双河洞小流域主要离子化学特征及其来源分析

Hydrogeochemical Characteristics and Analysis of Their Sources in Karst Small Watershed of Shuanghe Cave System

为探究岩溶地表水和地下水水化学特征及其各种盐类对主要离子的贡献,以喀斯特小流域为研究尺度,对贵州绥阳双河洞区域地表水和地下水水化学进行野外监测、采样和室内实验,并运用SPSS统计软件对水样点进行主成分分析研究。结果表明:(1)双河洞水化学阳离子主要以Ca^(2+)、Mg^(2+)为主,阴离子以HCO_3^-和SO_4^(2-)为主。水化学类型主要为Ca^(2+)·Mg^(2+)—HCO_3^-型水,而石膏洞为Ca^(2+)·Mg^(2+)—SO_4^(2-)型水。大多数离子的含量随采样点、季节和水体类型的不同而呈显著性差异;(2)岩石风化对流域离子组成影响显著,阴离子主要来自碳酸盐、蒸发盐或岩盐的溶解和风化,蒸发盐溶解是阳离子的主要控制机制,硅酸盐风化侵蚀作用对区域离子变化存在一定影响;(3)主成分分析法得出对区域离子化学组成的影响程度按碳酸盐、蒸发盐和硅酸盐递减,其中H_2CO_3风化碳酸盐岩的影响显著,但在个别地下水主要受H_2SO_4风化碳酸盐岩的影响显著,此外农业活动和居民生活也有一定影响。研究结果对双河洞洞区水资源的保护和开发利用及岩溶碳循环研究具有重要意义。

The aim of this study was tO explore the chemical characteristics of surface water and groundwater, and the contribution of various salts to the main ions. Karst small watershed was taken as the research scale, field monitoring and sampling, and laboratory experiments for surface water and groundwater chemistry in Shuanghe Cave area was carried out. SPSS statistical software was used to analyze the principal components of water samples. The results were as follows： （1） Caz＋ and Mg3＋ were the predominant cations of groundwater and surface water in Shuanghe Cave, and the predominant anions were HCO3- and SO4z-. The water chemistry could be classified as Ca2＋ Mgz＋ --HCO3-type, but Gypsum Cave was Caz＋ Mg2＋ --SO4- type. The contents of most ions varied with different sampling points, seasons and types of water; （2） Gibbs and trian- gular diagrams analyses revealed that the water compositions in the watershed were significantly impacted by rock weathering process. The main anions were derived from carbonate dissolution and evaporation, weathered rock or rock salt. Evaporation salt dissolution was the main controlling mechanism of cation, and the effect of silicate weathering and erosion also affected regional ion change; （3） The principal component analysis showed that the degree of influence on the regional composition of ion chemistry followed the order of carbonates evaporites：〉 silicates. Among them, the influence of H2CO3 weathering carbonate rock was obvious, but in certain underground river, water chemistry was mainly affected by H2SO4 weathering carbonate rock. In addition, agricultural and domestic activities also showed some impacts on water characteristics.The results of this study have a great significance for the protection, development, and utilization of water resources in Shuanghe Cave and for karst carbon cycle research.