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

暴露评估是环境风险分析的重要组成部分，需要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（VOCs）。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，普遍存在于几个超级基金站点。该项目通过开发考虑油田地质异质性的创新增产模块，对人类暴露进行评估。改进现有的预测模型需要更好地理解物理和化学异质性如何影响运输，矿物和有机物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，以及当化学混合物存在时这些变化是如何发生的。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知识，以预测复杂领域环境下的污染物运动和潜在的人类暴露，如加利福尼亚州的Aeroject NPL站点。该项目的第三个目标是探索有害废物修复技术。开展VOCs、高氯酸盐、混合化学品治理工作。一个特别的重点将是开发和应用新的风险评估程序，包括最先进的运输和命运建模方法，从而从概率上确定过去人类在Aeroject附近接触高氯酸盐的程度和持续时间。该项目将通过实验室批量和柱式实验，研究影响高氯酸盐、挥发性有机化合物以及这些化学物质在渗透带和地下水中的混合物的命运和运输的基本物理、化学和生物过程。它还将确定耦合过程对输运和命运的影响，并将研究空间变化过程和性质对场尺度行为的影响。对基本过程的理解将用于探索地下原位技术的潜力，以及在Aeroject现场修复高氯酸盐和TCE污染的泵和处理方法。还将利用随机运输和命运刺激模型，结合其他项目调查多种运输过程对野外潜在人类暴露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.