Processes influencing natural attenuation of organic con

该研究将为量化污染物暴露历史与微生物在天然多孔介质中生物降解能力调节之间的关系提供基础，这些关系代表了现场规模羽流污染情景（低底物浓度和低水平混合电子受体[氧和硝酸盐]）的流动条件。过程影响四种模式化合物的自然衰减，代表三类优先污染物（燃料碳氢化合物，氯化溶剂和多核芳香烃）将进行研究。表征良好的微生物/污染物/多孔介质系统将用于开发有效的数学工具，用于描述污染物的洗脱、运输和微生物转化。实验设计基于一系列综合研究，从分子（生物降解途径的调节）到批量（污染物利用动力学），到实验规模（流动柱研究），再到现场规模（现场条件的刺激）。批量和柱式研究建议：1)评估底物组成、多孔介质特性和浓度暴露史对自然衰减条件下生物降解基因表达的影响；2)研究污染物暴露史与生物降解功能调节之间的联系；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；4)开发最先进的数学模型来验证概念模型，测试假设，并在现场规模上探索实验室发现的含义。在现场规模。从本项目中获得的有关影响微生物转化过程的知识将为改进超级基金对氯化溶剂和碳氢化合物污染场地的修复提供基础。此外，这里提出的工作与项目4e相结合，将允许开发在内在和工程修复条件下评估“替代端点”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.