Distribution and rates of nitrogen fixation in the western tropical South Pacific Ocean constrained by nitrogen isotope budgets - Archive ouverte HAL Access content directly
Journal Articles Biogeosciences Year : 2018

Distribution and rates of nitrogen fixation in the western tropical South Pacific Ocean constrained by nitrogen isotope budgets

Abstract

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 fixa-tion 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 (" δ 15 N ") budgets. Comparing measurements of water column nitrate + nitrite δ 15 N with the δ 15 N of sinking particulate N at a western, central, and eastern station, these δ 15 N 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 prox-imal 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.
Fichier principal
Vignette du fichier
Knapp_et_al_BG_2018.pdf (978.18 Ko) Télécharger le fichier
Origin : Publisher files allowed on an open archive
Loading...

Dates and versions

hal-01790780 , version 1 (05-07-2018)

Identifiers

Cite

Angela Knapp, Kelly Mccabe, Olivier Grosso, Nathalie Leblond, Thierry Moutin, et al.. Distribution and rates of nitrogen fixation in the western tropical South Pacific Ocean constrained by nitrogen isotope budgets. Biogeosciences, 2018, 15 (9), pp.2619-2628. ⟨10.5194/bg-15-2619-2018⟩. ⟨hal-01790780⟩
294 View
144 Download

Altmetric

Share

Gmail Facebook X LinkedIn More