Concentrations, seasonal variations, and transport of carbonaceous aerosols at a remote Mountainous region in western China

Abstract

Carbonaceous aerosol concentrations were determined for total suspended particle samples collected from Muztagh Ata Mountain in western China from December 2003 to February 2006. Elemental carbon (EC) varied from 0.004 to 0.174 μg m-3 (average = 0.055 μg m-3) while organic carbon (OC) ranged from 0.12 to 2.17 μg m-3 and carbonate carbon (CC) from below detection to 3.57 μg m-3. Overall, EC was the least abundant fraction of carbonaceous species, and the EC concentrations approached those in some remote polar areas, possibly representing a regional background. Low EC and OC concentrations occurred in winter and spring while high CC in spring and summer was presumably due to dust from the Taklimakan desert, China. OC/EC ratios averaged 10.0, and strong correlations between OC and EC in spring-winter suggest their cycles are coupled, but lower correlations in summer-autumn suggest influences from biogenic OC emissions and secondary OC formation. Trajectory analyses indicate that air transported from outside of China brings ∼0.05 μg m-3 EC, ∼0.42 μg m-3 OC, and ∼0.10 μg m-3 CC to the site, with higher levels coming from inside China. The observed EC was within the range of loadings estimated from a glacial ice core, and implications of EC-induced warming for regional climate and glacial ice dynamics are discussed. © 2009 Elsevier Ltd. All rights reserved.