Volatilization dynamics in wetland systems

湿地系统的挥发动力学

• 批准号: 1133281
• 负责人: Peter Jaffe
• 金额: $ 31.04万
• 依托单位: Princeton University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-09-01 至 2016-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1133281&HistoricalAwards=false
• 关键词: Volatilization; dynamics; wetland; systems

1133281 PI JaffeWetlands, both natural and designed, can be a cost-effective tool for the remediation of groundwater contaminated with volatile organic compounds (VOCs) that discharge into these wetlands. The widespread use of wetlands for remediation has been hindered by uncertainties surrounding the rates and time scales of remediation mechanisms. Volatilization is perhaps the least understood of these removal mechanisms. Initial laboratory and modeling results suggest that volatilization represents a major removal pathway, with the strength and mechanism of volatilization highly dependent on the physiochemical properties of the target compound. Our understanding of the physiochemical drivers of volatilization pathways and rates remain incomplete, however, precluding any predictive modeling techniques to accurately estimate VOC fluxes from wetlands. Questions of fundamental importance to the transport of volatile compounds in saturated shallow, vegetated soils must be addressed in order to close this knowledge gap: What is the balance between gas-phase and transpiration-driven transport of VOCs through wetland plants? To what extent will plant-mediated volatilization vary as a function of vegetation type? How can plant uptake of volatile organic compounds be described appropriately with predictive models, and how can these models be validated in the field? To what extent do volatile compounds partition into subsurface bubbles, how does bubble ebullition contribute to atmospheric fluxes of VOCs, and what is the interplay between bubble dynamics and plant enhanced gas transfer? The PI will perform a comprehensive study into the fundamental dynamics of volatilization through emergent wetland plants. Measurements that will span multiple scales from single stems in controlled experiments to a field pilot study will be carried out. The experimental program will include: (1) systematic laboratory hydroponic studies using multiple volatile tracers and single stems to probe the fundamental relationships between the physiochemical properties of a compound and the rates and mechanisms for its volatilization; (2) greenhouse mesocosm studies to validate predictive models for phytovolatilization in saturated soil conditions and examine interspecies variability in contaminant removal rates; and (3) a pilot field test in a freshwater wetland to quantify spatial and temporal heterogeneities in rates of VOC removal from wetland systems. An important objective of this research is the development of a single-well ?push-pull? technique that will be developed in greenhouse mesocosms and implemented in the field, providing a novel and valuable tool for the assessment of volatilization rates in diverse wetland ecosystems where other mechanisms to determine gas exchange between the rhizosphere of wetland systems and the atmosphere are not feasible. In terms of the broader impacts, the proposed research will address fundamental questions concerning transport of chemicals in saturated soils and in vegetation that have implications across the earth sciences. Proposed technological innovations in measuring groundwater-atmosphere gas exchange will have multidisciplinary applications including the design and management of wetlands and assessment of attenuation in natural wetlands. This work will fund one Ph.D. student and contribute to the education of other graduate students in the PI?s laboratory and laboratories of outside collaborators, including Rutgers University and the Meadowlands Research Institute. Undergraduate students from different schools will be involved via an ongoing REU program. This REU program has been successful in recruiting minority and female students. Undergraduates will be involved via Senior Thesis Research. Outreach to the community is planned via participation in QUEST, a science institute for upper elementary school teachers taught by Princeton University faculty and staff, as well as by participation with the educational programs of the Stony Brook-Millstone Watershed Association, which also engages in active dialogue with municipal officials, citizens, and businesses concerning decisions that affect the local environment. Results of this research will be incorporated in undergraduate (Environmental Engineering Laboratory) and graduate (Water Quality Modeling) courses, and will be disseminated to the scientific community via presentations at National Conferences and peer-reviewed journal publications.

1133281 Pi Jaffewetlands是天然和设计的，可以是一种具有成本效益的工具，用于修复被排放到这些湿地的挥发性有机化合物（VOC）污染的地下水。 湿地进行修复的广泛使用受到了补救机制的速率和时间尺度的不确定性的阻碍。 在这些去除机制中，挥发性也许是最了解的。初始实验室和建模结果表明，挥发是一个主要的去除途径，挥发的强度和机制高度取决于靶化合物的生理化学特性。但是，我们对挥发途径和速率的生理化学驱动因素的理解仍然不完整，但是，排除了任何预测建模技术，无法准确估算湿地的VOC通量。对于饱和浅层中挥发性化合物的运输至关重要的问题，必须解决植被土壤以缩小这一知识差距：气相和通过湿地植物的蒸发驱动驱动的传输之间的平衡是什么？植物介导的挥发性在多大程度上随植被类型的作用而变化？如何通过预测模型适当地描述挥发性有机化合物的植物摄取，如何在现场验证这些模型？挥发性化合物在多大程度上分配到地下气泡中，气泡戒断如何促进VOC的大气通量，而气泡动力学与植物增强的气体转移之间的相互作用是什么？ PI将通过新兴湿地植物对挥发性的基本动态进行全面研究。 将在受控实验中跨越单个茎的多个尺度到现场试验研究的测量值。 实验计划将包括：（1）使用多个挥发性示踪剂和单个茎进行系统的实验室水培研究，以探测化合物的生理化学特性与其挥发的速率和机制之间的基本关系； （2）在饱和的土壤条件下验证植物元素化的预测模型的温室中库研究，并检查污染物去除率的种间变异性； （3）在淡水湿地中进行的试点现场测试，以量化湿地系统中VOC的空间异质性和时间异质性。这项研究的一个重要目标是开发单孔吗？将在温室中心开发并在该领域实施的技术，为评估各种湿地生态系统的挥发率提供了一种新颖而有价值的工具，在这些工具中，确定湿地系统和大气层根际之间气体交换的其他机制是不可行的。 就更广泛的影响而言，拟议的研究将解决有关饱和土壤中化学物质和在整个地球科学中具有影响的植被中运输的基本问题。拟议的技术创新在测量地下水大气交换中将具有多学科应用，包括湿地的设计和管理以及自然湿地的衰减评估。这项工作将资助一位博士学位。学生并为PI的实验室和外部合作者的实验室（包括罗格斯大学和Meadowlands Research Institute）的其他研究生的教育做出了贡献。来自不同学校的本科生将通过正在进行的REU计划参与。该REU计划成功地招募了少数群体和女学生。本科生将通过高级论文研究参与。计划通过参与普林斯顿大学教职员工和教职员工教授的科学院教师Quest，以及参与Stony Brook-Millstone水域协会的教育计划，并与市政官员，公民，公民，公民和企业的企业进行积极的对话，从而参与探索社区。这项研究的结果将纳入本科（环境工程实验室）和研究生（水质建模）课程，并通过在国家会议和同行评审期刊出版物上的演讲将科学界传播到科学界。