چكيده به لاتين
Intensification of the Middle East water bodies’ desiccation and drought occurrence, has led to dust storms increase in Iran particularly in Khuzestan province in recent years. Hence, understanding the physical and chemical characteristics of the dust fallouts in the province is prominent.
In this thesis, the concentration of heavy metals and polycyclic aromatic hydrocarbons in the dust fallout of Ahvaz were studied during the dusty and normal days. To this end, after samples collection and preparation from 5 stations, the concentration of heavy metals and polycyclic aromatic hydrocarbons were determined. X-Ray tests were also done to investigate the dust fallouts mineralogy. Laser particle size test was performed to determine particle size distribution of the dust fallouts. To investigate the similarities and differences of deposited dust emitted from different dust storms sources, source identification was made for studied dust storms using the HYSPLIT model. Using available indices, ecological risk, enrichment factor and health hazard risk were calculated. Heavy metals analysis results depicted Cd has significantly more concentration comparing upper earth crust content. The highest concentration of Pb and Cu were observed in dust fallouts of February 18 dust storm. Source identification results showed that Tigris-Euphrates zone in Iraq and Syria, Kuwait and Saudi-Arabia deserts, boundary areas of Khuzestan and Iraq, and western and southern parts of Khuzestan province were accounted as main sources of February 18, May 5, May 31 and July 26 dust storms respectively. The dust fallouts particle sizes were in the range of 5-65 µm. The major chemical composition of the dust fallouts included SiO2, CaO, Fe2O3 and Al2O3. An abundant amount of calcite and quartz were observed in the dust fallouts mineralogical composition. According to enrichment factor results, all metals except Cd had minimal and moderate enrichment. In ecological risk results, only Cd had a very high ecological risk. The most and least total concentration of 8 measured hydrocarbons were observed in February 18 dust storm and normal days respectively. Petrol emissions, petrogenic sources and biomass burning were determined as main sources of polycyclic aromatic hydrocarbons.
Keywords: The dust fallouts of dust storms, Source identification, Heavy metals, Polycyclic aromatic hydrocarbons, Enrichment factor, Mineralogy
