Elemental and carbonaceous characterization of TSP and PM during Middle Eastern dust (MED) storms in Ahvaz, Southwestern Iran.

Middle Eastern dust (MED) storms carry large amounts of dust particles to the Southern and Western cities of Iran. This study aimed to characterize the elemental and carbonaceous composition of total suspended particles (TSP) and PM in Ahvaz, Iran. TSP and PM samples were collected using two separate high-volume air samplers. The sampling program was performed according to EPA guidelines and resulted in 72 samples. Twenty-eight elements and two carbonaceous components in TSP and PM were measured. Over the entire study period, the mean concentration (SD) of TSP and PM was 1548.72 μg/m (1965.11 μg/m) and 1152.35 μg/m (1510.34 μg/m), respectively. The order of concentrations of major species were Si > Al > Ca > OC > Na > B > Zn > Mn > K > Mg and Si > Ca > Al > Na > OC > B > K > Mn > Cu > Mg for TSP and PM, respectively. Almost all elements (except for Cd, Cr, and Cu) and carbonaceous components (except for organic carbon) had dust days/non-dust days (DD/NDD) ratios higher than 1, implying that all components are somehow affected by dust storms. Crustal elements constituted the major portion of particles for both TSP and PM in both DDs and NDDs. The enrichment factor of elements such as Ca, Fe, K, Mg, Na, and Ti was near unity. Species such as Al, Ca, Fe, K, Na, Si, and EC had high correlation coefficients in both TSP and PM (except for EC). In conclusion, Ahvaz is exposed to high concentrations of TSP and PM during the MED period. Immediate actions must be planned to decrease the high concentrations of particulate matter in Ahvaz's ambient air.