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Hydrological regulation of chemical weathering and dissolved inorganic carbon biogeochemical processes in a monsoonal river |
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| Authors: | Jing Liu Jun Zhong Hu Ding Fu-Jun Yue Cai Li Sen Xu Si-Liang Li |
| Institution: | 1. School of Management Science, Guizhou University of Finance and Economic, Guiyang, China;2. Institute of Surface-Earth System Science, Tianjin University, Tianjin, China;3. The State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang, China
School of Geographical and Earth Sciences, University of Glasgow, Glasgow, UK;4. School of Geographical and Earth Sciences, University of Glasgow, Glasgow, UK;5. Institute of Surface-Earth System Science, Tianjin University, Tianjin, China School of Urban and Environment Science, Huaiyin Normal University, Huaian, China |
| Abstract: | To better understand the mechanisms relating to hydrological regulations of chemical weathering processes and dissolved inorganic carbon (DIC) behaviours, high-frequency sampling campaigns and associated analyses were conducted in the Yu River, South China. Hydrological variability modifies the biogeochemical processes of dissolved solutes, so major ions display different behaviours in response to discharge change. Most ions become diluted with increasing discharge because of the shortened reactive time between rock and water under high-flow conditions. Carbonate weathering is the main source of major ions, which shows strong chemostatic behaviour in response to changes in discharge. Ions from silicate weathering exhibit a significant dilution effect relative to the carbonate-sourced ions. Under high temperatures, the increased soil CO2 influx from the mineralisation of organic material shifts the negative carbon isotope ratios of DIC (δ13CDIC) during the high-flow season. The δ13CDIC values show a higher sensitivity than DIC contents in response to various hydrological conditions. Results from a modified isotope-mixing model (IsoSource) demonstrate that biological carbon is a dominant source of DIC and plays an important role in temporal carbon dynamics. Furthermore, this study provides insights into chemical weathering processes and carbon dynamics, highlighting the significant influence of hydrological variability to aid understanding of the global carbon cycle. |
| Keywords: | carbon isotope chemical weathering processes DIC dynamics hydrological variability karst monsoonal river |