[ACG42-P01] Mixing States of Aged Black Carbon Collected over the Western North Pacific Ocean
Keywords:Marine atmospheric aerosol, Black carbon, Sulfate, Organic carbon, The western north Pacific Ocean, TEM-EDX
Measurement and samplings of atmospheric aerosol particles were carried out during the R/V Hakuho-Maru cruise (14-30/11/2017). The ambient BC mass concentrations were measured by a particle soot/absorption photometer (PSAP). In this study, we focused on relatively high BC mass concentration events over the western north Pacific Ocean at 26.62°N, 137.93°E and at 25.51°N, 135.77°E on 19/11/2017. The aerosols collected in both events were analyzed using a transmission electron microscope and an energy dispersive X-ray spectrometer.
In both samples, most BCs were embedded in sulfate particles that have organic coatings. Only a few BCs were attached to sea-salt particles. The backward trajectory analyses suggested that the air masses of both events passed through the land of China and Japan. These results indicate that BCs were emitted in or around the land, and then SO2 condensed on their surface before organic carbon condensed during transportation. Our result is useful to understand the aging process of BC over the ocean.