ANNUAL BIOGENIC PARTICLE FLUXES TO THE INTERIOR OF THE NORTH-ATLANTIC OCEAN - STUDIED AT 34-DEGREES-N 21-DEGREES-W AND 48-DEGREES-N 21-DEGREES-W

In order to clarify the annual quality, quantity and export process of biogenic particles from the euphotic zone to the deep ocean interior, an array of automated time-series sediment traps were deployed for 1 year from 4 April 1989 to 17 April 1990 at 34-degrees-N 21-degrees-W and 48-degrees-N 21-degrees-W as part of the Joint Global Ocean Flux Program (JGOFS) North Atlantic Bloom Experiment (NABE). Three sediment traps with 13 time-series sediment collectors were placed at both stations approximately 1 and 2 km below the surface and 0.7 km above the bottom. They collected settling particles during 26 14-day intervals for 376 days with an 20-day hiatus in September-October 1989 for changeover of the trap moorings. The collection periods of the six traps were synchronized, forming a spatio-temporal matrix of 156 samples. The annual mass flux at about 2 km deep during this experiment was 22 and 27 g m-2 y-1 at the 34 and 48-degrees-N stations, consisting of biogenic particles with traceable quantities of lithogenic particle flux. The spring particle bloom, characterized by the sedimentation of particles relatively enriched by N(org), began in January at the 34-degrees-N station and in March at the 48-degrees-N station. The bloom continued for 4.5 and 3 months and provided 62 and 50% of the annual biogenic particte mass-flux at 2 km at the 34 and 48-degrees-N stations. The surface bloom penetrated to the ocean interior within a few weeks, with apparently accelerated settling speed at deeper layers. The order of susceptibility of biogenic elements to mineralization while settling in the 1-0.7 km a.b. water column was, from least to most resistant: P, N(org), C(org), Si and Ca. The C/N/P ratio at 0.7 km a.b. was 154 : 18 : 1 at the 34-degrees-N station and 148 : 18 : 1 at the 48-degrees-N station.