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Influence of Particle Sinking Velocities on Carbon Flux Attenuation and Export Efficiency
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  • Maria Villa-Alfageme,
  • Elena Ceballos-Romero,
  • Feliciano de Soto,
  • Frederic Le Moigne,
  • Sarah Lou Carolin Giering,
  • Stephanie Henson
Maria Villa-Alfageme

Corresponding Author:[email protected]

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Elena Ceballos-Romero
Universidad de Sevilla Escuela Tecnica Superior de Ingenieria de Edificacion
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Feliciano de Soto
Universidad Pablo Olavide Departamento de Sistemas Fisicos Quimicos y Naturales
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Frederic Le Moigne
Helmholtz-Zentrum fur Ozeanforschung Kiel
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Sarah Lou Carolin Giering
National Oceanography Centre
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Stephanie Henson
National Oceanography Centre
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Particle sinking velocity is an important determinant of carbon transport and sequestration to the deep-sea. It is however technically challenging to measure in situ particle sinking velocities. Recently, methods based on the radioactive pairs, (234Th-238U and 210Po-210Pb) were developed to estimate average sinking velocity (ASV), along the classical carbon export flux estimates. The influence of ASVs on key metrics of the biological carbon pump such as (i) the particle export efficiency (defined as the proportion of PP being exported below the surface ocean) (ii) carbon export fluxes and attenuation, still remain uncertain and need to be further evaluated. ASVs are calculated in five biogeochemically contrasting sites: high latitude (Irminger Basin; Scotia Sea), temperate (PAP site) and oligotrophic (BATS, Equator) North Atlantic. ASVs are also calculated for different bloom stages (bloom - post bloom) in the North Atlantic and at the start of the bloom in two contrasting sites in the Southern Ocean (Scotia Sea). A systematic increase of ASVs with depth, inversely correlated to carbon flux attenuation, is detected. We assess whether the increase in ASV with depth is correlated with either temperature or community structure (phytoplankton and/or zooplankton). Evidences of ASV correlation with carbon export efficiency are detected, but they vary strongly with season and location, e.g. very distinct relationships are found for the results from Scotia Sea, likely driven by zooplankton abundance.