Carbon and silica fluxes during a declining North Atlantic spring bloom as part of the EXPORTS program
Clevenger, Samantha J. (Massachusetts Institute of Technology)
Benitez-Nelson, Claudia (University of South Carolina. School of the Earth, Ocean and Environment)
Roca Martí, Montserrat (Universitat Autònoma de Barcelona. Institut de Ciència i Tecnologia Ambientals)
Bam, Wokil (Woods Hole Oceanographic Institution (Woods Hole, Estats Units d'Amèrica))
Estapa, Margaret (University of Maine. School of Marine Sciences)
Kenyon, Jennifer A. (Massachusetts Institute of Technology)
Pike, Steven (Woods Hole Oceanographic Institution (Woods Hole, Estats Units d'Amèrica))
Resplandy, Laure (Princeton Univeristy. Department of Geosciences)
Wyatt, Abigale (Princeton Univeristy. Department of Geosciences)
Buesseler, Ken (Woods Hole Oceanographic Institution (Woods Hole, Estats Units d'Amèrica))

Data:	2024
Descripció:	18 pàg.
Resum:	The goal of NASA's EXport Processes in the Ocean from RemoTe Sensing (EXPORTS) project is to develop a predictive understanding of the fate of global ocean primary productivity and export of carbon from the surface to the deep ocean. Thorium-234 (234Th, t1/2 = 24. 1 d) was used to measure sinking particle export from an anticyclonic eddy during the EXPORTS North Atlantic cruise (May 2021) at the Porcupine Abyssal Plain. The four-week sampling period was broken into three time periods ("epochs") where 800 234Th seawater samples were collected from over 50 CTD casts with high depth resolution over the upper 500 m. Size-fractioned particulate samples were collected to determine particulate organic carbon (POC) and biogenic silica (bSi) to 234Th ratios using in situ McLane pumps. A 234Th non-steady state model shows an eddy center epoch average progression of increasing 234Th export (∼2800 ± 300 (Epoch 1; standard deviation) to 4500 ± 700 (Epoch 3) dpm m−2 d−1) out of the top 110 m of the water column over the course of the cruise (29 d). This translates into an epoch average progression of ∼11 ± 1 to 14 ± 2 mmol C m−2 d−1 of sinking POC flux, and ∼ 3 ± 1 to 6 ± 1 mmol bSi m−2 d−1 of sinking bSi flux to deeper waters at 110 m. The overall efficiency of the biological carbon pump (amount of net primary production reaching 100 m below the euphotic zone) increases from ∼10% to ∼30% throughout the sampling period. The temporal trends discussed extensively in this paper show that POC and bSi export increase during diatom bloom evolution.
Ajuts:	Agència de Gestió d'Ajuts Universitaris i de Recerca 2021/BP-00109
Nota:	María de Maeztu CEX2019-000940-M
Drets:	Aquest document està subjecte a una llicència d'ús Creative Commons. Es permet la reproducció total o parcial i la comunicació pública de l'obra, sempre que no sigui amb finalitats comercials, i sempre que es reconegui l'autoria de l'obra original. No es permet la creació d'obres derivades.
Llengua:	Anglès
Document:	Article ; recerca ; Versió publicada
Matèria:	Biogenic silica export ; Biological carbon pump ; Carbon export ; Diatom bloom ; North Atlantic Ocean spring bloom ; Porcupine Abyssal Plain ; Radionuclides ; Thorium
Publicat a:	Marine Chemistry, Vol. 258 (January 2024) , art. 104346, ISSN 0304-4203

DOI: 10.1016/j.marchem.2023.104346

18 p, 7.3 MB

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