Microbial Processes at Interfaces Affect NAPL Distributions

9981494格里姆贝格地下环境中稠密非水相液体(DNAPL)的修复通常受到有机流体分布不均的限制。这项研究的总体目标是量化由于存在活跃的微生物群落而导致的NAPL-水界面过程变化的性质、程度和意义。假设NAPL-水-矿物体系中的界面现象随着生物渗出物的产生或微生物在界面上的附着而发生动态变化。例如，粘合张力的降低将降低非湿润NAPL进入孔隙的入口压力，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变性质，预计毛细管流也可能是非常瞬变的。这一努力的结果可能被用来增加可达性，从而在补救努力期间恢复DNAPL。已经确定了三个具体的任务：(1)量化在生物活动存在的情况下界面过程发生动态变化的速率和条件，(2)表征生物效应的主要机制，(3)量化这些动态过程对多孔介质中NAPL流动的意义。将开展的研究工作将使人们更好地了解在对环境具有重要意义的条件下管理非杀伤人员地雷迁移的机制，这将有助于改进对潜在环境影响和向环境排放非杀伤人员地雷的公众风险的评估。模拟结果将为量化与NAPL混合物、天然表面活性材料的存在和细菌粘附性相关的复杂性提供一个框架。因此，结果将改进预测工具，如多相污染物传输模型，该模型可能预测导致NAPL排入渗透率较高地区的条件，从而增加补救努力的潜在有效性。

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.***