Silica fluxes in the northeast Atlantic frontal zone of Mode Water formation (38 degrees-45 degrees N, 16 degrees-22 degrees W) in 2001-2002

• Published in: Journal of Geophysical Research
• Main Authors: Mosseri, J, Queguiner, B, Rimmelin, P, Leblond, N, Guieu, C
• Other Authors: Observatoire océanologique de Villefranche-sur-mer (OOVM), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC), Laboratoire d'océanographie de Villefranche (LOV), Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut de la Mer de Villefranche (IMEV), Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2005
• Subjects: [SDU.STU.OC]Sciences of the Universe [physics]/Earth Sciences/Oceanography; Northeast Atlantic
• Online Access: https://hal.archives-ouvertes.fr/hal-03494209; https://hal.archives-ouvertes.fr/hal-03494209/document; https://hal.archives-ouvertes.fr/hal-03494209/file/Journal%20of%20Geophysical%20Research%20Oceans%20-%202005%20-%20Mosseri%20-%20Silica%20fluxes%20in%20the%20northeast%20Atlantic%20frontal%20zone%20of%20Mode.pdf; https://doi.org/10.1029/2004JC002615

International audience [ 1] The biogenic (BSi) and lithogenic (LSi) silica export fluxes were investigated in the northeast Atlantic (38 degrees - 45 degrees N, 16 degrees - 22 degrees W) as part of the Programme Ocean Multidisciplinaire Meso Echelle (POMME) program in 2001 - 2002. They were measured at four stations located on both sides of a frontal zone (40 degrees - 42 degrees N) by means of permanent moorings of sediment traps deployed at 400 and 1000 m depth. Averaged over the area, the annual BSi fluxes ( corrected from Th-230 trapping efficiencies) ranged between 0.240 mmol m(-2) d(-1) at 400 m to 0.316 mmol m(-2) d(-1) at 1000 m. The bulk annual BSi fluxes are comparable to bulk BSi export fluxes recorded for oligotrophic areas. The annual export flux of LSi ( range 0.029 mmol m(-2) d(-1) at 400 m to 0.054 mmol m(-2) d(-1) at 1000 m) was lower than BSi and accounted for 10% of the total silica export flux. Results show a strong coupling between the two siliceous particulate fractions, which is interpreted as reflecting LSi scavenging by BSi and limitation of BSi production in surface water by lithogenic ( trace metals) inputs. BSi export was maximum at the beginning of the productive season during the spring bloom. However, annual BSi export fluxes in 2001 were quite higher at 400 m in the southern area ( e. g., 0.249 - 0.288 at the southeast station versus 0.211 mmol BSi m(-2) d(-1) at the northeast station) contradictory to the classical south-north surface production increase. We suggest an advective lateral transport within the upper 400 m of siliceous particles from the northern, more productive area to the southern region.