Granite > Charnockite > Fissile hornblende biotite gneiss > Flood plain alluvium >

Quartzite

Schematic of U concentration distribution along a groundwater flow path.

(Revised from Ivanovich et al. 1991).

Spatial distribution of U (ppb) and lineaments for all seasons a) PRM, b) SWM, c) NEM and d) POM

Seasons Statistics Fissile

Hornblende

biotite gneiss

Charnockite Quartzite Granite Flood Plain Alluvium

PRM

Maximum 43.00 15.00 70.00 123.00 6.00

Minimum 1.00 BDL 4.00 8.00 BDL

Average 8.00 4.65 31.20 50.17 2.29

SWM

Maximum 23.64 24.34 36.92 59.95 5.49

Minimum 0.77 24.34 7.13 7.59 BDL

Average 6.94 0.10 19.81 31.69 1.99

NEM

Maximum 43.26 5.43 91.90 211.60 6.20

Minimum BDL 0.00 0.20 BDL BDL

Average 7.75 4.50 37.74 72.65 2.26

POM

Maximum 64.49 14.88 80.16 98.26 5.84

Minimum BDL BDL 3.66 2.96 BDL

Average 9.00 3.16 35.07 40.35 2.12

Maximum, Minimum and average values of 222Rn (Bq/l) for four seasons of different lithologies

Granite> Quartzite> Fissile hornblende biotite gneiss> Charnockite> Flood Plain Alluvium

(a) (b)

(c) (d)

Spatial distribution of 222Rn (Bq/l) for groundwater samples of all seasons a. PRM; b. SWM; c. NEM, d. POM

Plot between U Vs 222Rn in groundwater

The mechanism for identification of major process for all samples (Gibbs 1970)

Piper plot exhibiting the chemical facies of

groundwater samples for different seasons

Chadha’s geochemical process evolution plot

Groundwater with more resident time

Weathering

Plot of U vs pH in groundwater samples of all seasons

Plot of U vs EC in groundwater samples

of all seasons

Plot of U vs HCO-3 in groundwater

samples of all seasons

Open system

Plot of pCO2 Vs U in groundwater samples of all seasons

Plot between ORP and U in groundwater for all

seasons

Correlation coefficients of U with

other parameters

Box plot for temperature irrespective of seasons

Plot of U vs Temperature in

groundwater samples of all seasons

Stacked plot for average concentration of Heavy

metals in different seasons

Correlation analysis of U with

Heavy metals

Plot for δ18O versus δD of groundwater samples

compared with GMWL and LMWL

Evaporation dominant

Precipitation dominant

Plot for d-excess versus δ18O permil data of

groundwater samples

Plot for δ18O versus U for groundwater samples

U (

pp

m)

d excess

Plot for d excess versus U for groundwater samples

Parameters Factor 1 Factor 2 Factor 3 Factor 4

Ca 0.94 -0.05 -0.03 -0.01

Mg 0.89 -0.10 0.06 -0.12

Na 0.31 0.84 0.06 0.16

K 0.27 0.71 0.14 -0.18

F -0.30 -0.02 0.01 0.49

Cl 0.90 0.31 -0.01 0.05

HCO3 0.13 0.70 0.08 -0.15

NO3 0.68 0.49 0.30 -0.07

PO4 -0.19 0.10 -0.06 -0.27

SO4 0.67 0.43 -0.25 0.03

H4SiO4 0.31 -0.12 0.22 0.65

pH -0.23 0.06 -0.20 0.75

EC 0.86 0.49 -0.01 0.02

Temperature -0.13 0.41 -0.10 -0.01

222Rn 0.00 -0.06 0.92 0.04

U -0.05 0.16 0.91 0.02

TDV (%) 34.58 12.43 10.90 8.59

Factor analysis of PRM samples (Varimax rotated)

Parameters Factor 1 Factor 2 Factor 3 Factor 4

Ca 0.84 0.05 -0.10 -0.27

Mg 0.87 0.08 0.08 0.08

Na 0.40 0.76 0.00 0.35

K 0.08 0.68 0.10 -0.29

F -0.11 0.00 0.15 0.68

Cl 0.94 0.28 -0.02 0.03

HCO3 0.06 0.71 0.17 0.00

NO3 0.18 0.65 -0.25 0.12

PO4 0.05 0.15 0.64 -0.50

SO4 -0.13 0.26 -0.12 -0.39

H4SiO4 -0.02 0.10 0.34 0.00

pH -0.63 0.13 -0.15 0.31

EC 0.84 0.37 -0.09 0.15

Temperature -0.08 0.18 -0.04 0.34

222Rn -0.14 -0.29 0.80 0.16

U 0.18 -0.04 0.88 0.21

TDV (%) 27.35 13.77 10.969 8.749

Factor analysis of SWM samples (Varimax rotated)

