Development of Screening and Modeling Tools for Colloid-Facilitated Transport of Contaminants in the Subsurface

0228911当忽略胶体促进的污染物迁移时，埃利米勒污染物迁移模型大大低估了强吸附污染物的迁移距离。由于胶体促进运输的机制相对知之甚少，因此预测在受污染的地下环境中胶体促进运输的潜力是相当具有挑战性的。因此，迫切需要一套保守的标准来预测胶体促进运输的潜力。拟议研究的主要目标是：(I)制定一套量化各种相关化学物质(Na+、K+、钙、镁、pH、配体、有机酸、腐植酸和富里酸)对胶体动员(释放)的影响的标准，(Ii)开发一种简单的方法来确定自然地下环境中的胶体沉积速率，以及(Iii)建立一套保守的标准和筛选工具来预测胶体促进迁移的可能性。上述工作的目标和以下相关假设为拟议的研究提供了基础：(A)通过考虑污染物在可移动的胶体颗粒上的不可逆吸附，可以获得胶体促进迁移的最坏情况。(B)在土壤和几种类型的含水层沉积物中，被动员的胶体颗粒与固定的固体基质具有相似的化学性质。因此，利用聚集和沉积动力学之间的类比，通过光散射测量简单的胶体聚集率，可以得到胶体促进传输潜力的保守标准。快速胶体聚集动力学可能表明胶体转运有限，而缓慢聚集动力学可能暗示胶体促进转运的可能性。拟完成的工作将涉及以下研究任务：(1)选择具有代表性的地下固体材料及其表征，(2)研究溶液化学对胶体动员的影响，(3)研究移动胶体颗粒的沉积行为，(4)移动胶体颗粒的表征，(5)开发一种快速测量移动胶体沉积速率的方法，以及(6)模拟胶体传输和胶体促进传输的可能情景。申请的大部分资金都用于培养博士生。学生将利用最先进的实验(如多角度光散射)和分析工具。在耶鲁大学，所有本科生都必须在大四期间完成一项原创项目(论文)；其中一名本科生将把自己的大四论文作为项目的一部分。外展将涉及与LEAP(领导力、教育和田径合作)的合作，LEAP是一个在纽黑文运营的非营利性组织，旨在帮助来自高度贫困的城市社区的7至14岁的儿童发展学习技能和自尊。

0228911 Eliimelech Contaminant transport models substantially underestimate migration distances of strongly sorbing contaminants when neglecting colloid-facilitated transport. Since the mechanisms of colloid-facilitated transport are relatively poorly understood, it is quite challenging to predict the potential for colloid-facilitated transport in a contaminated subsurface environment. Hence, there is a critical need for a set of conservative criteria that will enable prediction of the potential for colloid-facilitated transport.The major objectives of the proposed research are: (i) to develop a set of criteria for quantifyingthe effect of various relevant chemicals (Na + , K + , Ca 2+ , Mg 2+ , pH, ligands, organic acids, humic and fulvic acids) on colloid mobilization (release), (ii) to develop a simple approach to determine colloid deposition rates in natural subsurface environments, and (iii) to establish a set of conservative criteria and screening tools for prediction of the potential for colloid-facilitated transport.The objectives of the work outlined above and the following related hypotheses provide thefoundation for this proposed research: (a) The worst-case scenario for colloid-facilitated transport can be obtained by considering irreversible adsorption of contaminants to the mobile colloidal particles. (b) In soils and several types of aquifer sediments, the mobilized colloidal particles have similar chemical properties as the stationary solid matrix. Hence, conservative criteria for the potential of colloid-facilitated transport can be derived from simple colloid aggregation rate measurements by light scattering drawing on the analogy between aggregation and deposition kinetics. Fast colloid aggregation kinetics may suggest limited colloid transport whereas slow aggregation kinetics may suggest the potential for colloid-facilitated transport. Completion of the proposed work will involve the following research tasks: (1) selection of representative subsurface solid materials and their characterization, (2) studying the effect of solution chemistry on colloid mobilization, (3) studying the deposition behavior of the mobile colloidal particles, (4) characterization of the mobile colloidal particles, (5) development of a rapid method for measuring deposition rate of mobile colloids, and (6) modeling colloid transport and possible scenarios of colloid-facilitated transport.Broader Impacts. The majority of requested funds are directed toward the training of a doctoralstudent. The student will be utilizing state-of-the-art experimental (e.g., multiangle light scattering) and analytical tools. At Yale, it is mandatory for all undergraduate students to carry out an original project (thesis) during their senior year; one undergraduate student will carry out her/his senior thesis as part of this project. Outreach will involve work with LEAP (Leadership, Education, and Athletics in Partnership), a non-profit organization operating in New Haven, that seeks to help children aged 7 to 14 from high-poverty urban neighborhoods develop academic skills and self-esteem.