Dissolved aluminium in the Mediterranean

Three vertical profiles of dissolved Al and nutrients are reported from the eastern basin of the Meditenanean. Profiles of Al concentrations resemble those of the nutrient elements, except that a proportionally higher residual concentration remains in the surface layer. Concentrations of Al in the surface water inflow from the North Atlantic, which contains between 10 and 20 nM around Gibraltar, are elevated to 55, 59 and 75 nM at the stations occupied. Calculations indicate that these concentrations are probably produced by dissolution Al from aeolian dust and advective mixing of Al-rich deep waters into the surface layer, balanced by a biologically-associated removal process. The Al removed from the surface layer redissolves in the deep water to raise Al concentrations to about 160 nM. Samples were also recovered from anonic deep brines in the Tyro and Bannock basins. In the brines, Al concentrations fail to about 15 nM while Si concentrations approach 270 nM.