植物修复土壤重金属污染中外源物质的影响机制和应用研究进展

重金属进入土壤后难以被降解,并通过食物链在生物体内富集,长此以往会导致中毒、癌症、畸形、突变,严重影响了人类生产活动及地球生态系统的稳定。植物修复技术是一种经济有效的重金属污染修复技术,其依靠超富集植物强大的自身抗性机制,从土壤中提取或稳定重金属,达到污染治理的目的。然而修复土壤重金属污染的超富集植物通常生长缓慢、生物量低,其抗性机制也会受到植物本身对重金属胁迫的阈值限制,当胁迫超过这个阈值,植物修复的效率就会大大降低甚至失去修复功能。文章在解析植物重金属相互作用机制的基础上,综述了添加外源物质对重金属毒害植物的缓解效应以及其在强化植物修复土壤重金属污染中的应用研究进展;介绍了应用外源物质调控植物吸收转运重金属的3种途径,分别为提高土壤重金属生物利用度、促进植物生长以及增强植物耐性。提出了应用外源物质作为强化植物修复措施的潜力及今后的研究方向,其未来的研究应着重于以下方面:明确外源物质的应用浓度、时期、方式与植物吸收转运重金属之间的关系;从植物内源激素及信号分子间的互作、抗逆基因表达、内生及根际微生物等不同层面上揭示外源物质对植物积累重金属的调控机理;开展外源物质与其他植物修复强化技术的联合应用研究。这些研究可为土壤重金属污染的植物修复技术及其强化措施研究提供科学依据,同时也对植物修复工程技术的发展实践具有一定的指导意义。

Research Progress on Mechanism and Application of Exogenous Substances in Phytoremediation of Heavy Metal Contaminated Soil

Heavy metals are difficult to degrade after entering the soil environment,they can accumulate in organisms through the food chain,causing poisoning,cancer,deformity,mutation over time and this can then seriously affect human production activities and the stability of the earth's ecosystem.Phytoremediation technology is an economic and effective remediation technology for heavy metals,it relies on the strong self-resistance mechanism of hyperaccumulators to extract or stabilize the heavy metals to achieve pollution control.However,hyperaccumulators usually grow quite slow and have low biomass,and their resistance mechanism is often restrained by the threshold of heavy metal stress.When the stress exceeds this threshold,the phytoremediation efficiency will reduce greatly or even lose completely.Based on the analysis of the interaction mechanism of heavy metals in plants,this paper reviewed the mitigation effect of exogenous substances on heavy metal toxic plants and the relevant research progress on application of enhanced phytoremediation of soil heavy metal pollution,introduced three ways of using exogenous substances to regulate the absorption and transportation of heavy metals in plants to improve the bioavailability of heavy metals in soil,to promote plant growth and to enhance plant tolerance.Future research recommendations for applying exogenous substances as enhanced phytoremediation measures were proposed,more research should be undertaken in the following aspects:clarifying the relationship between the concentration,period and mode of exogenous substances application and plant absorption and transportation of heavy metals,study of the combined application of exogenous substances and other enhanced phytoremediation techniques,revealing the regulation mechanism of exogenous substances on heavy metal accumulation in plants from the aspects of the interaction of plant endogenous hormones and signal molecules,stress resistance gene expression,endophytic and rhizosphere microorganisms,these studies could provide a scientific basis for phytoremediation of heavy metal polluted soil and its enhancement measures,it could also provide guidance for the development and application of phytoremediation technology.