土壤有机-重金属复合污染植物增效修复研究

The high effective and safe remediation of co-contaminated soil with organic and heavy metals pollutants has become one of urgent problems required to solve in the field of environmental remediation at home and abroad. In this work, thiolated β-cyclodextrin was obtained by the modification reaction of β-cyclodextrin, on the hand, thiolated functional group has special coordination selection ability for the heavy metal, on the other hand, hydrophobic CD cavity has also inclusion ability for the week polarity organic compound, which can improve water-solubility of hydrophobic organic pollutant and insoluble heavy metal form from the soil, and used as a kind of extraction agent for the co-contaminated soil with organic and heavy metals pollutants. The effects of thiolated β-cyclodextrin on desorption ability and desorption speed of organic pollutants and heavy metals from the soil are investigated. This study focused on the transformation of organic pollutants and heavy metals from the soil and biologic mechanisms during the process of phytoremediation. On the base of the reaction process research about the interface among soil, soil solution and plant root systems, the transporting mechanisms of organic pollutants and heavy metals from the soil are studied during the process of thiolated β-cyclodextrin induced phytoremediation. The ecotoxicological tests of thiolated β-cyclodextrin are also investigated. This research can provide scientific basis and fundamental parameters for the practical application about the co-contaminated soil with organic and heavy metals pollutants, which has theoretical significance and broad application prospect.

有机-重金属复合污染土壤的高效、安全修复是国内外环境修复领域急需解决的重要问题之一。本项目在β-环糊精的基础上通过改性合成获得巯基化β-环糊精，其一方面既具有巯基功能基对重金属特有的配位选择能力，同时疏水性的CD空腔又具备对弱极性有机物包结的能力,能有效改善土壤中疏水性有机污染物和重金属难溶形态的水溶性，可作为有机-重金属复合污染土壤的新型提取剂。研究其促进土壤中有机污染物和重金属的解吸能力和解吸速度；重点研究植物修复过程中巯基化β-环糊精对污染土壤中有机物和重金属的迁移、转化及诱导植物修复的生物学机制。通过对土壤/土壤溶液/植物根系界面的反应过程研究，深入探讨改性β-环糊精诱导植物吸收、运输和积累有机物和重金属的传输机理；研究巯基化β-环糊精的生态毒理作用及环境风险。此项研究可以为有机物-重金属复合污染土壤的植物修复的实际应用提供科学依据和基础参数，既有理论意义，又有广阔的应用前景。

有机-重金属复合污染土壤的高效、安全修复是国内外环境修复领域急需解决的重要问题之一，植物修复技术治理污染土壤具有成本低、不破坏生态环境、能使土壤保持良好的结构和肥力状态及无二次污染等优点，是污染土壤治理的环境友好技术，然而污染土壤中重金属和有机物低的生物有效性对植物修复效率带来不利影响，利用增效剂来提高污染土壤中重金属和有机物的生物活性是针对有机-重金属复合污染土壤植物高效修复可行途径。本项目以环氧氯丙烷为交联剂，通过β-环糊精和氨基酸（半胱氨酸、天冬氨酸）的反应获得了水溶性极好的β-环糊精衍生物。红外光谱和核磁共振结果表明：β-环糊精衍生物在保留原内腔结构的同时还增加了氨基、羧基和巯基等基团。运用紫外光谱技术和XPS研究了β-环糊精衍生物与疏水性有机物和重金属之间的相互作用，结果表明β-环糊精衍生物能同时实现对疏水性有机物的包结作用和对重金属配位作用；增溶、解吸实验研究表明：β-环糊精衍生物对疏水性有机物和重金属难溶形态有明显的增溶效果，有助于提高复合污染土壤中疏水性有机物和重金属难溶形态的生物有效性。β-环糊精衍生物作用下有机-重金属复合污染土壤的植物修复实验研究表明：β-环糊精衍生物对复合污染土壤中有机物和重金属的植物修复有明显的增效作用，β-环糊精衍生物明显增加污染土壤微生物种群的数量和多酚氧化酶和脲酶的活性，有利提高污染土壤中重金属和有机物的生物活性，植物-微生物交互作用是污染土壤中有机物的主要去除途径，植物累积是污染土壤中重金属的主要去除途径，β-环糊精衍生物能进一步强化植物-微生物交互作用和植物累积。以斜生栅藻为受试生物进行的毒理学实验研究表明：β-环糊精衍生物对斜生栅藻没有明显的毒性，属于环境友好材料，而且β-环糊精衍生物对有机污染物、重金属的单一毒性及有机污染物和重金属复合毒性有明显的抑制作用。以β-环糊精衍生物为增效剂的植物修复技术对土壤有机-重金属复合污染的修复具有重要的参考价值和指导意义。