污灌区作物根与秸秆不同处置的重金属健康风险评价

为了评估污灌区作物秸秆不同处理方式的重金属健康风险，以天津污灌区为例，估算了该污灌区3类农作物根和秸秆中的Cd、As、Pb、Cu、Zn总量及其分布特征，采用健康风险评价模型对根和秸秆采取直接还田、燃用、直接还田+燃用处置可能引起的重金属健康风险进行评价。结果表明：作物中重金属的分布格局为“根多茎少”；还田处置对儿童和成人造成的累积致癌风险值分别为6.08×10-9和1.95×10-8，非致癌风险值分别为1.01×10-5和6.45×10-6，不会造成健康伤害；燃用处置对儿童和成人造成的累积致癌风险值分别为2.89×10-8和4.67×10-8，非致癌风险值分别为1.76×10-3和9.43×10-4，还田+燃用处置对儿童和成人造成的累积致癌风险值分别为2.05×10-8和4.28×10-8，非致癌风险值分别为8.88×10-4和3.78×10-4，这2种处置对儿童和成人造成的非致癌性健康风险是不可接受的。污灌区作物初级废弃物由于重金属总量大，在进行处置时，应优先考虑还田，其次谨慎考虑燃用，为农业固体废弃物管理提供了科学依据。

Health risk assessment of heavy metal of different treatments for roots and straws of crops in wastewater irrigation area

In order to evaluate the health risk of different treatments for roots and straws of crops in Tianjin wasterwater irrigation areas, authors estimated contents and distribution patterns of Cd, As, Pb, Cu, Zn in crops respectively. The contents of heavy metals in roots were more than those in stems. Health risks caused by returning field, burning and returning field plus burning of crops roots and straws were evaluated by using the environmental health risk assessment model. The contents of heavy metals in roots were higher than those of straw. For returning filed, the combined carcinogenic hazard index for child and adult were 6.08×10-9 and 1.95×10-8, respectively, and the combined noncarcinogenic hazard index were 1.01×10-5 and 6.45×10-6, respectively. It resulted negligible health risk for people. However, for burn treatment, the combined carcinogenic hazard index for child and adult were 2.89×10-8 and 4.67×10-8, respectively, and the combined noncarcinogenic hazard index were 1.76×10-3 and 9.43×10-4, respectively. The combined carcinogenic hazard index for child and adult were 2.05×10-8 and 4.28×10-8, respectively, and the combined noncarcinogenic hazard index were 8.88×10-4 and 3.78×10-4, respectively for returning filed plus burning. The noncarcinogenic hazard was unacceptable for burning or returning field plus burning. Considering large amount of heavy metals in crop straws, the top-priority treatment are suggested by returning field, then carefully considered by burning. These results made scientific suggestions for agricultural solid waste management.