Groundwater is the primary source of water for human development in the Yishu River basin, and therefore characterizing groundwater quality is essential for sustainable development of groundwater resources in the region. This study aimed to determine the hydrochemical characteristics and water quality of groundwater in the Yishu River basin by sampling 45 wells in October 2016 and May 2017. Hydrochemical characteristics of groundwater were determined using integrated hydrochemical analysis and the groundwater quality was evaluated based on the water quality index (WQI). Groundwater of the Yishu River basin was characterized as weak alkaline hard water with mean concentrations of total hardness and total dissolved solids of less than 500 mg L⁻¹ and 1000 mg L⁻¹, respectively, and the principal chemical components of groundwater were higher in 2016 than in 2017. A Piper diagram showed that 64.4% of the water samples contained Ca–HCO₃ type water and 27% contained mixed water (27%). The dominant processes driving the chemical composition of groundwater were found to be dissolution of silicate and carbonate minerals and cation exchange. The saturation index indicated that carbonate minerals were supersaturated, whereas gypsum, fluorite, and halite were unsaturated. The WQI indicated good groundwater quality in the Yishu River basin, with only one water sample classified as having "poor" water quality in 2016 and 2017, respectively. However, these samples contained high nitrate concentrations (> 200 mg L⁻¹), which may be the result of domestic sewage discharge and/or the use of agricultural fertilizers.

中文翻译：

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沂shu河流域地下水水化学特征及水质评价

地下水是沂shu河流域人类发展的主要水源，因此表征地下水质量对于该地区地下水资源的可持续发展至关重要。本研究旨在通过在2016年10月和2017年5月对45口井进行采样来确定沂shu河流域地下水的水化学特征和水质。采用综合水化学分析方法确定地下水的水化学特征，并根据水质对地下水水质进行评估。索引（WQI）。沂shu河流域的地下水特征为弱碱性硬水，其总硬度和总溶解固体的平均浓度分别小于500 mg L ^-1和1000 mg L ^-1Piper图显示，2016年地下水的主要化学成分分别高于2017年和2017年。Piper图显示，其中64.4％的水样本中含有Ca–HCO ₃型水，而27％的样本中含有混合水（27％）。发现驱动地下水化学成分的主要过程是硅酸盐和碳酸盐矿物的溶解和阳离子交换。饱和指数表明碳酸盐矿物是过饱和的，而石膏，萤石和岩盐是不饱和的。世界水质指数表明沂shu河流域地下水水质良好，2016年和2017年分别只有一个水样被归为“水质差”。但是，这些样品中硝酸盐浓度较高（> 200 mg L ^-1），这可能是生活污水排放和/或使用农业肥料的结果。