植物-微生物联合修复砷-多环芳烃复合污染土壤的方法及机理

Arsenic and polycyclic aromatic hydrocarbons (PAHs), the two widespread priority pollutants of great environmental concern and well-characterized as highly toxic, mutagenic and carcinogenic, are commonly found in environmental media and accumulate in the soil and vegetation, which is recognized as serious threat to human health. The combination of arsenic and PAHs could strongly potentiate the environmental risks with synergistic effect between arsenic and PAH-induced immunosuppression and cancer. The simultaneous accumulation of arsenic and polycyclic aromatic hydrocarbons (PAHs) are frequently found and extensively evaluated in several types of anthropogenic industry contaminated sites, such as coking & chemical industry site, mining and metallurgy industry site, lumber and wood production site, etc. However, up to date, methods for remediation of arsenic and PAHs co-contamination are scarce to report. The objective of the project is to investigate the mechanism of As and PAHs co-contamination remediated by hyperaccumulator-microbe symbiosis and develop the corresponding remediation technology. In the research, the remediation efficiency under different ecotypes of Pteris vitatta L. and PAHs-degrading bacterial treatment is evaluated and superiority combination of plant and bacteria is selected to optimize the technology design. The transformation and transportation process of arsenic and PAHs in the rhizosphere of plant and bacteria is identified and ecological risk is also assessed. Furthermore, the interactive effect between As and PAHs in plant accumulation and detoxification and the rhizosphere characteristis is analyzed. The research is prepared to carried out in the form of in-situ field experiment and biology simulation experiment by means of DGT, TPCLSM, DGGE, etc. This project integrates multi-disciplines such as environmental science, soil science, microbiology and molecular biology. The results of the research could enrich the theoretical basis for co-contamination remediation. Furthermore, the outcome of the research will provide practical significance for the combination of hyperaccumulator-microbe to remediate the heavy metal and organic pollutants co-contaminated soil.

砷和部分多环芳烃都被各国列为环境优先控制污染物，并且两者共存会产生协同危害效应。在焦化、矿冶等典型工业影响区土壤中均已发现砷和多环芳烃复合污染，然而国内外对该复合污染修复方法和机理研究甚少，尚缺乏安全、经济的修复对策。本项目针对这一特殊环境问题，拟开展超富集植物和PAHs高效降解菌联合修复砷-多环芳烃复合污染土壤方法和机理研究。采用DGT、TPCLSM、DGGE等试验手段，筛选不同生态型-PAHs降解菌优势组合，优化试验条件；探索联合体系下根际微域环境中砷的环境行为和PAHs的降解过程，并分析修复过程中污染物的归趋行为和生态风险；阐明植物-微生物联合体系植物富集以及解毒的交互效应，综合评估复合污染土壤修复的效果及生态风险。本项目有机结合环境科学、土壤学、微生物学和分子生物学等多学科知识和手段，研究成果丰富了环境科学的复合污染基础理论，也为发展有机-无机复合污染的生物修复技术提供新的科学思路

砷（As）和多环芳烃（PAHs）复合污染广泛出现在煤炭、化工、矿山、冶金等工业场地。目前，国内外对工业场地土壤中砷和多环芳烃复合污染修复方法和机理研究甚少，尚缺乏安全、经济的修复对策。本项目针对这一特殊环境问题开展研究，探明复合污染条件下多环芳烃在蜈蚣草中的赋存规律，揭示根际环境中砷的环境行为和多环芳烃的降解过程，阐明植物—微生物联合体系植物富集以及解毒的交互效应。取得的重要研究结果如下：1. 筛选出蜈蚣草-微生物优势组：与湖南生态型蜈蚣草相比，广西生态型蜈蚣草+菲降解菌对砷和菲提取率较高；添加菲降解菌显著提高蜈蚣草对砷的抗氧化能力，具体表现为蜈蚣草地上部和根部POD和COD活性升高。2. 探索了植物—微生物联合修复体系条件下根际中As和PAHs的环境行为：种植蜈蚣草处理，添加菲对溶液中砷形态有明显影响（P<0.0001），表现为超过75%的As(V)转化为As(III)，而不种植蜈蚣草溶液中As(V)未有向As(III)转化现象，而添加菲对溶液中总砷含量没有明显影响。3. 研究出As存在条件下PAHs的吸收与赋存机制：双光子共聚焦检测结果表明，PAHs（PHE、FLU、PYR、BaP）赋存于根部表皮细胞表面、茎部维管束组织中以及羽叶部的叶脉网络、上下表皮细胞和气孔细胞中。在亚细胞组织中，PAHs主要附着于细胞膜与细胞内部的细胞器膜结构及细胞核核膜附近。但随着苯环数量的增加，PAHs在蜈蚣草体内的含量降低。4. 研究了植物—微生物联合作用对土壤As和PAHs复合污染的修复效应：在实际土壤中，蜈蚣草对去除砷的相对贡献率为77.52%，微生物对去除砷的相对贡献率为22.48%；蜈蚣草和微生物对去除PAHs的相对贡献率都为50%。