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.
Type de document :
Article dans une revue
Biogeosciences, European Geosciences Union, 2018, 15 (9), pp.2619-2628. 〈10.5194/bg-15-2619-2018〉
Liste complète des métadonnées

https://hal.archives-ouvertes.fr/hal-01790780
Contributeur : Thierry Moutin <>
Soumis le : jeudi 5 juillet 2018 - 16:44:15
Dernière modification le : mercredi 19 septembre 2018 - 01:30:12
Document(s) archivé(s) le : lundi 1 octobre 2018 - 18:41:42

Fichier

Knapp_et_al_BG_2018.pdf
Fichiers éditeurs autorisés sur une archive ouverte

Identifiants

Citation

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, European Geosciences Union, 2018, 15 (9), pp.2619-2628. 〈10.5194/bg-15-2619-2018〉. 〈hal-01790780〉

Partager

Métriques

Consultations de la notice

197

Téléchargements de fichiers

37