Release of Colloids to Groundwater from Aquifer Solids

摘要CTS-9523824总体目标是了解悬浮在地下水中的胶体相存在的情况。据推测，在含水层沉积物中，作为成岩作用产生的涂层和基质的一部分，胶体的动员是这些微粒和大分子从含水层砂中进入地下水的最常见和最重要的来源。将确定含水层砂中存在的用于固定胶体的颗粒-颗粒接触。将确定这些附着表面对溶液组成变化的反应性，并将评估完整的原位含水层沉积物被变化的地下水冲刷时胶体的动员情况。高分辨率透射电子显微镜将用于在纳米尺度上观察含水层颗粒接触。通过在实验室中将这些特征良好的天然胶体储层暴露于确定的水溶液中，可以推断出表面-表面引力可以转变为排斥相互作用的机制。将根据实验室结果选择使用改良地下水成分的小规模现场注入/提取试验，以评估在现场分离胶体的难易程度。了解地下水中胶体动员发生的机制对于废物处理活动和“抽水处理”式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. ***