Collaborative Research: Evaluating the Unique Composition, Environmental Stability, and Export of Dissolved Pyrogenic Organic Matter in Wildfire-Impacted Watersheds

历史上，森林流域提供了原始水源，满足了全国约50%的饮用水需求。然而，森林流域野火的频率和严重程度的增加，由于沉积物、营养物质和溶解有机物的出口，对下游水质产生了不利影响。野火产生的热量引发并催化了土壤有机质中的一系列化学反应，导致热原有机质（PyOM）的形成。在受野火影响的流域，PyOM有可能影响地表水质量、水生生物地球化学过程和下游水处理厂的运行。该项目的总体目标是评估受野火影响的流域中PyOM的化学成分、环境命运和反应性以及释放时间。为了实现这一目标，首席研究员（pi）提议开展一个综合实验室和实地研究计划，1)利用光谱学和高分辨率质谱法表征PyOM的化学成分，2)评估PyOM在光降解和生物降解过程中的环境命运，3)利用原位光学传感器监测受野火影响的流域PyOM出口的时间。该项目的成功完成将通过产生新的基础知识和数据来促进对PyOM在森林流域的环境命运和运输及其对下游水质的潜在影响的评估和评价，从而造福社会。通过拓展和教育活动，包括指导德克萨斯州农工大学的一名研究生和华盛顿州立大学的一名研究生，将为社会带来额外的好处。野火可以极大地改变从燃烧的流域出口到下游地表水系统的溶解有机质（DOM）的数量和质量，因为形成了热原有机质（PyOM）。在野火影响的流域中，PyOM的存在有可能影响水生生物地球化学过程和饮用水处理过程中有机物的去除。该项目的目标是评估受野火影响的流域中溶解的PyOM的化学成分、环境稳定性和出口时间。本研究的具体目的是：(1)评价背景DOM和PyOM的化学成分差异；(2)评估PyOM在生物降解、光降解和光生物降解过程中的命运；(3)利用原位光学传感器评估受野火影响的流域中PyOM释放的时间。从实验室加热土壤的水浸实验中产生的PyOM将通过元素组成，光学测量和超高分辨率质谱法进行表征。一项为期数年的实地活动将利用原位光学传感器评估受野火影响的流域PyOM释放的时间动态。这项研究的成功完成有可能产生变革性的影响，通过从实验室和实地研究中产生新的见解和数据，促进对森林流域PyOM的命运和运输的基本理解，因为气候变化加剧了野火的频率和严重程度。为了实现该项目的教育和培训目标，pi将利用各自机构的现有项目，将本研究的结果整合到K-12教师培训计划(Spark！德克萨斯农工大学（Texas a&m University）的PK-12 Outreach项目，以及华盛顿州立大学（Washington State University）的实地培训项目（现场科学），旨在吸引和吸引来自代表性不足群体的学生。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。

Forested watersheds have historically provided pristine sources of water to address approximately 50% of the Nation’s need for drinking water. However, the increased frequency and severity of wildfires in forested watersheds are adversely impacting downstream water quality due to the exports of sediments, nutrients, and dissolved organic matter. Heat from wildfires initiates and catalyzes a series of chemical reactions in soil organic matter that result in the formation of pyrogenic organic matter (PyOM). In a wildfire impacted watershed, PyOM has the potential to impact surface water quality, aquatic biogeochemical processes, and the operation of downstream water treatment plants. The overarching goal of this project is to evaluate the chemical composition, environmental fate and reactivity, and timing of PyOM release from a wildfire impacted watershed. To advance this goal, the Principal Investigators (PIs) propose to carry out an integrated laboratory and field research program to 1) characterize the chemical composition of PyOM using optical spectroscopy and ultra-high resolution mass spectrometry, 2) evaluate the environmental fate of PyOM during photodegradation and biodegradation, and 3) monitor the timing of PyOM export from a wildfire-impacted watershed with in-situ optical sensors. The successful completion of this project will benefit society through the generation of new fundamental knowledge and data to advance the assessment and evaluation of the environmental fate and transport of PyOM in forested watersheds and its potential impact on downstream water quality. Additional benefits to society will be achieved through outreach and education activities including the mentoring of one graduate student at Texas A&M University and one graduate student at Washington State University.Wildfires can drastically change the quantity and quality of dissolved organic matter (DOM) that is exported from burned watersheds to downstream surface water systems due to the formation of pyrogenic organic matter (PyOM). The presence of PyOM in wildfire-impacted watersheds has the potential to impact aquatic biogeochemical processes and the removal of organic matter during drinking water treatment. The goal of this project is to evaluate the chemical composition, environmental stability, and timing of dissolved PyOM export from wildfire-impacted watersheds. The specific objectives of the research are to: (1) Evaluate the differences in chemical compositions between background DOM and PyOM; (2) Assess the fate of PyOM during biodegradation, photodegradation, and photobiodegradation; and (3) Evaluate the timing of PyOM release from a wildfire-impacted watershed using in situ optical sensors. PyOM generated from water leaching experiments of laboratory-heated soils will be characterized by elemental composition, optical measurements, and ultra-high resolution mass spectrometry. A multi-year field campaign will evaluate the temporal dynamics of PyOM release from a wildfire-impacted watershed using in situ optical sensors. The successful completion of this research has the potential for transformative impact through the generation of new insight and data from both lab and field studies to advance the fundamental understanding of the fate and transport of PyOM in forested watersheds as climate change exacerbates the frequency and severity of wildfires. To implement the educational and training goals of this project, the PIs will leverage existing programs at their respective institutions to integrate the findings from this research into a K-12 teacher training program (Spark! PK-12 Outreach) at Texas A&M University and a field training program (Science at the Site) at Washington State University designed to attract and engage students from underrepresented groups.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.