Bioavailability and Biodegradation of Organic Contaminants In Heterogenous Subsurface Environments

非均质地下环境中有机污染物的生物利用度和生物降解。原位生物修复是污染土壤和地下水最有前途和成本效益的环境清理技术之一。就地生物修复是利用微生物来恢复受污染的环境，而不必挖掘或以其他方式扰乱污染场地。许多自然环境中都含有能够降解（破坏）污染物的微生物群落。成功实施原位生物修复面临两个严重问题。这些是在自然环境中发现的物理和化学非均质性，以及由于污染物吸附（粘附）到固体表面（粘土或沙粒）而导致污染物的可用性降低。该项目的目标是使用综合的生物和物理/化学方法来研究控制自然（非均质）地下环境中生物修复的因素。本提案概述了一种独特的方法来理解异质性对污染物可得性的影响，以及如何克服可得性限制以提高生物修复的幅度和速度。这种方法结合了最先进的中等规模流动和运输实验，以及一种先进的技术，用于确定污染物降解微生物的数量和活性（发光微生物的光纤检测）。这种方法将允许同时检测污染物运输和微生物活动，这将允许调查空间异质性和微生物介导破坏的污染物可用性之间的关系。此外，该方法将用于评估控制异质环境中微生物运输的物理和生物参数，并将加强运输的微生物机制与它们加强不可接近的有机污染物降解的潜力联系起来。该方法还将用于评价加强原位生物修复的战略，例如，应用可能增加吸附污染物的表面活性剂（洗涤剂）。研究结果将提高我们对这些问题的理解，并将在预测污染物的迁移和命运、评估地下水污染潜力以及操纵地下系统以提高生物修复技术的有效性方面取得重大进展。

9523870 Miller Bioavailability and Biodegradation of Organic Contaminants in Heterogeneous Subsurface Environments. One of the most promising and cost-effective environmental cleanup technologies for contaminated soil and groundwater is in situ bioremediation. In situ bioremediation is the use of microorganisms to restore a contaminated environment without having to excavate or otherwise disturb the contaminated site. Many natural environments contain microbial communities capable of degrading (destroying) pollutants. There are two serious problems facing successful implementation of in situ bioremediation. These are the physical and chemical heterogeneities found in natural environments, and the reduced availability of contaminants that results from the sorption (sticking) of contaminants to solid surfaces (clay or sand particles). The goal of this project is to use an integrated biological and physical/chemical approach to investigate the factors controlling bioremediation in natural (heterogeneous) subsurface environments. This proposal outlines a unique approach to understanding the effect of heterogeneity on contaminant availability, and how availability constraints can be overcome to enhance the magnitude and rate of bioremediation. This approach combines state-of-the-art intermediate-scale flow and transport experiments with an advanced technique for the determination of both the number and activity of contaminant-degrading microorganisms (fiber optic detection of luminescing microorganisms). This approach will allow the simultaneous detection of contaminant transport and microbial activity, which will allow for the investigation of the relationship between spatial heterogeneity and availability of contaminants for microbially-mediated destruction. In addition, the approach will be used to evaluate the physical and biological parameters that control the transport of microorganisms in a heterogeneous environment, and to relate microbial mechanisms for enhanced transport to their potential to enhance the degradation of inaccessible organic contaminants. The approach will also be used to evaluate strategies to enhance in situ bioremediation, for example, the application of surfactants (detergents) that may increase the availability of sorbed contaminants. The results of the research will improve our understanding of these issues and will provide significant advancement in prediction of contaminant transport and fate, for evaluating groundwater contamination potential, and for the manipulation of subsurface systems to enhance the effectiveness of bioremediation technologies.