• L Elango

      Articles written in Journal of Earth System Science

    • Spatial and temporal variation of uranium in a shallow weathered rock aquifer in southern India

      K Brindha L Elango R N Nair

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      Uranium occurs naturally in groundwater and surface water. The objective of this study is to understand the causes for the occurrence of uranium and its spatio-temporal variation in groundwater in a part of Nalgonda district, Andhra Pradesh, south India. Uranium deposits occur in the southeastern part of this area. Groundwater samples were collected from 44 wells every two months from March 2008 to January 2009. The samples were analyzed for pH, ORP and uranium concentration. The uranium concentration in groundwater varies from 0.2 ppb to a maximum of 68 ppb with a mean of 18.5 ppb. About 21.6% of the samples were above the drinking water limit of 30 ppb set by USEPA. The uranium concentration varied with fluctuation in groundwater level, pH and ORP. Uranium concentration in groundwater changes depending on lithology, degree of weathering and rainfall recharge.

    • Geochemical processes controlling the groundwater quality in lower Palar river basin, southern India

      M Senthilkumar L Elango

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      Hydrogeochemical study of groundwater was carried out in a part of the lower Palar river basin, southern India to determine the geochemical processes controlling the groundwater quality. Thirty-nine groundwater samples were collected from the study area and analysed for pH, Eh, EC, Ca, Mg, Na, K, HCO3, CO3, Cl and SO4. The analysed parameters of the groundwater in the study area were found to be well within the safe range in general with respect to the Bureau of Indian Standards for drinking water except for few locations. The results of these analyses were used to identify the geochemical processes that are taking place in this region. Cation exchange and silicate weathering are the important processes controlling the major ion distribution of the study area. Mass balance reaction model NETPATH was used to assess the ion exchange processes. High concentration of Ca in groundwater of the study area is due to the release of Ca by aquifer material and adsorption of Na due to ion exchange processes. Groundwater of the study area is suitable for drinking and irrigation purposes except for few locations.

    • Geochemical and isotopic signatures for the identification of seawater intrusion in an alluvial aquifer

      Indu S Nair S P Rajaveni M Schneider L Elango

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      Seawater intrusion is one of the alarming processes that reduces the water quality and imperils the supply of freshwater in coastal aquifers. The region, north of the Chennai city, India is one such site affected by seawater intrusion. The objective of this study is to identify the extent of seawater intruded area by major geochemical and isotopic signatures. A total of 102 groundwater samples were collected and analysed for major and minor ions. Groundwater samples with electrical conductivity (EC) greater than 5000 𝜇S/cm and a river mouth sample were analyzed for Oxygen-18 (𝛿18O) and Deuterium (𝛿2H) isotopes to study their importance in monitoring seawater intrusion. The molar ratio of geochemical indicators and isotopic signatures suggests an intrusion up to a distance of 13 km from the sea as on March 2012 and up to 14.7 km during May 2012.

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