Pollution Characteristics of Carbon Fractions in PM_2.5 and Their Sources in Urban Area of Anshan City in Summer

A study on the PM_2.5 in the urban area of Anshan city in summer and pollution characteristics of carbon fractions in PM_2.5 was presented. PM_2.5 samples were collected at Anshan city in July, 2014. Thermal/Optical Carbon Analyzer (IMPROVE-TOR) was employed to detect the concentrations of eight carbon fractions in particulate samples. The results showed that the average mass concentration of PM_2.5 in Anshan in summer was (53.4±18) μg/m3. Organic Carbon(OC), Element Carbon(EC) and Total Carbon(TC) took (11.89±3.86)%, (4.79±1.31)% and (16.68±5.02)%, showing that carbon was the important component of PM_2.5 in Anshan in summer. The correlation between OC and EC was significant in PM_2.5, R=0.715. Moreover, the average of OC/EC ratios in PM_2.5 was 2.49±0.43. All the OC/EC ratios exceeded 2. This result suggested that there existed secondary organic carbon in ambient air contributing to OC. All of this showed the sources of OC and EC were the same in general. The percentage of eight carbon fractions（OC1、OC2、OC3、OC4、EC1、EC2、EC3、OPC）in PM_2.5 indicated that vehicle exhaust, road dust and coal combustion were primary sources of carbon in PM_2.5 in Anshan during summer.