Particle Export and Resuspension Fluxes in The Western North Atlantic

Abstract

Sediment traps were deployed at several locations throughout the Western North Atlantic to measure export and resuspension fluxes. Unpublished nephelometer profiles were examined prior to each cruise and water samples were filtered during each cruise to determine the distribution of particles in the water column, especially the nepheloid layer. Fluxes measured in boundary layers are probably overestimates of the net flux because of secondary circulation and turbulence. Therefore, export fluxes should be measured below the surface mixed layer and above the bottom boundary layer. In areas of active resuspension it is recommended that the export flux reaching the seafloor be measured at least 500 m above bottom to avoid including a resuspension flux component. Our flux data were combined with other data published for the Western North Atlantic to look for regional trends. Seasonal variations in the export flux of organic carbon measured 1000 m above the seafloor by Deuser (1987) (0.2–4.2 mgC/cm2/day) were larger than most of the spatial variations in the deep basin. Therefore, to accurately assess the spatial variations of export flux, it is necessary to measure the annual export flux, preferably in a time-series mode to determine the seasonal as well as the annual signal.