Characterizing in situ remediation strategies for metal contaminated soils

微量金属浓度升高在许多工矿场周围的表层土壤、射击场和反复使用生物固体的场地中很常见。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。目前的修复技术，如土壤挖掘，成本很高，可能不适用于现场规模。此外，使用磷(P)稳定铅(Pb)等金属的方法可能会对地表水造成环境风险(富营养化)。这项拟议研究计划的总体目标是确定控制铅污染土壤就地修复方法-植物修复和化学稳定化-性能的关键机制。对过程和机制的了解将有助于改进技术，以加快清理速度，同时最大限度地减少对地下水的淋洗。将进行一系列温室、实验室和田间试验，以(I)表征印度芥菜和玉米对铅污染场地的植物修复效果；(Ii)了解应用EDTA促进石灰性土壤中铅的植物提取时污染物动态的变化；(Iii)研究在EDTA存在下，铅与肥料或堆肥P的相互作用；(Iv)测定经EDTA和/或有机磷处理的污染土壤中铅和磷的形态；(V)确定影响根区EDTA结合态铅迁移的主要过程；(Vi)描述化肥或堆肥中磷对铅的化学稳定作用的基本机制，以及(Vii)确定铅污染土壤中铅和磷淋失的调控机制。研究结果将加强我们对这些补救方法所涉及的基本过程的了解，并有助于改善它们的实地表现。研究建立的模型还将帮助政府和行业根据场地特征对补救策略的潜在成功和风险进行特定场地的评估。

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.