Trans boundary transport of pollutants by atmospheric mineral dust.

ABSTRACT

The transport of anthropogenic pollution by desert dust in the Eastern Mediterranean region was studied by analyzing major and trace element composition, organic species, and Pb isotope ratios in suspended dust samples collected in Jerusalem, Israel. Dust storms in this region are associated with four distinct synoptic conditions (Red Sea Trough (RS), Eastern High (EH), Sharav Cyclone (SC), and Cold Depression (Cyprus low, CD)) that carry dust mostly from North African (SC, CD, EH) and Arabian and Syrian (RS, EH) deserts. Substantial contamination of dust particles by Pb, Cu, Zn, and Ni is observed, while other elements (Na, Ca, Mg, Mn, Sr, Rb, REE, U, and Th) display natural concentrations. Sequential extraction of the abovementioned elements from the dust samples shows that the carbonate and sorbed fractions contain most of the pollution, yet the Al-silicate fraction is also contaminated, implying that soils and sediments in the source terrains of the dust are already polluted. We identified the pollutant sources by using Pb isotopes. It appears that before the beginning of the dust storm, the pollutants in the collected samples are dominated by local sources but with the arrival of dust from North Africa, the proportion of foreign pollutants increases. Organic pollutants exhibit behavior similar and complementary to that of the inorganic tracers, attesting to the importance of anthropogenic-pollutant addition en route of the dust from its remote sources. Pollution of suspended dust is observed under all synoptic conditions, yet it appears that easterly winds carry higher proportions of local pollution and westerly winds carry pollution emitted in the Cairo basin. Therefore, pollution transport by mineral dust should be accounted for in environmental models and in assessing the health-related effects of mineral dust.