10th International Aerosol Conference September 2 - September 7, 2018 America's Center Convention Complex St. Louis, Missouri, USA
Abstract View
Long-term Characterization and Source Apportionment of Carbonaceous Aerosols over Five Sites in Northern India
DEEPIKA BHATTU, Jay G. Slowik, Francesco Canonaco, Imad EI Haddad, S.B. Tiwari, Purushottam Kumar, Shashi Tiwari, Rangu Venkata Satish, Neeraj Rastogi, Atul K. Srivastava, Deewan S. Bisht, Suresh Tiwari, Dilip Ganguly, S.N. Tripathi, Urs Baltensperger, Andre S.H. Prévôt, Paul Scherrer Institute
Abstract Number: 1227 Working Group: Source Apportionment
Abstract Carbonaceous aerosols form a major fraction (up to 90%) of fine mode particulate matter (PM2.5) and have important but highly uncertain implications for air quality, climate and human health. Therefore, identification and quantification of elemental and organic carbon sources is important to design effective mitigation strategies. In this context, PM2.5 filter samples are collected twice a day during first quarter of 2018 and bi-weekly during the rest of the year at five sites spreading upwind (sub-urban) and downwind (urban) of New Delhi.
New Delhi is typically situated 160 Km south of Himalayas and in close proximity to the Thar Desert. It is surrounded by the adjoining state of Haryana on three sides (North, West and South) and experiences prevailing north westerly winds from Himalayas sweeping the northern Plain during winter and south westerly winds during summer and monsoon (travelling from Arabian sea) and spring season affected by south west winds. To understand the effect of local and regional transport of the pollutants in the capital city, one upwind site in north west direction (IITM Hisar, Haryana), three sites in Delhi (North west: IITM, South west: IITD and South east: MRIU) and one downwind site in South east direction have been chosen. IITM Hisar is a sub-urban north western part of Haryana with moderate to high industrial activity (e.g. steel plants situated on periphery of the city). IITM is a central urban part of Delhi, surrounded by forest area and residential colonies. On the other hand, IITD is more of an urban residential site surrounded by moderate traffic density roads (~200 m away). Further, MRIU is also a residential campus in close proximity to the main road with both heavy and light heavy duty vehicles. Being a part of long mountain range (~692 Km) extending towards South west of the sampling site, it experiences humid subtropical and hot semi-arid continental climate similar to the upwind site. Further, extending to ~600 Km in South east direction is the next urban sampling site (IITK), which is also a residential campus with heavy traffic road in the close proximity of ~200 m and upwind of a coal power
In this study, the re-aerosolized filter extracts are analyzed by a newly developed and extensively used offline- aerosol mass spectrometer (AMS) method and extended to a novel extractive electrospray ionization long-time-of-flight (EESI-LToF) mass spectrometric technique. The resulting mass spectra are analyzed by positive matrix factorization implemented within the multilinear engine and Source Finder (SoFi) interface. Coupled with radiocarbon (14C) and major ion analysis, this approach will provide an unequivocal separation of fossil (traffic exhaust and coal burning) and non-fossil (biogenic emissions and biomass burning including heating and open fires of agricultural and other wastes) in both primary and secondary organic aerosol (SOA). Application of this analysis to a long-term dataset collected across five sites yields a spatially and temporally comprehensive overview of the predominant sources affecting New Delhi air quality. We expect that the potential outcomes of this study will help in constraining the potential primary and secondary organic as well as inorganic aerosol sources, facilitating the development of efficient control measures to control local and regional emission sources.