Collaborative Research: GEOTRACES Arctic Ocean section-Constraining Nitrogen Cycling in the western Arctic Ocean.

在这个项目中，来自康涅狄格大学、马萨诸塞大学达特茅斯分校和布朗大学的一组研究人员将参加2015年美国地理跟踪北极探险队，以确定该地区氮的生物地球化学。与国际地质勘测计划中的其他多国倡议一样，美国北极探险的目标是确定控制海洋中关键微量元素和同位素分布的过程和通量，并确定这些分布对不断变化的环境条件的敏感性。一些微量元素对生命是必不可少的，另一些是已知的生物毒素，还有一些很重要，因为它们可以用作海洋中各种物理、化学和生物过程的示踪剂。氮是海洋中浮游生物普遍需要的两大营养物质之一，北冰洋的这项研究将增加我们对海洋的认识？S的生态、生产力和碳循环。这项研究还将为研究生和本科生提供培训，并将通过公共宣传活动分享结果。与其他海洋盆地相比，北极氮(N)生物地球化学的知识状况仍然粗略，尽管了解北冰洋氮循环是了解其全球生物地球化学的核心。首先，北极大陆架上的底栖生物氮损失可能代表着全球范围内海洋固定氮的一个重要下沉。其次，北极大陆架和陆坡的底栖氮损失使硝酸盐与磷酸盐的比率大大低于浮游植物氮的平均需求量，从而限制了北冰洋西部无冰表面的初级生产力。鉴于北极气候学的迅速变化，描述其生物地球化学特征并建立监测未来变化的基线至关重要。研究人员将使用一套溶解的、颗粒物、大气、雪和海冰样品中硝酸盐、亚硝酸盐、氨和氮气中稳定的N同位素(15N/14N)比率，以更好地约束北极生物氮转化的时空变异性。这项研究的结果将提供对水团对区域氮收支的贡献的第一手了解，确定区域氮源和汇，并诊断发生在楚科奇陆架和中央盆地的重要生物氮转化。

In this project, a group of investigators from the University of Connecticut, the University of Massachusetts-Dartmouth, and Brown University will participate in the 2015 U.S. GEOTRACES Arctic expedition to determine the biogeochemistry of nitrogen in the region. In common with other multinational initiatives in the International GEOTRACES Program, the goals of the U.S. Arctic expedition are to identify processes and quantify fluxes that control the distributions of key trace elements and isotopes in the ocean, and to establish the sensitivity of these distributions to changing environmental conditions. Some trace elements are essential to life, others are known biological toxins, and still others are important because they can be used as tracers of a variety of physical, chemical, and biological processes in the sea. Nitrogen is one of the two major nutrients required universally by plankton in the ocean, and this study in the Arctic Ocean will increase our understanding of the ocean?s ecology, productivity, and carbon cycle. This study will also provide training for graduate and undergraduate students, and results will be shared through public outreach events.The state of knowledge of Arctic nitrogen (N) biogeochemistry remains cursory as compared to that in other ocean basins despite the fact that understanding Arctic Ocean nitrogen cycling is central to understanding its global biogeochemistry. For one, benthic nitrogen loss on Arctic continental shelves may represent a globally significant sink of oceanic fixed nitrogen. Second, benthic nitrogen loss on the Arctic continental shelf and slope reduces the ratio of nitrate to phosphate substantially below the mean requirements of phytoplankton nitrogen, consequently limiting primary production at the ice-free surface of the western Arctic Ocean. In light of the rapid changes in Arctic climatology, the characterization of its biogeochemistry and establishment of a baseline from which to monitor future changes is critical. Researchers will use the stable N isotope (15N/14N) ratio in nitrate, nitrite, ammonium, and nitrogen gas determined for a suite of dissolved, particulate, atmospheric, snow, and sea-ice samples to better constrain the spatial and temporal variability of biological nitrogen transformations in the Arctic. Results from this study will provide a first order understanding of the contribution of water masses to the regional nitrogen budget, identify regional nitrogen sources and sinks, and diagnose important biological nitrogen transformations that occur on the Chukchi shelf, and in the central basins.