survey of polycyclic aromatic hydrocarbons and heavy metals in ambient air of Isfahan, 2003

ABSTRACT

During the past two decades, the determination of heavy metals and Polycyclic Aromatic Hydrocarbons [PAH[5]] in the ambient air of industrialized cities has gained great importance. Heavy metals and PAH[5] in flue gas have received considerable attention in recent years due to their mutagenic or carcinogenic properties. PAH[5], are products of incomplete combustion of carbonaceous compounds at high temperatures The sources of PAH[5], into the atmosphere include waste incineration, exhaust emission of petrol and diesel engine automobiles power plants, and residential heating systems. Heavy metals are released into the ambient air from the same sources as those earlier mentioned for PAH[5]. The present study is carried out to investigate the influence of the quantity of heavy metals on PAH[5] formation in ambient air. Heavy metals encourage not only absorption of PAH[5] but also catalyze PAH[5] formation. In this study, air particulates were collected on glass fiber filters using a high-volume air sampler. Flow rate and sampling period were 0.5 m[3]/min and 24 hrs. respectively. Each filter was exactly cut into equal pieces. One piece was digested with HNO[3] as well as H[2]O[2] and used for determination of heavy metals. Another piece was extracted with DCM Using Soxhlet method. The latter was used for the determination of PAH [5]. The concentrations of heavy metals [Cr, Cd, Cu. Pb, and Zn] were measured by using Perkin-Elmer atomic absorption spectrometer PAH[5]. The concentration of PAH[5] was measured by a PU4400 gas chromatograph equipped with RD detector. The concentrations of PAH[5] and heavy metals were determined in different seasons, The results showed that the concentration of PAH[5] was minimum in the weekend and holidays, but maximum in winter. The relationship between ambient air concentrations of PAH[5] and heavy metals was investigated and an excellent agreement was found. The general trend of variations in concentratioll of heavy metals were found very similar to PAH[5] therefore it could be concluded that the source of pollution was same for both the pollutants