FN Archimer Export Format
PT J
TI Quantifying N2 fixation and its contribution to export production near the Tonga-Kermadec Arc using nitrogen isotope budgets
BT 
AF Forrer, Heather J.
   Bonnet, Sophie
   Thomas, Rachel K.
   Grosso, Olivier
   Guieu, Cecile
   Knapp, Angela N.
AS 1:1;2:2;3:1;4:2;5:3;6:1;
FF 1:;2:;3:;4:;5:;6:;
C1 Earth, Ocean, and Atmospheric Science Department, Florida State University, Tallahassee, FL, United States
   Aix Marseille University, Université de Toulon, CNRS, IRD, MIO Marseille, France
   Laboratoire d’Oceanographie de Villefranche, CNRS, Sorbonne University, Villefranche-sur-mer, France
C2 UNIV FLORIDA STATE, USA
   UNIV AIX MARSEILLE, FRANCE
   UNIV SORBONNE, FRANCE
IN DOAJ
TC 1
UR https://archimer.ifremer.fr/doc/00871/98264/107619.pdf
   https://archimer.ifremer.fr/doc/00871/98264/107620.docx
LA English
DT Article
CR TONGA 2019
   TONGA RECUP
BO L'Atalante
   Alis
DE ;N-2 fixation;nitrate d15N;Tonga Arc;South Pacific;hydrothermal vents;d15N budget
AB The spatial distribution of marine di-nitrogen (N2) fixation informs our understanding of the sensitivities of this process as well as the potential for this new nitrogen (N) source to drive export production, influencing the global carbon (C) cycle and climate. Using geochemically-derived δ15N budgets, we quantified rates of N2 fixation and its importance for supporting export production at stations sampled near the southwest Pacific Tonga-Kermadec Arc. Recent observations indicate that shallow (<300 m) hydrothermal vents located along the arc provide significant dissolved iron to the euphotic zone, stimulating N2 fixation. Here we compare measurements of water column δ15NNO3+NO2 with sinking particulate δ15N collected by short-term sediment traps deployed at 170 m and 270 m at stations in close proximity to subsurface hydrothermal activity, and the δ15N of N2 fixation. Results from the δ15N budgets yield high geochemically-based N2 fixation rates (282 to 638 µmol N m-2 d-1) at stations impacted by hydrothermal activity, supporting 64 to 92% of export production in late spring. These results are consistent with contemporaneous 15N2 uptake rate estimates and molecular work describing high Trichodesmium spp. and other diazotroph abundances associated with elevated N2 fixation rates. Further, the δ15N of sinking particulate N collected at 1000 m over an annual cycle revealed sinking fluxes peaked in the summer and coincided with the lowest δ15N, while lower winter sinking fluxes had the highest δ15N, indicating isotopically distinct N sources supporting export seasonally, and aligning with observations from most other δ15N budgets in oligotrophic regions. Consequently, the significant regional N2 fixation input to the late spring/summer Western Tropical South Pacific results in the accumulation of low-δ15NNO3+NO2 in the upper thermocline that works to lower the elevated δ15NNO3+NO2 generated in the oxygen deficient zones in the Eastern Tropical South Pacific. 
PY 2023
PD OCT
SO Frontiers In Marine Science
PU Frontiers Media SA
VL 10
UT 001103924400001
DI 10.3389/fmars.2023.1249115
ID 98264
ER

EF