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
Nitrogen fixation rates in the eastern Arabian Sea
Ayaz Ahmed,Mangesh Gauns,Siby Kurian,Pratirupa Bardhan,Anil Pratihary,Hema Naik,Damodar M. Shenoy,S.W.A. Naqvi +7 more
TL;DR: In this paper, the authors measured nitrogen fixation rates in the euphotic zone during one such event in the Eastern Arabian Sea using 15 N 2 tracer gas dissolution method and reported rates varied between 0.8 and 225μm.
44
Atmospheric pathways of phosphorous to the Bay of Bengal: Contribution from anthropogenic sources and mineral dust
Bikkina Srinivas,Manmohan Sarin +1 more
TL;DR: In this article, the authors report on the spatio-temporal variability of inorganic phosphorous (P Inorg = ) in the MABL and its dry-deposition flux to the surface BoB.
44
Unicellular diazotrophy as a source of nitrogen to Leeuwin Current coastal eddies
TL;DR: In this article, the authors measured 15N2 uptake and C-fixation rates of the natural phytoplankton assemblage in a pair of counter-rotating mesoscale eddies in the Leeuwin Current, off the coast of Western Australia in 2003.
44
Interactive effects of irradiance and co2 on co2 fixation and n2 fixation in the diazotroph trichodesmium erythraeum (cyanobacteria)(1).
Nathan S. Garcia,Fei-Xue Fu,Cynthia L. Breene,Peter W. Bernhardt,Margaret R. Mulholland,Jill A. Sohm,David A. Hutchins +6 more
TL;DR: This study suggests that elevated pCO2 may have a strong positive effect on Trichodesmium gross N2 fixation in intermediate and bottom layers of the euphotic zone, but perhaps not in light‐saturated surface layers.
43
Contribution of airborne microbes to bacterial production and N2 fixation in seawater upon aerosol deposition
TL;DR: In this article, the authors reported a diverse microbial community associated with dust and other aerosol particles, which differed significantly according to their geographical air mass origin, and calculated that airborne microbes can account for one third in bacterial abundance and 50-100% in bacterial production and N2-fixation rates following dust/aerosol amendments in the surface Mediterranean Sea (SEMS) water.
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