1. 2 A study on the seasonal variation of uranium in groundwater of hard rock terrain in south India Prof. S. Chidambaram Department of Earth Sciences Annamalai University

2.  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.

3. No.TypesTypical examples% of total deposits% of total uranium resources 1Quartz-Pebble-Conglomerate type Witwatersrand area, South Africa3.813.0 Elliot Lake region, Canada 2Unconformity relatedAthabasca basin, Canada4.033.0 Alligator river basin, Australia 3Vein type (hydrothermal or disseminations)-structurally controlled / stratabound Beverlodge, Uranium City, Canada23.79.0 Massif central, France Schwatzwalder, USA 4Sandstone typeOklo, Gabon42.818.0 Grants, USA Niger Kazakhstan 5Breccia complexOlympic Dam, Australia0.217 6IntrussiveRossing, Namibia2.210.0 Bancroft, Canada 7VolcanicJiang Xi, China7.4 Michelin, Canada 8MetasomatitesRoss Adams, USA2.1 Kriverozhsky-Zheltye, Ukraine 9Collapse breccia typeOrphan lode and Hack Canyon, Arizona, USA 1.7 10PhosphoriteMontpelier, USA1.7 11Black shaleChattanooga, USA1.5 Ranstad, Sweden 12LigniteSlim Buttes, South Western Williston Basin, USA 3.8 Czech Republic 13Surficial / Fluvial valley fillYeelerie, Australia2.7 14MetamorophicForstau, Austria2.4 15Others 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)

4. 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

5. S.NoCountry Range of Uranium concentration in water (µg/L) Average value (µg/L) Reference 1Ontario, Canada0.05-4.210.40 OMEE (1996), Moss et al. (1983) and Moss (1985) 2New York, USA0.03-0.08-Fissene and Welford (1986) 3USA-2.55US EPA (1900,1991) 4Argentina0.04-11.01.3Bomben et al. (1996) 5Japan-0.0009Nozaki et al. (1970) 6Norway 18% samples had U concentration in excess of 20 ppb --Frengstad et al. (2002) 7New Mexico>20 ppb-Hakonson-Hayes et al. (2002) 8Central Australia>20ppb-Hostetler et al. (1998) 9Jordan0.04-14002.4 Gedeon et al. (1994) and Smith et al. (2000) 10Kuwait0.02-2.48-Bou-Rabee (1995) 11United States0.01-652- Drury et al. (1981), Edgington(1965) and Cothern and Lappenbusch (1983) 12South Greenland0.5-1.0-Brown et al. (1983) 13Turkey0.24-17.65-Kumru (1995) 14India0.08-471.27-Talukdar et al. (1983), Bansal et al. (1985,1988), Singh et al.(1993,2003) and Mehra et al. (2007) Worldwide Uranium concentration in water

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

7. Study area map with classification of blocks (CGWB 2007)

8. EraAgeFormationLithology QuaternaryRecent Alluvium, Laterite Sand, Clay, Silt, Kankar pebbles and laterite UNCONFORMITY Azoic Granites with Pegmatites and Quartzites, Granite, Charnockite and complex gneisses The geological succession of the study area Lithology map of the study area

9. 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

10. Flow chart for methodology

11. 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)

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

13. SeasonsCationsAnions PRMNa + > Ca 2+ > K + > Mg 2+ Cl - > HCO - 3 > NO - 3 > SO 2- 4 > PO 3- 4 > F - SWMCa 2+ > Na + >Mg 2+ > K + Cl - > HCO - 3 > NO - 3 > SO 2- 4 > PO 3- 4 > F - NEMNa + > Mg 2+ > Ca 2+ > K + Cl - > HCO - 3 > NO - 3 > SO 2- 4 > PO 3- 4 > F - POMNa + > Ca 2+ > Mg 2+ > K + Cl - > HCO - 3 > NO - 3 > SO 2- 4 > PO 3- 4 > F - The order of dominance of cations and anions in different seasons

