CHARACTERIZATION OF TRACE METALS IN TSP ALONG A DENSE TRAFFIC HIGHWAY IN OGBOMOSO, NIGERIA

Total Suspended Particles (TSP) in ambient air were collected at seven spots along a dense traffic highway in Ogbomoso, Nigeria. Particulate matters in TSP were extracted from filters by digestion method using a mixture of HNO3 and H2O2, and the extract was analyzed for ten trace metals using Atomic Absorption Spectrophotometer (AAS). The concentration of TSP in air varied from 69.44 – 185.19 μg/m while the average concentration of the trace metals in TSP were 43.91, 36.99, 30.79, 48.28, 31.84, 302.5, 46.79, 105, 39.36 and 336 μg/m for Cd, Cr, Mn, Pb, Zn, Cu, AS, Ca, Ni and Fe, respectively. The mean concentrations of trace metals in TSP were found in the order of Fe > Cu > Ca > Pb > As > Cd > Ni > Cr > Zn > Mn. Correlation studies showed that the trace metals originated from common source along the highway: Cd was highly correlated with Cu (r = 0.8516), Cr was highly correlated with Mn (r = 0.7844), Pb with Mn (r = 0.7455), Ca with Cr (r = 0.7581) and Zinc (r = 0.8471), and Ni with Cd (r = 0.7325). Trace metals concentration in TSP along Ogbomoso Section of Ibadan-Ilorin highway were higher than WHO and FEPA standard limits of trace metals in air but much lower than the values reported in other cities of the world. Enrichment factor analysis showed that Cd, Cr Zn, Cu, As, Pb and Ni originated from anthropogenic sources, majorly traffic and industrial activities while Fe, Mn and Ca were of crustal origin. KeywordsTSP, Trace metals, Enrichment Factor,