VERTICAL DISTRIBUTION OF DISSOLVED ALUMINUM IN THE MEDITERRANEAN SEA

The vertical distribution of dissolved aluminium in the Mediterranean Sea offshore of Corsica has been followed during a period of high biological activity (April-September). In May and August, the concentration of dissolved aluminium is at a relatively low (1.5 μg Al1-1) and rather constant value in the surface waters, while exhibiting minimum values of about 0.5 and 0.8 μg Al1-1 in April and September. It increases under the seasonal thermocline to a depth of 150-500 m. The bottom waters are characterized by a constant and relatively high value of 4 μg Al1-1. The observed concentrations of dissolved aluminium are not compatible with a precipitation-dissolution mechanism of clay minerals. The general distribution pattern and the seasonal changes of dissolved aluminium exhibit strong analogies with those of dissolved silica and nitrogen, suggesting a pre-dominant role of biological activity. It is not possible at this stage to attribute the aluminium uptake in the photic zone solely to the activity of diatoms, as suggested earlier. © 1979.