AAAR 33rd Annual Conference
October 20 - October 24, 2014
Rosen Shingle Creek
Orlando, Florida, USA
Abstract View
Sources and Chemical Composition of Atmospheric Fine Particles in Rabigh, Saudi Arabia
HAIDER A KHWAJA, Omar S Abu-Rizaiza, Azhar Siddique, Shedrack R Nayebare, Mirza M Hussain, Jahan Zeb, King Abdulaziz University, Saudi Arabia
Abstract Number: 298 Working Group: Urban Aerosols
Abstract Air pollution is a major environmental problem of public concern in several developing countries of the world. Research into air pollution in Saudi Arabia and the whole of Middle East region is at its inception. There are significant gaps in policy guidelines related to air pollution control in the region, which has worsened the air quality over the years. This study presents the first detailed data on fine particulate matter (PM2.5) concentrations of Black Carbon (BC) and trace metals (Na, Mg, Al, Si, S, Cl, K, Ca, Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, Br, Sr, Cd, Sb, and Pb) at Rabigh, Saudi Arabia, and assesses their sources. Analytical results showed several characteristics aspects of air pollution at Rabigh area. Sulfur and BC mass concentrations ranged from 68.6 to 642 ng/m3, and from 0.39 to 1.31 µg/m3, respectively, while the PM2.5 mass concentration ranged from 12.2 to 75.9 µg/m3 with significant temporal variability. More than 90% of the time, the daily PM2.5 levels exceeded the 24 h WHO guideline of 20 µg/m3 . An Air Quality Index (AQI) was calculated for PM2.5 at Rabigh, with any PM2.5 level beyond moderate, reported as a “level of health concern” (good: <=12 µg/m3, moderate: 12.1 – 35.4 µg/m3, unhealthy for sensitive groups: 35.5–55.4 µg/m3, unhealthy: 55.5 – 150.4 µg/m3, very unhealthy: 151 – 250 µg/m3, and hazardous: 251 – 350 µg/m3). Based on the AQI, there were 44% days of moderate air quality, 33% days of unhealthy air quality for sensitive groups, and 23% days of unhealthy air quality throughout the study period. Two broad categories of aerosol trace metal sources were defined: anthropogenic (S, V, Cr, Ni, Cu, Zn, Br, Cd, Sb, and Pb) and naturally derived elements (Si, Al, and Fe). The extent of anthropogenic contribution was estimated by the degree of enrichment of these elements compared to the crustal composition. Soil resuspension and/ or mobilization appear to be the important source of “natural” elements, while "anthropogenic" elements originate primarily from fossil fuel combustion and industries. Ni and V correlated strongly pointing to combustion of heavy fuel oil as the likely source. A factor analysis method, positive matrix factorization (PMF), was used to obtain information about possible sources of aerosol.