TRANSPORT AND BIODEGRADATION OF VOLATILE ORGANIC COMPOUNDS IN THE VADOSE ZONE

渗气区挥发性有机化合物的迁移和生物降解

• 批准号: 6217602
• 负责人: DENNIS E ROLSTON
• 金额: $ 16.36万
• 依托单位: UNIVERSITY OF CALIFORNIA AT DAVIS
• 依托单位国家: 美国
• 财政年份: 1999
• 资助国家: 美国
• 起止时间: 1999-04-01 至 2000-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6217602
• 关键词: adsorption; bioassay; biotransformation; carbopolycyclic compound; diffusion; environmental contamination; environmental toxicology; environmental transport; ground water; halocarbon compound; hazardous substances; industrial waste; mathematical model; medaka; microorganism metabolism; model design /development; naphthalenes; organic chemicals; sedimentation; soil microbiology; soil pollution; toluene; trichloroethylene; vapor; water environment; water flow; water pollution

Exposure assessment, an essential component of environmental risk analysis, requires quantitative approaches for estimating the distribution and persistence of pollutants in environmental media. Volatile compounds (VOCs), such as TCE, DCE, toluene, p-nitrophenol, and naphthalene are on the EPA Priority Pollutants List and are commonly found at Superfund waste sites. Metam sodium is a fumigant used in large quantities in agriculture. From initial placement in the vadose zone, these volatile contaminants move into the groundwater and the air which are the two most important exposure routes for humans. While in the soil, they may be transformed by microbial metabolism into compounds which are either more or less hazardous than the original contaminants. Studies will be conducted to investigate the fundamental processes including diffusive and convective transport, sorption/desorption, and biodegradation that affect the fate and transport of both the liquid and vapor phases of VOCs in soil and geological sediments. Research will focus on the coupled and interdependent physical, chemical, and biological processes determining the transport and distribution of chemical mixtures. Laboratory-scale, column studies will be conducted using soil and geological sediments to determine the effect of multiple environmental processes on the potential for movement of VOCs to the groundwater and atmosphere. Persistent metabolites resulting from biodegradation will be identified with the assistance of the Immunochemical project and the Analytical Core. Estimates of vapor concentrations. likely for various waste site scenarios will be provided to investigators in the thermal remediation project. Samples of dust will be provided to the pulmonary exposure project in order to assess the potential health hazard of chemicals sorbed to dust. Chemicals and metabolites in leachate from soil will be tested for toxicity using the medaka and cell based bioassays. Relationships between VOC transport processes and field-scale geological attributes of the vadose zone such as depositional facies, grain size, organic carbon, sorting and mineralogy will be determined. Quantitative descriptions of these relationships will be incorporated into deterministic and stochastic models of transport in the vadose zone which include two and three-dimensional numerical modeling experiments of flow and transport of a single liquid phase (VOC dissolved in water) and a gaseous phase. A heat-water transport model for the vadose zone, which can be used under conditions of strong diurnal land surface heating, will be developed and tested with laboratory and field experiments. This model will be coupled with the models of chemical volatilization to obtain the flux into the atmosphere. The validation of the atmospheric component will be based on lidar measurements of the boundary layer over 100 m scale plots up to regional scales of a few kilometers. These models will be used to evaluate potential human exposure levels at the field scale.

暴露评估，环境风险的重要组成部分 分析，需要定量方法来估计 环境媒体中污染物的分布和持久性。 挥发性化合物（VOC），例如TCE，DCE，甲苯，P-硝基苯酚和 萘在EPA优先污染物清单上，通常是 在超级基金废物网站发现。元钠是一种熏蒸剂 农业数量。从vadose区的初始位置， 这些挥发性污染物移入地下水和空气 是人类的两个最重要的曝光路线。在土壤中， 它们可能会通过微生物代谢转化为化合物 与原始污染物相比，危险或多或少。 将进行研究以调查基本过程 包括扩散和对流的运输，吸附/解吸以及 影响液体和液体的命运和运输的生物降解 土壤和地质沉积物中VOC的蒸气阶段。研究将 专注于耦合和相互依存的物理，化学和 确定运输和分布的生物学过程 化学混合物。将进行实验室规模的专栏研究 使用土壤和地质沉积物来确定多重的影响 环境过程，关于将VOC运动推向的潜力 地下水和气氛。由 生物降解将在 免疫化学项目和分析核心。蒸气的估计 浓度。可能会提供各种垃圾场景 致热补救项目中的研究人员。灰尘样本将 提供给肺暴露项目，以评估 化学物质的潜在健康危害被吸附到灰尘。化学物质和 土壤中渗滤液中的代谢产物将通过使用 Medaka和基于细胞的生物测定。 VOC运输过程与现场尺度地质之间的关系 vadose区的属性，例如沉积相，晶粒尺寸， 将确定有机碳，排序和矿物学。定量 这些关系的描述将纳入 在vadose区的确定性和随机传输模型，该模型 包括两个流量的两个和三维数值建模实验 以及单个液相的运输（VOC溶于水）和A 气相。 vadose区的热水传输模型，该模型 可以在强烈的昼夜地面加热条件下使用 通过实验室和现场实验进行开发和测试。这个模型 将与化学挥发的模型相结合以获得 进入大气。大气成分的验证 将基于在100 m以上的边界层测量的激光雷达测量值 秤将几公里的区域尺度绘制。这些模型将 用于评估现场尺度上潜在的人类暴露水平。