Cyanate in the Sea: Sources, Sinks, and Quantitative Significance

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Nitrogen is a critical nutrient in the world's oceans because, among other things, it is a major component of living organisms and can be a driver in primary productivity. Nitrogen is present in the ocean in a number of organic and inorganic forms, which vary in their ease in being assimilated by marine organisms. Cyanate is a simple form of organic nitrogen present in the ocean, although its abundance and importance to the ocean nitrogen cycle is poorly understood. Using newly developed and tested methods for measuring ambient cyanate concentrations and its uptake in seawater, researchers will analyze the distribution, sources, and geochemistry of cyanate in shelf waters of the Atlantic Ocean. Results from this project will elucidate the importance of cyanate in the marine nitrogen cycle and transform understanding of cyanate production and assimilation in the sea. This project will provide a unique opportunity for both graduate student research and undergraduate training, and will likely expose underrepresented groups to marine sciences.Although physiological and genomic evidence suggest that marine microbes can utilize a broad array of inorganic and organic nitrogen compounds, cyanate's role in the marine nitrogen cycle has not yet been examined. As one of the simplest organic nitrogen compounds, cyanate has likely been present in the environment over Earth's long history. Evidence suggests that cyanate metabolism appeared early on in bacterial genomes and thus, the study of cyanate assimilation in the contemporary ocean may illuminate microbial processes with deep evolutionary roots. However, a decade since discovering the genomic capacity for cyanate utilization in marine cyanobacteria, little is still known about cyanate distributions in the environment, how it is produced, and how widespread cyanate utilization is among marine microbes. To further understanding of cyanate's role in the marine nitrogen cycle, a combination of geochemical approaches will be used to assess: 1) the distribution of cyanate in the marine environment, 2) potential sources of cyanate and the timescales at which cyanate is produced, 3) the rate of cyanate removal via microbial uptake and spontaneous decomposition, and 4) the geochemical coupling between cyanate production and consumption. Results generated from this study will be important for augmenting knowledge of the marine nitrogen cycle, refining biogeochemical models, and further understanding of the functioning of marine microbial communities.