EAGER: Collaborative Research: Detection limit in marine nitrogen fixation measurements - Constraints of rates from the mesopelagic ocean

EAGER：合作研究：海洋固氮测量的检测极限 - 中深海速率的限制

• 批准号: 1850588
• 负责人: Angelicque White
• 金额: $ 3.67万
• 依托单位: University of Hawaii
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2018
• 资助国家: 美国
• 起止时间: 2018-07-01 至 2020-04-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1850588&HistoricalAwards=false
• 关键词: EAGER; Collaborative; Research; Detection; limit

The availability of nitrogen is required to support the growth and production of organisms living in the surface of our global ocean. This element can be scarce. To alleviate this scarcity, a special class of bacteria and archaea, called nitrogen fixers, can derive the nitrogen needed for growth from nitrogen gas. This project would carefully examine one specific method for measuring nitrogen fixation that has been used recently to suggest the occurrence of small amounts of nitrogen fixation in subsurface ocean waters. If these reports are verified, then a revision of our understanding of the marine nitrogen cycle may be needed. The Ocean Carbon and Biogeochemistry program will be used as a platform to develop community consensus for best practices in nitrogen fixation measurements and detection of diversity, activity, and abundances of the organisms responsible. In addition, a session will be organized in a future national/international conference to communicate with the broader scientific community while developing these best practices.The goal of this study is to conduct a thorough examination of potential experimental and analytical errors inherent to the 15N2-tracer nitrogen fixation method, in tandem with comprehensive molecular measurements, in mesopelagic ocean waters. Samples will be collected and experimental work conducted on a cruise transect in the North Atlantic Ocean, followed by analytical work in the laboratory. The specific aims of this study are to (1) determine the minimum quantifiable rates of 15N2 fixation based on incubations of mesopelagic waters via characterization of sources of experimental and analytical error, and (2) seek evidence of presence and expression of nitrogen fixation genes via comprehensive molecular approaches on corresponding samples. The range of detectable rates and diazotroph activity from the measurements made in this study will be informative for the understanding of the importance of nitrogen fixation in the oceanic nitrogen budget.

氮的可用性需要支持生活在我们全球海洋表面的生物的生长和生产。这种元素可能是稀缺的。为了缓解这种短缺，一类特殊的细菌和古细菌，称为固氮菌，可以从氮气中获得生长所需的氮。这个项目将仔细审查最近用来表明在海洋地下沃茨中有少量固氮作用的一种测量固氮作用的具体方法。如果这些报告得到证实，那么我们对海洋氮循环的理解可能需要修改。海洋碳和生物地球化学计划将作为一个平台，为固氮测量和检测生物多样性，活动和丰度的最佳实践发展社区共识。此外，将在今后的国家/国际会议上组织一次会议，与更广泛的科学界交流，同时制定这些最佳做法，本研究的目标是进行一个彻底的检查潜在的实验和分析误差固有的15 N2示踪固氮方法，在综合分子测量，在中层海洋沃茨。将在北大西洋的一个巡航样带上采集样本并进行实验工作，然后在实验室进行分析工作。本研究的具体目的是（1）通过对实验和分析误差来源的表征，确定基于中层沃茨孵育的15 N2固定的最小可定量速率，以及（2）通过对相应样品的综合分子方法，寻求固氮基因存在和表达的证据。在这项研究中所作的测量的可检测率和固氮活性的范围将是信息的固氮在海洋氮预算的重要性的理解。