Sources of major ions and processes affecting the geochemical and isotopic signatures of subsurface waters along a tropical river, Southwestern India

Gurumurthy, G P and Balakrishna, K and Tripti, M and Riotte, Jean and Audry, Stéphane and Braun, Jean-Jacques and Lambs, L and Udayashankar, H N (2014) Sources of major ions and processes affecting the geochemical and isotopic signatures of subsurface waters along a tropical river, Southwestern India. Environmental Earth Sciences. ISSN 1866-6280

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Abstract

Systematic monitoring of subsurface hydrogeochemistry has been carried out for a period of one year in a humid tropical region along the Nethravati–Gurupur River. The major ion and stable isotope (d18O and d2H) compositions are used to understand the hydrogeochemistry of groundwater and its interaction with surface water. In the study, it is observed that intense weathering of source rocks is the major source of chemical elements to the surface and subsurface waters. In addition, agricultural activities and atmospheric contributions also control the major ion chemistry of water in the study area. There is a clear seasonality in the groundwater chemistry, which is related to the recharge and discharge of the hydrological system. On a temporal scale, there is a decrease in major cation concentrations during the monsoon which is a result of dilution of sources from the weathering of rock minerals, and an increase in anion concentrations which is contributed by the atmosphere, accompanied by an increase in water level during the monsoon. The stable isotope composition indicates that groundwater in the basin is of meteoric origin and recharged directly from the local precipitation during the monsoonal season. Soon after the monsoon, groundwater and surface water mix in the subsurface region. The groundwater feeds the surface water during the lean river flow season.

Item Type: Article
Uncontrolled Keywords: Major ions � Stable isotopes � Groundwater chemistry � Nethravati–Gurupur catchment � Southwestern India
Subjects: Engineering > MIT Manipal > Civil Engineering
Departments at MU > Manipal Centre for Natural Sciences
Depositing User: MIT Library
Date Deposited: 30 Jun 2014 07:53
Last Modified: 12 Jul 2014 07:16
URI: http://eprints.manipal.edu/id/eprint/139990

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