Tropical Dominance of N2 Fixation in the North Atlantic Ocean
PUBLICATIONS Global Biogeochemical Cycles RESEARCH ARTICLE Tropical Dominance of N2 Fixation in the North 10.1002/2016GB005613 Atlantic Ocean Key Points: Dario Marconi1 , Daniel M. Sigman1 , Karen L. Casciotti2 , Ethan C. Campbell3 , • fi Atlantic N2 xation rates are 1 4 5 6 calculated from nitrate isotopes and M. Alexandra Weigand , Sarah E. Fawcett , Angela N. Knapp , Patrick A. Rafter , 1 7 WOCE-derived nitrate transports Bess B. Ward , and Gerald H. Haug • N2 fixation north of 11°S is 27.1 Tg N/yr; 90% of this rate occurs south of 1Department of Geosciences, Princeton University, Princeton, NJ, USA, 2Department of Environmental Earth System 24°N, responding to excess P supply Science, Stanford University, Stanford, CA, USA, 3School of Oceanography, University of Washington, Seattle, WA, USA, • N fixation in the equatorial and North 2 4Department of Oceanography, University of Cape Town, Rondebosch, South Africa, 5Earth, Ocean, and Atmospheric Atlantic can stabilize the global ocean 6 N-to-P ratio, but this is not needed Science Department, Florida State University, Tallahassee, FL, USA, Department of Earth System, University of California, 7 today Irvine, CA, USA, Max Planck Institute for Chemistry, Mainz, Germany Supporting Information: Abstract To investigate the controls on N2 fixation and the role of the Atlantic in the global ocean’s fixed • Supporting Information S1 nitrogen (N) budget, Atlantic N fixation is calculated by combining meridional nitrate fluxes across World • Figure S1 2 15 14 • Figure S2 Ocean Circulation Experiment sections with observed nitrate N/ N differences between northward and • Figure S3 southward transported nitrate. N2 fixation inputs of 27.1 ± 4.3 Tg N/yr and 3.0 ± 0.5 Tg N/yr are estimated • Figure S4 north of 11°S and 24°N, respectively.
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