Ni-Mo多金属矿区土壤和农作物铬、钴污染及健康风险评价

Health risk assessment of chromium and cobalt in soils and crops around the Ni-Mo polymetallic mining area

为了阐明贵州遵义松林Ni-Mo多金属矿区土壤Cr、Co污染状况及该矿区土壤和农作物Cr、Co健康风险,采用ICP-MS分析矿区土壤和农作物Cr、Co含量,分别采用单因子指数法和健康风险模型评价了矿区土壤和农作物Cr、Co污染程度和健康风险水平。结果表明:(1)矿区旱地土、水稻土和森林土Cr平均含量分别为138mg·kg^-1、97.8 mg·kg^-1和114 mg·kg^-1,Co平均含量分别为26.3 mg·kg^-1、20.9 mg·kg^-1和23.3 mg·kg^-1,3种类型土壤Cr、Co含量均高于相应元素的贵州省土壤背景值。(2)6种农作物样品中,粮食类和蔬菜类Cr平均含量分别为7.32mg·kg^-1和6.23 mg·kg^-1,分别为国家食品限量标准(谷物类1.0 mg·kg^-1,蔬菜类0.5 mg·kg^-1)的7.3倍和12.5倍,Co平均含量分别为0.076 mg·kg^-1和0.266 mg·kg^-1,低于世界卫生组织给出的安全限值(0.48 mg·kg^-1)。(3)单因子指数法评价结果表明,旱地土和森林土Cr污染程度主要为轻度污染,水稻土大部分样点未出现Cr污染。3种类型土壤Co污染程度主要为轻度污染,部分旱地土存在Cr、Co重污染。(4)健康风险模型评价结果表明,6种农作物中的Cr存在较高的非致癌风险,成人和儿童在3种暴露途径下Cr的总非致癌健康风险指数(HI)大于1(成人:2.18E+00;儿童:1.78E+00),存在一定非致癌风险,土壤Cr和Co的致癌健康风险指数(CR)和总致癌风险指数(TCR)均低于致癌风险阈值(1.0×10-6),致癌风险在可接受范围内。

In order to shed light on the contamination degree of Cr and Co in soils around the Ni-Mo polymetallic mining area in Songlin, Zunyi, China and human health risk of the heavy metals in crops planted on the soils, the contents of Cr and Co in soils and crops in the mining area were analyzed using Inductively Coupled Plasma Mass Spectrometry(ICP-MS). The single factor index method and health risk model were used to evaluate the pollution degree and the health risk level of Cr and Co in the soils and crops, respectively. The results of the present study show that:(1)For the dryland soil, paddy soil and forest soil from the mining area, the averaged Cr content are 138 mg·kg^-1, 97.8 mg·kg^-1 and 114 mg·kg^-1, respectively, and the averaged Co content are 26.3 mg·kg^-1, 20.9 mg·kg^-1 and 23.3 mg·kg^-1, respectively. The edaphic contents of Cr and Co are higher than the corresponding background value of the soil in Guizhou Province.(2)The averaged content of Cr in cereals and vegetables are 7.32 mg·kg^-1 and 6.23 mg·kg^-1, respectively, and they are 7.3 and 12.5 times of national food limit standards(1.0 mg·kg^-1 for cereals and 0.5 mg·kg^-1 for vegetables), respectively. The averaged content of Co in cereals and vegetables are 0.076 mg·kg^-1 and 0.266 mg·kg^-1, respectively, which are lower than the safety limit(0.48 mg·kg^-1)proposed by the World Health Organization.(3)The assessment results by single factor index method indicate that the pollution degree of Cr in dryland soil and forest soil are mainly light pollution level, and that of Cr in paddy soil is mainly uncontaminated. The assessment results of Co in the three types of soil are mainly slight pollution. However, the assessment results of Cr and Co in a few dryland soil samples reach heavy pollution level.(4)The evaluation results through health risk model show that Cr in 6 crops would have non-carcinogenic risk. The total non-carcinogenic health risk index(HI) of Cr for adults and children under three exposure pathways is greater than 1(adults: 2.18 E+00;children: 1.78 E+00), which indicates that Cr in crops would have non-carcinogenic risk. The carcinogenic health risk index(CR) and total carcinogenic risk index(TCR) of Cr and Co in the soils are lower than the carcinogenic risk threshold(1.0×10-6), which implies that the carcinogenic risk of Cr and Co in the soils is within an acceptable range.