基于地理探测器的土壤重金属影响因子分析及其污染风险评价

地理探测器能快速定量化揭示驱动重金属含量影响因素的强度,这对于重金属空间预测模型构建变量的确定和土壤污染修复措施的精准实施具有重要意义。利用地理探测器模型,对5种土壤重金属元素Cu、Zn、Pb、Cr、Ni的空间分布和11种环境因子的交互作用进行定量评估,通过单因子指数法进行重庆市土壤重金属污染风险评价。结果表明:研究区内土壤Cu、Zn、Cr和Pb的平均含量是重庆市土壤背景值的1.3—1.4倍,Ni含量低于背景值;其中Cu、Pb达到重度污染水平,其余3种重金属为中度或轻度污染水平。5种重金属元素中Cu和Pb为高度变异(变异系数为0.57、0.4),Zn、Cr和Ni为中等变异(变异系数为0.22—0.29),且各重金属元素之间呈显著正相关性,表明研究区重金属富集受人为干扰影响较大,且污染具有复合性或同源性。地理探测器的因子探测发现高程、坡度和土壤类型对5种土壤重金属含量的解释力最显著,说明地势和土壤类型是土壤重金属含量分布差异的最主要影响因素。交互作用探测发现,高程与其他因子交互作用是重金属空间分异的主导因素,气候条件和土壤类型也是重要影响因子。土壤重金属空间分布是多种因素共同作用的结果,而高程、坡度和土壤类型具有较强的解释力,这些因子可作为土壤重金属含量空间预测模型的辅助变量,也可促进重金属污染治理措施的靶向实施。

Influence Factor Analysis of Soil Heavy Metal Based on Geographic Detector and Its Pollution Risk Assessment

Geographic detector can quickly and quantitatively reveal the intensity of driving factors of heavy metal content,which is of great significance for the driving variables determination of heavy metal spatial prediction model and the accurate implementation of soil pollution remediation measures.In this paper,the interaction of the spatial distribution of five soil heavy metals(Cu,Zn,Pb,Cr,Ni)and 11 environmental factors were quantitatively evaluated by using the geographic detector model,and the risk assessment of soil heavy metal pollution in Chongqing was carried out by using the single factor index method.Results showed that:the average content of Cu,Zn,Cr and Pb in the study area was 1.3?1.4 times of the background value of Chongqing,and the content of Ni was lower than the background value;among them,Cu and Pb reached the heavy pollution level,and the other three heavy metals were moderate or light pollution level.Among the five heavy metals,Cu and Pb were highly variable(coefficient of variation was 0.57,0.4),Zn,Cr and Ni were moderately variable(coefficient of variation was 0.22?0.29),and the correlation among the elements was significant,which indicated that the heavy metal enrichment in the study area was greatly affected by human disturbance,and the pollution was complex or homologous.The factor detection showed that elevation,slope and soil type had the most significant explanatory power for the five heavy metal content,indicating that terrain and soil type were the main factors for the distribution variation of soil heavy metal.Interaction detection showed that the interaction between elevation and other factors was the dominant factor for the spatial variation of heavy metals,and climate conditions and soil types were also important factors.The spatial distribution of soil heavy metals was the result of multiple factors,and elevation,slope and soil type had strong explanatory power.These factors can be used as auxiliary variables in the spatial prediction model of soil heavy metal content,and can also promote the targeted implementation of heavy metal pollution control measures.