洛阳城市污水处理厂污泥中重金属形态及潜在生态风险评价

Heavy metal speciation and its potential ecological risk assessment in sewage sludge of Luoyang

分析了洛阳市3个污水处理厂脱水污泥中Cu、Zn、Ni、Cr和Pb的含量,采用BCR法研究了污泥中重金属的形态分布特征,并利用地累积指数法(Igeo)和潜在生态危害指数法(RI)评价污泥在农用过程中重金属的潜在生态风险。结果表明,涧西污泥中Cu、Zn和Ni含量超过了农用泥质A级标准的限值(CJ/T309-2009),而新区污泥和瀍东污泥显示出良好的农用性质。污泥中Cu和Cr主要以可氧化态存在,Zn主要以酸溶态和可还原态存在,迁移性强,Ni含量分布相对比较均匀,Pb主要以残渣态存在。Igeo表明,污泥中Cu、Zn是潜在的污染元素。RI表明,Cu表现出高潜在生态风险;Zn的总含量虽高,但Zn的生物毒性响应因子低,对污泥的潜在风险贡献较低。

The total contents of heavy metals（ Cu,Zn,Ni,Cr,and Pb） in sludge samples were analyzed,and their speciation characteristics were studied by the BCR sequential extraction procedure. The potential ecological risk of heavy metal contamination was evaluated by the geoaccumulation index（ Igeo） and ecological risk index（ RI）. The results showed that the levels of Cu,Zn,and Ni in Jianxi sludge exceeded the A-level threshold of the control standard for agricultural use（ CJ / T309-2009）,whereas the Xinqu and Chandong sludges presented good agricultural levels of these heavy metals. Cu and Cr were mainly present as an oxidizable fraction,and Zn existed primarily in acid-soluble and reducible forms. Meanwhile,Ni was uniformly distributed among five chemical fractions,and Pb mainly occurred in its residual state. The values of Igeoidentified Cu and Zn as potential polluting elements. According to the RI values,Cu posed a high potential ecological risk. Zn was present at the highest levels of the metals studied,but its contribution to the potential risk of the sludge was lower due to its lower biological toxicity response factor.