Collaborative Research: Autonomous Lagrangian Floats for Oxygen Minimum Zone Biogeochemistry

世界海洋的高氧极小区(OMZ)虽然只占海洋总体积的一小部分，但拥有关键的生物地球化学过程，是理解海洋N循环及其生物地球化学和同位素特征的核心。OMZ是很大一部分海洋N结合损失到N_2(25%到50%)的地点，并通过15N和18O富含NO3-的共生来主导海洋N同位素收支。主要悬而未决的问题包括氮汇的大小，N3-损失和生物来源氮气产生之间的化学计量比，导致氮气产生的微生物途径，以及这些OMZ过程与有机物表面输出和物理循环之间的相互作用。PI要求提供资金，以开发一种新的、原位的、自主的工具，用于研究OMZ中的N损失。它将允许在时间和空间尺度上观察变化，这对于理解控制过程和更好地估计N损失的大小至关重要。自主平台可能进行的持续部署对于检测海洋管理区对气候变化的任何反应至关重要。广泛的影响：氮往往是海洋生物生产的限制营养物质，由于一些不确定和问题，目前全球海洋氮平衡一直处于激烈辩论中。这一拟议的传感器-浮动组件的成功开发可能有助于解决有关OMZ的空间和时间变化的一些重要问题。反过来，这些知识对于评估当前和未来海洋的全球氮平衡至关重要。这一拟议的项目将涉及本科生、研究生和博士后的积极参与，以及培训一名K-12科学教师。该项目还将促进与国际研究人员的合作。PI与新贝德福德海港的海洋探索中心合作，提供旨在帮助教师发展的教育外展部分，并为马萨诸塞州南海岸的教师创建实地考察计划。该提案将支持博士后、研究生和本科生。

Intense oxygen minimum zones (OMZ) of the world's oceans, though constituting a small fraction of total oceanic volume, host critical biogeochemical processes and are central to understanding the ocean's N cycle and its biogeochemical and isotopic signatures. OMZ's are sites for a large portion of marine combined N loss to N2 (25 to 50%) and dominate the ocean N isotope budget through cogeneration of 15N and 18O enriched NO3 -. Major outstanding issues include the magnitude of this N sink, the stoichiometry between NO3 - loss and the production of biogenic N2, the microbial pathways leading to N2 production, as well as the interaction between these OMZ processes and the surface export of organic matter as well as physical circulation. The PI's request funding to develop a new, in situ, autonomous tool for studying N loss in OMZ's. It will allow observation of variability over a range in temporal and spatial scales that are critical for understanding controlling processes and better estimating the magnitude of N-loss. The sustained deployments possible with autonomous platforms will be critical for detecting any response of OMZ's to climate change.Broader Impacts: Nitrogen is often the limiting nutrient for biological production in the oceans, and the current global marine nitrogen balance has been in much debate due to a number of uncertainties and questions. A successful development of this proposed sensor-float package may help in resolving some of the important questions on the spatial and temporal variabilities of the OMZs. In turn, such knowledge is essential in assessing the global nitrogen balance in the current and future oceans. This proposed project would involve active participation of undergraduates, graduates and postdocs, as well as the training of a K-12 science teacher. This project would also foster collaboration with international researchers. The PI's have partnered with Ocean Explorium at New Bedford Seaport to provide an educational outreach component designed to aid teacher development and create a field trip program for teachers in the south coast of Massachusetts. The proposal will support post-doc, graduate and undergraduate students.