Characterization of Particulate Matter and Carbonaceous Aerosol over Two Urban Environments in Northern India

ABSTRACT

Monitoring and simultaneous sampling of Particulate matter (PM₁₀ and PM_2.5) was carried out for the first time over two urban sites in Northern India (Jabalpur and Udaipur) during December 2010–November 2012 (up to August 2012 over Udaipur). The samples of PM_2.5 were analyzed for elemental carbon (EC) and organic carbon (OC) using advanced DRI Thermal optical carbon Analyzer. The monthly mean PM₁₀ values were as high as 149 ± 44 µg m^–3 over Jabalpur (JBL) and 171 ± 42.2 µg m^–3 over Udaipur (UDPR). PM_2.5 mass over JBL varied between 25–79 µg m–3 and over UDPR between 24–82 µg m^–3. The monthly mean OC concentration varied from 12.5 ± 7.3 µg m^–3 to 28.4 ± 10.7 µg m^–3 over JBL and from 7.8 ± 2.9 to 39.7 ± 11.6 µg m^–3 over UDPR. The variation of monthly mean EC concentration was from 3.9–10.3 µg m^–3 over JBL and from 3–10.9 µg m^–3 over UDPR. The contribution of TC to PM_2.5 was in the range of 31–75% over JBL and 30–83% over UDPR. The EC showed higher concentration in winter and minimal values in monsoon. The OC/EC ratio showed low variation over JBL compared to that over UDPR suggesting spectrum of sources responsible for EC and OC components over UDPR. Formation of secondary organic carbon (SOC) was also recognized as a potential component altering OC/EC ratio. Up on extracting the sub fractions, it is found that OC2 and OC3 are the major component over both the sites contributing up to 51% to the total OC in different months. EC1 (EC component derived at 580°C) was found to be the major EC component contributing up to 79% over the sites.