Ventilation and Timescales of Oxygen and Nutrient Cycling in the Oxygen Deficient Waters Of The Eastern Tropical South Pacific

全球海洋反硝化作用的向上修正导致人们猜测，海洋氮循环可能存在很大的不平衡。此外，一种新途径（厌氧氨氧化，即，厌氧氨氧化），导致海洋沉积物和水体缺氧区的固定氮的去除，动摇了长期以来对海洋氮循环的看法。与反硝化作用一样，厌氧氨氧化将固定氮转化为氮气，但没有溶解的N2 O作为中间阶段。在我们的知识，这些N-损失途径在海洋氧最小区（OMZs）的速度和幅度仍然存在很大的不确定性，从而阻碍了努力，以限制海洋氮。在这个项目中，华盛顿大学的一个研究小组将解决这个问题：在热带南太平洋东部的氧气最低区，氧气利用、反硝化和厌氧氨氧化的原位速率和幅度是多少？ 他们将通过进行三项重要的海洋学测量来解决这个问题，这些测量可以与东热带南太平洋现有的过程研究相结合，旨在区分和确定该地区对厌氧氨氧化物和反硝化作用的控制。首先，他们将测量溶解营养物沿着水文剖面的水柱分布，以帮助确定最低含氧量区营养物源和汇的特征。其次，他们将测量，以前所未有的覆盖面，溶解N2 O沿着水文剖面作为反硝化的诊断示踪剂。最后，他们将测量瞬态人为示踪剂（CFCs和SF6），以量化OMZ内的通风和循环时间尺度。示踪剂衍生的时间尺度将与溶解氧和营养物的测量相结合，以量化原位氧利用率和营养物去除/再生。这些比率将为船上培养研究期间体外确定的比率提供基准。更广泛的影响。 该项目将通过大气和海洋联合研究所（JISAO）暑期实习计划支持本科生参与者。JISAO通常支持5-8名本科生在西雅图度过夏季学期，参与大气和海洋研究;这样的项目在技术方面对海洋学和化学专业的学生具有吸引力，在其推广活动中对新闻专业的学生也具有吸引力。 其中一名主要研究人员将与华盛顿大学公共广播电台KUOW合作，设计有关海洋科学的简短公益故事。实习生的最后项目将包括编写一个简短的广播节目，在KUOW上播放，介绍第一年研究工作的背景、意义和结果，并与JISAO的其他本科实习生一起参加科学海报会议。

Upward revision of global marine denitrification has led to speculation that there may be a large imbalance in the marine nitrogen cycle. In addition, the discovery of a new pathway (anaerobic ammonium oxidation, i.e., anammox) that leads to the removal of fixed nitrogen from marine sediments and anoxic regions of the water column has shaken long-held perceptions of the marine nitrogen cycle. As with denitrification, anammox converts fixed nitrogen to nitrogen gas, but does so without dissolved N2O as an intermediate stage. Large uncertainties remain in our knowledge of the rates and magnitudes of these N-loss pathways in oceanic oxygen minimum zones (OMZs) thus hampering efforts to constrain the marine nitrogen. In this project, a research team at the University of Washington will address this question: What is the in-situ rate and magnitude of oxygen utilization, denitrification, and anammox in the oxygen minimum zone of the Eastern Tropical South Pacific? They will approach this problem by making three significant oceanographic measurements that can be combined with an existing process study in the Eastern Tropical South Pacific aimed at distinguishing and identifying controls on anammox and denitrification in this region. First, they will measure water column distributions of dissolved nutrients along the hydrographic sections to help characterize nutrient sources and sinks in the oxygen minimum zone. Second, they will measure, to unprecedented coverage, dissolved N2O along the hydrographic sections as a diagnostic tracer for denitrification. Finally, they will measure transient anthropogenic tracers (CFCs and SF6) to quantify ventilation and circulation timescales within the OMZ. The tracer-derived timescales will be combined with measurements of dissolved oxygen and nutrients to quantify in situ rates of oxygen utilization and nutrient removal/regeneration. These rates will provide benchmarks to the rates determined in-vitro during shipboard incubation studies. Broader Impacts. This project will support an undergraduate participant through the Joint Institute for Study of the Atmosphere and Ocean (JISAO) summer internship program. JISAO typically supports 5-8 undergraduates to spend summer quarter in Seattle participating in atmospheric and oceanic research;a project such as this would be attractive to oceanography and chemistry majors in its technical aspects, and to journalism students in its outreach activities. One of the principal investigators will work with KUOW, the University of Washington public radio station, to design brief public interest stories on ocean science. The intern's final project will involve preparation of a brief radio segment for broadcast on KUOW on the background, significance and findings of the first year's research efforts, and participation in a scientific poster session with the other undergraduate interns at JISAO.