AIR-BORNE DUST FLUXES TO A DEEP-WATER SEDIMENT TRAP IN THE SARGASSO SEA

The record of atmospheric dust deposition as recorded by a deep sea se diment trap in the Sargasso Sea is presented. The record is shown to b e consistent with the limited available data on directly measured atmo spheric dust loadings. The seasonality of the sediment trap dust flux is different from that of the atmospheric deposition as a result of se asonal biological cycles in the surface water. On the longer term the sediment trap dust flux undergoes quite large variations in the annual average flux from 3.6 to 9.4 mg m(-2) d(-1). These variations are sho wn to reflect changes in atmospheric transport efficiency from source regions in North Africa rather than changes in the strength of the dus t source in that region. The changes in the dust inputs to this area o f the Sargasso Sea appear not to have changed the flux of carbon reach ing the deep water, and the implications of this are discussed.