宁夏吴忠市金积水源地地下水水质影响因素的多元统计分析

Multivariate Statistical Approach to Identify Influencing Factors of Groundwater Quality in Jinji Water Source of Wuzhong City

根据吴忠市金积水源地地下水饮用水用途选择11项水化学指标,采集32个地下水水样进行测试分析及处理。在分析金积水源地地下水流场及水化学特征基础上,综合利用因子分析法和系统聚类分析方法对水质影响因素进行评价,2种方法评价结果基本一致。结果表明,该区地下水水质影响因素主要有:以Cl-、SO24-、Mg2+、NO3-、Ca2+质量浓度为代表变量的溶滤作用,该作用表现为西强东弱,综合主成分贡献率48.40%;以EC、总硬度及TDS、Na+、HCO-质量浓度为代表变量的蒸发浓缩作用,沿补给区和排泄区作用较强,综合主成分贡献率39.66%;以NH4-N质量浓度为主要载荷变量的人类活动影响因素,因子得分较高区域与企业分布及排污范围分布一致,综合主成分贡献率11.94%。水质影响因素分布总体表现为黄河沿岸蒸发浓缩作用相对较强;汉渠以北主要受溶滤作用及地下水蒸发浓缩共同影响;南干沟及南干沟入黄河口附近氨氮污染较明显。

32 water samples in Jinji water source of Wuzhong City are collected and 11 parameters for each sample are analyzed. Based on the analysis of flow field and hydrochemistry of groundwater, both of factor analysis method and hierarchical cluster analysis method are used to evaluate the comprehensive influence factors of groundwater quality. The results of these two methods are relatively consistent, both of which show that the groundwater quality here are mainly controlled by three kinds of impacts. The first kind of impact is from lixiviation mainly controlled by C1- , SO2- , Mg2＋ , NOr , and Ca2＋ , which appears stronger in east than west. The relative contribution of this impact is 48.4%. The second kind of impact is from evaporation-concentration mainly controlled by HCO, Na＋ , EC, TDS,and T-Hard, which appears stronger in east than in west. The relative contribution of this impact is 39.66~/oo. The third kind of impact is from human activities mainly associated with NH4 - N. The last impact has the same spatial distribution as the factories and pollution discharge areas. The relative contribution of this impact is 11. 94~. The distributions of three factors show that evaporation- concentration mainly occurs along the Yellow River. The combined effect of lixiviation and evaporation- concentration occur in north of the Han Drainage. Ammonia-nitrogen pollution is obvious along the Nangan Drainage.