Insights on the response of microbial communities to vegetation and biogeochemical properties in amended and unamended acid-generating mine wastes

Understanding the structure of microbial communities in acidic, metal contaminated tailings and waste rock in cool, continental northern temperate climates is important for identifying their potential for use in phytostabilization and bioremediation programs. In this study, microbial community compositions across two large mine waste sites in the Sudbury basin were analyzed along gradients of barren-to-vegetated tailings and waste rock. Microbial communities were less diverse, more homogenous, and mainly chemolithoautotrophic in barren sites, transitioning to more diverse communities of organoheterotrophs, nitrogen-fixing/plant-growth promoting bacteria, and ectomycorrhizal fungi in the vegetated areas. Network interaction analyses of microbial communities demonstrated higher levels of interactions of microbial groups in the barren tailings, which were related to the extreme environmental and chemical conditions and restricted anabolic nutrient availability of the substrates. We also show that vegetation and plant-derived organic matter in the tailings are associated with the shifts observed in the structure of microbial communities towards more soil-like communities, which sequentially further aids in the establishment of vegetation. These findings have implications for the optimization of phytoestablishment and bioremediation in mine tailings and waste rock in the cool, continental northern temperate and boreal climates.

解析寒冷大陆性北温带气候下酸性金属污染尾矿与废岩中的微生物群落结构，对于明确其在植物稳定修复（phytostabilization）与生物修复（bioremediation）项目中的应用潜力具有重要意义。本研究针对萨德伯里盆地（Sudbury Basin）两处大型矿山废弃物场地，沿裸地至植被覆盖的尾矿与废岩梯度开展微生物群落组成分析。裸地生境中的微生物群落多样性更低、群落结构更均质，且主要以化能自养型微生物为主；随着生境向植被覆盖区域过渡，微生物群落逐渐转变为以有机异养型微生物、固氮/促植物生长细菌以及外生菌根真菌（ectomycorrhizal fungi）为主的高多样性群落。微生物群落网络互作分析显示，裸地尾矿中的微生物类群间互作强度更高，这与极端环境与化学条件以及底物合成代谢营养可获得性受限密切相关。本研究同时证实，尾矿中的植被与植物源有机质，与微生物群落结构向类土壤群落的转变显著相关，而这一转变进而促进植被定植。上述研究结果可为寒冷大陆性北温带及寒带（boreal）气候下矿山尾矿与废岩的植物定植（phytoestablishment）优化与生物修复工作提供理论参考。