长江三角洲地区污水污泥与健康安全风险研究 Ⅲ. 苏、杭二城市污水污泥所施土壤中Cu和Zn的释放动态及其环境风险

未经处理的污泥农业利用后,不仅会增加土壤中污染物的含量,而且会威胁人类和其他生物的健康。室内培养试验结果表明,污泥中的重金属进入土壤后,表现出先释放,后固定的变化趋势,而且随培养时间的增加,施污泥土壤中EDTA和CaCl2提取态Cu和Zn含量逐渐增加,150d时其含量达到最高。与对照处理相比,施污泥土壤中EDTA提取态Cu和Zn含量分别增加了21.4mgkg-1和26.1mgkg-1,而CaCl2提取态Cu和Zn含量分别增加了0.10mgkg-1和3.37mgkg-1。重金属不合格的污泥农业利用存在一定程度的重金属污染风险,且其风险大小与土壤类型、污泥种类和培养时间及污泥的土壤施用量等因素密切相关。选择适宜的土壤类型、污泥种类、施用时间及控制污泥施用量等,能够在一定程度上降低污泥中重金属农业利用的环境风险。

SEWAGE SLUDGES AND HEALTH RISK IN YANGTZE RIVER DELTA Ⅲ. DYNAMIC AND ENVIRONMENTAL RISKS OF Cu AND Zn RELEASE FROM SEWAGE SLUDGE-AMENDED SOILS

Concentrations of pollutants will increase if sewage sludge is applied to soil, thus posing a risk to the health of human. An incubation experiment was carried out with results showing that concentrations of EDTA and CaCl₂ extracted Cu and Zn in the sludge-amended soils increased with time and reached to maximum 150 days after the incubation. The average concentration of EDTA-extracted Cu and Zn was 30.0 mg kg^-1 and 30.1 mg k^-1, and increased by 21.4 mg kg^-1 and 26.1 mg kg^-1 over the control, respectively. The average concentration of CaCl₂ extracted Cu and Zn was 0.11 mg kg^-1 and 3.65 mg kg^-1, about 0.10 mg kg^-1 and 3.37 mg kg^-1 higher, respectively, than in the control. Application of sewage sludge into the soil posed a potential risk of heavy metal pollution. Soil type, sludge characteristics and application time should be taken into account simultaneously for reducing the risk of heavy metal pollution of the soil in making agricultural use of sewage sludge.