Parameters Factor 1 Factor 2 Factor 3 Factor 4

Ca 0.58 0.13 -0.17 -0.09

Mg 0.85 -0.06 -0.08 0.03

Na 0.85 0.29 0.07 -0.04

K 0.35 0.67 0.33 0.04

F -0.29 0.16 -0.13 0.66

Cl 0.95 0.23 -0.09 0.00

HCO3 -0.10 0.68 0.38 -0.16

NO3 0.78 0.05 0.20 -0.13

PO4 0.04 -0.12 0.32 -0.01

SO4 0.50 0.26 0.04 0.17

H4SiO4 0.24 -0.21 0.16 0.80

pH -0.49 0.15 -0.20 0.01

EC 0.88 0.26 -0.02 0.03

Temperature -0.08 0.24 -0.17 0.46

222Rn -0.03 0.61 -0.04 -0.03

U 0.18 0.80 -0.04 0.17

TDV (%) 33.22 12.07 9.80 7.36

Factor analysis of NEM samples

Parameters Factor 1 Factor 2 Factor 3 Factor 4

Ca 0.91 -0.16 0.06 -0.19

Mg 0.91 -0.10 0.20 -0.14

Na 0.84 0.26 0.16 0.02

K 0.26 0.80 -0.10 0.14

F -0.05 -0.14 0.11 0.64

Cl 0.96 0.02 0.18 -0.05

HCO3 0.14 0.76 0.44 0.14

NO3 0.62 0.20 -0.21 -0.30

PO4 -0.09 0.64 -0.04 -0.21

SO4 0.72 0.15 -0.12 0.32

H4SiO4 -0.01 -0.09 0.61 0.13

pH -0.20 0.08 0.06 0.55

EC 0.84 0.25 0.30 0.07

Temperature -0.12 -0.30 -0.57 -0.01

222Rn -0.15 -0.05 0.18 -0.63

U 0.22 -0.02 0.64 -0.18

TDV (%) 34 12.18 8.82 8.53

Factor analysis of POM samples

Spatial distribution of dominant regions of four factors irrespective of all seasons

(A)

(D)(C)

(B)

Comparison of dominant factor with a. Lineaments, b. Water level, c. Lithology and d. Land use maps

The order of dominance of U species in groundwater with maximum values are as followsPRM - UO2 (CO3)2

2- >UO2 (CO3)34->UO2 (HPO4)2

2-

>UO2CO03

SWM - UO2 (HPO4)22-> UO2 (CO3)2

2- >UO2 (CO3)34-

>UO2CO03

NEM - UO2 (CO3)22- >UO2 (HPO4)2

2-> UO2 (CO3)34-

>UO2CO03

POM - UO2 (CO3)22- >UO2 (CO3)3

4->UO2 (HPO4)22-

>UO2CO03

Species is specific forms of an element, differing in oxidation state and exhibiting characteristic chemical reactivity and stability.

the speciation of ions in groundwater is very important to understand its hydrogeochemical evolution.

Speciation of Uranium is very important as it determines the availability and toxicity in water.

Each species will vary in its tendency to hydrolyse, sorb or combine with other species depending on its size and charge considerations.

Plot of pH vs U species(ppm) irrespective of seasons

(d)

(a)

(c)

(b)

Spatial distribution of U species (ppm) for a) PRM, b) SWM, c) NEM and d) POM

Eh-pH plot for U species in groundwater in all seasons

(c)

(a)

(d)

(b)

Correlation coefficients of U species (ppm) and other parameters for a) PRM, b)SWM, c)NEM and d) POM

(a)

(d)(c)

(b)

Variation of Saturation index of U minerals with total U for a) PRM, b) SWM, c) NEM and d) POM

U is highly correlated with 222Rn indicates the U may be the source for 222Rn in groundwater during PRM, SWM, NEM but it is noted that there is no significant correlation in POM.

The negative relation of pH with Mg indicates the dominance of ion exchange processes.

There are mainly two conditions prevailing in this region viz., enrichment of δ18O with low U content and depleted δ18O with high U content.

The higher concentration of U is observed in depleted δ18O samples. This is observed due to the direct relation to recharge from precipitation or due to weathering induced factor.

Using factor analysis four major processes has been identified 1. Anthropogenic and ion exchange processes, 2. Weathering processes, 3.Radionuclides dissolution processes and 4. Fluoride dissolution processes.

The spatial distribution of these processes for all seasons has been plotted to identify the hidden sources which shows that lineament, water level, land use and lithology are the major driving forces for change in chemical composition of groundwater.

The dominant species of Uranium in the study area during PRM and POM is UO2 (CO3)2

2- and in SWM and NEM is UO2 (HPO4)22-.

CONCLUSIONS