Source apportionment studies on particulate matter (PM10 and PM2.5) in ambient air of urban Mangalore, India

Abstract

Particulate matter (PM₁₀ and PM_2.5) samples were collected from six sites in urban Mangalore and the mass concentrations for PM₁₀ and PM_2.5 were measured using gravimetric technique. The measurements were found to exceed the national ambient air quality standards (NAAQS) limits, with the highest concentration of 231.5 μg/m³ for PM₁₀ particles at Town hall and 120.3 μg/m³ for PM_2.5 particles at KMC Attavar. The elemental analysis using inductively coupled plasma optical emission spectrophotometer (ICPOES) revealed twelve different elements (As, Ba, Cd, Cr, Cu, Fe, Mg, Mn, Mo, Ni, Sr and Zn) for PM₁₀ particles and nine different elements (Ba, Cd, Cr, Cu, Fe, Mn, Ni, Pb, Sr and Zn) for PM_2.5 particles. Similarly, ionic composition of these samples measured by ion chromatography (IC) divulged nine different ions (F^-, Cl^-, NO₃^-, PO₄^3-, SO₄^2-, Na⁺, K⁺, Mg²⁺ and Ca²⁺) for PM₁₀ particles and ten different ions (F^-, Cl^-, NO₃^-, PO₄^3-, SO₄^2-, Na⁺, NH₄⁺, K⁺, Mg²⁺ and Ca²⁺) for PM_2.5 particles. The source apportionment study of PM₁₀ and PM_2.5 for urban Mangalore in accordance with these six sample sites using chemical mass balance model (CMBv8.2) revealed nine and twelve predominant contributors for both PM₁₀ and PM_2.5, respectively. The highest contributor of PM₁₀ was found to be paved road dust followed by diesel and gasoline vehicle emissions. Correspondingly, PM_2.5 was found to be contributed mainly from two-wheeler vehicle emissions followed by four-wheeler and heavy vehicle emissions (diesel vehicles). The current study depicts that the PM₁₀ and PM_2.5 in ambient air of Mangalore region has 70% of its contribution from vehicular emissions (both exhaust and non-exhaust).

Keywords: Chemical mass balance; Mangalore; Particulate matter; Source apportionment; Vehicular emissions.