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Link Foundation Ocean Engineering and Instrumentation Fellowship Reports


Marine N2 fixation converts nitrogen gas into ammonia and accounts for the largest external nitrogen input to the oceans1. Since large portions of the global oceans are nitrogen deficient, marine N2 fixation can relieve the nitrogen limitation, thereby increasing the growth of phytoplankton and stimulating biological uptake of atmospheric carbon dioxide2,3,4. However, the magnitude and distribution of marine N2 fixation are poorly constrained5. In addition, the environmental controls on marine N2 fixation remain elusive6. This situation is in part attributable to the limited number of observations and poor coverage of marine N2 fixation measurements. Current observations rely on discrete sampling which cannot catch episodic events and hot spots7. We proposed to develop a shipboard instrument to determine marine N2 fixation rates continuously. By surveying the distribution of marine N2 fixation at high spatial and temporal resolution, we should be able to better estimate the marine nitrogen budget and evaluate how different environmental factors affect N2 fixation. Considering the substantial influence of human activities on marine ecosystems (including atmospheric nitrogen deposition8), assessing the oceans’ response to these changes is critical.


Nicolas Cassar

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