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GEOTRACES北极考察，以确定该地区氮的地球化学性质。 与国际GEOTRACES计划中的其他多国倡议一样，美国北极考察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量化通量，并确定这些分布对环境条件变化的敏感性。一些微量元素是生命所必需的，另一些是已知的生物毒素，还有一些是重要的，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种主要营养物质之一，这项在北冰洋的研究将增加我们对海洋的了解。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成果。尽管了解北冰洋氮循环是了解其全球地球化学的核心，但与其他海洋盆地相比，北极氮（N）地球化学的知识状况仍然很粗略。首先，北极大陆架的底栖氮损失可能是全球重要的海洋固定氮汇。第二，北极大陆架和陆坡的海底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，从而限制了北冰洋西部无冰表面的初级生产。鉴于北极气候的迅速变化，确定其地球化学特征和建立监测未来变化的基线至关重要。研究人员将使用硝酸盐，亚硝酸盐，铵和氮气中的稳定氮同位素（15 N/14 N）比率，确定一套溶解，颗粒，大气，雪和海冰样本，以更好地限制北极生物氮转化的空间和时间变化。 这项研究的结果将提供一个一阶的理解水团的区域氮收支的贡献，确定区域氮源和汇，并诊断发生在楚科奇大陆架上的重要生物氮转化，并在中央盆地。

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.