城市污泥重金属污染生态风险及健康风险评价

Potential Ecological Risk and Health Risk Assessment of Heavy Metals in a Sewage Treatment Plant in Bengbu

采集蚌埠市污水处理厂污泥,消解后用ICP-AES测定重金属Zn、Cu、Pb、Cr、Ni、As、Cd的含量,其结果依次为658.8、220.0、169.8、173.8、41.0、2.0、0.8 mg·kg-1。Tessier连续提取方法分析污泥重金属赋存形态,结果表明,Pb稳定态(RES+ORG)含量占其总形态量的83.33%,与其他重金属稳定态相比为最高,而Zn稳定态含量占其总形态量的33.05%,为最低。内梅罗指数法分析污泥重金属综合污染指数为0.50,属安全等级;污泥重金属潜在生态环境综合风险指数为17.18,属低生态风险等级。经手口、皮肤暴露途径污泥重金属健康风险评估,儿童致癌与非致癌综合指数分别为1.40×10^-5和1.71×10^-1;成人致癌与非致癌综合指数分别为4.97×10^-6和6.09×10^-2。儿童、成人的致癌指数均在可接受范围,非致癌指数均在警戒值下。样品污泥重金属含量均低于城市农用泥质A级污泥标准值,其潜在生态风险、健康风险均在安全范围。

The content of heavy metal Zn,Cu,Pb,Cr,Ni,As and Cd was determined by ICP-AES after digestion of the sludge collected from Bengbu sewage treatment plant,which was 658.8,220.0,169.8,173.8,41.0,2.0 and 0.8 mg·kg-1,respectively.The occurrence form of heavy metals in the sludge samples was analyzed by Tessier s continuous extraction.The Pb stable state(RES+ORG)accounted for 83.33%of its total morphogenesis,which was the highest compared with other heavy metal stable states,while the Zn stable state was the lowest(33.05%).The heavy metals comprehensive pollution index in sludge analyzed by nemero index method was 0.50,which belongs to the safety level.The potential ecological environmental comprehensive risk index of heavy metals in sludge was 17.18,which is of low ecological risk level.Through the hand-mouth and skin exposed way were identified based on the health risk assessment model,the health risk of children was assessed.The carcinogenic and non-carcinogenic comprehensive indexes of children are 1.40×10^-5、1.71×10^-1,respectively.Similar to children,adults have a comprehensive indexes of 4.97×10^-6、6.09×10^-2,respectively.Children and adults of the carcinogenic indexes were in an acceptable range,and non-carcinogenic indexes were under the alert value.The heavy metal content in sludge of Bengbu sewage treatment plant was lower than the standard value of urban agricultural grade A sludge,and its potential ecological and health risks was within the safe range.