耕地土壤重金属健康风险空间分布特征

以江苏省某市为研究区域,借助ArcGIS和SPSS分析工具,利用US EPA健康风险评估模型评估耕地土壤重金属Cr、 Pb、 Cd和Hg的健康风险,从地理学的视角构建包含地理探测器及优化后的位序-规模理论模型的健康风险分析方法体系,分析其健康风险空间分异度及风险水平差异.结果表明,研究区域Cr、 Pb、 Cd及Hg这4种耕地土壤重金属含量均值分别为65.207、 25.486、 0.238和0.045 mg·kg~(-1),均低于耕地土壤污染风险的最低筛选值; Hg和Cd的健康风险均处于可接受范围内,Cr和Pb的儿童非致癌风险均值以及Cr的成人及儿童致癌风险指数均值分别为2.914 385、 1.337 503、 4.312 679×10~(-6)及8.137 130×10~(-6),均超过可接受范围;不同耕地重金属健康风险q值的范围为0.005 523～0.204 238,高风险特征因子需要进一步引起关注;研究子区域1、子区域2、子区域3和子区域4的Cr与Pb的儿童非致癌风险及Cr的致癌风险的R值较大,均接近或超过1,其他研究子区域的R值均低于0.1,中、高风险区与低风险区R值差异相对较大,研究子区域的高风险区比较集中.以耕地土壤重金属健康风险评价结果为基础,地理学视角分析市域范围的空间分异程度以及市辖县的风险水平,对于丰富健康风险研究手段、衡量不同尺度的健康风险水平以及制定精细化的风险管控策略等具有积极的意义.

Assessment and Spatial Characteristics Analysis of Human Health Risk of Heavy Metals in Cultivated Soil

Spatial characteristics analysis of the human health risk posed by heavy metals in cultivated soils is of great significance, with the potential to prevent and control soil pollution, protect human health, provide a basis for risk management, etc. In this paper, a methodological system, including a USEPA health risk assessment model, differentiation and factor detector within a geographical detector, and optimized initial model of rank-size theory, was constructed from a geographical perspective. Taking a city in Jiangsu province as the research object, we obtained the spatial differentiation and relative level of human health risk of Cr, Pb, Hg, and Cd in cultivated land by using the methodological system constructed and SPSS and ArcGIS software. The average concentrations of heavy metals (mg·kg^-1) in the research area were Cr (65.207 mg·kg^-1), Pb (25.486 mg·kg^-1), Cd (0.238 mg·kg^-1), and Hg (0.045 mg·kg^-1), which were lower than the risk control standards for soil contamination of agricultural land in China. The children''s non-cancer risk of Cr and Pb and the cancer risk to children and adults of Cr were 2.914385, 1.337503, 4.312679×10^-6, and 8.137130×10^-6, respectively, all of which exceeded the maximum acceptable limit in the research. Meanwhile, the spatial differentiation (q) of heavy metal health risk was between 0.005523 and 0.204238, which indicated that the high health risk posed by heavy metals should be paid attention to. The health risk rankings (R) of the children''s non-cancer risk of Cr and Pb and the cancer risk of Cr in subregions 1, 2, 3, and 4 approached or exceeded 1, and were higher than in subregions 5, 6, and 7, for which R was lower than 0.1. The R values indicated than the high health risk is concentrated in the research region. This research has great significance in measuring the health risk of heavy metals in cultivated soil at different scales, and in forming control strategies with local conditions.