TY - JOUR
T1 - Chemical denudation in a small mountainous coastal river in the tropics
T2 - Insights from Kali River, Southwestern India
AU - Arun, Kumar
AU - Balakrishna, Keshava
AU - Amrish, Vadakkeveedu Narayan
AU - Nishitha, D'Souza S.
AU - Udayashankar, Harikripa Narayana
AU - Manjunatha, Busnur Rachotappa
AU - Khare, Neloy
N1 - Funding Information:
The first author is thankful to the DST-INSPIRE fellowship program ( IF180103 ), Department of Science and Technology , and Manipal Academy of Higher Education (MAHE) for providing fellowship and contingency support. Ministry of Earth Sciences, Government of India is thanked for the funding support to KB through a research project (MoES/CCR/PALEO-10/2015). Central Instrumentation Facility (CIF), MAHE, is thanked for providing ion chromatography facilities. Mrs. Akshitha V is thanked for help in the preparation of the study area map. The insightful comments of the anonymous referees' greatly contributed to refining the manuscript.
Publisher Copyright:
© 2022 Elsevier Ltd
PY - 2022/2
Y1 - 2022/2
N2 - A study was conducted for the first time to understand the geochemical processes controlling the chemistry of the Kali River in tropical southwestern India and to determine its chemical denudation and net carbon dioxide consumption. The samples were collected from the source to the mouth of the river (15 stations) during monsoon (July 2018), post-monsoon (December 2018), and pre-monsoon (May 2019) seasons. The catchment experiences intense chemical weathering on account of heavy rainfall accompanied by runoff during the summer monsoon. Seasonal variations in silicate weathering processes are significantly controlled by runoff, and their rates are proportional to the discharge. The annual chemical denudation rate (CDR) calculated exclusively from the upstream catchment that are dominated by silicate rocks estimated to be 48.2 tons/km2/yr with a silicate weathering rate (SWR) of 41.3 tons/km2/yr and carbonate weathering rate (CWR) of 6.9 tons/km2/yr. The CDR is two times higher than the global mean average rate. The mean CO2 consumption rate (CCR) for silicate weathering is 2.9 × 105 mol. km−2 y−1, which is three-fold higher than the global average. Silicate rock weathering intensity (Re) values indicate the formation of the gibbsite. The Re does not show variations from upstream to downstream, implying the rapid transport of weathered material from the river catchment area. Intense rain, runoff, and temperature are the dominant climatic factors that accelerate weathering in the study area. This underscores the significance of small mountainous coastal rivers as drivers of intense chemical weathering in humid tropical environments, which removes the atmospheric CO2. This study adds to the existing database on chemical weathering and associated fluxes in granitic catchments across the globe.
AB - A study was conducted for the first time to understand the geochemical processes controlling the chemistry of the Kali River in tropical southwestern India and to determine its chemical denudation and net carbon dioxide consumption. The samples were collected from the source to the mouth of the river (15 stations) during monsoon (July 2018), post-monsoon (December 2018), and pre-monsoon (May 2019) seasons. The catchment experiences intense chemical weathering on account of heavy rainfall accompanied by runoff during the summer monsoon. Seasonal variations in silicate weathering processes are significantly controlled by runoff, and their rates are proportional to the discharge. The annual chemical denudation rate (CDR) calculated exclusively from the upstream catchment that are dominated by silicate rocks estimated to be 48.2 tons/km2/yr with a silicate weathering rate (SWR) of 41.3 tons/km2/yr and carbonate weathering rate (CWR) of 6.9 tons/km2/yr. The CDR is two times higher than the global mean average rate. The mean CO2 consumption rate (CCR) for silicate weathering is 2.9 × 105 mol. km−2 y−1, which is three-fold higher than the global average. Silicate rock weathering intensity (Re) values indicate the formation of the gibbsite. The Re does not show variations from upstream to downstream, implying the rapid transport of weathered material from the river catchment area. Intense rain, runoff, and temperature are the dominant climatic factors that accelerate weathering in the study area. This underscores the significance of small mountainous coastal rivers as drivers of intense chemical weathering in humid tropical environments, which removes the atmospheric CO2. This study adds to the existing database on chemical weathering and associated fluxes in granitic catchments across the globe.
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U2 - 10.1016/j.apgeochem.2022.105198
DO - 10.1016/j.apgeochem.2022.105198
M3 - Article
AN - SCOPUS:85122760860
SN - 0883-2927
VL - 137
JO - Applied Geochemistry
JF - Applied Geochemistry
M1 - 105198
ER -