14. CategoryGradePRMSWMNEMPOMCategoryGradePRMSWMNEMPOMCategoryPRMSWMNEMPOM Na% Wilcox (1955)USGS HardnessTDS Classification(USSL,1954) Excellent0-2051354Soft<753423<2004444 Good20-40719612Slightly Hard75-150160192200-50021101211 Permissible40-6020152027 Moderately Hard150-30023142331500-150027353229 Doubtful60-802172311Very Hard>30012361081500-30002347 Unsuitable>801000IBE Schoeller (1965)Cation Facies Na% Eaton (1950) (Na+k)rock->Ca/Mg g.w.40121621Ca-Mg Facies1620 Safe<6032473143 (Na+k)g.w.->Ca/Mg rock14423833Ca-Na Facies52455154 Unsafe>602272311Schoeller Classification (1967)Na-Ca Facies1310 S.A.R. Richards (1954)Type I50 Na Facies0000 Excellent0-1054 5354Type II2222Anion facies Good10-180010Type III2222HCO 3 Facies0000 Fair18-260000Type IV0000HCO 3 -Cl-SO 4 Facies0000 Poor>260000Corrosivity Ratio (Ryzner 1990)Cl-SO 4 -HCO 3 Facies47 3447 R.S.C. Richards(1954)Safe<118284535Cl- Facies77207 Good<1.2537484948Unsafe>13626919Hardness Classification (Handa,1964) Medium1.25-2.59012Chloride Classification (Stuyfzand,1989)Permanent Hardness (NCH) Bad>2.58644Extremely fresh0000A181857 EC Wilcox (1955)Very fresh0010A28231117 Excellent<2504444Fresh29171819A3762216 Good250-75019799Fresh Brackish21151721Temporary Hardness (CH) Permissible750-225029382831Brackish4201612B14236 Doubtful2250-500014129Brackish-salt0222B217222 Unsuitable>50000111Salt0000B383115 Hyperhaline0000 Summary of Geochemical classification by WATCLAST Program for all four seasons (Chidambaram, et al 2003)

15. U (ppb) 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

16. Schematic of U concentration distribution along a groundwater flow path. (Revised from Ivanovich et al. 1991).

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

18. Seasons Statistics Fissile Hornblende biotite gneiss CharnockiteQuartziteGraniteFlood Plain Alluvium PRM Maximum43.0015.0070.00123.006.00 Minimum1.00BDL4.008.00BDL Average8.004.6531.2050.172.29 SWM Maximum23.6424.3436.9259.955.49 Minimum0.7724.347.137.59BDL Average6.940.1019.8131.691.99 NEM Maximum43.265.4391.90211.606.20 MinimumBDL0.000.20BDL Average7.754.5037.7472.652.26 POM Maximum64.4914.8880.1698.265.84 MinimumBDL 3.662.96BDL Average9.003.1635.0740.352.12 Maximum, Minimum and average values of 222 Rn (Bq/l) for four seasons of different lithologies Granite> Quartzite> Fissile hornblende biotite gneiss> Charnockite> Flood Plain Alluvium

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

20. Plot between U Vs 222 Rn in groundwater

21. 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

22. 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 pCO 2 Vs U in groundwater samples of all seasons

23. Plot between ORP and U in groundwater for all seasons Correlation coefficients of U with other parameters

24. Box plot for temperature irrespective of seasons Plot of U vs Temperature in groundwater samples of all seasons

25. Stacked plot for average concentration of Heavy metals in different seasons Correlation analysis of U with Heavy metals

26. Plot for δ 18 O versus δD of groundwater samples compared with GMWL and LMWL Evaporation dominant Precipitation dominant Plot for d-excess versus δ 18 O permil data of groundwater samples

