为了研究喀斯特地区源头流域化学侵蚀输出河流溶解无机碳(DIC)而消耗大气CO₂的碳汇效应,自2010年6月至2011年5月对乌江源地区喀斯特广泛发育的三岔河流域源头白泥河的向阳水文站断面的水文与水化学过程进行了一个水文年的观测。分析了该断面的总溶解固体物(TDS)及其碳汇通量和强度变化规律。结果表明,白泥河向阳断面的TDS的年输出通量和侵蚀强度分别约为6.37×10¹⁰g和7.495×10⁷g·km^-2·a^-1,化学侵蚀的同时,断面DIC的年输出通量和侵蚀强度分别达到5.483×10⁸mol和6.45×10⁵mol·km^-2·a^-1。按照98%的化学侵蚀来源于流域碳酸盐岩溶蚀作用估算,该流域化学侵蚀过程消耗大气CO₂约2.819×10⁸mol,其碳汇强度约为3.32×10⁵mol·km^-2·a^-1,其中95%的化学侵蚀和碳汇发生在高温多雨的6—11月。受到强烈的岩溶作用影响,白泥河流域化学风化及其碳汇强度与流域地貌、气候条件和水文过程密切相关。

For understanding the law on the atmospherical CO₂ consumption effect due to Dissolved Inorganic Carbon (DIC) discharged from the chemical weathering processes in the Source Drainage Basins Area of the Karst region, a riverine hydro-chemical investigation is carried out during the entire hydrologic year from June 2010 to May 2011 in the water channel of the Xiangyang Hydrological Stations located at the Bainihe watershed in Wujiang River Source Drainage Basins Area, that the cover layer is mainly carbonate as well as Karst landforms are widely developed. The variation of the Total Dissolved Substances (TDS), its sink flux to atmospherical carbon, and intensity change in the cross-section studied are analyzed. Result indicates that the annual fluxes on the TDS are amount of 6.37×10¹⁰g with 7.495×10⁷g·km^-2·a^-1 in chemical weathering modulus, and the annual fluxes of the DIC are amount of 5.483×10⁸mol with 6.45×10⁵mol·km^-2·a^-1 in DIC weathering modulus. Based on the carbonate weathering contribution rate amounting to 98% of the riverine DIC, the annual fluxes of the atmospherical CO₂ consumption at Xiangyang Hydrological Stations of the Bainihe watershed are about 2.819×10⁸mol with 3.32×10⁵mol·km^-2·a^-1in modulus, about 95% of which are discharged during the hot-rainy period from June to November in the year surveyed. Impacted strongly by Karst process, the chemical weathering and its carbon consumption are closely related to the characteristics of watershed land surface, climatic condition, as well as hydrological processes in the Bainihe watershed.