Characteristics and sources of carbonaceous aerosol in the urban Chengdu during spring of 2009

Aerosol samples for PM _2.5 were collected from 19 April to 17 May 2009 in Chengdu. The concentrations of eight carbon fractions, water-soluble organic carbon (WSOC), levoglucosan and water-solubility ions of all particle samples were obtained by chemical analyses. The characteristics and sources of carbonaceous aerosols were investigated. The results showed that the average mass concentration of PM _2.5 was (133.2 ± 55.5)μg · m ^-3. The average value of total carbon (TC), organic carbon (OC), elemental carbon (EC) and WSOC were (26.4 ± 7.2), (20.7 ± 6.0), (5.7 ± 1.8) and (10.4 ± 3.4)μg · m ^-3, respectively. The averaged levoglucosan concentration was (396.5 ± 405.3) ng · m ^-3 with maximum of 1820.9 ng · m ^-3. Factor analysis indicated that OC2, OC3, OC4 and WSOC came mainly from biomass burning, while EC1 from coal combustion and EC2 and EC3 from vehicle exhaust. Calculation by LC/OC ratio of biomass burning emission factor in China showed that the contribution rate of biomass burning to OC and TC was 46.0% and 36.6%, respectively.