Collaborative Research: Abiotic Attenuation of Chlorinated Hydrocarbons in the Vapor Intrusion Pathway: Overlooked Nanoscale Chemistry on Soil Mineral Surfaces

合作研究：蒸汽入侵途径中氯化烃的非生物衰减：土壤矿物表面被忽视的纳米化学

• 批准号: 1033502
• 负责人: Yusong Li
• 金额: $ 11.4万
• 依托单位: University of Nebraska-Lincoln
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-10-01 至 2014-09-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1033502&HistoricalAwards=false
• 关键词: Collaborative; Research; Abiotic; Attenuation; Chlorinated

AbstractPI: Chongzheng NaProposal Number: CBET-1033848Institution: University of Notre DamePI: Yusong LiProposal Number: CBET-1033502Institution: University of Nebraska-LincolnTitle: Collaborative Research: Abiotic Attenuation of Chlorinated Hydrocarbons in the Vapor Intrusion Pathway: Overlooked Nanoscale Chemistry on Soil Mineral SurfacesChlorinated hydrocarbons are prevalent contaminants in soils and sediments due to improper disposal and accidental spillage. An important pathway for human exposure of these contaminants is the intrusion of their vapors into occupied buildings through the unsaturated vadose zone. Understanding the physical, chemical, and biological regulators of the vapor intrusion (VI) pathway is crucial to assess the health risks associated with chlorinated hydrocarbon contaminants (CHCs) at tens of thousands of pollution sites across the U.S. The overarching goal of the proposed research is to investigate an important, yet overlooked, chemical regulator of the chlorinated hydrocarbon vapor intrusion pathway, namely the nanoscale, heterogeneous reactions between vapor compounds and soil mineral surfaces. The proposed research takes an integrated approach combining experimental and modeling efforts. State-of-the-art analytical and surface-sensitive techniques, including gas chromatography mass spectrometry (GC/MS), atomic force microscopy (AFM), and X-ray photoelectron spectroscopy (XPS), will be used to identify reaction products, quantify reaction kinetics, and elucidate reaction mechanisms. A multicomponent, multi-phase simulator, Michigan Soil Environment Remediation (MISER), will be modified to incorporate the new nanoscale chemistry into the assessment of vapor intrusion. In support of the goal of this project, three research objectives will be used to guide the formulation of hypotheses and the design and selection of experiments: (a) The first objective is to determine the prevalence of nanoscale surface reactions using representative chlorinated hydrocarbon compounds and soil minerals (including aged minerals). (b) The second objective is to investigate the effects of environmental parameters such as humidity and temperature on the reaction mechanisms, kinetics, and product stability. (c) The third objective is to mathematically evaluate the significance of vapor-mineral reactions as a chemical regulator of the vapor intrusion pathway.The proposed project has five tasks. First, eleven representative CHC compounds, three classes of soil minerals, and reconstructed calcite will be screened for their potentials to react with one another in the vapor intrusion pathway. The CHC compounds are selected based on their prevalence at various contamination sites as well as structural diversity. The soil minerals are five carbonates, quartz, and two feldspars. Calcite reconstructed under high humid conditions is used to evaluate the reactivity of aged minerals. Second, the kinetics of CHC-mineral reactions will be quantified by monitoring both gas-phase and surface products in an AFM fluid cell. The fluid cell serves as a continuously stirred tank reactor. The evolution of the reactions will be quantified by GC/MS (for CHC vapor and gas-phase products) and AFM (for surface nanostructure growth). Third, the changes of reaction products and kinetics under varying humidity will be determined using the AFM fluid cell. The condensation of water monolayers from humid air can have complicated consequences for CHC-mineral reactions, including generating reactive hydroxyl groups, creating reactive mobile ions, and blocking reactive surface sites. The variation of humidity is a typical environmental condition that happens between seasons. Forth, the release of volatile compounds from CHC-induced nanostructures will be evaluated using batch reactors at elevated temperatures. Temperature change is another seasonal variation. The increase of temperature that occurs during the transition from a cold season to a warm one may destabilize the CHC-induced nanostructures and release toxic volatile compounds unexpectedly. Last, a numerical model will be developed to simulate the vapor intrusion pathway with the abiotic attenuation. The evaluation will be performed usingsite specific information acquired from the Indiana Department of Environmental Management. The main intellectual merit of the proposed research is to provide a knowledge base for more sophisticated and accurate modeling of chlorinated hydrocarbon vapor intrusion. The research team also plans to make broader impacts in the proposed project by (1) training students from underrepresented groups on environmental nanogeochemistry research, (2) incorporating new knowledge obtained from the research frontier to the undergraduate-level courses for environmental science and engineering, and (3) providing local high-school students with research opportunities through outreach activities.

