会仙岩溶湿地地下水主要离子特征及成因分析

以我国最大的低海拔岩溶湿地会仙岩溶湿地为研究区,对该区丰水期、平水期和枯水期共采集的27组地下水样品中常规离子进行检测和分析,在分析会仙岩溶湿地地下水主要离子化学特征和不同时期变化基础上,运用单指标污染标准指数法对不同时期地下水进行污染评价,利用多元统计、Gibbs模型和离子比例关系识别地下水主要离子成因.结果 表明,...

Major Ionic Characteristics and Factors of Karst Groundwater at Huixian Karst Wetland, China

To investigate the major ionic chemical characteristics and seasonal variations, 27 groundwater samples were collected from the wet season, flat season, and dry season during 2018-2019 in the Huixian Karst wetland, which is the largest low-altitude karst wetland in China. The single pollution standard index was applied to evaluate the groundwater pollution during different periods, and the major ionic factors of the karst groundwater were analyzed using the statistical analysis method, Gibbs diagram, and ion ratio. The results revealed that the groundwater samples were a weakly alkaline fresh water that were rich in Ca²⁺ and HCO₃^-. The average concentrations of the primary ions followed the order of flat season > wet season > dry season; meanwhile, the water quality in the dry season was better than that in the wet and flat seasons. The K⁺ and NO₃^- in the karst groundwater were mostly affected by the spatial distributions of the aquifers, and the Mg²⁺, SO₄^2-, NO₂^-, NH₄⁺, and TDS were related to the space-season scale. Na⁺, Ca²⁺, HCO₃^-, and Cl^- were relatively stable ions in the karst groundwater. The hydrochemical characteristics were primarily determined by carbonate rock dissolution and were found to be the HCO₃-Ca type, which accounted for 77.78%, 77.78%, and 88.89% in the wet season, flat season, and dry season, respectively. The karst groundwater was predominantly polluted by SO₄^2-, NO₃^-, and NO₂^-; particularly, NO₃^- exhibited serious pollution points, and SO₄^2- had heavy pollution points in the wet and flat seasons. The chemical composition of the karst groundwater was controlled mostly by water-rock interactions. Ca²⁺ and HCO₃^- primarily came from calcite dissolution, and the high concentrations of Mg²⁺ and SO₄^2- in a few number of points were controlled by dolomite, dolomitic limestone, and pyrite. K⁺, Na⁺, SO₄^2-, NO₃^-, and Cl^- partly came from atmospheric precipitation, and Na⁺ and Cl^- partly came from human activities; K⁺ was related to potash fertilizer, and the main source of NO₃^- was chemical fertilizer.