Chemical characterization of PM₁₀ and PM₂.₅ mass concentrations emitted by heterogeneous traffic

In this paper, the chemical characterization of PM₁₀ and PM₂.₅ mass concentrations emitted by heterogeneous traffic in Chennai city during monsoon, winter and summer seasons were analysed. The 24-h averages of PM₁₀ and PM₂.₅ mass concentrations, showed higher concentrations during the winter season (PM₁₀=98 μg/m³; PM₂.₅=74 μg/m³) followed by the monsoon (PM₁₀=87 μg/m³; PM₂.₅=56 μg/m³) and summer (PM₁₀=77 μg/m³; PM₂.₅=67 μg/m³) seasons. The assessment of 24-h average PM₁₀ and PM₂.₅ concentrations was indicated as violation of the world health organization (WHO standard for PM₁₀=50 μg/m³ and PM₂.₅=25 μg/m³) and Indian national ambient air quality standards (NAAQS for PM₁₀=100 μg/m³ and PM₂.₅=60 μg/m³). The chemicals characterization of PM₁₀ and PM₂.₅ 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 PM₁₀ and PM₂.₅ mass. The ionic species concentration in PM₁₀ and PM₂.₅ mass consists of 47-65% of anions and 35-53% of cations with dominance of SO₄²⁻ ions. Comparison of the metallic and ionic species in PM₁₀ and PM₂.₅ mass indicated the contributions from sea and crustal soil emissions to the coarse particles and traffic emissions to fine particles.