湿地植物根表微生物膜调控尾矿库铁硫循环及重金属沉淀的机制

The geochemical cycle of iron and sulfur elements, ubiquitously existing in metal mine tailing ponds, dominate the speciation and migration of heavy metals. The unique electron transfer process of iron and sulfur oxidizing/reducing microorganisms possess significant regulating ability in iron and sulfur cycle as well as heavy metal deposition, and hence reduce heavy metal toxicity in the rhizosphere for the purpose of improving the ecological restoration of mine tailing ponds. In this project, to meet the ecological restoration needs particularly in typical metal mine tailing ponds in south China, we propose to carry out field survey, in-door incubation coupled with molecular biological methods and molecular biological information analysis methods, to investigate (1) microorganism community and distribution of iron, sulfur, heavy metal crystal forms on the rhizoplane of wetland plant employed in metal mine tailing pond remediation, (2) special rhizoplane biofilm structure, namely aerobic inside while anaerobic outside, on wetland plant surface attributed to radial oxygen loss, (3) inhibition of iron sulfide acidification and deposition of heavy metals on the rhizoplane by iron and sulfur oxidizing/reducing bacteria, and (4) regulating pathway of iron and sulfur cycle and heavy metal deposition by iron and sulfur oxidizing/reducing bacteria in the rhizoplane biofilm. The results obtained are expected to explain the contribution of wetland plant rhizoplane biofilm to the biogeochemical activities of heavy metals, which is supposed to complete the theory of phyto-microbial remediation of metal mine tailing ponds.

在铁、硫伴生的金属矿尾矿库中，铁、硫的地球化学循环主导重金属元素的形态、迁移行为，而铁硫氧化/还原微生物的特异性电子转移过程，对铁、硫循环及重金属沉淀具有重要的调控作用，可降低植物根际重金属毒性以强化尾矿库生态恢复过程。项目针对华南地区金属矿尾矿库的生态恢复需求，通过野外调查、室内培养、分子生物学方法及生物信息学分析方法，分析金属矿尾矿库湿地修复植物根表微生物群落结构及铁、硫、重金属元素晶型分布，证实因湿地植物根系泌氧而形成的内层好氧、外层厌氧的特异性根表微生物膜结构，探讨铁硫氧化/还原微生物抑制铁硫化学产酸及促进重金属在植物根表沉淀的途径，并阐明根表微生物膜中铁硫氧化/还原微生物调控铁硫循环及重金属沉淀的机制。项目的实施有助于揭示湿地植物根表微生物膜对重金属的生物地球化学行为的贡献，研究结果可进一步完善金属矿尾矿库植物-微生物修复的相关理论。

在铁、硫伴生的金属矿尾矿库中，铁、硫的地球化学循环主导重金属元素的形态、迁移行为，而铁硫氧化/还原微生物的特异性电子转移过程，对铁、硫循环及重金属沉淀具有重要的调控作用，可降低植物根际重金属毒性以强化尾矿库生态恢复过程。项目针对华南地区金属矿尾矿库的生态恢复需求，通过野外调查、室内培养、分子生物学方法及生物信息学分析方法，分析了金属矿尾矿库湿地根际土和修复植物根表微生物群落结构，及环境因子pH、C、N、S、Pb、Zn、Cu、Cd、Fe在体系中对细菌群落结构的影响,证实了香蒲对尾矿土的修复作用。进一步通过野外示范和室内模拟证实了因湿地植物根系泌氧而形成的内层好氧、外层厌氧的特异性根表微生物膜结构，并基于这一结构探讨了在不同土壤情况和土壤分层中，土壤理化性质和微生物结构的差异及二者之间的相互联系。项目的实施有助于揭示湿地植物根表微生物膜对重金属的生物地球化学行为的贡献，研究结果进一步完善了金属矿尾矿库植物-微生物修复的相关理论。