RUI: Restoration of lead (Pb) contaminated soils through chemically enhanced phytoextraction by switchgrass (Panicum virgatum)

尽管在限制新的铅(铅)排放源方面取得了很大进展，但慢性铅危害仍然存在，特别是在城市地区。在美国城市，土壤中的弥漫铅(从含铅汽油燃烧废气等来源分散在土壤中的铅)是持久的铅蓄积物，导致长期长期接触铅。开发有效的除铅技术的努力包括一些生物和地球化学操作，每一种操作本身都产生了显著的增量改进。该项目的一个目标是将影响铅吸收的各个因素结合起来，以提高从常见的、快速生长的模式植物(柳枝花)土壤中去除铅的效率。项目研究人员正在研究一系列土壤改良剂，包括杀菌剂、金属螯合剂和植物生长调节剂，以改善土壤中铅的去除并将其集中到植物的地上部分。开发有效的铅植物修复技术的努力包括土壤杀菌剂(苯菌灵)处理以下调丛枝菌根真菌(AMF)的金属排斥作用，以及在土壤中应用铅螯合剂，如柠檬酸，以动员铅并增强其对植物生物量的吸收。然而，在这种情况下，铅的植物毒性限制了植物的寿命，并限制了吸收能力。项目研究人员正在研究，通过叶面铁(Fe)、植物生长调节剂和外源一氧化氮供体的协同应用，是否可以进一步提高植物对铅的提取能力。这些操作可能有助于提高高生物量柳枝柳(Panicum Virgatum)的植物提取效率。研究小组正在使用肯纳索州立大学最先进的实验温室设施，以及从亚特兰大市区和佐治亚州塞德敦的前超级基金遗址采集的受污染土壤。系统地改变了土壤杀菌剂、螯合物和铁、植物生长调节剂和外源一氧化氮(NO)供体的叶面施药、单独和组合使用的实验条件，以优化每种方法并测试其协同效应。将提取和分析铅污染和非污染土壤中AMF组合的高通量DNA序列，以表征AMF的种类组成。正在对土壤和植物组织样本中的铅、铁、磷(P)以及全套宏微营养素进行化学分析。该研究项目有可能为植物修复的科学知识做出贡献，同时也培训本科生研究人员进行高水平的研究。该项目的成果有可能极大地提高植物萃取率，并指导开发适合技术转让的土壤恢复技术。

Despite great progress in limiting new lead (Pb) sources of emissions, chronic lead hazards remain particularly in urban areas.  In U.S. cities, diffuse lead in soils (lead that has been dispersed in soils from a source such as leaded gasoline combustion exhaust) is a persistent reservoir of lead, contributing to long term chronic exposure. Efforts to develop efficient lead removal techniques have included a number of biological and geochemical manipulations that each, alone, has produced significant incremental improvements. A goal of this project is to combine the individual factors affecting lead uptake to increase the efficiency of lead removal from soils in a common, fast growing model plant (switchgrass). The project researchers are investigating a series of soil amendments, including a fungicide, metal chelator, and plant growth regulator, for improving lead removal from the soil and concentrating it into the above-ground parts of the plant. The plants could then be removed and disposed of in a safe manner.Efforts to develop efficient lead phytoremediation techniques have included soil fungicide (benomyl) treatments to down-regulate the metal exclusion actions of arbuscular mycorrhizal fungi (AMF) and the application of lead chelating agents, such as citric acid, in soil to mobilize lead and enhance its uptake to plant biomass. In such cases, however, the phytotoxicity of lead limits plant life and creates a limit on uptake capacity. The project researchers are studying whether phytoextraction of lead can be enhanced further by a coordinated application of foliar iron (Fe), plant growth regulator and exogenous nitric oxide donors. These manipulations may serve to increase the phytoextraction efficiency of the high biomass producing switchgrass (Panicum virgatum). The research team is using state-of-the-art experimental greenhouse facilities at Kennesaw State University, along with contaminated soils sampled from urban Atlanta and a former Superfund site in Cedertown, GA. Experimental conditions are being systematically varied among soil fungicide, chelate, and foliar application of iron, plant growth regulator and exogenous nitric oxide (NO) donor, singly and in combination, to optimize each and test for synergistic effects. High throughput DNA sequences of AMF assemblages in lead-contaminated and non-contaminated soils will be extracted and analyzed to characterize AMF species composition. The chemical analysis of lead, iron, phosphorous (P), and the full suite of macro- and micro-nutrients are being determined in soil and plant tissue samples. The research project has the potential for contributing to scientific knowledge on phytoremediation while also training undergraduate student researchers in high level research. Results of this project have the potential to dramatically improve phytoextraction rates and guide the development of a soil restoration technique appropriate for technology transfer.