荔波板寨小流域水化学和溶解无机碳的稳定同位素特征

通过采集贵州荔波自然保护区内的板寨地上河小流域的地表和地下水样品,测试了阴阳离子含量及其HCO_3~-中的δ~(13)C同位素值,分析不同季节该流域水体的水化学特征,并结合δ~(13)C同位素值探讨水体溶质的来源和水化学过程。结果表明:小流域水体的主要阴离子为HCO_3~-和SO_4~(2-),二者分别占了水体总阴离子当量的86.2%和10.4%,主要阳离子Ca~(2+)和Mg~(2+)则分别占总阳离子当量的76.9%和20.5%。河水较多的Mg~(2+)表明其可能受白云岩风化的影响。小流域水体DIC的δ~(13)C值在-16.87‰至-10.80‰之间,夏季相对于冬季偏负,并且HCO_3~-含量与其δ~(13)C值之间存在负相关关系,这可能是不同季节温度和降水强度共同作用的结果。水体的SO_4~(2-)含量与DIC的δ~(13)C同位素值之间存在明显正相关性,这说明H_2SO_4可能参与了小流域内碳酸盐岩的风化过程。

Stable Carbon Isotope Characteristics of Dissolved Inorganic Carbon and Hydrochemistry in Banzhai Watershed,Libo

Abstract：In this study, the surface and groundwater samples of Banzhai River, in Libo Nature Reserve, Guizhou Province were collected; the contents of main anions and cations and stable carbon isotopes of HCO3- were measured.The hydrochemical characteristics of Banzhai watershed in different seasons were analyzed, and the source of water solutes and the hydrochemical processes were discussed based on the isotope values of δ13C.The results showed that the main anions of the watershed were HCO3- and SO42- which accounted for 86.15% and 10.37% of the total anion equivalent respectively, while the main cations of Ca2+ and Mg2+ accounted for 76.92% and 20.50% of the total anion equivalent respectively.The relatively large amount of Mg2+ in river water indicates that it may be partly derived from dolomite weathering.The relatively higher SO42, K+ and Na+ in the groundwater of school sampling sites indicated this site may be influenced by anthropogenic sources.The δ13C values of DIC in Banzhai watershed ranges from -16.87‰ to -10.80‰, which is negative in summer and positive in winter, and there is a negative correlation between HCO3- content and its value of δ13C, which may be the result of the combined action of temperature and precipitation intensity in different seasons.There is a significant positive correlation between SO42- content and theδ13C values of DIC, which indicates that H2SO4 may be contributes to the weathering process of carbonate rocks in Banzhai watershed.