新疆和田河流域绿洲区地下水质量演化特征

以新疆和田河流域绿洲区1980、2014和2017年地下水化学检测数据为基础,运用单指标评价法进行地下水质量评价及关键指标识别,并分析该区域地下水质量在时间与空间上的演化特征。结果表明:和田河流域绿洲区潜水质量总体较差,1980年浅层地下水有Ⅱ类水存在,Ⅳ类和Ⅴ类水共占总水样的61.8%;2014年Ⅳ类和Ⅴ类水共占91.1%;2017年Ⅳ类和Ⅴ类水共占72.5%。影响地下水质量的关键指标除TDS、TH、Cl^-、Na⁺和SO₄^2-常量组分外,还有F^-、Fe、Mn和BaP等微量组分。1980和2017年绿洲区地下水质量在水平方向上的分布规律相似,冲洪积细土平原中上部区域,尤其是出山口河流渗漏影响带的地下水质量较好;冲洪积细土平原尾部地下水质量较差。2014年Ⅴ类水的分布面积最大,Ⅲ类和Ⅳ类水零星分布。垂直方向上,浅层地下水质量普遍劣于中深层地下水。1980-2014年绿洲区地下水质量逐渐下降,2014-2017年地下水质量出现略微好转的趋势。

Evolution characteristics of groundwater quality in Hotan River Basin oasis, Xinjiang

Based on the chemical test data of groundwater in the oasis area of Hotan River Basin, Xinjiang in 1980, 2014 and 2017, the single index evaluation method was used to evaluate the groundwater quality and identify the key influencing indicators. Meanwhile, the spatio-temporal evolution characteristics of groundwater quality in this area was analyzed. The results show that the quality of unconfined groundwater in the oasis area was generally poor. In 1980, 61.8% of groundwater was classified as IV and V, 91.1% of groundwater was classified as IV and V in 2014, class IV and V water accounted for 71.0% in 2017. In addition to the major components (such as TDS, TH, Cl^-, Na⁺ and SO₄^2-), the key indicators affecting groundwater quality also included trace components such as F^-, Fe, Mn and BaP. In the horizontal direction, the distribution law of groundwater quality in the oasis area in 1980 and 2017 was similar, and the groundwater quality in the middle and upper part of the alluvial-diluvial plain, especially in the area affected by river seepage at the mountain pass was better, whereas that at the end of alluvial-diluvial plain was poor. In 2014, the distribution area of class V water was the largest, whereas class III and IV water were scattered. In the vertical direction, the quality of shallow groundwater was generally inferior to that of middle and deep groundwater. The quality of groundwater in the oasis area decreased gradually from 1980 to 2014, and then showed a slightly improving trend from 2014 to 2017.