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: 1033848
• 负责人: Chongzheng Na
• 金额: $ 22.29万
• 依托单位: University of Notre Dame
• 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=1033848&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.

摘要PI：Chongzheng Na提案编号：CBET-1033848机构：圣母大学PI：Yusong Li提案编号：CBET-1033502机构：内布拉斯加大学林肯分校标题：合作研究：蒸汽入侵途径中氯化烃的非生物衰减：被忽视的土壤矿物纳米级化学 表面由于处置不当和意外泄漏，氯化碳氢化合物是土壤和沉积物中普遍存在的污染物。 人类接触这些污染物的一个重要途径是它们的蒸气通过不饱和包气区侵入占用的建筑物。 了解蒸气入侵 (VI) 途径的物理、化学和生物调节剂对于评估与美国数以万计的污染地点的氯化烃污染物 (CHC) 相关的健康风险至关重要。拟议研究的总体目标是研究氯化烃蒸气入侵途径的一个重要但被忽视的化学调节剂，即纳米级、 蒸气化合物与土壤矿物表面之间的非均相反应。 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 射线光电子能谱 (XPS)，将用于识别反应产物、量化反应动力学和阐明反应机制。 多组分、多相模拟器——密歇根土壤环境修复（MISER）将被修改，以将新的纳米级化学纳入蒸汽入侵的评估中。 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）第一个目标是确定使用代表性氯化烃化合物和土壤矿物（包括老化矿物）的纳米级表面反应的普遍性。 (b)第二个目标是研究湿度和温度等环境参数对反应机理、动力学和产物稳定性的影响。 (c) 第三个目标是从数学角度评估蒸汽-矿物反应作为蒸汽入侵途径化学调节剂的重要性。拟议项目有五项任务。 首先，将筛选 11 种代表性 CHC 化合物、三类土壤矿物和重构方解石，以确定它们在蒸汽侵入途径中相互反应的潜力。 CHC 化合物的选择基于其在不同污染地点的普遍性以及结构多样性。 土壤矿物有五种碳酸盐、石英和两种长石。 在高湿条件下重建的方解石用于评估老化矿物的反应性。 其次，CHC-矿物反应的动力学将通过监测 AFM 流体池中的气相和表面产物来量化。 流体池用作连续搅拌釜反应器。 反应的演变将通过 GC/MS（针对 CHC 蒸气和气相产物）和 AFM（针对表面纳米结构生长）进行量化。第三，使用 AFM 流体池确定不同湿度下反应产物和动力学的变化。 潮湿空气中的水单分子层的凝结可能会对 CHC-矿物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以及阻塞反应性表面位点。 湿度变化是季节之间发生的典型环境条件。 第四，将使用间歇式反应器在高温下评估CHC诱导的纳米结构中挥发性化合物的释放。 温度变化是另一种季节变化。 从寒冷季节向温暖季节过渡期间发生的温度升高可能会破坏 CHC 诱导的纳米结构的稳定性并意外释放有毒的挥发性化合物。 最后，将开发一个数值模型来模拟非生物衰减的蒸汽入侵路径。评估将使用从印第安纳州环境管理部获得的现场特定信息进行。 拟议研究的主要智力价值是为氯化烃蒸气入侵的更复杂和准确的建模提供知识库。研究团队还计划通过以下方式在拟议项目中产生更广泛的影响：（1）培训弱势群体的学生进行环境纳米地球化学研究；（2）将从研究前沿获得的新知识融入到环境科学与工程的本科课程中；（3）通过外展活动为当地高中生提供研究机会。