title: Sensitivity of chemical weathering and dissolved carbon dynamics to hydrological conditions in a typical karst river.
abstract: To better understand the mechanisms that hydrological conditions control chemical weathering and carbon dynamics in the large rivers, we investigated hydrochemistry and carbon isotopic compositions of dissolved inorganic carbon (DIC) based on high-frequency sampling in the Wujiang River draining the carbonate area in southwestern China. Concentrations of major dissolved solute do not strictly follow the dilution process with increasing discharge, and biogeochemical processes lead to variability in the concentration-discharge relationships. Temporal variations of dissolved solutes are closely related to weathering characteristics and hydrological conditions in the rainy seasons. The concentrations of dissolved carbon and the carbon isotopic compositions vary with discharge changes, suggesting that hydrological conditions and biogeochemical processes control dissolved carbon dynamics. Biological CO2discharge and intense carbonate weathering by soil CO2should be responsible for the carbon variability under various hydrological conditions during the high-flow season. The concentration of DICbio(DIC from biological sources) derived from a mixing model increases with increasing discharge, indicating that DICbioinflux is the main driver of the chemostatic behaviors of riverine DIC in this typical karst river. The study highlights the sensitivity of chemical weathering and carbon dynamics to hydrological conditions in the riverine system.
authors.affiliation: The State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China.|University of Chinese Academy of Sciences, Beijing 100049, China.
authors.forename: Jun
authors.initials: J
authors.lastname: Zhong
authors.affiliation: Institute of Surface-Earth System Science, Tianjin University, Tianjin 300072, China.|State Key laboratory of Hydraulic Engineering Simulation and Safety, Tianjin University, Tianjin 300072, China.
authors.forename: Si-Liang
authors.initials: SL
authors.lastname: Li
authors.affiliation: The State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China.
authors.forename: Faxiang
authors.initials: F
authors.lastname: Tao
authors.affiliation: The State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China.
authors.forename: Fujun
authors.initials: F
authors.lastname: Yue
authors.affiliation: The State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China.
authors.forename: Cong-Qiang
authors.initials: CQ
authors.lastname: Liu