RII Track-4: NSF: Understanding Wildfire Risks to Drinking Water Source Waters: Pyrogenic Changes to Organic Matter and Disinfection By-product Formation

由于干旱、森林管理和气候变化，野火的规模、严重程度和频率都在增加。野火通过局部燃烧调动土壤有机质。这些部分燃烧的有机物在降水事件后被输送到下游的饮用水处理厂。消毒是饮用水处理和灭活病原体的关键组成部分。然而，用于消毒的化学品也会与所有水源中存在的各种有机化合物发生反应。其中一些反应会产生致癌的消毒副产物，这在美国环境保护署制定的饮用水成品中有监管限制。目前，关于部分燃烧的土壤有机质是否会导致更多或更少的消毒副产物的形成，存在相互矛盾的证据，这给野火易发地区未来的供水安全带来了不确定性。本研究的首要目标是了解火灾严重程度如何影响下游饮用水处理厂消毒副产物的形成。为了实现这一目标，PI和一名研究生将与目前担任教师的野火和有机物质专家合作，前往科罗拉多大学博尔德分校进行实验。这项研究基础设施改善轨道4 EPSCoR研究研究员（RII轨道4:NSF）项目将为内华达大学里诺分校的一名助理教授提供奖学金，并为一名研究生提供培训。这项工作将与科罗拉多大学博尔德分校的研究人员合作进行。PI和一名研究生将1)向该领域的专家学习新的有机物质表征方法，并将其应用于PI所在机构附近收集的Caldor Fire样品，2)将所学技能应用于在高度控制的实验室条件下生产的样品。这两个目标的成功将证明或否定总体假设，即中度野火严重程度导致最大限度地产生消毒副产物前体，这些前体在较高温度下（例如，高于350°C）被销毁。拟议研究的基本原理是，消毒副产物对人类健康有害，如果不了解特定的火灾条件如何影响热原有机物的动员和反应性，减少暴露（即满足监管标准）对饮用水公用事业具有挑战性。这些发现将推进野火对饮用水水源集水区中所含有机物影响的基础知识，这在物质运输方面得到了很好的理解，但在涉及消毒剂和小的、饮用水调节的热原分子运输的潜在氧化化学方面还没有得到很好的理解。研究结果还将告知科学家、监管机构和当地公用事业公司在野火事件期间和之后可能出现的监管违规行为。这项合作研究最终将提高国内机构的研究能力，并使内华达州受益，内华达州是美国最干旱的州，同时也受到水资源短缺和野火的影响。研究生也将受益于接触主题专家，提高他们的技术和沟通技巧，并提供网络机会。一到两名本科生将获得在偏远地区取样的经验。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Wildfires are growing in size, severity, and frequency due to drought, forest management, and climate change. Wildfire mobilizes soil organic matter through partial combustion. This partially combusted organic matter is then transported after precipitation events to downstream drinking water treatment plants. Disinfection is a key component of drinking water treatment and inactivates pathogens. However, the chemicals used for disinfection also react with the diverse organic compounds present in all water sources. Some of these reactions result in the production of carcinogenic disinfection by-products, which have regulatory limits in finished drinking water set by the U.S. Environmental Protection Agency. There is currently conflicting evidence of whether partially combusted soil organic matter causes more or fewer disinfection by-products to form than would otherwise, leaving uncertainty about the future security of water supplies in wildfire-prone regions. The overarching goal of this research is to understand how fire severity affects the formation of disinfection by-products at downstream drinking water treatment plants. To achieve this goal, the PI and a graduate student will travel to and conduct experiments at the University of Colorado-Boulder in collaboration with wildfire and organic matter experts currently serving as faculty.This Research Infrastructure Improvement Track-4 EPSCoR Research Fellows (RII Track-4:NSF) project will provide a fellowship to an Assistant Professor and training for a graduate student at the University of Nevada Reno. This work would be conducted in collaboration with researchers at the University of Colorado-Boulder. The PI and one graduate student will 1) learn new organic matter characterization methods from experts in the field and apply them to Caldor Fire samples collected near the PI’s home institution, and 2) apply the learned skills to samples produced under highly controlled laboratory conditions. Success of the two aims will prove or disprove the overall hypothesis, that moderate wildfire severity results in the greatest production of disinfection by-product precursors, which are destroyed at higher temperatures (e.g., above 350°C). The rationale for the proposed research is that disinfection by-products are hazardous to human health, and mitigating exposure (i.e., meeting regulatory standards) is challenging for drinking water utilities without an understanding of how specific fire conditions affect pyrogenic organic matter mobilization and reactivity. The findings will advance the fundamental knowledge of wildfire impacts on organic matter contained in drinking water source catchments, which is somewhat well understood in terms of material transport, but not well understood in terms of potential oxidation chemistry involving disinfectants and transport of small, drinking-water-regulated, pyrogenic molecules. The findings will also inform scientists, regulators, and local utilities of the potential for regulatory exceedances during and after wildfire events. The collaborative research will ultimately improve the research capacity of the home institution and benefit the State of Nevada, which is the driest state in the nation and subject to both water scarcity and wildfire. A graduate student will also benefit through exposure to subject matter experts, improving their technical and communication skills, and providing networking opportunities. One to two undergraduate students will gain experience in sampling remote areas.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.