1. Sensitivity of hydrochemistry and dissolved carbon dynamics to storms based on high-resolution data at the karst critical zone, SW China.
- Author
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Qin, Caiqing, Li, Si-Liang, Zhong, Jun, Yue, Fu-Jun, and Chen, Xi
- Subjects
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WATERSHEDS , *WATER springs , *DATABASES , *CARBON , *DILUTION , *GROUNDWATER analysis , *BARRIER islands - Abstract
Hydrochemical behaviour and dissolved carbon dynamics have high sensitivity to hydrologicvariations during high-flow periods in monsoonal-influenced regions, especially inthe critical zone of agricultural karstic catchment where existing anthropogenicinterference and carbonate weathering with rapid kinetics. Here we selected Chenqicatchment, a 1.5 km2 sub-catchment of Houzhai basin in Puding, SW China, as studyarea to analyze the response of hydrochemistry and dissolved carbon dynamicsto discharge changes, through hourly sampling campaigns in the outlet of springwater during the high-flow period. Most dissolved ions exhibit distinct responsesto discharge variations, their concentrations are negatively correlated with springwater discharge, which can be well fitted using power-law function, indicating theirchemostatic behaviours as discharge increases, but biogeochemical processes influencingdifferent ions are miscellaneous. Ca2+, Mg2+ and HCO3− are mainly controlled bydissolved soil CO2 and carbonate weathering, while NO3− and Cl− both haveanthropogenic inputs and may exist some link about their source areas or transport processesactivated during high-flow periods. Other ions are generally affected by the dilution ofrainwater. Hydrological conditions and biogeochemical processes regulate dissolvedcarbon dynamics, resulting in the variation of δ13CDIC. There are two sources forDIC in spring water of Chenqi catchment, namely biological source (DICbio) andgeological source (DICcarb). The contribution ratio of DICbio is around thrice that ofDICcarb, and they both show chemostatic response to varying discharge althoughthe degrees for DICbio is stronger. The response of dissolved carbon dynamics todischarge variations display different degrees at different stages of the wet season. Itwas find that most dissolved solutes (except DOC) normally present clockwisehysteresis loops plotting from the top-left to bottom-right due to the dilution onthe rising limb of the storm, but the loop area and hysteresis index are differentwithin or between diverse storms. The pattern is related to rain intensity/amount andantecedent conditions, which can affect flow pathways and likely source areas, leadingto different transport time and loads. These hysteresis behaviours are generallycontrolled by antecedent conditions of storms, range/peak of discharge and soluteconcentrations, and storm duration. Overall, this study highlighted the sensitivecharacteristics of hydrochemistry and dissolved carbon dynamics to hydrologicalvariations in small agricultural karstic catchment based on high resolution information. [ABSTRACT FROM AUTHOR]
- Published
- 2019