The Influence of Saharan and Middle Eastern Desert-Derived Dust on the Trace Metal Composition of Mediterranean Aerosols and Rainwaters: An Overview

Abstract

The particulate aerosol over the Mediterranean Sea consists largely of a ‘background’ of European-derived anthropogenic-rich material which has a trace metal composition similar to that over other European coastal seas, but which is subject to sporadic inputs of crustal-rich material from Saharan and Middle East desert sources which are often transported in the form of dust ‘pulses’. The input of Saharan dust results in increases in the total concentrations of crust-controlled trace metals (NEEs), such as Al and Fe, and to decreases in the values of AEEs, such as Cu, Zn and Pb, in the aerosol. Variations in the concentrations of trace metals at any one site in the Mediterranean Sea are largely controlled by: (i) the magnitude of the inputs of crust-rich dusts which are mixed with the anthropogenic-rich ‘background’ material, and (ii) precipitation scavenging, which removes both anthropogenic and crust-rich material from the air.