西北盐湖流域地下水水化学特征及控制因素

以内蒙古吉兰泰盐湖盆地图格力高勒流域为研究对象，2021年丰、枯水期采集22组地下水样品并测定主要水化学特征指标，综合运用数理统计、Piper三线图、Gibbs图、离子比值和因子分析等方法对不同时期地下水化学特征和主要控制因素进行了分析和探讨，利用水质指数（WQI）法评价了地下水水质，并综合健康风险评价模型对地下水Cr⁶⁺和F^-的潜在风险进行了评估.结果表明，研究区内地下水整体呈弱碱性，不同时期地下水中的优势阴、阳离子均为Cl^-和Na⁺，水化学类型均以Cl^--Na⁺型为主；研究区地下水水质整体较好，在丰水期和枯水期水质差异不显著；健康风险评价表现为成人和儿童在枯水期均有较高的致癌风险，儿童的健康风险明显高于成人，成人和儿童由Cr⁶⁺经饮水途径暴露的致癌健康风险最大值均高于最大可接受风险水平（5×10^-5）；研究区地下水化学演化过程主要受蒸发浓缩作用、蒸发盐岩溶解和阳离子交换作用综合影响，主要控制因素分别是蒸发浓缩作用（贡献率为54.19%）、原生地质环境因子（贡献率为12.99%）和碳酸盐岩溶解作用（贡献率为11.66%）.研究成果对盐湖流域地下水资源可持续开发利用和环境保护具有重要意义.

Hydrochemical Characteristics and Control Factors of Groundwater in the Northwest Salt Lake Basin

Taking the Tugeligaole sub-basin of the Jilantai Salt Lake Basin in Inner Mongolia as the typical study area, the groundwater samples of 22 points were collected, and their main characteristic indexes were tested during the wet season and the dry season separately in 2021. Mathematical statistics, Piper triangular diagrams, a Gibbs plot, ionic relations, and factor analysis were used to analyze and discuss the hydrochemical characteristics and formation mechanism of groundwater in different periods. Based on the evaluation of the groundwater quality using the water quality index(WQI) method, the potential risks of groundwater Cr⁶⁺ and F^- were evaluated using the health risk evaluation model. The results showed that the groundwater was overall weakly alkaline; the dominant anions and cations during the different periods were Cl^- and Na⁺, and the water chemistry type was mainly Cl^--Na⁺; the groundwater quality was generally good, and the difference in water quality between the wet season and the dry season was not significant; adults and children had higher carcinogenic health risks in the dry season than that in the wet season, and the health risks of children were significantly higher than those in adults. The maximum carcinogenic health risk of drinking water exposure to Cr⁶⁺ in adults and children was higher than the maximum acceptable risk level(5×10^-5). The chemical evolution of groundwater was mainly affected by evaporative concentration, evaporative salt rock dissolution, and cation exchange, and the main control factors were evaporative concentration(contribution rate of 54.19%), native geological environment factors(contribution rate of 12.99%), and carbonate rock dissolution(contribution rate of 11.66%). The study results have significance to some degree to the sustainable exploitation and utilization of groundwater resources and environmental protection of the salt lake basin.