Chemical Composition and Source Apportionment of Wintertime Airborne PM 2.5 in Changchun, Northeastern China

This study presents field observations and laboratory analyses of wintertime airborne particulate matter (PM 2.5 ) and its chemical components in the Changchun metropolitan area, the geographical center of northeastern China. Twenty-four hour PM 2.5 filter samples were collected from 23 December 2011 to 31 January 2012 at four sites in the types of traffic, residential, campus, and a near-city rural village, respectively. Daily PM 2.5 concentrations ranged from 49 to 466 µg m −3 , with an arithmetic average of 143 µg m −3 . Laboratory analyses showed that among all measured chemical species, mineral dust contributed the largest proportion (20.7%) to the total PM 2.5 mass, followed by secondary inorganic aerosols (SIA, including SO 4 2− , NO 3 − and NH 4 + ), which constituted 18.8% of PM 2.5 mass. Another notable feature of PM 2.5 chemical composition was high halogen (Cl − and F − ) loadings at all sites, which was likely due to emissions from coal combustion, plastic manufacturing, and glass melting. Among the four sampling sites, the suburban site exhibited the highest PM 2.5 levels and extremely high Cl − and F − loadings due to residential wood burning and nearby industrial facilities lacking effective emission controls. Our results report one of the earliest observations of PM 2.5 composition in this region, providing a baseline of aerosol profiles of aerosol before PM 2.5 was routinely measured by environmental protection agencies in China, which could be useful for assessing long-term trends of air quality and effectiveness of mitigation measures.