Journal Article10.1038/NATURE02550
Iron and phosphorus co-limit nitrogen fixation in the eastern tropical North Atlantic
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TL;DR: The results support the hypothesis that aeolian mineral dust deposition promotes nitrogen fixation in the eastern tropical North Atlantic and show that community primary productivity was nitrogen-limited, and that nitrogen fixation was co-limited by iron and phosphorus.
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Abstract: The role of iron in enhancing phytoplankton productivity in high nutrient, low chlorophyll oceanic regions was demonstrated first through iron-addition bioassay experiments1 and subsequently confirmed by large-scale iron fertilization experiments2. Iron supply has been hypothesized to limit nitrogen fixation and hence oceanic primary productivity on geological timescales3, providing an alternative to phosphorus as the ultimate limiting nutrient4. Oceanographic observations have been interpreted both to confirm and refute this hypothesis5, 6, but direct experimental evidence is lacking7. We conducted experiments to test this hypothesis during the Meteor 55 cruise to the tropical North Atlantic. This region is rich in diazotrophs8 and strongly impacted by Saharan dust input9. Here we show that community primary productivity was nitrogen-limited, and that nitrogen fixation was co-limited by iron and phosphorus. Saharan dust addition stimulated nitrogen fixation, presumably by supplying both iron and phosphorus10, 11. Our results support the hypothesis that aeolian mineral dust deposition promotes nitrogen fixation in the eastern tropical North Atlantic.
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Citations
Carbon sequestration in the deep Atlantic enhanced by Saharan dust
Katsiaryna Pabortsava,Richard S. Lampitt,Jeff Benson,Christian Crowe,Robert McLachlan,Frédéric A. C. Le Moigne,C. Mark Moore,Corinne Pebody,Paul Provost,Andrew P. Rees,Gavin H. Tilstone,E. Malcolm S. Woodward +11 more
TL;DR: In this article, the authors present a two-year time series of sediment trap observations of particulate organic carbon flux to 3,000m depth, measured directly in two locations: the dust-rich central North Atlantic gyre and the dustpoor South Atlantic gyres.
Nitrous oxide in the North Atlantic Ocean
TL;DR: In this paper, a depth-dependent calculation of excess N2O (ΔN2O) was proposed to account for the history of atmospheric N 2O, which showed that the formation of nitrous oxide via nitrification occurs in the tropical region rather than in the cold-temperate region of the North Atlantic Ocean.
Analogous nutrient limitations in unicellular diazotrophs and Prochlorococcus in the South Pacific Ocean
Pia H. Moisander,Ruifeng Zhang,Ruifeng Zhang,Edward A. Boyle,Ian Hewson,Ian Hewson,Joseph P. Montoya,Jonathan P. Zehr +7 more
TL;DR: Lack of phytoplankton response to nutrient additions in the Pacific warm pool waters suggests diazotroph growth in this area is controlled by different factors than in the higher latitudes, which may partially explain previously observed variability in community composition in the region.
Cross-talk between iron and nitrogen regulatory networks in anabaena (Nostoc) sp. PCC 7120: identification of overlapping genes in FurA and NtcA regulons.
Sara Lopez-Gomollon,Jose A. Hernandez,Silvia Pellicer,Vladimir Espinosa Angarica,M. Luisa Peleato,María F. Fillat +5 more
TL;DR: The identification of common elements overlapping the NtcA and FurA regulons allows us to establish a previously unrecognized transcriptional regulatory connection between iron homeostasis, redox control and nitrogen metabolism.
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Organic and redox speciation of iron in the eastern tropical North Pacific suboxic zone
TL;DR: In this paper, the organic and redox speciation of iron was examined in the strongly layered upper water column of the eastern tropical North Pacific, including oxic and suboxic waters, in a region 100-1300 km offshore.
99
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