Carbonaceous components in particulate matter during a haze episode at a typical industrial area in the North China Plain

Severe airborne particulate pollution frequently occurs over the North China Plain (NCP) region in recent years. To better understand the characteristics of carbonaceous components in particulate matter (PM) over the NCP region.,PM samples were collected at a typical area affected by industrial emissions in Handan, in January 2016. The concentrations of organic carbon (OC) and elemental carbon (EC) in PM of different size ranges (i.e. PM2.5, PM10 and TSP) were measured. The concentrations of secondary organic carbon (SOC) were estimated by the EC tracer method.,The results show that the concentration of OC ranged from 14.9 μg m−3 to 108.4 μg m−3, and that of EC ranged from 4.0 μg m−3 to 19.4μg m−3, when PM2.5 changed from 58.0μg m−3 to 251.1μg m−3 during haze days, and the carbonaceous aerosols most distributed in PM2.5 rather than large fraction. The concentrations of OC and EC PM2.5 correlated better (r = 0.7) than in PM2.5−10 and PM>10, implying that primary emissions were dominant sources of OC and EC in PM2.5. The mean ratios of OC/EC in PM2.5, PM2.5–10 and PM>10 were 4.4 ± 2.1, 3.6 ± 0.9 and 1.9 ± 0.7, respectively. Based on estimation, SOC accounted for 16.3%, 22.0% and 9.1% in PM2.5, PM2.5–10 and PM>10 respectively.,The ratio of SOC/OC (48.2%) in PM2.5 was higher in Handan than those (28%–32%) in other megacities, e.g. Beijing, Tianjin and Shijiazhuang in the NCP, suggesting that the formation of SOC contributed significantly to OC. The mean mass absorption efficiencies of EC (MACEC) in PM10 and TSP were 3.4 m2 g−1 (1.9–6.6 m2 g−1) and 2.9 m2 g−1 (1.6–5.6 m2 g−1), respectively, both of which had similar variation patterns to those of OC/EC and SOC/OC.