Trace elements in atmospheric particulates over the Eastern Mediterranean; Concentrations, sources, and temporal variability

The first long-term, land-based sampling of the atmosphere above the Turkish coast of the Northeastern Mediterranean Sea (36° 33′ 54″ N and 34° 15′ 18″ E) has demonstrated the dominance of Sahara desert particles over the basin. Atmospheric samples, collected on Whatman-41 filter papers, had been analyzed for Al, Fe, Ca, Mg, Mn, Ni, Cr, Co, Cd, Pb, Zn, V and Na by flame and flameless modes of AAS. Analysis of 339 samples collected during the period August 1991 to December 1992 has shown that pulses of desert particles invade the region from March–May and October–November and during such events the concentrations of the crustal elements (Al, Fe) in atmospheric particulate increase by an order of magnitude. The concentrations of such anthropogenic elements as Zn and Cd reach their maximum levels during the dry season. Three days backward, three-dimensional air-mass trajectory analysis has confirmed the invasion of the basin by sporadic but intense concentrations of dust originating from the Sahara. The elemental composition of size fractionated samples collected over the basin in summer and fall also verifies the existence of particles of both anthropogenic and crustal origins. The geographic position of the sampling tower lies downstream of the tracks of all major air masses affecting the area and therefore the data set can be used to define the atmospheric particulate over the Eastern Mediterranean.