锰矿区周边农田土壤重金属污染特征、来源解析及风险评价

为了解锰矿周边农田土壤重金属污染和生态风险情况,采集某矿区周边174份农田土壤样品,分析了土壤中8种重金属(Cu、 Zn、 Pb、 Cr、 Ni、 Mn、 As和Hg)的含量,采用主成分分析(PCA)和正定矩阵因子分解模型(PMF)分析土壤重金属的来源,通过单因子污染指数法、地累积指数法、潜在生态风险指数法和人体健康风险评价模型评价土壤重金属生态环境风险.结果表明,研究区农田土壤Cu、 Zn、 Cr、 Ni、 Mn和Hg含量的均值均高于贵州省土壤背景值,100%样本Zn和38.86%样本Cu均超过农用地土壤污染风险筛选值.源解析显示农田土壤重金属的主要来源为矿业开采排放源,其次为农业活动和交通运输混合源、自然源和农业活动源.风险评价结果表明,土壤中Ni、 Cr、 Pb和As属于清洁水平,Hg和Cu属于轻度污染水平,Zn属于偏中度污染水平,Mn属于偏重污染水平.Cu、 Zn、 Pb、 Cr、 Ni、 Mn和As存在轻微潜在生态风险,Hg存在强潜在生态风险.研究区整体存在强潜在生态风险,8种重金属存在致癌风险和0～5岁儿童非致癌风险,主要贡献因子分别是Cr和Mn.

Pollution Characteristics, Source Analysis, and Risk Assessment of Heavy Metals in the Surrounding Farmlands of Manganese Mining Area

In order to understand the status of heavy metal pollution and the resulting ecological risk of farmland soil surrounding the manganese mining area, 174 soil samples were collected, and the heavy metals(Cu, Zn, Pb, Cr, Ni, Mn, As, and Hg) were analyzed. Principal component analysis (PCA) and the positive matrix factorization (PMF) model were used to determine the source of heavy metals in the soils. The single-factor pollution index method, geo-accumulation index method, potential ecological risk assessment method, and US EPA health risk assessment model were used to evaluate the ecological environment risk of heavy metals. The results showed that the average values of Cu, Zn, Cr, Ni, Mn, and Hg exceeded the background value of Guizhou. 100% of Zn samples and 38.86% of Cu samples exceeded the risk screening value for agricultural land soil pollution. Source analysis revealed that the main sources of soil heavy metals were mining emission, mixed agricultural activity and transportation, nature, and agricultural activities. The risk evaluation showed that Ni, Cr, Pb, and As belonged to the clean level, Hg and Cu were in a light pollution stage, Zn fell into the category of moderate contamination, and Mn reached the heavy pollution level. Cu, Zn, Pb, Cr, Ni, Mn, As, and Cd posed low potential ecological risk, while Hg caused a considerable potential ecological risk. In total, the integrated potential ecological risk of heavy metals was ranked "strong", eight types of heavy metals had carcinogenic risks and non-carcinogenic risks for children aged 0-5 years, and the main contributing factors were Cr and Mn, respectively.