Release of Colloids to Groundwater from Aquifer Solids

摘要CTS-9523824 总体目标是了解胶体相悬浮在地下水中的情况。 据推测，作为含水层存款内的成岩产生的涂层和基质的一部分预先存在的胶体的流动，是从含水层砂到地下水的这种微粒和大分子的最常见和最重要的来源。 将确定含水层砂中用于包裹胶体的颗粒-颗粒接触。 将确定这种附着表面对溶液成分变化的反应，并评估在被变化的地下水冲洗时，原状含水层沉积物中胶体的流动情况。 高分辨率透射电子显微镜将被用来检查含水层颗粒接触的纳米尺度。 通过在实验室中将这种特征良好的天然胶体储层暴露于定义的水溶液中，将推导出表面-表面吸引力可以改变为排斥相互作用的机制。 将使用根据实验室结果选择的改良地下水成分进行小规模现场注入/抽取试验，以评估胶体在现场分离的难易程度。 了解地下水中胶体流动的机制对于废物处置活动和“泵送-处理”型补救措施的运动非常重要。 ***

ABSTRACT CTS-9523824 The overall goal is to understand the circumstances in which colloidal phases exist suspended in groundwater. It is hypothesized that mobilization of colloids, pre-existing as part of diagenetically produced coating and matrix within the aquifer deposit, is the most common and important source of such microparticles and macromolecules to the groundwater from aquifer sands. The particle-particle contacts present in aquifer sands that serve to immobilize colloids will be identified. The responsiveness of such attached surfaces to changes in solution composition will be determined, and the mobilization of colloids within intact in situ aquifer deposits when these are flushed by changed groundwater will be assessed. High resolution transmission electron microscope will be used to examine aquifer grain contacts on the nanometer scale. By exposing such well-characterized natural colloid reservoirs to defined aqueous solutions in the laboratory, the mechanisms by which the surface-surface attractive forces can be changed to repulsive interactions will be deduced. Small scale field injection/withdrawal tests using modified groundwater compositions, chosen based on the laboratory results, will be performed to assess the ease with which the colloids are detached in the field. Understanding the mechanisms by which colloid mobilization occur in groundwater is important for waste disposal activities and the movements of "pump-and-treat" type remediations. ***