10:45 AM - 12:15 PM
[MIS09-P09] Black Carbon in Atmospheric Aerosol in Sapporo, Japan
Keywords:Black Carbon, Dissolved Black Carbon
Black carbon (BC) is produced by incomplete combustion of biomass and fossil fuels. It is considered to play a significant role in the global carbon cycle and climate, because the majority of BC resist degradation by environmental microbes. BC is generated on land and transported to the ocean by river and atmospheric deposition. Dissolved black carbon (DBC), which is polycyclic aromatic compounds and particularly small in molecular size, accounts for 2% of dissolved organic carbon (DOC) in the ocean and forms relatively large BC pools. The global DBC fluxes to the ocean were estimated to be about 18 Tg yr-1 from river and 1.8-4.5 Tg yr-1 from atmospheric deposition. The total of these DBC fluxes is reported to be smaller than the DBC removal flux in the ocean. The imbalance in the oceanic DBC budget can be attributed to the uncertainty in the estimated fluxes. Since, only two studies have evaluated effect of atmospheric deposition as the origin of oceanic DBC, further observations are needed to understand the controlling factors of DBC concentration in atmospheric aerosols and to accurately evaluate the DBC flux from the atmosphere.
In the study, atmospheric aerosol samples were collected in Sapporo, Japan from August 19 to November 22, 2022, using a high-volume aerosol sampler. The BC and organic carbon (OC) concentrations in the aerosol samples were measured by thermal optical transmittance carbon analyzer, and the water-soluble organic carbon (WSOC) concentrations were measured by a total organic carbon analyzer. DBC concentrations were determined using the benzene polycarboxylic acid (BPCA) method and quantified using high-performance liquid chromatography. The quantity and quality of brown carbon (BrC) in WSOC were determined by a UV-visible spectrophotometer.
The concentrations and ranges of OC, BC, and WSOC in the atmospheric aerosols were relatively lower than those in the previous studies conducted in China coastal seas and rural area of Malaysia, but similar to those conducted in Sapporo. The concentration of DBC was also lower than that in the previous studies conducted in China coastal seas and rural area of Malaysia. Furthermore, the ratios of DBC/BC, OC/BC, and DBC/WSOC were smaller, and the ratio of WSOC/OC was larger compared to previous studies. Additionally, the smaller BPCA composition of DBC observed in this study suggests that fossil fuel combustion generates lower condensed DBC. A strong positive linear relationship was observed between DBC and BrC. The linearity was stronger than those of the linear relationship between DBC and WSOC and BC, indicating that DBC is similar in origin and alteration process to BrC.
In the study, atmospheric aerosol samples were collected in Sapporo, Japan from August 19 to November 22, 2022, using a high-volume aerosol sampler. The BC and organic carbon (OC) concentrations in the aerosol samples were measured by thermal optical transmittance carbon analyzer, and the water-soluble organic carbon (WSOC) concentrations were measured by a total organic carbon analyzer. DBC concentrations were determined using the benzene polycarboxylic acid (BPCA) method and quantified using high-performance liquid chromatography. The quantity and quality of brown carbon (BrC) in WSOC were determined by a UV-visible spectrophotometer.
The concentrations and ranges of OC, BC, and WSOC in the atmospheric aerosols were relatively lower than those in the previous studies conducted in China coastal seas and rural area of Malaysia, but similar to those conducted in Sapporo. The concentration of DBC was also lower than that in the previous studies conducted in China coastal seas and rural area of Malaysia. Furthermore, the ratios of DBC/BC, OC/BC, and DBC/WSOC were smaller, and the ratio of WSOC/OC was larger compared to previous studies. Additionally, the smaller BPCA composition of DBC observed in this study suggests that fossil fuel combustion generates lower condensed DBC. A strong positive linear relationship was observed between DBC and BrC. The linearity was stronger than those of the linear relationship between DBC and WSOC and BC, indicating that DBC is similar in origin and alteration process to BrC.