A Preliminary Assessment of Chemical Constituents of Atmospheric Particulate Matter and their Sources in Faisalabad, Pakistan

Atmospheric total suspended particulate matter (TSP) mass and chemical constituents were characterized, collected on glass fiber filters using high volume air sampler in Faisalabad, Pakistan from May 2012 to April 2013. Two receptor models Principal Component Analysis (PCA) and UNMIX were used for the source identification in the study area. High volume TSP samples (n=288) were subjected to gravimetric and quantitative chemical analyses for determining trace elements (Pb, Cd, Ni, Zn, Cu, Fe) using atomic absorption spectroscopy and water-soluble cations (Ca2+, Mg2+, Na+, K+, NH4+) and anions (Cl-, SO42- and NO3-) by ion chromatography. The average TSP concentration was 575 mu g m(-3) that is 1.6 and 8 times higher than Pak NEQS (360 mu g m(-3)) and US EPA (75 mu g m(-3)) annual limits, respectively. The crustal elements Ca, Fe, Mg and Na were the largest contributors to TSP mass while elements of anthropogenic origin Pb, Cd, Ni, Cu and Zn had relatively lower concentrations. The enrichment factors (EFs) for elements indicated that Pb, Cd, Cu, Zn and Ni (with EFs>100) were highly enriched and are of anthropogenic origin. Both PCA and UNMIX models produced comparable factor compositions and identified four possible sources: (1) crude oil combustion, (2) re-suspended crustal/road dust, (3) combination of coal and biomass burning and (4) secondary particles. Results of EF, cluster analysis and correlation analysis also duly supported the model results of source identification.