Comprehensive urban air quality studies of Islamabad: elemental characterization of PM10 and PM2.5, source apportionment and transboundary pollutant migration (abstract)

Long term urban air quality of Islamabad, the capital city of Pakistan, has been investigated as a part of the joint UNDP/IAEA/RCA/RAS/7/015 project, entitled Characterization and source identification of particulate air pollution in the Asian region (RCA). Around 380 pairs of fine (PM2.5) and coarse (PM10-2.5) polycarbonate filters from the Nilore area were collected using GENT sampler. The average PM2.5 and PM2.5-10 masses at this site were found to be 15.02 and 37.01 g/m/sup 3/ respectively that are far below to the Pakistani limit for PM10 of 100 g/m/sup 3/. The average Black Carbon (BC) was found to be 2.58 and 1.22 g/m/sup 3/ corresponding to 20.7% and 4.54% of the fine and coarse mass respectively. The non destructive Ion Beam Analysis method, Proton induced X-ray emission (PIXE) and Proton induced gamma ray emission (PIGE) were employed to quantify more than 40 elements in both fine and coarse fractions. The acquired elemental data has been statistically treated and subjected to mass closure studies, principal component and factor analysis to calculate correlation matrices. The reconstructed mass (RCM) was calculated for both particle modes using soil, sulphate, smoke, sea salt and BC as pseudo sources. Data analysis performed using EPA-PMF3 shows that the fine and coarse data for the suburban site identifies 4 sources; biomass/ combustion, road dust, soil and automobile. Long range transport of pollutants was studied using HYSPLIT4 model. It was observed that high fine soil contributions in this area were mainly from dust storms arriving from west and North West of the country. (author)