渭河西安段沿河小麦种植区土壤重金属分布特征及健康风险评价

Distribution characteristics and health risk assessment of heavy metals in soil of wheat planting areas in Xi’an section of Weihe River

目的了解渭河西安段小麦种植区土壤重金属的分布特征及健康风险。方法2018年4—5月以渭河西安段沿河小麦种植区土壤重金属为研究对象,测定其中As、Hg、Pb、Cd和Cr的含量,利用地累积指数(I_(geo))评价小麦种植区土壤的污染水平,利用美国国家环境保护局(US EPA)健康风险评价模型,对渭河西安段小麦种植区土壤重金属元素污染的潜在健康风险进行评估。结果研究区土壤中Cd的I_(geo)污染程度为轻-中度污染,Hg、Pb、Cr和As的I_(geo)污染程度则为无污染态势。研究区土壤中5种重金属元素在3种暴露途径下成人和儿童的非致癌指数依次是As>Cr>Pb>Cd>Hg。研究区土壤中3种重金属元素在3种暴露途径下致癌风险排序为As>Cr>Cd。结论渭河西安段沿河小麦种植区土壤重金属对儿童的非致癌危害指数和潜在致癌风险均高于成人,As是最主要的潜在致癌风险因子。

Objective To understand the distribution characteristics and health risks of heavy metals in the soil of wheat growing area in Xi’an section of Weihe River.Methods From April to May 2018,the contents of As,Hg,Pb,Cd and Cr in the soil of wheat planting area along the Xi’an section of Weihe River were determined.The soil pollution level in the wheat planting area was evaluated by the ground accumulation index(I_(geo)).The potential health risks of heavy metal pollution in soil of wheat planting area along the Xi’an section of Weihe River were evaluated by the health risk assessment model of US Environmental Protection Agency(US EPA).Results The I_(geo)pollution level of Cd in the soil of the study area was light to medium pollution,while the I_(geo)pollution level of Hg,Pb,Cr and As was non-polluting.The non carcinogenic index of five heavy metal elements in the soil of the study area for adults and children was As>Cr>Pb>Cd>Hg in turn.The sequence of carcinogenic risk of five heavy metals in the soil of the study area was As>Cr>Cd under three exposure routes.Conclusion In wheat planting areas in Xi’an section of Weihe River,the non carcinogenic index and potential carcinogenic risk of heavy metals in soil for children are higher than those for adults,and As is the main potential carcinogenic risk factor.