27. Plot for δ 18 O versus U for groundwater samples U (ppm) d excess Plot for d excess versus U for groundwater samples

28. Parameters Factor 1Factor 2Factor 3Factor 4 Ca 0.94 -0.05-0.03-0.01 Mg0.89-0.100.06-0.12 Na0.310.840.060.16 K0.270.710.14-0.18 F-0.30-0.020.010.49 Cl0.900.31-0.010.05 HCO 3 0.130.700.08-0.15 NO 3 0.680.490.30-0.07 PO 4 -0.190.10-0.06-0.27 SO 4 0.670.43-0.250.03 H 4 SiO 4 0.31-0.120.220.65 pH-0.230.06-0.200.75 EC0.860.49-0.010.02 Temperature-0.130.41-0.10-0.01 222 Rn0.00-0.060.920.04 U-0.050.160.910.02 TDV (%)34.5812.4310.908.59 Factor analysis of PRM samples (Varimax rotated) Parameters Factor 1Factor 2Factor 3Factor 4 Ca0.840.05-0.10-0.27 Mg0.870.08 Na0.400.760.000.35 K0.080.680.10-0.29 F-0.110.000.150.68 Cl0.940.28-0.020.03 HCO 3 0.060.710.170.00 NO 3 0.180.65-0.250.12 PO 4 0.050.150.64-0.50 SO4-0.130.26-0.12-0.39 H 4 SiO 4 -0.020.100.340.00 pH-0.630.13-0.150.31 EC0.840.37-0.090.15 Temperature-0.080.18-0.040.34 222 Rn-0.14-0.290.800.16 U0.18-0.040.880.21 TDV (%)27.3513.7710.9698.749 Factor analysis of SWM samples (Varimax rotated)

29. Parameters Factor 1Factor 2Factor 3Factor 4 Ca0.580.13-0.17-0.09 Mg0.85-0.06-0.080.03 Na0.850.290.07-0.04 K0.350.670.330.04 F-0.290.16-0.130.66 Cl0.950.23-0.090.00 HCO 3 -0.100.680.38-0.16 NO 3 0.780.050.20-0.13 PO 4 0.04-0.120.32-0.01 SO 4 0.500.260.040.17 H 4 SiO 4 0.24-0.210.160.80 pH-0.490.15-0.200.01 EC0.880.26-0.020.03 Temperature-0.080.24-0.170.46 222 Rn-0.030.61-0.04-0.03 U0.180.80-0.040.17 TDV (%)33.2212.079.807.36 Factor analysis of NEM samples Parameters Factor 1Factor 2Factor 3Factor 4 Ca0.91-0.160.06-0.19 Mg0.91-0.100.20-0.14 Na0.840.260.160.02 K0.260.80-0.100.14 F-0.05-0.140.110.64 Cl0.960.020.18-0.05 HCO 3 0.140.760.440.14 NO 3 0.620.20-0.21-0.30 PO 4 -0.090.64-0.04-0.21 SO 4 0.720.15-0.120.32 H 4 SiO 4 -0.01-0.090.610.13 pH-0.200.080.060.55 EC0.840.250.300.07 Temperature-0.12-0.30-0.57-0.01 222 Rn-0.15-0.050.18-0.63 U0.22-0.020.64-0.18 TDV (%)3412.188.828.53 Factor analysis of POM samples

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

31. (A) (D) (C) (B) Comparison of dominant factor with a. Lineaments, b. Water level, c. Lithology and d. Land use maps

32. The order of dominance of U species in groundwater with maximum values are as follows PRM-UO 2 (CO 3 ) 2 2- >UO 2 (CO 3 ) 3 4- >UO 2 (HPO 4 ) 2 2- >UO 2 CO 0 3 SWM-UO 2 (HPO 4 ) 2 2- > UO 2 (CO 3 ) 2 2- >UO 2 (CO 3 ) 3 4- >UO 2 CO 0 3 NEM-UO 2 (CO 3 ) 2 2- >UO 2 (HPO 4 ) 2 2- > UO 2 (CO 3 ) 3 4- >UO 2 CO 0 3 POM-UO 2 (CO 3 ) 2 2- >UO 2 (CO 3 ) 3 4- >UO 2 (HPO 4 ) 2 2- >UO 2 CO 0 3  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.

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

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

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

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

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

38. U is highly correlated with 222 Rn indicates the U may be the source for 222 Rn 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 δ 18 O with low U content and depleted δ 18 O with high U content. The higher concentration of U is observed in depleted δ 18 O 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 UO 2 (CO 3 ) 2 2- and in SWM and NEM is UO 2 (HPO 4 ) 2 2-. CONCLUSIONS