Characterizing in situ remediation strategies for metal contaminated soils

在许多工业和采矿场所、射击场以及反复施用生物固体的场所周围的表层土壤中，痕量金属浓度升高是一种常见现象。尽管严格的法规有助于减少此类污染，但遗留污染物仍然对人类和生态健康构成重大威胁。目前的补救技术，如土壤挖掘，费用昂贵，可能不适用于实地规模。此外，采用磷（P）来稳定金属如铅（Pb）的方法可能对地表沃茨造成环境风险（富营养化）。这项拟议的研究计划的总体目标是确定关键的机制，调节性能的原位修复方法-植物修复和化学稳定-铅污染的土壤。了解这些过程和机制将有助于改进技术，加快清理速度，同时尽量减少对地下水的沥滤。通过一系列的温室、室内和田间试验，研究了印度芥菜和玉米对铅污染土壤的植物修复效果;研究了EDTA对石灰性土壤中铅的植物提取作用;研究了EDTA对土壤中铅与肥料或堆肥磷的相互作用;（iv）测定EDTA和/或粪肥磷处理的污染土壤中Pb和P的分级;（v）确定影响EDTA结合Pb在根区移动的主要过程;（vi）表征使用来自肥料或堆肥的P控制Pb的化学稳定的基本机制，以及（vii）确定磷处理铅污染土壤中铅和磷淋溶的调控机制。研究结果将增强我们对这些修复方法所涉及的基本过程的理解，并有助于改善其现场性能。根据研究制定的模型还将协助政府和工业界根据场地特点对补救战略的潜在成功和风险进行针对具体场地的评估。

Elevated trace metal concentrations are a common occurrence in surface soils around many industrial and mining sites, in shooting ranges, and in sites that have received repeated applications of biosolids. Although stringent regulations have helped reduce such contamination, legacy contaminants remain a significant threat to human and ecological health. Current remediation technologies, such as soil excavation, are costly and may not be applicable on a field scale. Additionally, approaches that employ phosphorus (P) to stabilize metals such as lead (Pb) may present environmental risk (eutrophication) to surface waters. The overall objective of this proposed research program is to identify critical mechanisms regulating the performance of in situ remediation approaches - phytoremediation and chemical stabilization - for Pb-contaminated soils. An understanding of the processes and mechanisms will allow improvement of the technologies to speed up cleanup while minimizing leaching to groundwater. A series of greenhouse, laboratory, and field experiments will be performed to (i) characterize the efficacy of Indian mustard and corn for phytoremediation of Pb-contaminated sites; (ii) understand the change in contaminant dynamics when EDTA is applied to enhance Pb phytoextraction in calcareous soils; (iii) study the interaction of Pb with fertilizer or compost P in the presence of EDTA; (iv) determine Pb and P fractionation in contaminated soils treated with EDTA and/or manure phosphorus; (v) identify the dominant processes influencing the mobility of EDTA-bound Pb in the root zone; (vi) characterize the basic mechanisms controlling chemical stabilization of Pb using P derived from fertilizer or compost, and (vii) identify the mechanisms regulating Pb and phosphorus leaching in P-treated Pb-contaminated soils. Results from the research will enhance our understanding of the fundamental processes involved in these remediation approaches and help improve their field perfomance. Models formulated from the research will also assist government and industry in the site-specific assessment of potential success and risks of the remediation strategies based on site characteristics.