Statistical analysis of atmospheric trace metals and particulate fractions in Islamabad, Pakistan

Airborne suspended particulate matter was collected on glass fibre filters in urban atmosphere of Islamabad, Pakistan, using high volume sampler. The particulate samples were analysed for 10 selected metals (Fe, Na, Zn, K, Pb, Mn, Cr, Ni, Co and Cd) by FAAS method. Maximum mean contribution was noted for Fe (1.761 mu g/m(3)), followed by Na (1.661 mu g/m(3)), Zn (1.021 l mu g/m(3)), K (0.488 mu g/m(3)) and Pb (0. 128 mu g/m(3)). The particle size determination on vol.% basis for nine fractions (PM < 1.0, PM1.0-2.5, PM2.5-5, PM5-10, PM10-15, PM15-25, PM25-50, PM50-100 and PM > 100) was carried out using Mastersizer. PM5.0-10) were found to be most abundant in the local atmosphere followed by PM2.5-5.0 and PM15-25 while coarse/giant particles (PM50-100 and PM > 100) showed lower contribution. The trace metals were found to be mainly associated with smaller particulate fractions UP to PM10-15. Among the climatic parameters temperature has significant relationship with fine particles and airborne metal levels while relative humidity showed negative correlation. The source identification was carried out by principal component analysis and cluster analysis. Five metal sources were identified: industrial, vehicular emissions, metallurgical operations, garbage incineration and soil derived dust. The metal levels were also compared with those reported for other rural and urban parts around the world. (c) 2007 Elsevier B.V. All rights reserved.