Statistical modeling of atmospheric trace metals in Lahore, Pakistan for correlation and source identification

Heavy metals in airborne suspended particulate matter were collected on glass fiber filters from four different locations from urban atmosphere of Lahore, Pakistan. The particulate matter was analyzed for eight trace metals (Fe, Pb, Ni, Cu, Cr, Mn, Zn and As) using Atomic Absorption Spectrophotometer. Mean concentration of iron (23.08 µg/m3), lead (6.23 µg/m3), nickel (7.95 µg/m3) and zinc (15.36 µg/m3) were higher while copper (3.14 µg/m3), chromium (1.23 µg/m3), manganese (2.0 µg/m3) and arsenic (1.59 µg/m3) concentrations were low. Symmetrical (Fe, Pb, Ni, and As) and non symmetrical (Cr, Mn, Cu, and Zn) distribution was observed. Spearman’s correlation showed similar sources while Analysis of Variance (ANOVA) data justified some relationship between sampling sites and trace metals. Principal component analysis and cluster analysis data identified five different sources i.e. metallurgical operations, industrial emissions, vehicular emission, burning of biomass and anthropogenic activities. The findings of study were supported by reports in different parts of the world.