Collaborative Research: Colloid Mobilization and Transport in the Vadose Zone

[909508] [au:]在降雨期间，水蛭在渗流带内被动员起来，将污染物清除并携带到地下地下水中。尽管胶体作为渗流区污染物运输的重要因素，但影响胶体通过部分饱和多孔介质运动的因素尚未得到严格探索，也未形式化为定量模型。特别是，在固体-水界面、空气-水界面和水薄膜中，流动瞬态对胶体相互作用的作用迄今尚未得到充分的研究。这项研究由耶鲁大学和弗吉尼亚大学的研究人员联合开展，将把实验室规模和现场规模的实验与数学模型结合起来。我们将在理想介质和完整岩心的实验室实验中测量胶体输运，并将利用这些数据指导非饱和土壤中胶体平流-色散耦合输运和传质的数值模型的开发。从实验室规模实验分析中确定的数值模型结构将构成随机流管模型的基础，该模型能够解释土壤性质的空间变异性对胶体命运和运输的影响。流管模型将根据现场实验的数据进行测试，在现场实验中，胶体的动员和运输是根据受控洒洒引起的瞬态流动事件而测量的。我们的工作代表了在瞬态流动条件下确定水不饱和介质中胶体运动控制的第一个系统方法，并提供了一种评估胶体轨迹对渗流带环境中污染物通量的贡献的方法。

9909508SaiersColloids, mobilized within the vadose zone during rainfall events, scavenge and carry contaminants to underlying groundwater. Despite the importance of colloids as agents of vadose-zone contaminant transport, the factors influencing colloid movement through partially saturated porous media have not been rigorously explored nor formalized into a quantitative model. In particular, the role of flow transients on colloid interactions at solid-water interfaces, at air-water interfaces, and within thin films of water has not been adequately investigated to date. This research, carried out jointly by investigators at Yale and at UVA, will integrate laboratory-scale and field-scale experiments with mathematical modeling. We will measure colloid transport in laboratory experiments conducted with ideal media and with intact cores, and we will use these data to guide the development of a numerical model for the coupled advective-dispersive transport and mass transfer of colloids in unsaturated soils. The structure of the numerical model identified from analysis of the laboratory-scale experiments will form the foundation for a stochastic streamtube model, a model capable of accounting for the effects of spatial variability in soil properties on colloid fate and transport. The streamtube model will be tested against data from a field experiment in which colloid mobilization and transport is measured in response to transient flow events induced by controlled sprinkling over an instrumented field plot. Our work represents the first systematic approach to identifying the controls on colloid movement in water-unsaturated media under transient-flow conditions and provides a means to evaluate the contribution of the colloid track to contaminant fluxes within vadose-zone environments.