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


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 (δ 18O) and Deuterium (δ 2H) 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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The authors wish to acknowledge the Department of Science and Technology, New Delhi, India for providing fund to this research (Grant no.: DST/ WAR-WSI/05/2010). Co-funding for the collaborative project ‘Enhancement of natural water systems and treatment methods for safe and sustainable water supply in India – Saph Pani’ ( from the European Commission within the Seventh Framework Programme (grant agreement no. 282 911) is also gratefully acknowledged. Stable isotope analysis at the Museum für Naturkunde in Berlin by Dr. Ulrich Struck is greatly acknowledged.

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Correspondence to L Elango.

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Nair, I.S., Rajaveni, S.P., Schneider, M. et al. Geochemical and isotopic signatures for the identification of seawater intrusion in an alluvial aquifer. J Earth Syst Sci 124, 1281–1291 (2015).

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  • Isotopic signatures
  • geochemical indicators
  • seawater intrusion
  • major ionic ratios
  • Arani and Koratalaiyar rivers
  • coastal aquifers
  • Chennai, India.