Phytostablization of Mine Tailings

美国西南部干旱和半干旱生态系统的大规模采矿活动导致了大量的尾矿场地，金属浓度升高，范围在0.1%至5%（w/w）之间。由于金属毒性和低pH值，这些桩中有许多是贫瘠的或只有最少的植被，因此容易受到风和水的侵蚀。植物稳定化已被提议作为一种替代的经济补救策略，以稳定金属污染物，防止人类和动物接触大气中的颗粒悬浮物（灰尘）或溶解在地下和地表沃茨中。虽然这种策略作为更持久的金属去除方法的经济替代方案而受到关注， 需要进行大量研究，以提高这一办法的可行性，并系统地评估重新植被作为一种补救战略的持久性。首先，大量的有机物质（堆肥或生物固体）和水传统上被用于植被建设，这两种方法在许多废弃尾矿堆所在的偏远地区都不可行。第二，很少有研究进行评估的物理，化学和生物特性的尾矿在植被重建过程中随时间的变化。具体而言，关于有机物添加、植物建立和相关微生物群落对金属的演变的影响的信息很少 生物利用度、溶解度和形态。该项目的总体目标是制定一项可行的重新植被战略，以植物稳定干旱和半干旱生态系统中尾矿堆中的金属污染物，并评估这一方法对尾矿的物理、生物和化学特性的影响。这项战略将调查是否具体选择耐金属和耐旱的本地植物物种，并控制使用从本地植物生长促进细菌中开发的种子接种物， 最大限度地减少对有机物的需求。其次，植物根际污染金属的生物利用度，形态和相分布将在温室和田间试验中进行监测，以评估重新植被是否会导致永久性减少现场毒性。此外，将调查特定根微生物尾矿协会对当地土壤地球化学和根际金属形态的影响，以确定在微米和亚微米尺度上参与植物稳定和解毒的机制。这项研究产生的信息将确定建立工厂作为稳定尾矿中金属的方法的可行性，并评估重新植被作为补救战略的潜在寿命。

Extensive mining activity in arid and semi-arid ecosystems of the southwestern United States has resulted in large numbers of tailings sites with elevated metal concentrations ranging between 0.1 and 5% (w/w). Many of these piles are barren or have minimal vegetation due to metal toxicity and low pH and thus are vulnerable to wind and water erosion. Phytostabilization has been proposed as an alternative economical remediation strategy to stabilize the metal contaminants and prevent human and animal exposure resulting from particle suspension (dust) in the atmosphere or dissolution in ground and surface waters. Although this strategy is receiving attention as an economical alternative to more permanent metal removal approaches, considerable research is needed to improve the feasibility of the approach as well as to systematically assess the longevity of revegetation as a remediation strategy. First, large amounts of organic matter (compost or biosolids) and water have traditionally been used for vegetation establishment, neither of which are feasible in many of the remote areas where abandoned mine tailing piles are located. Second, little research has been conducted to evaluate the time-dependent changes in physical, chemical, and biological properties of mine tailings during revegetation. Specifically, little information is available on the effect of organic matter addition, plant establishment, and the evolution of associated microbial communities on metal bioavailability, solubility and speciation. The overall goal of this project is to develop a feasible revegetation strategy for the phytostabilization of metal contaminants in mine tailing piles in arid and semi-arid ecosystems and to assess the impact of this approach on the physical, biological and chemical properties of the mine tailings. This strategy will investigate whether the specific selection of metal- and drought-tolerant native plant species in conjunction with the controlled use of a seed inoculum developed from indigenous plant growth promoting bacteria can minimize the requirement for organic matteramendment and irrigation. Second, the bioavailability, speciation, and phase distribution of contaminating metals in the plant rhizosphere will be monitored in both greenhouse and field trials in order to assess whether revegetation results in a permanent reduction in site toxicity. In addition, the effects of specific root-microbe-tailings associations on the local biogeochemistry and metal speciation of the rhizosphere will be investigated in order to identify mechanisms involved in phytostabilization and detoxification at the micrometer and submicrometer scale. Information generated from this research will define the feasibility of plant establishment as an approach to metal stabilization in mine tailings and evaluate the potential longevity of revegetation as a remediation strategy.