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Huang Q.,Wuhan University | Huang Q.,Chinese Academy of Geological Sciences | Huang Q.,Guangxi Key Laboratory of Karst Dynamics | Qin X.,Chinese Academy of Geological Sciences | And 5 more authors.
Diqiu Kexue - Zhongguo Dizhi Daxue Xuebao/Earth Science - Journal of China University of Geosciences

Quantitative evaluation of the impact of sulfuric acid to karst carbon sink not only improves the estimation accuracy of karst carbon sinks, but also facilitates research on global climate change. In this paper, Guilin karst area affected by acid rain is selected for studying. The results of testing and analysis of the chemical composition and inorganic carbon isotope in 14 karst spring and 15 subterraneans show that in both karst spring and subterranean, Mg2+ and Ca2+ are the main negative ions, and HCO3- is the main positive ion, which were accounted for more than 90% of negative ion and positive ion respectively, and SO42- has a lower content, which content range was 0.004-0.213 mmol/L and the composition ratio was 0.12%-6.11%; The δ13CDIC, [Ca2++Mg2+]/[HCO3-] are more inclined to carbonate dissolution endmember, and the longer distance from sulfuric acid dissolution endmember indicates the limited impact of sulfuric acid dissolution of carbonate rocks involved in groundwater inorganic carbon (DIC) and δ13CDIC. Same as the situation of Sr2+/Ca2+ values, δ13CDIC could reflect the run-off condition of groundwater to some degree. Using the stoichiometry method calculate, the average proportion of DIC(HCO3 H2SO4-) produced by sulfuric acid gained by stoichiometric relationship is 22. 64%, accounts for 13.04%, while that produced by carbonic acid accounts for 86.96%, of which 43.48% comes from the soil atmosphere. Deducting DIC contribution of sulfuric acid to the groundwater, 13.04% karst carbon sink will be reduced. ©, 2015, China University of Geosciences. All right reserved. Source

Qin X.-Q.,Chinese Academy of Geological Sciences | Qin X.-Q.,Guangxi Key Laboratory of Karst Dynamics | Liu P.-Y.,Chinese Academy of Geological Sciences | Liu P.-Y.,Guangxi Normal College | And 4 more authors.
Acta Geoscientica Sinica

The atmospheric/soil CO2 consumption by rock weathering has become the main carbon sink. The flux of CO2 consumed by rock weathering increases with the increasing carbonate rock outcrop area and the water drainage intensity. In this paper, with the rock, water runoff and water chemistry data of the valley as the main data, the authors estimated the flux of atmospheric/soil CO2 consumed by chemical erosion of continental rocks in the Pearl River Valley based on a global erosion model (GEM-CO2) developed by Amiotte Suchet. The total carbon consumption is about 252×109 mol·a-1 (571×103 mol·km-2·a-1), about 71.4% of which are caused by carbonate rocks, with about 180×109 mol·a-1 (1030×103 mol km-2·a-1) CO2 consumed flux. About 79.4% of the consumption of CO2 is localized in Xijiang tributary basin, because of a high proportion of carbonate rocks and high humidity in this area. In contrast, the Beijiang tributary basin and the Dongjiang tributary basin only possess 13% and 4.9% of the total CO2 consumption amount respectively. The flux of atmospheric/soil CO2 consumed in the Pearl River Valley is 2.3 times higher than the average CO2 consumption of the major river basins in the world. Source

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