Characteristics and the Origins of the Carbonaceous Aerosol at a Rural Site of PRD in Summer 2006

摘要

Carbonaceous aerosol including organic carbon (OC) and elemental carbon (EC) was measured at a sub-urban site near Guangzhou City in July 2006 during PRIDE-PRD campaign, using a semi-continuous thermal-optical analyzer. The average OC concentrations for three type periods during the campaign (local emission, typhoon and normal days) were 28.1μgC/m3, 4.0μgC/m3 and 5.7μgC/m3, respectively, and EC were 11.6μgC/m3, 1.8μgC/m3, and 3.3μgC/m3 orderly. Compared to the constant diurnal enhancement ratios of primary EC, the enhancement ratio of OC (OC versus CO-CObackground) remained n a relative high level in the afternoon which showed similar diurnal variation to oxygenated organic aerosol (OOA ), indicating the strong photochemical formation of OC in the afternoon. We modified the traditional EC tracer method and used this modified approach to estimate the daily secondary organic carbon formation, which showed that the average SOC concentration in BG site was about 2.0±2.3 μgC/m3 , accounting for about 47 % mass value of OC.