Nitrous oxide cycling in the Western Arctic Ocean from stable isotopic and concentration data

一氧化二氮在对流层中是一种强有力的温室气体，在平流层中是一种消耗臭氧的物质，但它在海洋中的来源和汇既没有得到很好的量化，也没有得到很好的理解。一氧化二氮由微生物过程产生和消耗；它是由不同的过程产生的，这取决于当地存在的氧气量。北冰洋可能是大气中氧化亚氮的一个重要来源。最近在具有生产力的北极浅海陆架水域观测到高氧化亚氮饱和度。拟议的研究将检验这样一种假设，即北冰洋西部的生产性大陆架区域（例如楚科奇海和波弗特海）刺激了一氧化二氮的产生，并促进了一氧化二氮向北极中部的海上运输。除了为北极科学界开发重要的基线数据集外，该项目还将以多种方式促进STEM劳动力的发展。它将支持一位早期职业女性科学家在她职业生涯的形成阶段。它将为本科生提供暑期教育研究机会。它将为小学教师举办研讨会，并在当地一所公立学校提供简短的课堂演讲，并为一项致力于为有风险的青少年提供高质量教育项目的课后非营利活动做出贡献。这项拟议研究的主要目标是从其浓度、稳定同位素和同位素体来评估北冰洋西部氧化亚氮的循环。该项目将使用大陆架和近海水域的同位素和同位素测量来限制对北极一氧化二氮循环的估计。这些数据将用于评估1)水柱中有机物分解后的硝化作用或沉积物中耦合硝化-反硝化作用产生氧化亚氮的途径，以及2)这些过程如何影响表层与大气之间的氧化亚氮交换。将白令海和楚科奇海沿岸和大陆架站的观测结果与加拿大深海盆近海站的观测结果进行比较，将能够评价混合和远距离输送对地球化学信号的影响。这些度量也将作为将来评估变化的基线。这个项目的利润来自于NSF和主要研究者的其他投资？国际合作伙伴，从美国GEOTRACES北极部分和2016年中国北极巡航期间收集的测量和样本中受益。

Nitrous oxide is a potent greenhouse gas in the troposphere and an ozone-depleting substance in the stratosphere, yet its sources and sinks in the ocean are neither well-quantified nor well understood. Nitrous oxide is both produced and consumed by microbial processes; it is produced by different processes dependent upon the amount of oxygen present locally. The Arctic Ocean may represent an important source of nitrous oxide to the atmosphere. High nitrous oxide saturations were recently observed in productive shallow Arctic shelf waters. The proposed research will test the hypotheses that productive shelf regions of the Western Arctic Ocean (e.g., Chukchi and Beaufort seas) stimulates nitrous oxide production and contributes to offshore transport of nitrous oxide toward the central Arctic. Besides developing an important baseline data set for the Arctic science community, this project will contribute to STEM workforce development in numerous manners. It will support an early-career female scientist during the formative years of her career. It will provide summer educational research opportunities to undergraduate students. It will develop seminars for elementary school teachers and provide short classroom presentations at a local public school and contribute to an afterschool non-profit effort devoted to providing high quality educational programs to at risk youth.The primary goal of this proposed research is to evaluate nitrous oxide cycling in the Western Arctic Ocean from its concentrations, stable isotopes and isotopomers. The project will use isotopic and isotopomer measurements from both shelf and offshore waters to constrain estimates of nitrous oxide cycling in the Arctic. The data will be used to evaluate 1) the pathways of nitrous oxide production from either nitrification following organic matter decomposition in the water column or coupled nitrification-denitrification in the sediments and 2) how these processes influence nitrous oxide exchanges between the surface layer and the atmosphere. Comparisons of observations at coastal and shelf stations in the Bering and Chukchi seas with those offshore in the Deep Canadian Basin will allow the evaluation of the effects of mixing and long-range transport on geochemical signals. The measurements will also serve as a baseline for future assessment of change. The project profits from leveraging of other investments by NSF and the principal investigators? international collaborators, benefitting from measurements and samples collected during the U.S. GEOTRACES Arctic section and the 2016 CHINARE Arctic cruises.