Identifying the role of dissolved organic matter composition in complete and partial photooxidation in diverse lakes

确定溶解有机物成分在不同湖泊完全和部分光氧化中的作用

• 批准号: 2104716
• 负责人: Christina Remucal
• 金额: $ 32.64万
• 依托单位: University of Wisconsin-Madison
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-08-01 至 2024-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2104716&HistoricalAwards=false
• 关键词: Identifying; role; dissolved; organic; matter

This award is funded in whole or in part under the American Rescue Plan Act of 2021 (Public Law 117-2).Inland waters, such as lakes and rivers, cover a small percentage of the Earth's surface yet play a central role in the carbon cycle. Dissolved organic matter (DOM), which is made up of chemicals from plants and microorganisms, is a critical component of the carbon cycle within lakes. For example, natural processing of DOM by microorganisms or by reaction with sunlight can produce carbon dioxide, a key greenhouse gas. As a result, lakes are hotspots of carbon cycling and emission in the landscape. However, the reaction of DOM with sunlight is frequently ignored in carbon cycling models and little is known about how the type of DOM, which varies in different lakes, influences its reactivity. This project will study DOM from eleven lakes in the North Temperate Lakes-Long Term Ecological Research (NTL-LTER) program, along with two well-studied DOM isolates. The DOM will be evaluated for its photochemical reactivity using multiple approaches. Importantly, the DOM will be thoroughly analyzed using state-of-the-art techniques, including high-resolution mass spectrometry, before and after reaction with simulated sunlight to identify how sunlight reacts with this complex material. This project will yield important insights into the properties that determine the reactivity of DOM in inland waters by isolating the impact of photochemical reactions, which could ultimately be used to model carbon dioxide production from lakes. A better understanding of the carbon cycle, particularly in sensitive hydrologic environments, is critical for predicting and ultimately adapting to a changing climate.The composition of dissolved organic matter (DOM) is critical to its reactivity. One example of DOM reactivity is its susceptibility to complete and partial photooxidation in sunlit waters, such as lakes. This process is increasingly recognized as an important component of the global carbon cycle. However, a mechanistic understanding of how DOM composition influences its photochemical reactivity is lacking. This research will fully characterize waters collected from the eleven core lakes of the North Temperate Lakes-Long Term Ecological Research (NTL-LTER) program, along with two well-studied DOM isolates. These lakes include dystrophic, oligotrophic, mesotrophic, and eutrophic systems that range widely in DOM composition. Photochemical reactivity will be assessed by quantifying photomineralization rates, measuring quantum yields and steady-state concentrations of photochemically produced reactive intermediates (triplet DOM, singlet oxygen, hydroxyl radical, and carbonate radical anion), and using quencher experiments to distinguish between direct and indirect photolysis of DOM. The DOM samples will be characterized before and after photolysis using UV-visible spectroscopy, fluorescence spectroscopy, antioxidant measurements, and Fourier transform-ion cyclotron resonance mass spectrometry. Multivariate statistics, including multiple linear regressions, hierarchical cluster analysis, and principal component analysis, will be used to identify how DOM is altered during photooxidation, derive new measurements of partial photooxidation, and identify the roles of direct and indirect photolysis in complete and partial photooxidation. The work will yield important insights into the fundamental properties that govern the reactivity of DOM in inland waters by isolating the impact of photochemical reactions. This knowledge can be used to develop relationships between DOM composition and reactivity that could ultimately be used to model the potential for carbon dioxide production from lakes.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.

该奖项是根据2021年《美国救援计划法》的全部或部分资助（公共法第117-2）。由植物和微生物的化学物质组成的溶解有机物（DOM）是湖泊内碳循环的关键组成部分。例如，通过微生物或与阳光反应对DOM进行自然加工可以产生二氧化碳，这是一种关键的温室气体。结果，湖泊是景观中碳循环和排放的热点。但是，在碳循环模型中经常忽略DOM与阳光的反应，并且关于不同湖泊在不同湖泊中如何影响其反应性的DOM的类型几乎没有知识。该项目将研究北部温带湖泊长期生态研究（NTL-lter）计划中的11个湖泊的DOM，以及两个经过深入研究的DOM分离株。将使用多种方法评估DOM的光化学反应性。重要的是，将使用最先进的技术（包括高分辨率质谱法）在与模拟阳光反应之前和之后对DOM进行彻底分析，以确定阳光与这种复杂材料的反应。该项目将通过隔离光化学反应的影响来对确定内陆水域中DOM反应性的特性产生重要的见解，这些反应最终可用于模拟湖泊中二氧化碳的产生。更好地了解碳循环，尤其是在敏感的水文环境中，对于预测和最终适应不断变化的气候至关重要。溶解有机物（DOM）的组成对其反应性至关重要。 DOM反应性的一个例子是它在湖水（例如湖泊）中完成和部分光氧化的敏感性。该过程越来越被认为是全球碳循环的重要组成部分。但是，缺乏对DOM成分如何影响其光化学反应性的机械理解。这项研究将充分表征从北部温带湖泊长期生态研究（NTL-ter）计划的11个核心湖泊以及两个良好研究的DOM分离株中收集的水。这些湖泊包括营养不良，贫营养，中营养和富营营养的系统，这些系统在DOM组成方面广泛。光化学反应性将通过量化光学矿化速率，测量量子产率和光化学产生的反应性中间体（三重dom，单粒氧，羟基自由基和碳酸盐自由基阴离子）的量子产率和稳态浓度，并使用淬火实验来区分直接和间接光学的光化光层。使用紫外可见光谱，荧光光谱，抗氧化剂测量和傅立叶转化离子基因共振共振质谱法之前和之后，将在光解之前和之后表征DOM样品。多元统计数据，包括多个线性回归，层次群集分析和主成分分析，将用于确定在光氧化过程中如何改变DOM，得出部分光氧化的新测量，并确定直接和间接光解的作用，并在完整和部分光氧化中的作用。这项工作将通过隔离光化学反应的影响来对控制内陆水域的反应性的基本特性产生重要的见解。这些知识可用于建立DOM组成和反应性之间的关系，最终可以用来模拟湖泊中二氧化碳生产的潜力。该奖项反映了NSF的法定任务，并被认为是通过基金会的智力优点和更广泛影响的评估标准来评估值得通过评估来支持的。