Chemical characterization of PM 10 and PM 2.5 mass concentrations emitted by heterogeneous traffic

Abstract

In this paper, the chemical characterization of PM 10 and PM 2.5 mass concentrations emitted by heterogeneous traffic in Chennai city during monsoon, winter and summer seasons were analysed. The 24-h averages of PM 10 and PM 2.5 mass concentrations, showed higher concentrations during the winter season (PM 10 = 98 μg/m 3; PM 2.5 = 74 μg/m 3) followed by the monsoon (PM 10 = 87 μg/m 3; PM 2.5 = 56 μg/m 3) and summer (PM 10 = 77 μg/m 3; PM 2.5 = 67 μg/m 3) seasons. The assessment of 24-h average PM 10 and PM 2.5 concentrations was indicated as violation of the world health organization (WHO standard for PM 10 = 50 μg/m 3 and PM 2.5 = 25 μg/m 3) and Indian national ambient air quality standards (NAAQS for PM 10 = 100 μg/m 3 and PM 2.5 = 60 μg/m 3). The chemicals characterization of PM 10 and PM 2.5 samples (22 samples) for each season were made for water soluble ions using Ion Chromatography (IC) and trace metals by Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES) instrument. Results showed the dominance of crustal elements (Ca, Mg, Al, Fe and K), followed by marine aerosols (Na and K) and trace elements (Zn, Ba, Be, Ca, Cd, Co, Cr, Cu, Mn, Ni, Pb, Se, Sr and Te) emitted from road traffic in both PM 10 and PM 2.5 mass. The ionic species concentration in PM 10 and PM 2.5 mass consists of 47–65% of anions and 35–53% of cations with dominance of SO 4 2− ions. Comparison of the metallic and ionic species in PM 10 and PM 2.5 mass indicated the contributions from sea and crustal soil emissions to the coarse particles and traffic emissions to fine particles.