Characterization of the Khamaseen (spring) dust in Jordan

摘要

During the spring each year, the Eastern Mediterranean is affected by Khamaseen dust cyclones sourced from the North African Sahara. In order to characterize Khamaseen dust in Jordan, we collected dust from ten localities during the spring of 2006. The collected dust was analyzed for grain size, mineralogy, and chemical composition. The dust is predominantly aluminosilicates (clay minerals and feldspars), quartz and carbonates with minor amounts of phosphate. The particles are mostly subrounded to subangular and generally between 5 and 20 μm in size. The majority of the elements analyzed have a natural abundance and distribution. However, several elements such as As, Cd, Cr, Cu, Pb, Se and Zn have higher than natural abundances due to anthropogenic enrichment by various enrichment factors. The analyzed dust samples are chemically homogenous, indicating a similar provenance and good mixing by the Khamaseen winds. The rare earth elements patterns are similar to those of the upper continental crust composition and average shale. Total amount of dust deposited on Jordan during the spring of 2006 is around 0.3 million tons.