Chemical characteristics of PM 2.5 aerosol in Incheon, Korea Jong-Kyu Choi a , Jong-Bae Heo c , Soo-Jin Ban b , Seung-Muk Yi a , Kyung-Duk Zoh a, * a Department of Environmental Health, School of Public Health, Seoul National University, Seoul 151-742, Republic of Korea b National Institute of Environmental Research, Ministry of Environment, Seo-gu, Incheon 404-708, Republic of Korea c Environmental Chemistry and Technology Program, University of WisconsineMadison, Madison, WI 53706, United States highlights < We examined the characteristics, sources, distributions of PM 2.5 and carbonaceous species in Incheon, Korea. < The variation and difference of all the measured compounds were compared and evaluated by each season and daily episode. < Organic compounds in PM 2.5 samples were measured using GC  GCeTOFMS. < We identified the source/contribution of the aerosol components in the site using PCAeMLRA analysis. article info Article history: Received 26 December 2011 Received in revised form 21 May 2012 Accepted 25 June 2012 Keywords: PM 2.5 Primary organic aerosol (POA) Secondary organic aerosol (SOA) Water-soluble organic carbon (WSOC) Principal component analysis (PCA) GC  GCeTOFMS abstract We examined the characteristics, sources, and distribution of PM 2.5 and carbonaceous species in particulate samples collected from June 2009 to May 2010 in Incheon, Korea. The average PM 2.5 concentration (41.9  9.0 mgm 3 ) exceeded the annual level set by the United States’ National Ambient Air Quality Standards (15 mgm 3 ). The major fraction of PM 2.5 consisted of ionic species (accounting for 38.9  8.8%), such as NO 3  , SO 4 2 , and NH 4 þ , as well as organic carbon (OC) (accounting for 18.9  5.1%). We also analyzed the seasonal variation in PM 2.5 and secondary aerosols such as NO 3  and SO 4 2 in PM 2.5 . While SO 4 2 concentrations were higher in spring and summer, the concentration of PM 2.5 and NO 3  were the highest in winter. SO 4 2 concentrations were higher during the spring and summer, but PM 2.5 and NO 3  were highest during the winter. As an important aerosol indicator, water-soluble organic carbon (WSOC) (mean 4.7  0.8 mgm 3 , 58.9  10.7% of total OC) showed a strong relationship with NO 3  , SO 4 2 , and SOC (R 2 ¼ 0.56, 0.67, and 0.65, respectively), which was indicative of favorable conditions for SOC formation during the sampling period. Among the individual organic aerosols measured, n-alkanes, n- alkanoic acids, levoglucosan, and phthalates were major components, whereas PAHs (polycyclic aromatic hydrocarbons), oxy-PAHs, hopanes, and cholestanes were minor components. The concentration of organic compounds during smoggy periods was higher than during non-event periods. The n-alkane and n-alkanoic acid species during the smoggy periods were 10e14 times higher than during the normal period. Using principal component analysis coupled with multiple linear regression analysis, we identified the primary sources of PM 2.5 to be motor vehicle/sea salt, secondary organic aerosols, combustion, biogenic/meat cooking, and soil sources. Ó 2012 Elsevier Ltd. All rights reserved. 1. Introduction Airborne particles are chemically and physically nonspecific, and may originate from various natural or anthropogenic sources (Russel and Allen, 2004). Airborne particles also play an important role in human health, visibility degradation, and global climate change (Charlson et al., 1992; Laden et al., 2000; Ito et al., 2006). In particular, fine particles that can more readily penetrate into the lung are associated with an increased incidence of respiratory and cardiovascular disease (Dockery et al., 1993; Schwartz et al., 2002). Fine particles consist of numerous compounds including nitrate, sulfate, inorganic compounds, and organic species. Organic carbon (OC) in particles is a mixture of hundreds of compounds, and can be formed by various sources and complex atmospheric processes. OC and elemental carbon (EC) also play an important role in climate change, influencing the properties of particles and the nucleation of organic material cloud condensation (Ram and Sarin, 2010). Thus, further characterization of the chemical composition of PM 2.5 is required to understand the effects of PM 2.5 on the global climate and human health. * Corresponding author. Tel.: þ82 2 880 2737; fax: þ82 2 762 2888. E-mail address: zohkd@snu.ac.kr (K.-D. Zoh). Contents lists available at SciVerse ScienceDirect Atmospheric Environment journal homepage: www.elsevier.com/locate/atmosenv 1352-2310/$ e see front matter Ó 2012 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.atmosenv.2012.06.078 Atmospheric Environment 60 (2012) 583e592