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

一氧化二氮是对流层中的一种强有力的温室气体，也是平流层中的一种臭氧消耗物质，但它在海洋中的来源和汇既没有得到很好的量化，也没有得到很好的了解。一氧化二氮既由微生物过程产生，也由微生物消耗；它由不同的过程产生，取决于当地存在的氧气量。北冰洋可能是大气中一氧化二氮的重要来源。最近在多产的北冰洋浅水大陆架水域观察到一氧化二氮饱和程度很高。拟议的研究将检验以下假设：西部北冰洋多产的大陆架区域(如楚科奇海和博福特海)刺激一氧化二氮的产生，并有助于一氧化二氮向北极中部的离岸运输。除了为北极科学界开发一个重要的基准数据集之外，该项目还将以多种方式为STEM劳动力发展做出贡献。它将支持一位职业生涯早期的女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。它将为小学教师开发研讨会，并在当地一所公立学校提供简短的课堂演讲，并为致力于为高危青年提供高质量教育项目的课外非营利性努力做出贡献。这项拟议研究的主要目标是从一氧化二氮的浓度、稳定同位素和同位素异构体评估西部北冰洋的一氧化二氮循环。该项目将使用大陆架和近海水域的同位素和同位素测量，以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)水体中有机物分解后的硝化作用或沉积物中的硝化-反硝化作用产生一氧化二氮的途径，以及2)这些过程如何影响表层和大气之间的一氧化二氮交换。在白令海和楚科奇海的沿海和陆架观测站与加拿大深水盆地的近海观测站进行比较，将能够评估混合和长距离运输对地球化学信号的影响。这些测量还将作为未来评估变化的基线。该项目是否从NSF和主要调查人员的其他投资中获利？国际合作者，受益于在美国地理跟踪北极部分和2016年中国北极邮轮期间收集的测量和样本。

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.