Role of desert aerosol in metal fluxes in the Mediterranean area.

Aerosols and precipitations collected over Sardinia are mainly controlled by two end-members: Saharan and European. European background aerosols in Sardinia show a 3 to 25-fold decrease in EFcrust values for Cd, Zn, Pb, and Cr compared with coastal stations in the Western Mediterranean. Partitioning of total atmospheric deposition between the soluble and the insoluble phases shows that Al, Si, Fe and Pb originating from the atmosphere are mostly in the insoluble form. For Ca, Cd, Cr metals the dissolved fraction represents 50-90 % of the total input. \ud Aerosol dissolution experiments performed at particle concentrations ranging from 3 to 300 mg l-1 show Cd and Pb exhibiting low solubility at the high mass particle concentration. Solubility of Pb increases with the EFcrust values and the finest grain-size of the aerosols (