A marine nitrogen cycle fix?
In: Nature: International Weekly Journal of Science. Nature Publishing Group: London. ISSN 0028-0836; e-ISSN 1476-4687, more
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| Abstract |
Nitrogen fixation is crucial for maintaining biological productivity in the oceans, as it replaces biologically available nitrogen lost through denitrification, in which nitrites and nitrates are converted to nitrogen gas. The factors that control this process remain uncertain, but there is a widely held view that the rate of supply of iron to nitrogen-fixing bacteria is rate limiting. A new approach to the problem, which derives fixation rates from nutrient distributions in an ocean circulation model, has arrived at a surprising finding: the nitrogen fixation rate is highest in the Pacific Ocean, where the supply of iron from the atmosphere is low and denitrification rates high, and lowest in the Atlantic, where iron is more plentiful. This suggests that oceanic nitrogen fixation is not tied to iron levels, but is stimulated by denitrification, helping to stabilize the oceanic reservoir of fixed nitrogen. |
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