THE DISTRIBUTION OF AL IN THE IOC STATIONS OF THE NORTH-ATLANTIC AND NORWEGIAN SEA BETWEEN 52-DEGREES AND 65-DEGREES NORTH

The vertical distribution of dissolved and reactive aluminium was dete rmined at nine stations in the eastern and western North Atlantic, the Norwegian Sea and on a surface water transect during the Internationa l Oceanographic Commission's second open ocean baseline survey. The pr ofile results show that the distribution of dissolved Al is primarily the result of advective movement of the various water masses that appe ar in these stations. Control of the dissolved Al distribution in the central and upper waters of the eastern and western basin of the North Atlantic appears to be related to the mixing series forming these wat ers. Namely, in the eastern basin by mixing of low salinity, low Al co re North Atlantic Central Water (NACW) with high salinity, high Al Med iterranean Water (MW), Dissolved Al concentrations in a series of remn ant mixed layers seen immediately above the NACW are consistent with t he production of this water mass by deep wintertime convection. In the western basin and Charlie Gibbs Fracture Zone, the influence of the M W is restricted by the invasion of eastward spreading Labrador Sea Wat er (LSW), The central waters of the western basin primarily reflect a two end-member mixing of core LSW and high salinity moderate to low Al surface waters. Dissolved Al in surface waters along the ship's track range between 0.88 and 3.3 nM and generally reflect the prevailing sa linity distribution. We show that the elevated deep water Al concentra tions seen in the North Atlantic cannot be supported by either advecti on of high Al waters from the Arctic seas or by addition of Al from re suspension of bottom material in the high energy overflow zones. We pr esent a mass balance of Al in the North Atlantic. Our calculations sho w that there is a 'missing' flux of some 6.1 X 10(9) mol of Al yr(-1) entering the North Atlantic Ocean. We examine the potential for the pa rtial dissolution of eolian dust to provide this missing Al and demons trate that a dissolution of 3% provides a balance within the errors in herent in these calculations, We suggest that atmospherically deposite d Al is rapidly scavenged from the surface waters and removed to the s ediment-sea water interface where remobilisation of labile particulate Al occurs and leads to a basin-wide diffusive type profile enriching the deep waters of the North Atlantic. (C) 1998 Elsevier Science B.V.