Chemical Weathering and CO 2 Consumption Inferred from Riverine Water Chemistry in the Xi River Drainage, South China

Yanpu Zhao (), Jan R. Wijbrans, Hua Wang (), Pieter Z. Vroon, Jianghao Ma and Yanqiong Zhao
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Yanpu Zhao: Key Laboratory of Tectonics and Petroleum Resources, Ministry of Education, China University of Geosciences, Wuhan 430074, China
Jan R. Wijbrans: Department of Earth Sciences, Vrije Universiteit Amsterdam, 1081 HV Amsterdam, The Netherlands
Hua Wang: Key Laboratory of Tectonics and Petroleum Resources, Ministry of Education, China University of Geosciences, Wuhan 430074, China
Pieter Z. Vroon: Department of Earth Sciences, Vrije Universiteit Amsterdam, 1081 HV Amsterdam, The Netherlands
Jianghao Ma: Key Laboratory of Tectonics and Petroleum Resources, Ministry of Education, China University of Geosciences, Wuhan 430074, China
Yanqiong Zhao: School of Economics and Management, China University of Geosciences, Wuhan 430074, China

IJERPH, 2023, vol. 20, issue 2, 1-26

Abstract: Hydrochemistry and strontium isotope data were analysed in water samples from the Xi River Drainage system to reveal the spatial and seasonal variations in chemical weathering, associated CO 2 consumption fluxes, and their control factors. The main ions were Ca 2+ , Mg 2+ , and HCO 3 − , which are characteristic of a drainage system on carbonate-dominated bedrock. The dissolved loads were derived from four major end-member reservoirs: silicate, limestone, dolomite, and atmosphere. The silicate weathering rates (SWRs) increased downstream from 0.03 t/km 2 /year to 2.37 t/km 2 /year. The carbonate weathering rates (CWRs) increased from 2.14 t/km 2 /year in the upper reaches, to 32.65 t/km 2 /year in the middle reaches, and then decreased to 23.20 t/km 2 /year in the lower reaches. The SWR values were 281.38 and 113.65 kg/km 2 /month during the high- and low-water periods, respectively. The CWR values were 2456.72 and 1409.32 kg/km 2 /month, respectively. The limestone weathering rates were 2042.74 and 1222.38 kg/km 2 /month, respectively. The dolomite weathering rates were 413.98 and 186.94 kg/km 2 /month, respectively. Spatial and seasonal variations in chemical weathering were controlled mainly by lithology, vegetation, and climate (temperature, water discharge, and precipitation). The CO 2 consumption flux by chemical weathering was estimated at 189.79 × 10 9 mol/year, with 156.37 × 10 9 and 33.42 × 10 9 mol/year for carbonate and silicate weathering, respectively. The CO 2 fluxes by chemical weathering are substantially influenced by sulfuric acid in the system. The CO 2 flux produced by sulfuric acid weathering was estimated at 30.00 × 10 9 mol/year in the basin. Therefore, the Xi River Basin is a CO 2 sink with a net consumption of CO 2 flux of 3.42 × 10 9 mol/year.

Keywords: chemical weathering; CO 2; sulfuric acid; Xi River drainage (search for similar items in EconPapers)
JEL-codes: I I1 I3 Q Q5 (search for similar items in EconPapers)
Date: 2023
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