腐殖质改良植物修复重金属污染土壤的研究进展

Humic Substances Amendments for Improving Phytoremediation of Heavy Metal Polluted Soils:A Review.

腐殖质(HS)是土壤有机质的重要组分,广泛应用于土壤改良。通过文献调研,在综述HS对土壤重金属的作用及其机制基础上,分析了HS在植物修复重金属污染土壤领域的应用潜力。已有研究表明:(1)大分子胡敏素(HM)和胡敏酸(HA)可钝化重金属离子,降低重金属对植物的毒害作用,小分子富里酸(FA)则可促进重金属从植物地下部向地上部迁移;(2)除受土壤理化性质影响外,HS与重金属离子的结合主要受HS的pH、溶液离子强度、分子量大小和活性官能团数量等条件影响;(3)叶面喷施HS可以抑制重金属向植物体内运输,保护光合系统不受重金属危害;土壤添加低浓度HS可以促进重金属转运,高浓度HS则会对植物产生负面效应;(4)根据HS与重金属作用下的生态毒理学效应、土柱淋溶效果和植物生长发育评估结果,认为HS不会产生次生环境风险。因此,HS可以作为重金属污染土壤植物修复的环境友好型促进剂,扩大重金属污染土壤植物修复的应用范围。

Humic substances(HS)is widely used in agriculture and soil improvement as an important component of soil organic matter.Based on summarizing the effect and mechanism of HS on heavy metals in soil,the potential of phytoremediation of heavy metal pollution in soil was analyzed by literature investigation:(1)Macromolecule humin(HM)and humic acid(HA)could passivate heavy metal ions and reduce the toxicity of heavy metals to crops.However,smaller molecular-weight fulvic acid(FA)could promote the migration of heavy metals from the underground part to the upper part of the plant.(2)In addition to the physical and chemical properties of soil,the binding of HS with metal ions was mainly influenced by the ionic strength,molecular weight and the quantity of active functional groups and the pH of HS.(3)There are two methods of adding HS:foliar spraying and soil addition.Foliar spraying can inhibit the transport of heavy metals into plants and protect the photosynthetic system from heavy metals.Adding low concentration of HS in soil can promote the transport of heavy metals,but high concentration will have a negative effect on plants.(4)According to the ecotoxicological effects of the interaction of HS and heavy metals,the leaching effects of soil column and the growth development of plants,the secondary environmental risk caused by HS could be evaluated.Therefore,HS can be used as an environmental friendly phytoremediation enhancer to expand the application of phytoremediation in heavy metal contaminated soils.