Project 5: Phytoremediation to Degrade Airborne PCB Congeners from Soil and

这项建议调查的工作假设，植物修复可以用来降解 来自土壤和地下水源的多氯联苯同系物。植物刺激微生物群落 在根区，并有助于RGBs的微生物降解（根降解）。高氯化 多氯联苯在还原（厌氧）条件下脱氯;产生氯化程度较低的同系物 可以在有氧条件下进行氧化矿化。交替还原氧化 根际条件使植物-土壤系统成为初始PCB的天然两级生物反应器 转型氯化程度较低的多氯联苯也可以在植物组织内吸收和转化。的 该项目的具体目标是：（1）检验白杨植物可以吸收和解毒的假设 通过确定多氯联苯的代谢途径和编码基因， 对于分解代谢酶，（2）检验根际细菌可以还原 使高氯化度的多氯联苯脱氯，并可使生成的低氯化度同系物矿化， 氧化条件;这将使用根际厌氧和好氧分批生物反应器进行测试 土壤污染的多氯联苯，（3）测试的假设，植物修复将允许显着 减少来自废物处置场的多氯联苯的空中转移，并减少人类接触 这一创新的清理战略（基于假设1和假设2）将在2010年进行测试。 实验室规模和盆栽研究，在温室中，（4）以测试的假设， 在植物组织中是无毒的，或通过进行生态毒理学， 使用一系列毒性测试评估植物修复过程，以及（5）测试 假设高等植物在空气中多氯联苯的环境循环中发挥重要作用， 多氯联苯在植被上累积的实地分析。这个项目的意义在于它提供了一个 对受污染的废物场地采取干预和补救措施，这将有助于打破 大气中的多氯联苯以及随后对人类的暴露。

This proposal investigates the working hypothesis that phytoremediation can be used to degrade airborne PCB congeners from soil and groundwater sources. Plants stimulate the microbial community in the root zone and contribute to microbial degradation of RGBs (rhizodegradation). Higher-chlorinated PCBs are dechlorinated under reducing (anaerobic) conditions; resulting lesser-chlorinated congeners can undergo oxidative mineralization under aerobic conditions. Alternating reducing and oxidizing conditions in the rhizosphere makes the plant-soil system a natural two-stage bioreactor for initial PCB transformation. Lesser-chlorinated PCBs can also be taken-up and transformed inside plan tissues. The specific aims of the project are (1) to test the hypothesis that poplar plants can take up and detoxify lesser-chlorinated PCB congeners by identifying metabolic pathways of PCBs and genes that encode for catabolic enzymes, (2) to test the hypothesis that bacteria in the rhizosphere can reductively dechlorinate higher-chlorinated PCBs and can mineralize resulting lesser-chlorinated congeners under oxidizing conditions; this will be tested using anaerobic and aerobic batch bioreactors with rhizosphere soils contaminated with PCBs, (3) to test the hypothesis that phytoremediation will allow for significant reductions in the airborne transfer of PCBs from waste disposal sites and mitigate exposure to humans and ecosystems; this innovative cleaning up strategy (based on hypotheses 1 and 2) will be tested at the bench scale and by pot-studies in the greenhouse, (4) to test the hypothesis that residues of PCBs in plant tissues are non-toxic or of greatly reduced toxicity to biota by conducting an eco-toxicological evaluation of the phytoremediation process using a battery of toxicity tests, and (5) to test the hypothesis that higher plants play a significant role in the environmental cycling of airborne PCBs by field analyses of PCB accumulation on vegetation. The significance of this project is that it provides an intervention and remedy for contaminated waste sites that will help to break the continuous cycling of PCBs in the atmosphere and the subsequent exposure to humans.