Abstract Number: 1231 Working Group: Source Apportionment
Abstract A rapid economic growth and high energy demand in developing countries such as India have resulted in the massive discharge of atmospheric particulate matter (PM). PM concentration in Delhi and other metro cities is often found to exceed the Indian National Ambient Air Quality Standards (NAAQS) and recent studies have identified PM as one of the key public health risks, particularly in urban regions such as Delhi. In the past three years, the PM concentration in Delhi significantly exceeded the permissible limits during the autumn season (October and November) when smog-like conditions prevail. This has been qualitatively attributed to the burning of biomass/crop residuals in areas adjoining Delhi. However, very few quantitative studies have focused on the chemical composition of PM2.5 to obtain the source of PM. The present study focuses on PM2.5 measurement and its chemical characterization as carbonaceous aerosol [Elemental carbon (EC) and Organic Carbon (OC)], trace elements during summer and autumn season in Delhi and its relation with the regional meteorology. PM2.5 samples were collected on Teflon and Quartz filters using a dual stage multi-stream sampler equipped with a cyclone separator (URG Corporation, USA) and two filter holders operated at 10 LPM using critical orifices. The samples were collected from June 2017 to November 2017. The mass collected on backup quartz filters was used for the artifact correction. During the study period, the 24-hour mean concentration of PM2.5 was observed as 71.9 ± 4.2 (n=29) and 179.1 ± 10.8 (n=22) µg m−3 for summer and autumn season, respectively, i.e., the PM2.5 concentration in the autumn season was twice that of the summer season. Interestingly, it was found that the PM2.5 concentration during the episodic smog was ~10 times higher than the NAAQS standards, and also eight times higher compared to the non-episodic days. Further, the chemical composition of trace element and OC/EC will be analyzed by Energy Dispersive X-ray Fluorescence (ED-XRF) and Thermal Optical Transmittance (TOT) analyzer. A source apportionment study of PM2.5 using the Positive Matrix Factorization (PMF) model also will be conducted and discussed.