RII Track 4: Arctic Nitrous Oxide (N2O): Training and Technical Advances to Quantify Emission of a Powerful Greenhouse Gas

RII 轨道 4：北极一氧化二氮 (N2O)：量化强大温室气体排放的培训和技术进步

• 批准号: 1929217
• 负责人: Tamara Harms
• 金额: $ 12.62万
• 依托单位: University of Alaska Fairbanks Campus
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2019
• 资助国家: 美国
• 起止时间: 2019-12-01 至 2023-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1929217&HistoricalAwards=false
• 关键词: RII; Track; Arctic; Nitrous; Oxide

Nitrous oxide is a potent greenhouse gas, with about ~300 times the climate warming potential of carbon dioxide. Nitrous oxide is produced and released to the atmosphere by microbes that cycle nitrogen in soils and sediment, often in response to excess nitrogen. High-latitude ecosystems typically contribute little nitrous oxide to the atmosphere because of limited availability of the forms of nitrogen conducive to nitrous oxide production. However, exceptionally large fluxes of nitrous oxide are increasingly documented from arctic and sub-arctic soils that are subject to cryoturbation or thawing permafrost. It remains unclear how this nitrous oxide is produced and how long disturbed soils might generate emissions. This project will support training in several analytical approaches for determining the quantity and pathways of nitrous oxide production in soils. Research will focus on Alaskan ecosystems that are subject to wildfire and permafrost thaw. Researchers will also adapt and apply novel methods with stable isotopes to determine the microbial pathways producing nitrous oxide. Determining how nitrous oxide is produced will decrease uncertainty in predicting how ecosystems respond to changing regimes of fire and permafrost and clarify how ecosystems might in turn influence the climate system. Several studies over the past decade have documented significant emissions of nitrous oxide (N2O) from arctic soils where permafrost is thawing. However, these studies have not revealed the biological processes generating N2O, which might include denitrification, nitrification, and nitrifier-denitrification. Because the pathways of N2O production in high-latitude soils remain unknown, it is presently difficult to forecast potential emissions under warmer, more nutrient-rich, and fire-prone conditions predicted for high-latitude ecosystems. An Alaska-based research team will work with the nitrogen analytical facility at the Cary Institute of Ecosystem Studies to apply and optimize novel analytical approaches. These studies will include real-time production of N2O in response to manipulated soil conditions, and analysis of isotopomers (describing site preference of 15N), which can identify the microbial pathway producing N2O. These approaches will be applied across precipitation events, seasonal, and successional time scales and spatial gradients encompassing variation in nitrogen inputs, permafrost, and burn history within the region of spatially discontinuous permafrost in Interior Alaska. Goals of the research include identifying the microbial pathways that produce N2O in high-latitude soils and testing hypothesized relationships between nitrogen cycling and the fire, permafrost, and moisture regimes of the boreal forest. Establishing these relationships is an essential step toward identifying potential positive feedback loops between nitrogen cycling and climate warming in high-latitude ecosystems.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.

一氧化二氮是一种有效的温室气体，其二氧化碳的气候变暖潜力约为300倍。一氧化二氮是通过循环氮和沉积物中循环氮的微生物产生并释放到大气中的，通常是响应过量的氮。高纬度生态系统通常由于有利于一氧化二氮的产生形式的有限的氮供应有限，因此对大气中的一氧化二氮几乎没有贡献。然而，越来越多地记录在北极和亚北极土壤中，越来越多的一氧化二氮的通量受到冷冻扰动或融化的多年冻土。目前尚不清楚这种一氧化二氮是如何产生的，以及可能产生排放的时间多长时间。该项目将支持几种分析方法的培训，以确定土壤中一氧化二氮的数量和途径。研究将侧重于野火和多年冻结融化的阿拉斯加生态系统。研究人员还将适应并应用具有稳定同位素的新型方法来确定产生一氧化二氮的微生物途径。确定如何生产一氧化二氮将减少不确定性，以预测生态系统如何应对不断变化的火灾和多年冻土制度，并阐明生态系统可能如何影响气候系统。 在过去的十年中，几项研究表明，来自北极土壤中的一氧化二氮（N2O）的显着排放，这些北极冻土正在解冻。但是，这些研究尚未揭示产生N2O的生物学过程，其中可能包括反硝化，硝化和硝基硝化剂。由于高纬度土壤中N2O产生的途径尚不清楚，因此目前很难在温暖，更富含营养的且容易发生的条件下预测高纬度生态系统的潜在排放。总部位于阿拉斯加的研究团队将与卡里生态系统研究所的氮分析设施合作，以应用和优化新颖的分析方法。这些研究将包括针对受操纵的土壤条件的实时生产，以及对同位素的分析（描述15N的现场偏好），可以鉴定产生N2O的微生物途径。这些方法将在降水事件，季节和继承时间尺度以及空间梯度上应用，包括氮输入，多年冻土和阿拉斯加内部空间不连续冻土区域内的变化。该研究的目标包括鉴定在高纬度土壤中产生N2O的微生物途径，并测试氮与火与火，多年冻土和北方森林的水分方案之间的假设关系。建立这些关系是在高纬度生态系统中识别氮循环和气候变暖之间潜在积极反馈回路的重要一步。该奖项反映了NSF的法定任务，并被认为是值得通过基金会的知识分子优点和更广泛的影响审查标准来评估的支持。