Vertical particle flux in the northeast Atlantic Ocean (POMME experiment)

Abstract

In the framework of the Programme Océan Multidisciplinaire Méso Echelle (POMME) experiment, a 1.5 year record (February 2001–June 2002) of downward particle flux at 400 m and 1000 m was measured by sediment traps at four moorings located in the northeast Atlantic between 39°–43°N and 17°–19°W. Thorium‐230 was used to estimate sediment trap efficiency, revealing values ranging from 18.5 to 55%. The lowest trapping efficiency was observed for the trap having experienced the highest currents. Significant interannual variability between 2001 and 2002 was clearly linked to the differences observed in the mixed layer depth. At some sites, particulate organic carbon (POC) export was higher (up to a factor of 1.6) during summer than during the spring event. This could be related to the occurrence of short wind events that deepened the thermocline along with the presence of anticyclonic eddies, yielding an input of new nutrients. The average percentage of POC exported compared to the primary production of organic carbon in the surface waters ranged between 1.3 and 5.0%, with higher export efficiency during the spring. Finally, although the area was shown to present a relatively high mesoscale activity that might impact the geochemistry, POC export was rather homogeneous over the POMME area: 4.9 ± 1.6 gC m−2 yr−1 were exported below 1000 m between February 2001 and February 2002. Therefore a large fraction of the new production may be exported through convection and mode water circulation rather than by particle settling.

Vertical distribution of aggregates (>110 µm) and mesoscale activity in the northeastern Atlantic: Effects on the deep vertical export of surface carbon

“…9. Comparison between UVP potential mass fluxes and mass fluxes from sediment traps at (A) 400 m and (B) 1,000 m. The sediment traps were corrected for trapping efficiency, which was estimated to range from 20% to 50% (Guieu et al 2005).…”

A four‐dimensional mesoscale map of the spring bloom in the northeast Atlantic (POMME experiment): Results of a prognostic model

“…In the model, this has been achieved by taking into account only slow (3 m d −1 ) sinking particles. This suggests that a large contribution of the export is achieved later in the season, either in the form of sinking particles (but this hypothesis seems not to be confirmed by the results of fixed sediment traps [ Guieu et al , 2005]) or rather through winter convection of dissolved organic material. This is the case at similar latitudes in the Mediterranean Sea [ Lévy et al , 1998].…”

The impact of Saharan dust on the particulate export in the water column of the North Western Mediterranean Sea

“…For samples treated at LOV, the concentration of total carbon and nitrogen was analysed in triplicate with a Perkin Elmer 2400 elemental analyser on 3-4 mg sub-samples of the desiccated samples, all according to Guieu et al (2005).…”