Short and Long-Term Transport of Crustal and Anthropogenic Inorganic Components of Coarse and Fine Aerosols over Beirut, Lebanon

Abstract

Beirut is an interesting experimental environmental chamber for its a cross road for several meteorological phenomena. Hence, measurements of fine and coarse particles were carried out during a whole year between February 2004 and January 2005 in a congested place (BH) in Beirut, Lebanon. The ionic and elemental compositions of PM collected in BH were determined using ion chromatography and PIXE analysis, respectively. Other PM 10 mass concentrations and chemical speciation were conducted in several urban places in Beirut for comparison purposes. BH results showed that crustal elements mainly Ca, Ti, Mn and Fe, which were typical products of the calcite and basaltic rocks specific to Lebanon, were higher than most reported values in the eastern Mediterranean region and constituted the main component of the coarse particles. In addition, coarse nitrate and sulfate ions resulted from the respective reactions of nitric and sulfuric acids with a relatively high amount of dust, i.e., calcium carbonate. In the fine particles, ammonium sulfate predominated with higher amounts determined in the summer. While nitrate was mainly due to local heavy traffic, sulfates were due to local and long-range transport phenomena. Chlorine levels were high when the wind originated from the sea and low during sand storms. In addition to sea salt, elevated levels of chloride were also attributed to waste mass burning in proximity to the site. Variability of the different elements seemed to be strongly dependent upon meteorological and atmospheric stability conditions and, in particular, wind regimes. Anthropogenic elements like Cu and Zn were generated from local industrial emission and vehicle exhausts whereas elevated levels of Pb were directly linked to a southerly wind originated from Egypt and Israel. The comparison of BH to other micro environmental sites in Beirut showed that high diurnal and seasonal variations in PM10 concentrations and ionic composition confirmed the dynamicity of the eastern Mediterranean environment. Nevertheless, higher PM10 levels seemed to correlate with congested areas. Considering the location in Beirut at the levant of the eastern Mediterranean region, its local atmospheric environment is highly affected by the regional pollution and the meteorological conditions.