The distribution of Al in the IOC stations of the eastern Atlantic between 30 ° S and 34 ° N

Abstract

Abstract The aluminium content of samples collected from four vertical stations and 74 surface samples in the southern and eastern basins of the central Atlantic was determined on board ship during the International Oceanographic Commission's first baseline cruise. The profile results show that the distribution of Al can be interpreted as the result of advective movement of the various water masses that appear within these stations. The Al content of these water masses is directly related to the magnitude of the eolian impact in their formation regions. The differences between deep-water Al concentrations in the southern and northern basins of the eastern Atlantic appear to be related to differences in the Al content of the source waters feeding through the Romanche and Vema Fracture Zones. The elevated deep-water Al concentrations found in the Seine Abyssal Plain in the eastern Atlantic are identical to those previously reported in the western basin of the North Atlantic suggesting that there is either a direct advective relation between the two regions or a common mechanistic cause for the bottom-water elevations in both basins. The near-surface distribution of Al at 24 ° N indicates that the element is capable of recording the recent mixing and stratification history of the upper waters. Surface-water concentrations of Al, which vary from 0.2 to 86 nM, reveal an almost point-like source in the Guinea Basin resulting from the ITCZ induced rain-out of Saharan origin dust. The subsequent advection of this signal illuminates many of the major circulation features of the region.