Project 9: Phytostabilization of Mine Tailings in the Southwestern

尾矿处理场普遍存在于世界各地的干旱和半干旱地区，包括美国西南部。未回收的采矿废料通常几十年到几百年都没有植被，暴露的尾矿可以通过风和水的侵蚀扩散到大片地区。包括金属毒性、低有机质、酸性pH、高盐度、极端温度、低降水和微生物群落严重受压在内的多种因素共同导致了植被的缺乏。对于这类尾矿，风载分散是附近社区和环境敏感地区的重要暴露途径。

Mine tailings disposal sites are prevalent in arid and semiarid regions throughout the world including the US Southwest. Unreclaimed mining wastes generally remain unvegetated for tens to hundreds of years, and exposed tailings can spread over vast areas via wind and water erosion. A combination of factors, including metal toxicity, low organic matter, acidic pH, high salinity, extreme temperatures, low precipitation, and severely stressed microbial communities contribute to this lack of vegetation. For such tailings, wind-borne dispersion is an important exposure route for nearby communities and environmentally sensitive areas. Specifically, tailings are a significant source of air pollution in the form of particulates <10 ¿mu¿m (PM10) and <2.5 ¿mu¿m (PM2.5). Exposure to these particulates has consequences for respiratory and other diseases even in the absence of toxic metals. The fact that many sites additionally contain toxic metals exacerbates the human health impact. A cost effective remedial technology for such sites is phytostabilization, the establishment of a permanent vegetative cover that does not accumulate metals into plant shoot tissues. While of great promise, there is currently little documentation of this technology in accessible scientific literature. The overall goal of this project is to determine how plant-microbe-metal interactions affect the short- and long-term requirements for, and mechanisms of, revegetation of arid mine tailings and to identify the biological and physico-chemical markers that indicate successful remediation. This project focuses on examining field application of phytostabilization while retaining several key basic research questions identified as important for success in the field. Specific objectives include: (1) to translate phytostabilization technology from the greenhouse to the field; (2) to determine if a multi-variate, spatial analysis of initial biophysico-chemical characteristics of mine tailings can serve as a useful predictor of phytostabilization success; (3) to evaluate the progress toward development of a "healthy" soil as a function of time following revegetation of mine tailings; and (4) to determine the influence of microbial inocula on phytostabilization including plant biomass production and development of the rhizosphere community.