Characteristics and Source Apportionment of Carbonaceous Aerosols During Summer Period in Typical Cities

To study the characteristics and sources of PM_2.5and its carbonaceous components in typical cities of Beijing-Tianjin-Hebei region,PM_2.5sampling was conducted in five sites of Beijing and Tangshan from July 3rd to 30 th,2012. Concentrations and variation characteristics of PM_2.5,OC and EC were analyzed. The OC/EC minimum ratio method was used to estimate the concentration of SOC,and the factor analysis method was used to analyze the source apportionment of carbonaceous materials. Results showed that the concentration of PM_2.5,OC and EC in Beijing was 76.2 ± 38.5 μg/m³,7.0 ± 2.2μg/m³,and 3.0 ± 1.4 μg/m³,respectively,which was lower than the corresponding concentration of97. 7 ± 38. 8 μg/m³,11.7 ± 6.3 μg/m³,and 7.0 ± 5.0 μg/m³,in Tangshan,respectively. The concentration of PM_2.5,OC and EC in haze weather was 2.0,1.2 and 1.8 times of that in non-haze weather in Beijing and 1.4,1.5,and 1.6 times of that in Tangshan. The concentration of SOC was 3. 0μg/m³ and 5.1 μg/m³,accounting for 42.9% and 43.6% of the total OC concentration in Beijing and Tangshan,respectively. The two main sources of carbonaceous aerosols in PM_2.5 were coal combustion and vehicle exhaust. The joint contributions of the two sources were both larger than 75% in Beijing andTangshan. Therefore,effective emission mitigation measures for the above two sources,such as clean energy substitution,vehicle population growth control and fuel quality improvement are needed.