Hydrogen production and nitrogen fixation in the North Pacific Subtropical Gyre

在这个项目中，夏威夷大学马诺阿分校的研究人员将进行一系列实地和实验室研究，以定量了解北太平洋贫营养海洋中溶解氢（H2）的循环。海洋表面的溶解H2浓度通常在1-3 nM之间，相对于大气浓度，这代表了300-900%的过饱和。亚热带和热带海洋表层水中溶解H2的持续过饱和使海洋成为大气H2的来源，全球H2来源的编制预算估计海洋排放量为每年3至6 Tg H2。本研究的主要目标是：(1)量化开放海域表层海水中H2生成和N2固定之间的联系和化学计量；(2)确定驱动这种关系的因素，包括微生物群落组成和光强的影响。实地研究将在ALOHA站进行为期两年的时间，并将补充正在进行的夏威夷海洋时间序列（HOT）计划。更广泛的影响：量化上层水柱地表水中的H2循环将限制现有的全球海洋H2排放估计。此外，对H2循环的进一步了解将有助于预测H2排放增加或气候驱动的海洋重氮营养体群落结构变化的潜在影响。这些结果将对微生物生态学家、生物地球化学家和气候变化科学家有价值。所有结果的海洋学和实验室数据集将存档在在线HOT和微生物海洋学中心：研究和教育（C-MORE）数据中心，并向公众提供。至少有一名本科生将通过C-MORE学者计划接受，该计划特别针对夏威夷原住民和太平洋岛民，主修海洋或地球科学相关领域。

In this project, researchers at the University of Hawaii a Manoa will conduct a series of field and laboratory studies to develop a quantitative understanding of dissolved hydrogen (H2) cycling in the oligotrophic North Pacific Ocean. Dissolved H2 concentrations in the surface ocean typically range from 1-3 nM which represents 300-900% supersaturation relative to atmospheric concentrations. This persistent supersaturation of dissolved H2 in the surface waters of subtropical and tropical oceans makes the oceans a source of atmospheric H2 and compiled budgets of global H2 sources estimate marine emissions from 3 to 6 Tg H2 yr-1. The broad objectives of the research are: (1) to quantify the linkages and stoichiometry between H2 production and N2 fixation in surface seawater of the open ocean, and (2) to determine the factors that drive this relationship including the microbial community composition and the influence of light intensity. The field research will be conducted over a two-year period at Station ALOHA and will complement the ongoing Hawaii Ocean Time-series (HOT) program. Broader Impacts: Quantifying the H2 cycling in surface waters of the upper water column will constrain existing estimates of global marine H2 emissions. Furthermore, an improved understanding of H2 cycling will help predict potential effects of increasing anthropogenic emissions of H2 increase or a climate-driven change in the community structure of marine diazotrophs. These results will be valuable to microbial ecologists, biogeochemists, and climate change scientists. All resulting oceanographic and laboratory datasets will be archived in the online HOT and Center for Microbial Oceanography: Research and Education (C-MORE) data centers and made publicly available. At least one undergraduate student will be hosted through the C-MORE scholars program which particularly targets Native Hawaiians and Pacific Islanders majoring in an ocean or earth science-related field.