Extreme silicate weathering rate in a tropical river, southwest coast of India

Gurumurthy, G P and Balakrishna, K and Riotte, Jean and Braun, Jean-Jacques and Audry, Stéphane and Udayashankar, H N (2010) Extreme silicate weathering rate in a tropical river, southwest coast of India. In: Goldschmidt Conference Abstracts.

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Abstract

The rate of silicate weathering (SWR) and associated carbon dioxide consumption (CCR) of granite gneissic terrain of southwestern India is calculated, for the first time in a west flowing peninsular river, the Nethravati. Monthly samples (n=56) were collected from five fixed locations along the river Nethravati and its two tributaries over a period of twelve months. The total dissolved salts of the samples are in the range of 29 to 66 mg/l, with least values recorded during the months of peak discharge. Silicate weathering rate for the entire catchment is deduced by applying seawater correction using river chloride as a tracer. The SWR in the river Nethravati is estimated as 59.3 tons/km2/yr. Such value is higher by 3.5 times than those reported for granitic rocks, at Rio Icocos, Puerto Rico [1] and comparable to Jalisco Highlands, Mexico [2]. The SWR in the river Nethravati is also comparable to the rivers draining Deccan basalts, located on the west coast of peninsular India [3]. Similarly, the CCR for river Nethravati is estimated as 11.6x105 mol/km2/yr. The calculated molecular ratio (RE)[4] from the river water variability in the intensity of silicate weathering; gibbsite precipitation during high flow and at upper catchments and kaolinite precipitation during base flow and at lower catchments. High SWR in the study area is likely due to the extreme precipitation and runoff induced by the Western Ghats. The annual fluxes of total dissolved salts discharged in to the Arabian Sea from the river Nethravati is estimated as 5.48 x 105 tons/yr, of which silicate derived cation flux amounts to 0.81x105 tons/yr.

Item Type: Conference or Workshop Item (Paper)
Subjects: Engineering > MIT Manipal > Civil Engineering
Depositing User: MIT Library
Date Deposited: 05 Aug 2013 06:35
Last Modified: 05 Aug 2013 06:35
URI: http://eprints.manipal.edu/id/eprint/136717

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