基于PMF模型的县域尺度土壤重金属来源分析及风险评价

Source Analysis and Risk Assessment of Heavy Metals in Soil of County Scale Based on PMF Model

为探究小尺度空间区域土壤重金属的污染特征、风险和来源,以广东省揭阳市榕城区为例,运用富集系数、污染负荷指数、生态风险评价模型、健康风险评价模型进行风险评价,结合相关性分析、空间分析和正定矩阵因子分解(PMF)模型进行来源解析.结果表明,土壤中ω(Cr)、ω(Hg)、ω(As)、ω(Pb)、ω(Ni)、ω(Cd)、ω(Cu)和ω(Zn)的均值分别为54.87、 0.25、 8.35、 56.00、 15.38、 0.35、 30.56和124.23 mg·kg^(-1),均超过广东省土壤背景值;Cr、 As、 Pb和Ni无富集,Zn和Cu轻微富集,Hg和Cd中等富集;污染负荷指数的均值为2.37,总体上属于重度污染水平,8种元素处于不同的污染水平.研究区土壤重金属整体处于重度生态风险,其中Hg和Cd属于强烈生态风险,其他元素属于轻微生态风险.不同元素在3种暴露途径下产生的非致癌风险处于可接受范围;成人和儿童的致癌风险分别为9.81E-05和5.59E-04,Cr和As是致癌风险的主要贡献者,需重点关注.研究区土壤重金属共有4种主要来源:交通来源(37.02%)、成土母质来源(18.53%)、大气沉降来源(26.49%)和工业来源(17.96%).

This study explores the pollution characteristics,risks,and sources of heavy metals in small⁃scale areas.Rongcheng District,Jieyang City,Guangdong Province was considered as the study area and enrichment factor(EF),pollution load index(PLI),potential ecological risk index(RI),and US EPA health risk assessment model were used to evaluate its environmental risk.Moreover,the source apportionment of heavy metals was analyzed through correlation analysis,the characteristic of spatial distribution,and a PMF model.The results showed that the mean concentrations ofω(Cr),ω(Hg),ω(As),ω(Pb),ω(Ni),ω(Cd),ω(Cu),andω(Zn)were 54.87,0.25,8.35,56.00,15.38,0.35,30.56,and 124.23 mg·kg^(-1),respectively.The mean concentrations of all elements exceeded the local soil background value.In terms of EF level,Cr,As,Pb,and Ni showed negligible accumulation;Zn and Cu showed minor accumulation;and Hg and Cd showed moderate accumulation.The mean value of the pollution load index was 2.37,with a severe pollution level,and the eight elements were in different pollution levels.In total,the study region suffered severe ecological risk,Hg and Cd presented strong ecological risk,and other elements presented slight ecological risk.The non⁃carcinogenic risks under the three exposure paths were within the acceptable level.The carcinogenic risks(CR)of adults and children were 9.81E-05 and 5.59E-04,respectively,and Cr and As were the main contributors of CR.The results showed that the four sources of heavy metals were transportation sources(37.02%),parent material sources(18.53%),atmospheric deposition sources(26.49%),and industrial sources(17.96%).