Competitive Sorption of Volatile Organics in Model and Natural Solids

9803563 Werth本研究的目的是了解有机化学混合物在土壤和地下水沉积物中的竞争吸附机制，并预测其对生物有效性的影响。 这种理解可以导致模型和速率参数的发展，以更好地预测土壤和地下水沉积物中的有机混合物的原位生物修复的结果。 混合物中化学品之间的竞争可以显著改变平衡分布，减缓单个化合物测量的解吸速率;因此，基于单个化合物研究的模型不能准确反映实践中的观察结果。 本研究的具体目标是：1）确定竞争吸附平衡分布值的影响，作为土壤成分和结构的函数，2）确定竞争吸附的影响，快速和缓慢的扩散速率作为土壤成分和结构的函数和3）开发一个基于机械的数值模型，预测土壤和沉积物中的混合物的生物利用度。 研究结果预计将使决策者能够衡量竞争性吸附是否限制了生物利用度，并评估地下山梨酸盐混合物的持久性和风险。 它还将提供一种分析工具，使在相关领域工作的研究人员能够测量混合物的长期解吸等温线和快速解吸动力学。 几种新的分子筛（UTD-1和MCM-41）将被用来比较竞争吸附在微孔和小的中孔的天然固体的竞争吸附的影响。 ***

9803563 Werth The goal of this research is to understand the mechanisms of competitive sorption of organic chemical mixtures in soils and groundwater sediments and to predict its effect on bioavailablility. Such understanding could lead to development of models and rate parameters to better predict results of in situ bioremediation of organic mixtures in soils and groundwater sediments. Competition between chemicals in a mixture can dramatically alter equilibrium distributions and slow desorption rates from those measured for individual compounds; therefore, models based on studies of individual compounds do not accurately reflect observations in practice. Specific objectives of this research are to: 1) determine the effects of competitive sorption on equilibrium distribution values as a function of soil composition and structure, 2) determine the effects of competitive sorption on fast and slow diffusion rates as a function of soil composition and structure and 3) develop a mechanistically based numerical model that predicts the bioavailability of mixtures in soils and sediments. Results of the research are expected to allow decision makers to gauge if competitive sorption limits bioavailablilty and to evaluate the persistence and risk of sorbate mixtures in the subsurface. It will also present an analytical tool to allow researchers working in related areas to measure long term desorption isotherms and fast desorption kinetics for mixtures. Several new molecular sieves (UTD-1 and MCM-41) will be used to compare the effects of competitive sorption in micropores and small mesopores to the effects of competitive sorption in natural solids. ***