重庆市浅层地下水污染源解析与环境影响因素识别

为了有效防控山地城市复杂地质条件下的浅层地下水污染，明晰地下水污染的影响因素，基于重庆82个浅层地下水监测点的15项水质指标，运用绝对主成分-多元线性回归模型(APCS-MLR)，解析不同水质指标的污染源因子，量化因子对地下水质的贡献率；基于地下水脆弱性理论，借助地理探测器识别岩溶区、非岩溶区地下水污染的关键影响因素. 结果表明:①重庆市浅层地下水受人类活动影响大，总大肠杆菌群、Fe、Mn等元素超标率在50%以上；②重庆市浅层地下水污染源因子主要包括淋溶富集-城镇生活污染因子(贡献率42%)、地质环境背景因子(17.83%)、工业污染因子(13.74%)、农业污染因子(6.78%)，方差累计贡献率为80.34%；③重庆市浅层地下水污染强度空间分布总体呈现西部都市区及周边>中部>东南部>东北部的空间分布格局. 土地利用类型、坡度、土壤质地等3个因子对全域地下水污染具有较高的解释力，是浅层地下水污染的关键影响因子；④土地利用类型与降雨强度、土地利用类型与水力传导系数、土壤与坡度等双因子交互非线性增强了对重庆市浅层地下水污染的解释力. 研究显示:污染源强与路径因子相结合能更好地解释地下水污染差异化；地理探测器为识别地下水污染影响因子提供了有效的探索方法. 

Analysis of Pollution Sources and Identification of Environmental Influencing Factors of Shallow Groundwater in Chongqing,China

In order to effectively prevent the shallow groundwater pollution under complex geological conditions in mountain city Chongqing, and to clarify the environmental impact of regional shallow groundwater pollution, based on 82 shallow groundwater samples and 15 key groundwater quality indicators, this study used absolute principal component score-multiple linear regression model (APCS-MLR) to quantify the source contribution rate of each pollution factor. Based on the theory of groundwater vulnerability, the key environmental factors of groundwater pollution in non-karst/karst areas were identified by geographical detectors. The results showed that: (1) Human activities significantly influenced the shallow groundwater quality in Chongqing, and the exceed rate of E. coli group, Fe, Mn reached 50%. (2) The pollution factors of shallow groundwater included leaching enrichment-urban living pollution with contribution of 42%, geological environment 17.83%, industrial pollution 13.74%, agriculture pollution 6.78% and the cumulative variance contribution of 80.34%. (3) The spatial distribution of shallow groundwater pollution intensity from large to small was in order of the western cities, the middle, the southeast, the northeast. (4) The land use, slope, soil texture were key influencing factors of the shallow groundwater pollution in karst/non-karst region in Chongqing. Land use and rainfall intensity, land use types and rock hydraulic conductivity coefficient, soil and slope enhanced their influence on the shallow groundwater pollution. The combination of pollution source strength and path factors can better explain the difference of groundwater pollution. Geographical detector provides an effective exploration method for identifying factors of groundwater pollution.