农田重金属污染原位钝化修复研究进展

In situ immobilization remediation of heavy metals in contaminated soils:A review

污染土壤重金属原位钝化修复是通过向土壤中施加一些活性钝化修复材料,通过溶解沉淀、离子交换吸附、氧化还原、有机络合等反应来改变重金属在土壤中的赋存状态,降低土壤中重金属的有效浓度、迁移性和生物有效性。这种方法成本较低、操作简单、见效快且适合大面积推广,在重金属污染土壤修复中有着不可替代的作用。尤其对主要由污水灌溉、大气沉降等造成的农田土壤面源污染,一些具有吸附固定土壤中重金属离子特性的天然物质和工业副产品都可运用在实地的钝化修复中,且不同类型的钝化修复剂对重金属污染土壤的钝化修复效果各不相同。采用实验室评价和实地应用评价,一方面可以评估钝化修复材料对污染土壤中重金属离子的固定效率;另一方面可以评估钝化修复材料对土壤理化性状、养分状况和生物活性的影响。对重金属污染土壤原位钝化修复中不同来源的钝化剂进行了分类,目前广泛使用的钝化修复剂主要包括硅钙物质、含磷材料、有机物料、黏土矿物、金属及金属氧化物、生物碳及新型材料等,概述了它们各自对重金属污染土壤的钝化修复效果。从研究方法、评价指标、环境影响因子、钝化机制以及环境风险评价等方面分析了该领域的研究现状以及存在的主要问题,今后应重点关注钝化修复剂对土壤-作物系统的潜在环境风险以及钝化材料修复效果的田间长期稳定性评价。

In situ immobilization of heavy metal in contaminated soils with active amendments could decrease the available fractions, mobility, and bioavailability of heavy metals by changing occurrence state of heavy metals in soils, caused by the reactions of dissolution/precipitation, exchange/adsorption, oxidation/reduction and organic complex. The method has been considered as a cost-effective and operation-easy measure, which is becoming non-replaceable for contaminated soil remediation at a large scale. Natural materials and industrial by-products with high sorption characteristics could be applied to the remediation of non-point contaminated arable soils by sewage irrigation and atmospheric sedimentation, and different amendments had distinct effects on contaminated soils. The immobilization efficiency of amendments on heavy metals in soils and the effect of amendments on physicochemical properties and biological activities of soils in laboratory and field. This paper summarized the remediation effects of amendments on soils polluted by heavy metals, which include Si/Ca substances, phosphorus materials, organic compost, clay minerals, metal oxides, biochar and new materials. The present researches about thein situ immobilization of heavy metals in soil were presented, involving research methods, immobilization indexes, environmental factors, stabilization mechanisms and relevant environmental risk assessment, and moreover, the limitations and prospects of thein situ immobilization of heavy metals in soil were discussed. Future work should focus on the potential risks of immobilization amendments applied to the soil-crop system and its long-term effect on field.