植物修复技术在污染治理中的应用现状

RECENT DEVELOPMENTS OF PHYTOREMEDIATION

植物修复技术是利用活的植物对污染土、污染地下水等介质进行修复。植物对金属元素的净化机理是植物积累、根系过滤、植物根系对土的稳定作用;植物对有机物的净化机理是植物降解、生物刺激和植物的蒸发作用;此外植物的水力控制也是控制污染的主要途径。目前国外在利用植物修复卤代烃、农药、汽油、柴油、重金属、放射性物质、废旧炸药、处理污染填土淋滤液、利用植物分解处理空气中的污染物质或将氧化氮转化为氮气等多方面的研究已取得很多重要成果,而其中最为显著的是利用杂交植物对卤代烃污染地下水进行修复和研究利用转基因植物吸收土壤中的甲基汞。我国在植物修复技术方面的研究也取得重大成果,如利用凤眼莲修复污水中的某些农药、利用蜈蚣草叶片富集砷,利用印度芥菜对土壤中难溶态镉的吸收等。

Phytoremediation is a recent emerging technology that is used to stabilize or remove wastes from soils, groundwater or other medium by using living plants. Plants are used to remove metals through three mechanisms: phytoextra-ction, rhizofiltration, and phytostabilization. At sites contaminated with organic contaminants, plants are used for remediation of organic wastes in several ways: phytodegradation, rhizodegradation, and phytovolatilization. Besides, hydraulic control of plants is also an important mechanism controlling contaminants. The applications of trees to clean up chlorinated solvents, pesticides, crude oil, heavy metals, radionuclides, explosives, landfill leachates from soils and ground water have been achieved aboard. Plants have been used to treat wastes in air and transform nitrogen oxides to nitrogen gas in overseas countries. Among these achievements, the successful applications of hybrid plants to remove chlorinated solvents from ground water and transgenic plants to transform methyl-mercury into elemental mercury and releasing it into the atmosphere are the most remarkable. In China, the researchers have successfully used water hyacinth (Eichhornia crassipes Solms) to re-mediate some pesticides in wasted water. Arsenic hyperaccumulation in some plant species have been found and the achievements on the phytoremediation of insoluble fates of cadmium by Indian Mustard are also elegant.