Organic carbon and elemental carbon associated with PM₁₀ in Beijing during spring time

A continuous observation of organic carbon (OC) and elemental carbon (EC), and PM₁₀ 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, PM₁₀ 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 PM₁₀ account for 9.3 ± 5.7%, 4.7 ± 2.7%, and 19.6 ± 11.6%, respectively. Good correlations (R² = 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. PM₁₀, OC, and EC concentration increase while PM_2.5 concentration, OC/EC ratio, PM_2.5/PM₁₀, and TCA/PM₁₀ 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 PM₁₀ in Beijing during spring time.