Characteristics and temporal variations of organic and elemental carbon aerosols in PM1 in Changchun, Northeast China.

The present study offers the first evaluation of organic and elemental carbon (OC and EC) of submicron (PM1) fraction in Changchun (Northeast China) during a year-long sampling period (October 24, 2016 to October 23, 2017). More than 288 PM1 (particulate matter with an aerodynamic diameter of less than 1 μm) samples were collected. The PM1 concentrations ranged from 3.78 to 451.08 μg·m-3, with an average of 57.73 μg·m-3, which was 1.65 times higher than the Chinese National Standard II. Following the concept of the well-known IMPROVE algorithm, OC and EC values were obtained. The OC values ranged from 1.18 to 82.54 μg∙m-3, and the EC values were from 0.30 to 14.19 μg∙m-3. Total carbon (TC = EC + OC) constituted 9.11-40.35% of the total PM1 mass, and OC dominated over EC. The average OC/EC ratio was 4.78, which implied a low percentage for vehicles and a high contribution of coal and biomass consumption to PM1. Among OC, the annual primary organic carbon (POC) value was 7.69 μg∙m-3, accounting for 63% of the OC, while secondary organic carbon (SOC) contributed 37% with 4.12 μg∙m-3. Among EC, CHAR (EC1) dominated over SOOT (EC2 + EC3), and the CHAR/SOOR ratio ranged from 2.91 to 28.55. The results of the OC and EC values as well as the OC/EC and CHAR/SOOT ratios suggest that possible sources of PM1 include vehicles, coal burning, cooking, and biomass burning.