TRANSPORT, TRANSFORMATION & REMEDIATION OF VOCS IN THE VADOSE ZONE & GROUND WATER

暴露评估是环境风险分析的一个重要组成部分，需要采用定量方法来估计超级基金场址污染物的分布和持久性。最常见的污染物是挥发性有机化合物（VOC）。除了挥发性有机化合物，高氯酸盐最近被发现是一种重要的地下水污染物，在几个超级基金的网站普遍存在。该项目通过开发创新的刺激模块，考虑到现场的地质异质性，对人类暴露进行评估。改进现有的预测模型需要更好地了解物理和化学异质性如何影响运输，矿物和有机物的组成如何影响反应性，氧化状态的变化如何控制非生物和生物转化的耦合，以及当存在化学混合物时，这些变化如何发生。该项目的第一个目标是阐明决定土壤和地质沉积物中高氯酸盐和挥发性有机化合物的运输，转化和修复的物理，化学和生物过程。第二个目标是整合这一过程级的知识，以预测污染物的移动和潜在的人类暴露在复杂的领域设置，如在加利福尼亚州的Aeroject NPL网站。 该项目的第三个目标是探索危险废物补救技术。我们将研究挥发性有机化合物、高氯酸盐和化学混合物。一个特别的重点将是开发和应用新的风险评估程序，其中包括国家的最先进的运输和归宿建模方法，从而确定概率的程度和持续时间的过去人类暴露于高氯酸盐附近的Aeroject。该项目将调查的基本物理，化学和生物过程影响的命运和运输的高氯酸盐，挥发性有机化合物，以及这些化学品的混合物在包气带和地下水使用实验室批次和柱实验。它还将确定耦合过程对迁移和归宿的影响，并将调查空间变化过程和特性对实地规模行为的影响。这种对基本过程的理解将用于探索原位地下技术的潜力，以及用于修复Aeroject现场高氯酸盐和TCE污染的泵和处理。还将结合其他项目，利用随机迁移和归宿刺激模型，研究多种迁移过程对实地范围内潜在人类接触水平的影响以及对人类健康的影响。

Exposure assessment, an essential component of environmental risk analysis, requires quantitative approaches for estimating the distribution and persistence of pollutants at Superfund sites. The most common pollutants are volatile organic compounds (VOCs). In addition to VOCs, perchlorate has recently been discovered as an important groundwater contaminant prevalent at several Superfund sites. This project provides an evaluation of human exposure through the development of innovative stimulation module that considers the geological heterogeneity of field sites. Improving upon existing predictive models requires improved understanding of how physical and chemical heterogeneity impact transport, how mineral and organic matter composition affect reactivity, how variations in oxidation status control both abiotic and biological transformations are coupled, and how each of these changes when chemical mixtures are present. The first goal of this project is to elucidate the physical, chemical, and biological processes that determine the transport, transformation and remediation of perchlorate and VOCs in soil and geologic sediments. The second goal is to integrate this process-level knowledge to predict contaminant movement and potential human exposure under complex field setting such as the Aeroject NPL site in CA. A third goal of the project is to explore techniques for remediation of hazardous waste. We will work on VOCs, perchlorate, and chemical mixtures. A particular focus will be on developing and applying new risk assessment procedures that include state-of-the-art transport and fate modeling approaches, thereby determining probabilistically the extent and duration of past human exposure to perchlorate near Aeroject. This project will investigate the basic physical, chemical, and biological processes affect the fate and transport of perchlorate, VOCs, and mixtures of these chemicals in the vadose zone and groundwater using laboratory batch and column experiments. It will also determine the effect of coupled processes on transport and fate and will investigate the effects of spatially varying processes and properties on field-scale behavior. This understanding of the fundamental processes will be used to explore the potential of in situ subsurface techniques as well as pump-and-treat for remediating perchlorate and TCE contamination at the Aeroject site. Using stochastic transport and fate stimulation models, the effects of multiple transport processes on potential human exposure levels at the field scale as well as human health effects will also be investigated with conjunction with other projects.