Characterization, Long-Range Transport and Source Identification of Carbonaceous Aerosols during Spring and Autumn Periods at a High Mountain Site in South China

PM10 (particulate matter) samples were collected at Mount Lu, a high elevation mountain site in south China (August and September of 2011; and March, April and May of 2012). Eight carbonaceous fractions of particles were analyzed to characterize the possible carbonaceous emission sources. During the sampling events, daily average concentrations of PM10 at Mount Lu were 97.87 mu g/m(3) and 73.40 mu g/m(3) in spring and autumn, respectively. The observed mean organic carbon (OC) and element carbon (EC) concentrations during spring in PM10 were 10.58 mu g/m(3) and 2.58 mu g/m(3), respectively, and those in autumn were 6.89 mu g/m(3) and 2.40 mu g/m(3), respectively. Secondary organic carbon concentration was 4.77 mu g/m(3) and 2.93 mu g/m(3) on average, accounting for 28.0% and 31.0% of the total OC in spring and autumn, respectively. Relationships between carbonaceous species and results of principal component analysis showed that there were multiple sources contributing to the carbonaceous aerosols at the observation site. Through back trajectory analysis, it was found that air masses in autumn were mainly transported from the south of China, and these have the highest OC but lowest EC concentrations. Air masses in spring transported from northwest China bring 7.77 mu g/m(3) OC and 2.28 mu g/m(3) EC to the site, with lower levels coming from other sites. These air mass sources were featured by the effective carbon ratio (ECR).