Black carbon aerosols at Mt. Muztagh Ata, a high-altitude location in the Western Tibetan Plateau

Measurements of equivalent black carbon (EBC) were conducted for 8 months from November 2009 to September 2010 at Mt. Muztagh Ata to determine its seasonal variation, transport, and potential contribution source areas. The daily EBC concentrations ranged from 33.6 to 330.2 ng m^-3 with an average of 133.1 ± 55.0 ng m^-3 during the period. Higher values were observed in summer and autumn (approximately 164.0 ng m^-3) than in winter (approximately 96.5 ng m^-3). The diurnal variation in all seasons was stable throughout the day but slightly increased during the nighttime. The results of the potential source contribution function analysis indicated four potential source areas for EBC, with the contributions of polluted trajectory clusters ranging from 4% to 50%. High EBC concentrations were found to be associated with regional circulations developed in high aerosol optical depth areas, resulting in recirculation and accumulation of EBC.