Colloid Mobilization and Transport in the Vadose Zone: New Observations and Modeling Approaches

包气带中的胶体动员和传输：新的观察和建模方法

• 批准号: 1014478
• 负责人: James Saiers
• 金额: $ 26.35万
• 依托单位: Yale University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-10-01 至 2014-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1014478&HistoricalAwards=false
• 关键词: Colloid; Mobilization; Transport; Vadose; Zone

Predictive approaches for the transport of colloids (microscopic, waterborne particles) through unsaturated soils are unavailable. Consequently, it is impossible to evaluate the risks associated with the transmission of colloid-sized contaminants through the vadose zone and into drinking-water aquifers or to inform management decisions intended to minimize these risks. Our work is aimed at addressing these deficiencies. In particular, we (the PI, a postdoctoral associate, and a Ph.D. student) will: (1) measure the effects of infiltration rate and soil texture on colloid transport through vadose-zone soils during transient flow;(2) elucidate the responses of colloid mobility within vadose-zone soils to changes in colloid size and composition and pore-water chemistry; and(3) develop a mathematical model that is suitable for quantifying colloid mobilization and transport during transient, unsaturated flow through geologic media.Our work will begin with laboratory experiments on the movement of mineral colloids through real vadose-zone soils. This laboratory component will involve column experiments designed to illuminate the sensitivity of colloid mobilization, transport, and deposition during soil imbibition and drainage to changes in soil texture, pore-water ionic strength, and the physicochemical properties of the colloids themselves. The column experiments will be supplemented by pore-scale visualization experiments that will reveal the principal mechanisms of colloid mobilization and retention under the physicochemical conditions examined in the column experiments. These experiments will also elucidate the changes in air-water configuration that occur during transient flow and that presumably drive colloid release. The visualization experiments, together with the column experiments, will be used to guide the development of a model for coupled transient porewater flow, colloid transport, and colloid mass transfer. This model will be based on modern conceptualizations of air-water configuration within unsaturated porous media and will approximate the effects of multiple mechanisms on colloid mobilization, rather than treating mobilization as a lumped process without a physical basis. By the end of the project period, a comprehensively evaluated model will be created that is suitable for making inferences on colloid mobility within unsaturated soils. The overall findings from this research should gain the attention of hydrologists, soil scientists, aquatic chemists, and engineers interested in two-phase flow phenomena, the fate and transport of engineered nanoparticles in geologic environments, soil formation processes, and the transmission of pathogens and colloid bound pollutants through unsaturated soils and towards the water table.

预测方法的胶体（微观，水性颗粒）通过非饱和土壤的运输是不可用的。 因此，无法评估胶体大小的污染物通过包气带进入饮用水含水层的相关风险，也无法为旨在尽量减少这些风险的管理决定提供信息。 我们的工作旨在解决这些缺陷。 特别是，我们（PI，博士后助理和博士。学生）将：（1）测量瞬时流动期间渗透率和土壤质地对包气带土壤中胶体迁移的影响;（2）阐明包气带土壤中胶体流动性对胶体尺寸和组成以及孔隙水化学变化的响应;和（3）开发一种数学模型，该模型适合于在瞬态期间量化胶体移动和运输，我们的工作将从矿物胶体在真实的渗流带土壤中运动的实验室实验开始开始。 该实验室部分将涉及柱实验，旨在阐明土壤吸胀和排水过程中胶体动员、运输和沉积对土壤质地、孔隙水离子强度和胶体本身物理化学性质变化的敏感性。 柱实验将辅以孔隙尺度可视化实验，该实验将揭示柱实验中检查的物理化学条件下胶体动员和保留的主要机制。 这些实验还将阐明在瞬态流动过程中发生的空气-水配置的变化，并推测驱动胶体释放。 可视化实验，连同柱实验，将用于指导耦合瞬态孔隙水流动，胶体运输和胶体传质模型的开发。该模型将基于不饱和多孔介质内空气-水配置的现代概念化，并将近似多种机制对胶体动员的影响，而不是将动员视为没有物理基础的集总过程。 到项目期结束时，将建立一个综合评价模型，适用于推断非饱和土壤中的胶体流动性。 这项研究的总体结果应该引起水文学家，土壤科学家，水生化学家和工程师的注意，他们对两相流现象，工程纳米颗粒在地质环境中的命运和运输，土壤形成过程以及病原体和胶体结合污染物通过非饱和土壤和地下水位的传播感兴趣。