Characterizing in situ remediation strategies for metal contaminated soils

在许多工业和采矿场所、射击场和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常见的现象。尽管严格的法规有助于减少这种污染，但遗留污染物仍然是对人类和生态健康的重大威胁。目前的修复技术，如土壤挖掘，成本昂贵，可能不适用于现场规模。此外，使用磷(P)来稳定铅（Pb）等金属的方法可能会给地表水带来环境风险（富营养化）。本研究计划的总体目标是确定调节原位修复方法（植物修复和化学稳定）对铅污染土壤性能的关键机制。对过程和机制的了解将有助于改进技术，以加快清理工作，同时尽量减少对地下水的浸出。将进行一系列温室、实验室和田间实验，以(i)确定印度芥菜和玉米对铅污染场地的植物修复效果；（ii）了解EDTA用于提高钙质土壤中铅的植物提取时污染物动态的变化；（iii）在EDTA存在的情况下，研究铅与肥料或堆肥P的相互作用；测定经EDTA和/或粪肥磷处理的污染土壤中铅和磷的分异；(v)确定影响edta结合的Pb在根区迁移的主要过程；（vi）描述了利用来自肥料或堆肥的磷控制铅化学稳定的基本机制；（vii）确定了在磷处理的铅污染土壤中调节铅和磷淋溶的机制。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，并有助于提高它们的现场性能。该研究建立的模型还将协助政府和工业界根据场地特征对具体场地的修复策略的潜在成功和风险进行评估。

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.