海南岛半干旱区农用地土壤重金属富集因素、健康风险及来源识别

为了解海南岛半干旱区农业土壤中重金属富集因素和污染状况，在感城镇采集1818件表层土壤样品，测定其重金属含量和化学组成.采用相关分析、地累积指数（I_geo）、综合生态风险指数（RI）、危害指数（HI）、致癌风险指数（CR）和正定矩阵因子分析（PMF）开展重金属风险评价和来源识别.结果显示，重金属ω（As）、ω（Cd）、ω（Cr）、ω（Cu）、ω（Hg）、ω（Ni）、ω（Pb）和ω（Zn）的平均值分别为22.7、0.128、33.4、14.5、0.032、9.32、32.5和43.3 mg ·kg^-1，除Zn外，均高于海南岛土壤背景值.相关分析表明，重金属富集与土壤中Fe、Mn、Al和有机质含量密切相关.I_geo结果表明，研究区农业土壤主要受到As的污染，其次为Cd和Cu；RI结果显示，高风险以上的样品占比为29.4%，其中As是潜在生态风险的主要贡献者；健康风险评估结果显示，As、Cr和Ni对儿童存在致癌风险，需要引起注意.基于PMF模型，确定了研究区重金属的4种主要来源，其中Hg主要来自工业排放；As主要来自农业活动；Ni、Cu、Cr和Zn主要来自与成土母质密切相关的自然来源；Pb和Cd主要来自农业活动和机动车尾气的混合源.研究表明PMF模型与相关分析相结合，能够有效识别土壤重金属来源.

Enrichment Factors, Health Risk, and Source Identification of Heavy Metals in Agricultural Soils in Semi-arid Region of Hainan Island

To understand the enrichment factors and pollution levels of heavy metals in agricultural soils in the semi-arid region of Hainan island, 1818 surface soil samples were collected in Gancheng Town and analyzed for their heavy metal contents and physicochemical composition. Correlation analysis was used to determine the heavy metal enrichment factors. The geo-accumulation index (I_geo), comprehensive ecological risk index (RI), and hazard index (HI), as well as carcinogenic risk (CR), were used to assess the degree of pollution and health risk. Positive matrix factorization (PMF) was used to determine the primary sources of pollution and priority sources. The average values of heavy metal contents in the topsoil were 22.7, 0.128, 33.4, 14.5, 0.032, 9.32, 32.5, and 43.3 mg·kg^-1 for As, Cd, Cr, Cu, Hg, Ni, Pb, and Zn, respectively. With the exception of Zn, the concentrations of other heavy metals in the topsoil were higher than the soil background values of Hainan, showing different degrees of heavy metal accumulation effect. The I_geo revealed that the major pollutant element in soils was As, followed by Cd and Cu. The RI showed that the proportion of soil samples that were high-risk level or worse was 29.4% of the total number of samples, among which As was the major source of risk. The health risk assessment results indicated that As, Cr, and Ni exposure presented carcinogenic risk for children with high CR values. Based on PMF, four major sources of heavy metals were identified in the study area. Hg was derived mainly from industrial sources, and As was closely associated with agricultural activities. Ni, Cu, Cr, and Zn were related to soil parent materials. Pb and Cd were associated with agricultural activities and traffic emissions. The PMF models combined with correlation analysis were useful for estimating the source apportionment of heavy metals in soils.