深圳市典型工业区土壤重金属污染特征及健康风险评价

Pollution Characteristics and Health Risk Assessment of Heavy Metals in Soil of Typical Industrial District of Shenzhen

为了解深圳市工业土壤重金属污染水平,对深圳市典型工业区——宝安区土壤进行调查采样,以当地森林土壤作为背景点,对照分析工业土壤Cu、Zn、Ni、Pb、Cr、Cd、Hg、As等8种重金属污染特征,采用单因子指数法并结合内罗梅综合指数法进行重金属综合污染评价,采用商值法进行生态风险评估,采用美国环保署(US EPA)推荐的健康风险评价模型对其进行健康风险初步评价,最后采用主成分分析并结合实地调查进行源解析,以期为当地的土壤环境管理提供参考依据。结果表明,同一种重金属元素在不同采样点土壤中的含量差异较大,其中,Cu和Pb的变异系数均大于1。8种重金属元素的测定值均高于当地森林土壤,污染累积指数均大于1,表明8种重金属均存在不同程度的累积现象。工业土壤样品各重金属元素的污染指数大小为:Ni>Cu>As>Pb>Cd>Zn>Hg>Cr,综合污染指数为1.33,表明研究区工业土壤样品重金属综合污染处于轻度污染水平。除Ni存在低生态风险外,其他7种重金属生态风险均很低。Cu、Ni、Pb、Cd、As的总非致癌危害指数为0.648<1,致癌总风险为4.79×10^(-15)<10^(-6),可认为研究区工业土壤重金属不存在健康风险。主成分分析结果表明,Zn、Ni、Cr、Pb主要来源于金属表面处理、电镀等工业生产过程,其中,Pb还来源于交通源污染;Hg、As主要来源于燃煤、生活垃圾燃烧、印染废水排放等过程;Cu、Cd主要来源于电器生产、金属加工等过程。

In order to evaluate the pollution level of heavy metals in industrial soil in Shenzhen,soils of Bao'an District which was the typical industrial district of Shenzhen were subjects to be investigated.Forest soils were used as background points to get out the pollution characteristics of heavy metal.Then the single pollution index combined with Nemerow's integrated index was adopted for pollution evaluation.The ecological risk assessment was done by risk quotients and the preliminary health risk assessment was evaluated by the model recommended by US EPA,so as to provide reference for the local soil environment regulation and remediation.The results showed that the concentrations of the same heavy metal in the soil from different sampling points were significantly different,and the variation coefficient of Cu and Pb was greater than1.The concentration of8heavy metals was higher than that of forestry soils,and the contamination accumulation indexes were greater than1,which showed that there were different degrees of accumulation phenomenon among8heavy metals.The decreasing order of pollution index of8heavy metals in the industrial soils was Ni>Cu>As>Pb>Cd>Zn>Hg>Cr,while the integrated pollution index was1.33,meaning that the pollution of heavy metals in the industrial soils was at the low grade.There was very low ecological risk from heavy metals,except Ni which presented low ecological risk.The total non-carcinogenic hazard index of Cu,Ni,Pb,Cd and As was0.648and the total carcinogenic risk index was4.79×10-15,so it was considered that the non-carcinogenic hazard or carcinogenic risk from heavy metals should be all negligible for the industrial soils.The result of principal component analysis showed that Zn,Ni,Cr and Pb mainly came from industrial production such as the metal surface treatment,electroplating,and meanwhile,traffic also contributed to Pb pollution.Hg and As came from coal and garbage burning and also from printing and dyeing wastewater discharge.Cu and Cd came from electronical production and metal processing.