湖南省郴州市苏仙区重点污染企业影响区的土壤重金属污染源解析

为实现重点污染企业影响区内土壤重金属来源贡献程度的定量化分析，选取湖南省郴州市苏仙区表层（0~20 cm）土壤为研究对象，测定土壤中w（Cd）、w（Hg）、w（As）、w（Pb）、w（Cr）；使用正定矩阵因子分解模型（PMF）对5种重金属元素进行污染源解析，并结合地统计空间分析法识别各源的主要影响区域；基于地统计分析结果，运用莫兰指数表征重点污染企业与污染源的空间关系，以探讨不同行业排放的工业废弃物对土壤中5种重金属元素含量的影响.结果表明:研究区土壤中w（Cd）、w（Hg）、w（As）、w（Pb）、w（Cr）的平均值分别为1.474、0.291、65.165、217.974、66.697 mg/kg，除w（Cr）以外，其余4种重金属元素含量均高于湖南省土壤环境背景值，表明这4种重金属元素受人为活动的影响较大.研究区5种重金属元素受4类源影响，其中，自然源是Cr的主要来源，其贡献率为88.2%，主要影响区域分布在苏仙区北部；大气干湿沉降是Hg的主要来源，其贡献率为80.6%，主要影响区域分布在苏仙区中东部；采选业的工业废弃物是Cd和Pb的主要来源，其贡献率分别为63.2%和65.9%，主要影响区域分布在苏仙区中部；工业混合源是As的主要来源，其贡献率为75.1%，主要影响区域分布在苏仙区中部及中北部.研究显示，莫兰指数与PMF模型的结合运用，一方面可以辅助解析验证PMF模型的有效性，另一方面可以使解析结果更加具体，可为区域企业管理和土壤污染治理决策提供行之有效的支撑. 

Heavy Metal Pollution Sources in Soil Affected by Key Pollution Enterprises in Suxian District,Chenzhou City,Hunan Province

In order to quantify the contribution of soil heavy metal sources in the area affected by key polluting enterprises, the surface soil (0-20 cm) of Suxian District, Chenzhou City, Hunan Province was selected as the research object, and the content of Cd, Hg, As, Pb, and Cr in the soil was determined. The positive definite matrix factorization model (PMF) was used to analyze the pollution sources of the heavy metals, and the main influence areas of each source were identified in combination with geostatistical analysis. Based on the results of geostatistical analysis, the Moran's I index was used to characterize the spatial relationship between key polluting enterprises and pollution sources to explore the impact of industrial waste discharged by different industries on the content of the heavy metals in the soil. The results showed that the average content of Cd, Hg, As, Pb, and Cr in the soil was 1.474, 0.291, 65.165, 217.974, and 66.697 mg/kg, respectively. Except for the Cr content, the contents of the other 4 heavy metals were higher than the soil environmental background value in Hunan Province, indicating that they were significantly affected by human activities. The heavy metals in the study area were affected by four sources. Natural sources were the main source of Cr, with a contribution rate of 88.2%, and the main affected areas were in the north of Suxian District. Atmospheric dry and wet deposition was the main source of Hg, with a contribution rate of 80.6%, and the main affected areas were in the central and eastern Suxian District. Industrial waste from the mining and dressing industry was the main source of Cd and Pb, and their contribution rates were 63.2% and 65.9%, respectively. The main affected areas were in the middle of Suxian District. Industrial mixed sources were the main sources of As, with a contribution rate of 75.1%, and the main affected areas were in the central and north-central Suxian District. The combined application of the Moran's index and PMF model is an effective method to obtain the potential source distribution, and can provide an effective support for enterprise management and soil pollution control decision-making.