relationship between polycyclic aromatic hydrocarbons and heavy metals in Isfahan city

ABSTRACT

During the past two decades, determination of heavy metals and Polycyclic Aromatic Hydrocarbons [PAH,] in the atmosphere of industrialized cities have gained great importance. Heavy metals arc toxic and polycyclic aromatic hydrocarbons are known as toxic, carcinogenic and mutagenic compounds. PAHs are products of incomplete combustion of carbonaceous compounds at high temperatures. The sources of PAHs into the atmosphere include waste incineration, exhaust emissions of petrol and diesel engine automobiles, plant powers, and residential heating systems. Heavy metals are released into the atmosphere from the same sources as those earlier mentioned for PAHs 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 12 hrs respectively. Each filter was exactly cut into equal pieces. One piece was digested with HNO3 as well as H2O2 and used for determination of heavy metals. Another piece was extracted with dichloromethane [DCM] using Soxhlet method. The latter was used for the determination of PAHs. The concentrations of heavy metals were measured using Perkin-Elmer atomic absorption spectrometer. The concentration of PAHs was measured by a PU4400 gas chromatograph equipped with Fill detector. The concentrations of PAHs and heavy metals were determined in different seasons. Lead and cadmium were higher than similar cities in Iran. The results showed that the concentration of PAHs was minimum in the weekends and holidays. But it was maximum in winter. The relationship between the atmospheric concentrations of PAHs and heavy metals was investigated and an excellent agreement was found. The determination of concentrations of PAHs by HPLC-GC was also investigated and the results were compared to those determined by CGC. An excellent agreement between the results of two techniques was also found. The general trend of variations in concentration of heavy metals was found very similar to PAHs, therefore, it could be concluded that the source of pollution was same for both the pollutants