A study on relationship between the atmospheric quantity of heavy metals and PAHs in the city of Isfahan

Abstract Background: Heavy metals are toxic and polycyclic aromatic hydrocarbons are known as toxic, carcinogenic and mutagenic compounds. Objective: To determine the concentration of PAHs and heavy metals in sample and the relationship between these two pollutants in the atmosphere of the city of Isfahan. Methods: In present study, air particulates were collected on glass fiber filters by using a high-volume air sampler. Flow rate and sampling period were 0.5m3/min and 12 hrs, respectively. Each filter was exactly cut into two equal pieces. One piece was digested with HNO3 and H2O2, and the second piece was extracted with DCM, using soxhlet method. The later was used for determination of PAHs. Determination of heavy metals concentrations were performed using a Perkin-Elmer atomic absorption spectrometer. The concentrations of PAHs were measured using a PU 4400 gas chromatograph equipped with a FID detector. Findings: The concentration of lead was higher than other metals (748.5 ng/m3) however it was lower than the standard value (2000 ng/m3).The extraction efficiency of PAHs with soxhlet method was 92-100 percent. The concentration of Benzo (α) pyrene, index of aromatic hydrocarbons, was 2.72 ng/m3. PAHs concentration in non-working days was lower than working days of a week. Correlation coefficient between PAHs and heavy metals was 0.9 (P<0.005). The changing pattern of heavy metals and PAHs was closely similar. Conclusion: The concentrations of PAHs and heavy metals were determined in different samples. The relationship between the atmospheric concentrations of PAHs and heavy metals was investigated and an excellent agreement was found.