Processes influencing natural attenuation of organic con

这项研究将提供一个基础，定量污染物暴露历史和监管的微生物生物降解能力在自然多孔介质中的流动条件下，代表现场规模羽流污染的情况下（低基板浓度和低水平的混合电子受体[氧气和硝酸盐]。过程影响自然衰减的四个模型化合物，代表三类优先污染物（燃料碳氢化合物，氯化溶剂和多核芳烃）将进行调查。良好的特征微生物/污染物/多孔介质系统将被用来开发有效的数学工具，用于描述污染物洗脱，运输和微生物转化。实验设计是基于一系列的综合研究，范围从分子（生物降解途径的调节），批量（污染物利用的动力学），实验室规模（流动柱研究），现场规模（现场条件的刺激）。批式和柱式研究的目的是：1）评价基质组成、多孔介质特性和浓度暴露历史对自然衰减条件下生物降解基因表达的影响; 2）研究污染物暴露历史与生物降解功能调控之间的联系; 3）评价自然衰减条件下表面附着对生物降解能力表达的影响;以及4）开发最先进的数学模型，以验证概念模型，测试假设，并探索实验室发现在现场规模的影响。in the field场scale规模.从该项目中获得的有关影响微生物转化过程的知识将为改善氯化溶剂和碳氢化合物污染场地的超级基金场地补救提供基础。此外，这里提议的工作，连同项目4 e，将允许制定评估内在和工程补救条件下的“替代终点”清理标准的方法。

This research will provide a basis for quantifying the relationship between contaminant exposure history and regulation of microbial biodegradative capabilities in natural porous media under flowing conditions representative of field scale plume contamination scenarios (low substrate concentrations and low levels of mixed electron acceptors [oxygen and nitrate]. Processes influences natural attenuation of four model compounds, representing three classes of priority contaminants (fuel hydrocarbons, chlorinated solvents, and polynuclear aromatic hydrocarbons) will be investigated. Well-characterized microbial/contaminant/porous media systems will be used to develop validated mathematical tools for the description of pollutant elution, transport, and microbial transformation. The experimental design is based on a series of integrated studies that range in scale from molecular (regulation of biodegradative pathways), to batch (kinetics of contaminant utilization), to bench-scale (flowing column studies), to field scale (stimulations of field conditions). Batch and column studies are proposed to: 1) evaluate the influence of substrate composition, porous media characteristics, and concentration exposure history of biodegradative gene expression under natural attenuation conditions; 2) investigate links between contaminant exposure history and regulation of biodegradative functions; 3) evaluate the influence of surface attachment on expression of biodegradative capabilities under natural attenuation conditions; and 4) develop state-of-the-art mathematical models to validate conceptual models, test hypotheses, and explore the implications of laboratory findings at the field scale. at the field scale. Knowledge gained from this Project pertaining to processes influencing microbial transformations will provide the foundation for improved Superfund site remediation at chlorinated solvent and hydrocarbon contaminated sites. In addition the work proposed here, in conjunction with Project 4e, will allow for development of approaches for assessment of 'alternative endpoint' clean- up standards under intrinsic and engineered remediation conditions.