AbstractPI: Chongzheng NaProposal Number: CBET-1033848Institution: University of Notre DamePI: Yusong LiProposal Number: CBET-1033502Institution: University of Nebraska-LincolnTitle: Collaborative Research: Abiotic Attenuation of Chlorinated Hydrocarbons in the Vapor Intrusion Pathway: Overlooked Nanoscale Chemistry on Soil Mineral表面氯的碳氢化合物是由于处置不当和意外溢出而导致土壤和沉积物中普遍的污染物。 这些污染物的人类暴露的重要途径是通过不饱和雾化区域将其蒸气侵入被占用的建筑物中。 了解蒸气侵入途径（VI）途径的物理，化学和生物学调节剂对于评估与美国成千上万的污染地点相关的健康风险至关重要蒸气化合物和土壤矿物质表面之间的异质反应。 拟议的研究采用了结合实验和建模工作的综合方法。 最先进的分析和表面敏感技术，包括气相色谱质谱法（GC/MS），原子力显微镜（AFM）和X射线光电子光谱（XPS），可用于鉴定反应产物，定量反应反应动力学和阐明反应动力学和阐明反应动力学。 将修改多相的多相模拟器，密歇根州土壤环境修复（MISER），以将新的纳米级化学纳入蒸气侵入评估中。 为了支持该项目的目标，将使用三个研究目标来指导假设的制定以及实验的设计和选择：（a）第一个目标是使用代表性的氯化碳氢化合物化合物和土壤矿物质（包括老年矿物）来确定纳米级表面反应的患病率。 （b）第二个目标是研究环境参数（例如湿度和温度）对反应机理，动力学和产品稳定性的影响。 （c）第三个目标是数学上评估蒸气时代反应作为蒸气侵入途径的化学调节剂的重要性。拟议的项目具有五个任务。 首先，将筛选11种代表性的CHC化合物，三类土壤矿物质和重建方解石，以筛选其在蒸气侵入途径中相互反应的潜力。 CHC化合物是根据其在各种污染位点以及结构多样性的流行率选择的。 土壤矿物质是五个碳酸盐，石英和两个长石。 在高潮湿条件下重建的方解石用于评估老化矿物质的反应性。 其次，将通过监测AFM流体电池中的气相和表面产物来量化CHC矿物质反应的动力学。 流体电池充当连续搅拌的储罐反应器。 反应的演变将通过GC/MS（对于CHC蒸气和气相产物）和AFM（用于表面纳米结构生长）来量化。第三，将使用AFM流体细胞确定反应产物和动力学的变化。 潮湿空气中水单层的凝结可能会对CHC矿物质反应产生复杂的后果，包括产生反应性羟基，产生反应性移动离子和阻断反应性表面位点。 湿度的变化是季节之间发生的典型环境条件。 从CHC诱导的纳米结构中释放挥发性化合物将使用高温下的批次反应器进行评估。 温度变化是另一种季节性变化。 从寒冷季节过渡到温暖的温度的升高可能会使CHC诱导的纳米结构稳定，并意外释放有毒挥发性化合物。 最后，将开发一个数值模型，以模拟使用非生物衰减的蒸气侵入途径。评估将从印第安纳州环境管理部获得的USISESITE特定信息进行。 拟议的研究的主要知识优点是为氯化碳氢化合物蒸气侵入的更复杂和准确的建模提供知识库。研究小组还计划通过（1）培训来自代表性不足的纳米地质地球化学研究小组的学生对拟议项目产生更大的影响，（2）纳入了从研究边界获得的新知识，从研究边界到本科级别的环境科学和工程课程，以及（3）通过研究机会提供当地高中生的研究机会。