Chemical weathering and carbon dioxide consumption in a small tropical river catchment, southwestern India

Nisha, Baby Krishnan and Balakrishna, K and Udayashankar, H N and Manjunatha, B R (2021) Chemical weathering and carbon dioxide consumption in a small tropical river catchment, southwestern India. Aquatic Geochemistry, 27. pp. 173-206. ISSN 1380-6165

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Abstract

Studies done on small tropical west-fowing river catchments located in the Western Ghats in southwestern India have suggested very intense chemical weathering rates and associated CO2 consumption. Very less studies are reported from these catchments notwithstanding their importance as potential sinks of atmospheric CO2 at the global scale. A total of 156 samples were collected from a small river catchment in the southwestern India, the Payas�wini–Chandragiri river Basin, during pre-monsoon, monsoon and post-monsoon seasons in 2016 and 2017, respectively. This river system comprises two small rivers originating at an elevation of 1350 m in the Western Ghats in peninsular India. The catchment area is domi�nated by biotite sillimanite gneiss. Sodium is the dominant cation, contributing~50% of the total cations, whereas HCO3 − contributes~75% of total anions. The average anion con�centration in the samples varied in the range HCO3 − > Cl− > SO4 2− > NO3 − > F−, whereas major cation concentration varied in the range Na+ > Ca2+ > Mg2+ > K+. The average sili�cate weathering rate (SWR) was 42 t km−2 y−1 in the year 2016 and 36 t km−2 y−1 in 2017. The average annual carbon dioxide consumption rate (CCR) due to silicate rock weathering was 9.6× 105 mol km−2y−1 and 8.3× 105 mol km−2 y−1 for 2016 and 2017, respectively. The CCR in the study area is higher than other large tropical river catchments like Ama�zon, Congo-Zaire, Orinoco, Parana and Indus because of its unique topography, hot and humid climate and intense rainfall

Item Type: Article
Uncontrolled Keywords: Tropical river system · Water geochemistry · Silicate weathering rate · Atmospheric CO2 consumption · Southwest coast of India
Subjects: Engineering > MIT Manipal > Civil Engineering
Depositing User: MIT Library
Date Deposited: 05 Oct 2021 09:35
Last Modified: 05 Oct 2021 09:35
URI: http://eprints.manipal.edu/id/eprint/157482

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