河北省典型污灌区农田镉污染特征及环境风险评价

以河北省石家庄市典型历史污灌区农田为研究对象,对污灌区内土壤和小麦、玉米植株内Cd的含量进行分析,评价污灌区农田Cd污染程度、潜在生态风险和潜在健康风险.结果表明,上游污灌区和中下游污灌区土壤表层Cd含量分别为ND～3.88、0.10～2.30 mg·kg~(-1),明显高于清灌区(0.13～0.23 mg·kg~(-1))及河北土壤背景值(0.094 mg·kg~(-1)),超农用地土壤污染风险筛选值(0.3 mg·kg~(-1))点位分别达42.9%和35.2%;小麦和玉米籽粒平均Cd含量均未超标,小麦籽粒富集浓度高于玉米,污灌区小麦和玉米籽粒已出现明显累积现象.潜在生态风险表明上游污灌区和中下游污灌区表层土壤基本处于轻度～中度风险,部分区域生态风险较高～极高.健康风险评价结果表明Cd通过皮肤、呼吸、经口摄入暴露途径对人体健康造成的风险在可接受范围内.研究结果为污灌区农田土壤的安全利用和管理决策依据,并为开展农田土壤修复工程提供科学参考.

Cadmium distribution characteristics and environmental risk assessment in typical sewage irrigation area of Hebei Province

Soil, wheat and maize plants samples were collected and were analyzed for their respective Cd spatial distributions in the typical sewage-irrigated farmland of Shijiazhuang, Hebei Province. Results showed that the concentrations of Cd in upstream and downstream sewage irrigation area were ND~3.88, 0.10~2.3 mg·kg^-1, respectively, which exceeded that in soil with clean water irrigation (0.13~0.23 mg·kg^-1) and background value of soil in Hebei (0.094 mg·kg^-1). 42.9% and 35.2% of soil samples from upstream and downstream sewage irrigation area were exceeded the risk screening values of farmland soil (0.3 mg·kg^-1). The concentrations of Cd in wheat and maize in sewage irrigation were higher than those in soil with clean water irrigation, and the grain concentrations of Cd in wheat were higher than those in maize. Potential ecological risks of Cd in some soil samples of upstream and downstream sewage irrigation area were at a mild to moderate ecological hazard. The health risks caused by Cd through skin, breathing and mouth exposure pathways were within an acceptable range. The results can provide the basis for safe use and management decision of farmland soil in sewage irrigation areas, and provide scientific reference for the remediation of soils.