Collaborative Research: Opening the black box of oxygen deficient zone biogeochemistry through integrative tracers

缺氧区是海洋中溶解氧消失的区域。这些地区拥有独特的生态系统，只有在没有氧气的沃茨才能找到，它们对地球的气候很重要。具体来说，通过厌氧氨氧化和反硝化这两种微生物过程产生的氮气可以控制海洋的生产力。然而，每个过程在多大程度上影响了这些区域内的海洋化学仍然是未知的。该项目旨在研究北太平洋热带东部缺氧的沃茨，以更好地了解海洋氮和碳化学的形成机制。通过这项工作，该项目将培训三所大学的本科生和研究生。该项目旨在通过制作关于所使用的方法和项目背后的科学的公共视频，扩大对海洋科学的参与和了解。 调查人员将在最大的缺氧区北太平洋热带东部进行研究巡航。他们将测量许多营养物质，包括无机碳和氮以及氮化合物的天然丰度稳定同位素。他们将使用这些模式来确定主要反应如何共同控制氮循环和气态氮的产生。此外，一个高分辨率的海洋模型将揭示海洋混合的影响，确定反应的时间尺度，并将测量结果综合到全球范围内。这项工作将确定通过混合输入的氧气如何控制化学反应，并将区分限于永久缺氧核心的过程与那些耐受偶尔氧化（或通过偶尔氧化而增强）的过程。总的来说，该项目将提供有关整个地区氮循环途径（厌氧氨氧化，反硝化和亚硝酸盐氧化）的新信息，并将由此产生的同位素信号与全球氮收支联系起来。该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

The oxygen deficient zones are regions in the ocean where dissolved oxygen disappears. These regions harbor unique ecosystems only found in waters without oxygen, and they are important for Earth’s climate. Specifically, the production of nitrogen gas by two microbial processes, anammox and denitrification can control how productive the oceans are. Yet how much each process shapes ocean chemistry within these areas remains unknown. This project aims to study the oxygen deficient waters of the eastern tropical North Pacific ocean to better understand the mechanisms shaping marine nitrogen and carbon chemistry. Through this work, the project will train undergraduate and graduate students at three universities. The project aims to broaden participation in and understanding of ocean sciences by developing public videos about the methods used and the science behind the project. The investigators will conduct a research cruise in the eastern tropical North Pacific ocean, the largest oxygen deficient zone. They will measure many nutrients including inorganic carbon and nitrogen and natural abundance stable isotopes of nitrogen compounds. They will use these patterns to establish how the major reactions work together to control nitrogen cycling and gaseous nitrogen production. In addition, a high-resolution model of the ocean will reveal the influence of ocean mixing, set the timescales for reactions, and enable synthesis of the measurements into a global context. The work will determine how the input of oxygen through mixing controls chemistry, and it will distinguish between the processes restricted to the permanently anoxic core vs. those that tolerate (or are enhanced by) occasional oxygenation. Overall, the project will provide new information about nitrogen cycling pathways (anammox, denitrification, and nitrite oxidation) across the region and link the resulting isotopic signals to the global nitrogen budget.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.