Organic carbon and elemental carbon associated with PM 10 in Beijing during spring time

Abstract

A continuous observation of organic carbon (OC) and elemental carbon (EC), and PM 10 was conducted at an urban site of Beijing to investigate the characterization of carbonaceous aerosols during spring time. The mean value and standard deviations of OC, EC, PM 10 concentration, and OC/EC ratio were 13.5 ± 7.0 μg m −3, 7.1 ± 4.1 μg m −3, 187.8 ± 136.9 μg m −3, and 2.0 ± 0.4, respectively. OC, EC, and total carbonaceous aerosols (TCA) in PM 10 account for 9.3 ± 5.7%, 4.7 ± 2.7%, and 19.6 ± 11.6%, respectively. Good correlations ( R 2 = 0.7) between OC and EC were observed in spring season. Average OC concentrations are 13.5 μg m −3 in both daytime and nighttime. Average EC concentrations in daytime (7.4 μg m −3) are slightly higher than those in nighttime (6.8 μg m −3). Both OC and EC concentrations reach maximum value in morning time (07:30–10:30) due to motor vehicles during the traffic rush hour. PM 10, OC, and EC concentration increase while PM 2.5 concentration, OC/EC ratio, PM 2.5/PM 10, and TCA/PM 10 ratio decrease in dust period in Beijing. During the observation period, the carbonaceous aerosols from motor vehicle and coal combustion accounted for 76% and 24%, respectively. It shows that the motor vehicle represents the dominant emitter of carbonaceous aerosols associated with PM 10 in Beijing during spring time.