基于风险分级的镉砷污染稻田修复治理

Remediation of Cadmium and Arsenic Contaminated Rice Fields Based on Risk Grading

研究基于稻米镉砷含量构建了农田重金属污染5级风险分级分区体系,并结合土壤镉砷含量及pH值等理化性质制定了以石灰质复合材料和镉钝化剂或镉砷同步钝化产品为核心的4个组合修复模式,在祁阳市肖家镇和白水镇开展了重金属污染耕地修复治理示范。结果表明:基于稻米镉砷污染风险分级分区治理的4个耕地修复模式使土壤pH值提升了0.68-1.29个单位,土壤有效态镉含量降低了12.50%-29.63%,稻米镉含量降低了20.00%-87.30%,皆达显著差异水平;而4个模式对土壤有效态砷含量、有机质、阳离子交换量等均无显著影响,且降低稻米砷含量的效果也不理想。

A 5-level risk grading and zoning system for heavy metal pollution in farmland was established based on Cd and As contents in rice,and four-combination remediation patterns mainly consisted of calcareous composite materials and Cd passivators or Cd and As simultaneous passivators were developed according to soil physicochemical properties such as soil pH,and Cd and As contents.The four remediation patterns were applied in Xiaojia Town and Baishui Town,Qiyang City.The results showed that the four remediation patterns of arable land based on the risk grading and zoning management of Cd and As pollution in rice caused the soil pH to rise by 0.68-1.29 units,the available Cd content in soil to decrease by 12.50%-29.63%and the Cd content in rice to decrease by 20.00%-87.30%,all of which reached the significant level.However,the four patterns had no significant effects on soil available As content,organic matter and cation exchange capacity;and their effect on reducing arsenic content in rice was unsatisfactory.