Characterization and Elemental Composition of Atmospheric Aerosol Loads during Springtime Dust Storm in Western Saudi Arabia

ABSTRACT

Dust storm is a common phenomenonand, a severe environmental hazard in western Saudi Arabia. In this study, simultaneous measurement of PM₁₀, PM_2.5 and PM_1.0 and elemental compositions analysis of PM_2.5 in Jeddah city during springtime (March 2012) dust storm (DS) and non-dust storm (non-DS) periods were carried out to investigate the impact of DS on the levels, characterization and elemental compositions of atmospheric particles. Results indicate that PM fractions concentrations were higher in DS environment compared to non-DS. The diurnal variation of PM fractions concentrations was uni-modal in non-DS environment and bimodal in DS. PM_1.0/PM₁₀, PM_2.5/PM₁₀ and PM_2.5/PM_2.5–10 ratios were relatively lower in DS, indicating that sand-dust events in spring carry much more coarse than fine particles to Jeddah. PM₁₀, PM_2.5 and PM_1.0 in DS and PM₁₀ and PM_2.5 in non-DS might originate from similar sources. PM₁₀, PM_2.5, PM_1.0 in DS and PM₁₀ in non-DS were correlated negatively with relative humidity and positively with wind speed. PM_2.5 and PM_1.0 in non-DS were correlated positively with relative humidity and negatively with wind speed. The crustal elements accounted for 44.62 and 67.53% of the total concentrations of elements in non-DS and DS, respectively. The elements concentrations increased in DS, with highest DS/non-DS ratios for Ca, Si, Al and Fe. This indicates that the soil originating species contributed mainly in DS particles.The enrichment factors values and non-crustal fractions in both non-DS and DS indicate that the main sources of Na, Mg, Si, K, Ca, Ti, Cr, Mn, Fe, Rb and Sr are of a crustal type, whereas S, Cl, Co, Cu, Zn, Ga, As, Pb and Cd are anthropogenic. V and Ni in DS only are emitted from anthropogenic sources. The enrichment factors of these anthropogenic elements were lower in DS. They might originate mainly from local sources in Jeddah.