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

这项提案调查了植物修复可用于退化的工作假说。 空气中来自土壤和地下水来源的多氯联苯同系物。植物刺激微生物群落 在根区，并有助于微生物降解RGB(根部降解)。高氯化 多氯联苯在还原(厌氧)条件下脱氯；导致氯化程度较低的同系物 可以在好氧条件下进行氧化矿化。氧化还原交替进行 根际条件使植物-土壤系统成为初始印刷电路板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被吸收，并在计划组织内转化。这个 该项目的具体目标是(1)检验杨树植物可以吸收和解毒的假设 通过确定多氯联苯和编码多氯联苯的基因的代谢途径，减少氯化多氯联苯的同系物 对于分解代谢酶，(2)检验根际细菌可以还原的假设 脱氯高氯化多氯联苯，并可矿化产生的低氯化同系物 氧化条件；这将使用具有根际的厌氧和好氧间歇生物反应器进行测试 被多氯联苯污染的土壤，(3)测试植物修复将允许显著 减少废物处置场的多氯联苯空中转移并减少对人类的暴露 和生态系统；这一创新的清理战略(基于假设1和2)将在 试验台规模和温室盆栽研究，(4)检验多氯联苯残留假设 在植物组织中对生物群无毒或极大地降低毒性，通过进行生态毒理学 使用一组毒性测试对植物修复过程进行评估，以及(5)测试 高等植物在空气中多氯联苯的环境循环中起重要作用的假说 多氯联苯在植被上积累的田间分析。这个项目的意义在于它提供了一个 对受污染的废物场地进行干预和补救，有助于打破环境污染的持续循环 大气中的多氯联苯和随后对人类的暴露。

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.