Distribution of aluminium in waters of the North East Atlantic 25°N to 35°N

Dissolved Al concentrations from the NE Atlantic, between 25°N and 35°N off the coast of NW Africa, range from 16 nM to 32 nM in a well-mixed surface layer extending to 150 m depth, increasing towards the maximum of the Saharan dust plume. Mediterranean outflow water is detected as a high Al anomaly corresponding to the salinity signal of the Mediterranean water. Other than in surface and Mediterranean waters Al concentrations are invariant with depth, but increase from 6 nM to 11 nM towards the continental margin. The magnitude of the dissolved Al signal in the surface layer is compatible with dissolution of Al from the highest of present estimates of dust input to this area. Comparison with data from other areas indicates that Al cannot be cycled through the oceans in parallel to silica as has been previously suggested.