非岩溶水和硫酸参与溶蚀对湘南地区地下河流域岩溶碳汇通量的影响  

The Influence of Allogenic Water and Sulfuric Acid to Karst Carbon Sink in Karst Subterranean River in Southern Hu'nan

作　　者：黄奇波[1,2,3] 覃小群[2,3] 刘朋雨[2,3] 张连凯[2,3] 苏春田[1,2,3] 

机构地区：[1]中国地质大学环境学院,湖北武汉430074 [2]中国地质科学院岩溶地质研究所,广西桂林541004 [3]国土资源部广西岩溶动力学重点实验室,广西桂林541004

出　　处：《地球科学进展》2017年第3期307-318,共12页Advances in Earth Science

基　　金：中国地质调查局地质调查项目"西江中下游岩溶峰林区1:5万水文地质环境地质调查"(编号:121201107000150005);国家自然科学基金项目"半干旱岩溶区溶蚀作用季节分异与影响机制"(编号:41302211)资助~~

摘　　要：研究非岩溶水和硫酸参与溶蚀对地下河流域岩溶碳汇通量的影响,有助于提高岩石风化碳汇通量估算精度,对于推进地质作用与全球气候变化研究意义重大。选取湘南北江上游武水河流域内4条典型地下河为对象,通过水化学对比分析,揭示硅酸盐岩风化对流域地下水化学的重要影响。运用Galy方法计算流域非岩溶地层中的硅酸盐岩风化消耗大气/土壤CO_2对岩石风化碳汇的重要贡献,并评价了H_2SO_4参与下碳汇通量的扣除比例。结果显示:(1)流域内有非岩溶地层的L01,L02地下河,Na^+,K^+和SiO_2浓度明显高于纯碳酸盐L03和L04地下河,非岩溶地层中的硅酸盐的风化对地下河水中K^+,Na^+,SiO_2浓度有一定贡献;(2)4条地下河的[Ca^(2+)+Mg^(2+)]/[HCO_3^-]当量比值为1.05~1.15,[Ca^(2+)+Mg^(2+)]/[HCO_3^-+SO_4^(2-)]的当量比值为0.99~1.08,Ca^(2+)+Mg^(2+)相对于HCO_3^-过量,过量的Ca^(2+)+Mg^(2+)与SO_4^(2-)相平衡,证实硫酸参与流域碳酸盐岩的溶蚀;(3)L01和L02地下河岩石风化消耗的CO_2通量中非岩溶地层中的硅酸盐风化消耗所占比例分别为3.36%和2.22%,而L03和L04地下河中硅酸盐风化消耗比例小于0.50%,表明有非岩溶地层存在的地下河流域,其岩石风化消耗的CO_2通量中硅酸盐风化消耗占有一定比例;(4)在考虑硫酸参与碳酸盐岩溶蚀时,4条地下河的碳汇通量分别扣除4.84%,4.52%,6.20%和9.36%。Evaluating the impact of allogenic water and sulfuric acid on karst carbon sink not only helps to improve the accurate calculation of soil CO2 uptake by rock weathering, but also obtains a complete understanding of the global carbon cycle. Groundwater samples were collected from four karst subterranean rivers watershed within different lithology strata in Wushui Basin, upstream of Beijiang Basin, Hunan Province, for revealing the important impact of silicate weathering on hydrochemistry of groundwater. To estimate the contribution of soil CO2 uptake by silicate weathering to CO2 uptake by rock weathering, the Galy model was employed in this article. The important impact of sulfuric acid on CO2 uptake by carbonate weathering resulting from the substitution of carbonic acid by protons from sulfuric acid was investigated. Our results showed that the concentration of Na^＋ , K^＋ and SiO2 in L01, L02 subterranean river with silicate strata in watershed were higher than that in L03, L04 subterranean river without silicate strata in watershed, which implied that the contribution of silicate weathering to Na^＋ , K^＋ and SiO2 was very important in watershed within silicate strata . The changeable equivalent ratio between （Ca^2＋ ＋Mg^2＋） and HCO3^- was 1.05 to 1.15, and the value of [ Ca^2＋ ＋Mg^2＋ ]/[ HCO3^- ＋SO4^2- ] was 0.99 to 1.08. The concentrations of Ca^2＋ and Mg^2＋ exceeded the equivalent concentrations of HCO~, and the excess of Ca^2＋ and Mg^2＋cations were compensated by SO4^2-, which suggested that sulfuric acid has an important influence on carbonate dissolution. The contribution of soil COzuptake by silicate weathering to CO2 consumption in L01 and L02 subterranean river were 3.36% and 2.22% , respectively, whereas the contribution in L03, L04 subterranean river were less than 0.50%, indicating that the contribution of soil CO2 uptake by silicate weathering was important in the subterranean river basin within silicate strata. Due to the contributions made by sulfuric acid, the CO

关 键 词：地下河 碳酸盐岩风化 硅酸盐岩风化 碳汇通量 硫酸 

分 类 号：P641.134[天文地球—地质矿产勘探]