10th International Aerosol Conference September 2 - September 7, 2018 America's Center Convention Complex St. Louis, Missouri, USA
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Wintertime Study of Ambient Aerosols (PM1 and PM2.5): Insights to Source Characterization and Atmospheric Transformation
GYANESH KUMAR SINGH, Prashant Rajput, Pradhi Rajeev, Dharmendra Kumar Singh, Amit Kumar Singh, Debajyoti Paul, Tarun Gupta, Indian Institute of Technology Kanpur
Abstract Number: 347 Working Group: Source Apportionment
Abstract Indo-Gangetic plain (IGP) is heavily polluted especially during winter-time due to its topography, meteorological conditions and elevated particulate (PM) emissions. Various studies have been conducted to understand the sources as well as different processes undergoing in the atmosphere over this region. For a better understanding of the contribution of various sources to aerosols, stable isotope ratios have been assessed in this study. Ambient aerosols (PM1 and PM2.5) collected during wintertime from Kanpur (central part of IGP) were studied for their chemical composition such as organic carbon (OC), elemental carbon (EC), water-soluble organic carbon (WSOC), water-soluble inorganic species (WSIS) and stable carbon isotope composition (δ13C). During the study period, predominant origin from north-west direction was seen in the air-mass back trajectories arriving at the receptor site. PM mass along with higher total carbonaceous aerosols (TCA) concentrations can be attributed to the impact of massive emissions from anthropogenic sources (vehicular exhaust, industrial emissions, and biomass burning) and meteorological conditions like low wind speed and low mixing height. The contribution from OC was nearly 22% and 15% and EC was nearly 2% and 0.14% of ambient PM2.5 and PM1 mass respectively. There is a significant increase in the concentration of ions like NH4+, NO3−, and SO42− during this time period due to stagnant air condition and various fog/haze events. Variability in aerosol mixing comprising of primary and secondary emission products can be deduced from observed significant variability in OC/EC ratio and WSOC/OC ratio in ambient samples. δ13C of TC in ambient aerosols found were quite comparable in both PM2.5 and PM1 in this study. δ13C of samples from some possible sources (coal, gasoline, diesel, and bio-diesel) were analyzed to ascertain their different characteristics. Also, the possible contribution from several sources can be inferred from large scatter between δ13C and TC content. Variable δ13C in short and long-range transported aerosols suggests the plausibility of mixing of variable sources of carbon resulting in the observed variability of δ13C.