Temporal variability of atmospheric trace element concentrations over the eastern Mediterranean Sea

Concentrations of elements and ions measured in aerosol samples collected between March 1992 and December 1993 were investigated to understand temporal variability of elemental concentrations. Collected samples were analyzed by atomic absorption spectrometry, instrumental neutron activation analysis, ion chromatography and colorimetry for approximately 40 elements and major ionic species. Concentrations of elements were found to vary greatly on time scales ranging from days to seasons. Short-term variations in the concentrations of pollution-derived elements are explained by transport from source regions. Short-term variations in the concentrations of sea-salt and crustal elements, on the other hand, are due to the episodic nature of wind-induced particle generation mechanisms. Transport failed to explain long-term variations due to lack of seasonal changes in air mass transport patterns. The seasonal variations in the concentrations of anthropogenic elements are determined by the wet deposition of particles, which is more extensive in the wet season, and distances between source regions and the sampling site. The long-term variations in the concentrations of crustal and sea-salt elements are explained by seasonal changes in their source strengths. Distant rains on the path of the air masses which transport anthropogenic particles to the eastern Mediterranean are more influential on the observed seasonal behavior of pollution-derived elements than local rain events.