Isotope Hydrology Section

Sri Lanka

Isotope Hydrology Section

Sri Lanka
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Edirisinghe E.A.N.V.,Isotope Hydrology Section | Karunarathne G.R.R.,Water Resources Board | Samarakoon A.S.M.N.B.,Water Resources Board | Pitawala H.M.T.G.A.,University of Peradeniya | And 2 more authors.
Isotopes in Environmental and Health Studies | Year: 2016

Extensive extraction of groundwater has resulted in deterioration of the groundwater quality in the Puttalam area in the northwestern coastal zone of Sri Lanka. This situation led us to carry out the present comprehensive study based on environmental isotopic (18O, 2H, 3H) and geochemical evaluation to understand the root cause for water quality deterioration. The isotopic data suggest that the surface water and shallow groundwaters are subjected to intensive evaporation and, as a result, increase in their salinity. Deep groundwater of the area is mostly recharged by direct infiltration of rainwater and at few places by nearby surface water bodies. The salinity increase of deep groundwater depends on the specific hydrogeological zones and would be due to dissolution of salts which are precipitated in soil through the seawater spray over the time, dissolution of minerals in geological matrix and leaching of salts from salterns. The quality of the deep groundwater is relatively good in the granitic gneiss zone and nearby areas outside the sedimentary aquifer. There is no evidence from isotope and hydrogeochemical evaluation for seawater intrusion into groundwater in the Puttalam area. © 2016 Taylor & Francis

Chandrajith R.,University of Peradeniya | Chaturangani D.,University of Peradeniya | Abeykoon S.,University of Peradeniya | Barth J.A.C.,Lehrstuhl fur Angewandte Geologie | And 4 more authors.
Environmental Earth Sciences | Year: 2014

The Panama coastal aquifer system is an important water resource in the southeast coast of Sri Lanka that provides adequate supplies of water for agriculture and domestic uses. One of the biggest threats to these fragile aquifers is the sea water intrusion. In this study, recharging mechanism and geochemical evaluation of groundwater in the coastal sandy aquifer of Panama were evaluated using chemical and stable isotope techniques. Thirty groundwater samples were collected and analyzed for their major ion concentrations and stable isotope ratios of oxygen (18O/16O) and hydrogen (D/H). All studied samples showed a ranking of major anions in the order Cl-> HCO 3 - > SO4 2- > N-NO3 - while cations showed a decreasing order of abundance with Na+> Ca2+> Mg2+> K+. Dominant groundwater hydrogeochemical types were Na-Cl and mixed Ca-Mg-Cl. Results of saturation index calculations indicate that the investigated groundwater body was mostly saturated with respect to calcite, dolomite and gypsum. In addition, stable isotope and geochemical data suggest that fresh groundwater in the aquifer is recharged mainly by local precipitation with slight modification from evaporation and saline water intrusions. Isotope data suggest that mixing of salt water with freshwater occurs in aquifers which are located towards the lagoon. Since the communities in the study area depend entirely on groundwater, an understanding of the hydrogeochemical characteristics of the aquifer system is extremely important for the better water resource management in the region. © 2013 Springer-Verlag Berlin Heidelberg.

Thilagavathi R.,Annamalai University | Chidambaram S.,Annamalai University | Thivya C.,University of Madras | Prasanna M.V.,University Malaysia Sarawak | And 2 more authors.
Natural Resources Research | Year: 2016

Carbon, which is an essential element found in rocks and minerals, is used by biologically diverse life forms as a source of energy. Natural organic carbon is mainly derived from decomposing vegetation and other organic matter in the soil zone. Dissolved organic carbon (DOC) is an important component in biogeochemical cycling of elements characterized by high susceptibility to leaching. The significance of DOC was studied in layered coastal aquifers of the Pondicherry region during four different seasons. Pondicherry region has varied geological setup ranging from Cretaceous to Recent formations. A total of 324 groundwater samples were collected from various aquifers, namely Alluvium, Tertiary, Cretaceous, and Mixed formations, during different seasons of pre-monsoon, southwest monsoon, northeast monsoon, and post-monsoon. The samples were analyzed for major ions and DOC. The range of DOC in the study area is 0–10 mg/l. Very high DOC concentrations were measured in most of the samples from Alluvium and Upper Cuddalore Formation and in few samples from the Lower Cuddalore Formation. The relationships of DOC with other ions in this study indicate that the hydrochemistry of groundwater was controlled by both aerobic and anaerobic environments in the different formations of the study area. © 2016 International Association for Mathematical Geosciences

Thilagavathi R.,Annamalai University | Chidambaram S.,Annamalai University | Pethaperumal S.,State Groundwater Unit and Soil Conservation | Thivya C.,Annamalai University | And 4 more authors.
Environmental Earth Sciences | Year: 2016

Groundwaters of the coastal region are significant and serve as a fragile ecosystem in the sedimentary terrain. The Pondicherry region is characterized by different geological formations of distinct geological epochs Cretaceous, Tertiary and Quaternary. Ninety-three samples were collected from specific aquifers with respect to spatial distribution [Alluvium (31), Upper Cuddalore (13), Lower Cuddalore (13), Other Tertiary (7), Cretaceous (24) and Mixed—multiple completion aquifer (5)]. The collected samples were analyzed for major ions Ca2+, Mg2+, Na+, K+, HCO3 −, Cl−, PO4 2−, SO4 2−, F and DOC. Stables isotopes of δ18O, δD and δ 13C were also analyzed along with heavy metals like Al, Ba, Fe, Sr, Cd and Zn. The δ18O ranges between −6.85 and −2.15 ‰, and δD ranges between −43.94 and −19.41 ‰. The distribution of these environmental isotopes in groundwater of this layered aquifer sequence was also attempted. A comparison of the isotopic data with the rainfall, Local Meteoric Water Line with a equation of δD = 7.398 * δ18O + 5.067, Indian Meteoric Water Line and Global Meteoric Water Line was performed. The δ13C values for groundwater ranges from −5.3 to −18.1 ‰. The result indicates that the groundwater in the study area is mainly meteoric in origin, and few samples show evidence of evaporation. The dissolved organic carbon (DOC) is a very important component in biogeochemical cycling of elements characterized by high susceptibility to leaching. The range of the DOC in the study area is 0–16 mg/L. Factor analysis was applied to classify the groundwater samples and to identify geochemical processes controlling groundwater geochemistry. The Alluvium aquifers show a complex hydrogeochemistry than the older aquifers. The major factor influencing the hydrogeochemistry of the region is rock–water interaction and anthropogenic processes. Hence, metal mobility of the groundwater shows the correlation of metal bonding and DOC. The relation between the DOC and heavy metal concentration in the aquifers was also identified. © 2015, Springer-Verlag Berlin Heidelberg.

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