Microbial Processes at Interfaces Affect NAPL Distributions

地下环境中致密非水相液体（DNAPLs）的修复通常受到有机流体的不均匀分布的限制。 本研究的总体目标是量化的性质，程度和意义的变化，NAPL水界面过程中，导致一个活跃的微生物群落的存在。 据推测，NAPL-水-矿物系统中的界面现象经历动态变化，产生生物渗出物或微生物粘附在界面处。 例如，粘附张力的降低将降低非润湿NAPL进入孔隙的进入压力，导致NAPL在比预期更小的孔隙空间中的潜在分布。 由于微生物生长和整体吸附反应的瞬时性质，预计毛细管流动也可能是非常瞬时的。 这项工作的结果可能会被用来增加可访问性，因此，在补救工作中的DNAPL的恢复。 已经确定了三个具体任务：（1）量化的速率和定义的条件下，在生物活性的存在下，在界面过程中发生的动态变化，（2）表征的生物效应的主要机制和（3）量化的意义，这些动态过程的流动NAPL在多孔介质中。 将开展的研究工作将使人们更好地了解非水杀伤人员地雷在对环境有重大影响的条件下的迁移机制，从而能够更好地评估非水杀伤人员地雷释放到环境中的潜在环境影响和公共风险。 建模结果将提供一个框架，用于量化与NAPL混合物，天然表面活性物质的存在下，和细菌粘附的复杂性。 因此，研究结果将改进预测工具，如多相污染物迁移模型，这些模型可能预测导致非水相污染物排入渗透性较高地区的条件，从而提高补救工作的潜在有效性。

9981494 Grimberg The remediation of dense non-aqueous phase liquids (DNAPLs) in subsurface environments is often limited by the heterogeneous distribution of the organic fluid. The overall goal of this research is to quantify the nature, extent and significance of changes in NAPL-water interfacial processes that result from the presence of an active microbial community. It is hypothesized that interfacial phenomena in NAPL-water-mineral systems undergo dynamic changes as biological exudates are produced or microorganisms adhere at interfaces. For example, reductions in adhesion tension would reduce the entry pressure for a nonwetting NAPL to enter a pore, resulting in the potential distribution of NAPL in smaller pore spaces than would otherwise be expected. Due to the transient nature of the microbial growth and overall adsorption reactions, it is expected that capillary flow could also be very transient. Results of this effort could potentially be used to increase the accessiblility and, therefore, the recovery of DNAPL during remediation efforts. Three specific tasks have been identified: (1) Quantify the rates and define conditions under which dynamic changes in the interfacial processes occur in the presence of biological activity, (2) Characterize the primary mechanisms of the biological effects and (3) Quantify the significance of these dynamic processes on the flow of NAPLs in porous media. The research work to be conducted will provide a better understanding of the mechanisms governing the migration of NAPLs under environmentally significant conditions, which will allow for an improved assessment of potential environmental impacts and public risk of NAPL release to the environment. Modeling results will provide a framework for quantifying complexities asssociated with NAPL mixtures, the presence of natural surface-active materials, and bacterial adhesion. Results will therefore improve predictive tools, such as multiphase contaminant transport models that might predict conditions that result in drainage of NAPL into areas of higher permeability, thereby increasing the potential effectiveness of remediation efforts.***