Hydrochemical characterization and pCO2 dynamics in the surface waters of Himalayan River: A case study of river Alaknanda

• Published in: Environmental monitoring and assessment Vol. 196; no. 11; p. 1138
• Main Authors: Bhanot, Kunarika, Sharma, M. K., Kaushik, R. D.
• Format: Journal Article
• Language: English
• Published: Cham Springer International Publishing 01.11.2024; Springer Nature B.V
• Subjects: Anions; Atmospheric Protection/Air Quality Control/Air Pollution; Calcium ions; Carbon budget; Carbon cycle; Carbon dioxide; Carbon sources; Carbonates; Cations; Chemical composition; Chemical weathering; Dolomite; Dolostone; Earth and Environmental Science; Ecology; Ecotoxicology; Environment; Environmental Management; Feldspars; Hydrochemicals; Hydrochemistry; Hydrogeochemistry; Limestone; Magnesium; Monitoring/Environmental Analysis; Monsoons; Principal components analysis; River water; Rivers; Sediment concentration; Silicates; Solutes; Streams; Surface water; Suspended sediments; Water chemistry; Weathering; Alaknanda River; Alaknanda River; Spatial and temporal variations; Partial pressure of CO; Chemical weathering; Open and closed system
• ISSN: 0167-6369; 1573-2959; 1573-2959
• DOI: 10.1007/s10661-024-13310-w

Chemical weathering processes are becoming increasingly important in studies on carbon cycling because they are responsible for increased solute fluxes in the proglacial zone, can effectively sequester atmospheric CO 2 and raise carbon budgets for lateral transport via rivers. Here, we examined the hydrochemical and hydrogeochemical processes, solute sources and factors controlling riverine p CO 2 of the Alaknanda River and its tributaries for three sampling seasons, viz. pre-monsoon (May 2021), post-monsoon (October 2021) and winter (January 2022). The surface water is enriched with Ca 2+ and Mg 2+ as the dominant cations, while HCO 3 − and SO 4 2− were the major anions. Gibbs’s plot confirmed rock weathering as the leading mechanism in controlling the hydrochemistry of the basin. The chemical composition of river water was mainly regulated by the weathering of carbonate end members: dolomite, limestone and feldspar along with small inputs from silicate weathering. The mean p CO 2 values in the mainstream (1702.7 µatm), Pindar (2267.9 µatm) and Mandakini (1136.1 µatm) revealed the streams were oversaturated with CO 2 having a higher rate of exporting excess CO 2 gas to the atmosphere. The study showed the persistence of high p CO 2 closed system characteristics associated with increased suspended sediment concentration resulting from carbonate weathering, dominance of HCO 3 − over SO 4 2− and thereby results in high values of C ratio. Principal component analysis of the water chemistry suggests that weathering contributes about 41%, while humans contribute about 13% of the ionic load to the river. This study is one of its kind to understand the system characteristics of Alaknanda River water.