%0 Journal Article
%9 ACL : Articles dans des revues avec comité de lecture répertoriées par l'AERES
%A Knapp, A. N.
%A McCabe, K. M.
%A Grosso, O.
%A Leblond, N.
%A Moutin, T.
%A Bonnet, Sophie
%T Distribution and rates of nitrogen fixation in the western tropical South Pacific Ocean constrained by nitrogen isotope budgets
%D 2018
%L fdi:010072839
%G ENG
%J Biogeosciences
%@ 1726-4170
%K PACIFIQUE SUD
%M ISI:000431435900003
%N 9
%P 2619-2628
%R 10.5194/bg-15-2619-2018
%U https://www.documentation.ird.fr/hor/fdi:010072839
%> https://horizon.documentation.ird.fr/exl-doc/pleins_textes/divers18-05/010072839.pdf
%V 15
%W Horizon (IRD)
%X Constraining the rates and spatial distribution of dinitrogen (N-2) fixation fluxes to the ocean informs our understanding of the environmental sensitivities of N-2 fixation as well as the timescale over which the fluxes of nitrogen (N) to and from the ocean may respond to each other. Here we quantify rates of N-2 fixation as well as its contribution to export production along a zonal transect in the western tropical South Pacific (WTSP) Ocean using N isotope ("delta N-15") budgets. Comparing measurements of water column nitrate + nitrite delta N-15 with the delta N-15 of sinking particulate N at a western, central, and eastern station, these delta N-15 budgets indicate high, modest, and low rates of N-2 fixation at the respective stations. The results also imply that N-2 fixation supports exceptionally high, i.e. >= 50 %, of export production at the western and central stations, which are also proximal to the largest iron sources. These geochemically based rates of N-2 fixation are equal to or greater than those previously reported in the tropical North Atlantic, indicating that the WTSP Ocean has the capacity to support globally significant rates of N-2 fixation, which may compensate for N removal in the oxygen-deficient zones of the eastern tropical Pacific.
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