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Geochemical Perspectives on River Water of the Tropical Basins, Southwestern India

Gurumurthy, G P and Tripti, M (2015) Geochemical Perspectives on River Water of the Tropical Basins, Southwestern India. In: Environmental management of River Basin Eco Systems. Springer, pp. 329-353. ISBN 978-3-319-13424-6

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Abstract

The Southwestern part of Peninsular India is one among the shield terrains experiencing extreme geological, geomorphological and climatic gradients.Many small rivers originate in the western slope of Western Ghats and flow towards the Arabian Sea. The moisture from the Arabian Sea carried by the southwesterly winds forms the primary source of water for these rivers. These west flowing rivers exhibit characteristic water chemistry distinct from that of the east flowing rivers and the rivers draining the Deccan traps. The lithological heterogeneity and the intensity of weathering have significant effect on the river water as observed by the difference in water chemistry between the Deccan, East flowing and West flowing rivers. The geomorphological settings of the Western Ghats (which brings-in the rainfall over its western slope) induce higher surface runoff which has significant effect on the weathering process and thus, on the water chemistry. However, the slope of the terrain has minimal effect on the chemistry of water in this region. The weathering of sedimentary formations in the plains leads to elevated fluxes of silica and radiogenic strontium. The weathering of bedrock forms the main source of trace elements to the river water in this region. The abundance of trace elements in monsoon dominated terrain is controlled primarily by the discharge. However,the secondary processes namely, redox reactions and oxidative scavenging of surface reactive metals by the oxyhydroxides of Fe and Mn appears to have significant role in determining the geochemical abundance. Unlike the tropical river basins of Africa and South America where the organic carbon complexation plays a vital role in dissolved metal abundance, in the rivers of Southwestern India, the control of organic complexation on the dissolved metal chemistry varies widely between rivers. This could be due to variable abundance of labile fraction of organic carbon in these rivers. The secondary geochemical processes lead to the enrichment.

Item Type: Book Section
Uncontrolled Keywords: Geochemistry � Weathering � Trace elements � Tropical rivers � West flowing rivers � Peninsular india
Subjects: Departments at MU > Manipal Centre for Natural Sciences
Depositing User: MCNS Editor
Date Deposited: 12 Mar 2016 11:38
Last Modified: 12 Mar 2016 11:38
URI: http://eprints.manipal.edu/id/eprint/145548

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