1596 / 2024-10-14 08:58:14
Black carbon (BC) and brown carbon (BrC) over South China Sea and the eastern Indian Ocean
Black carbon (BC),brown carbon (BrC),radiocarbon (14C),light absorption property,South China Sea (SCS),Indian Ocean,ship emission,biomass burning (BB)
Session 25 - IGAC-SOLAS: Chemistry and physics at surface ocean and lower atmosphere
Abstract Accepted
Black carbon (BC) and brown carbon (BrC) are the key light-absorbing components of atmospheric particulate matter (PM). The sources, compositions, and light absorption properties of BC and BrC over South/East Asian marine regions remain poorly constrained. We carried out ship-based and island-based sampling campaigns. For BC, the source apportionment, using δ13C–14C dual-carbon isotope signatures, showed that ship emission was the predominant BC source (54%) in the South China Sea (SCS) where at proximity to mainland China, while biomass burning (BB) was the major contributor in the open north-eastern Indian Ocean and the open SCS (40-56%). A contribution from BB up to 70% during BB period in Southeast Asia was observed at a coastal background site along the western SCS. For BrC, we found that the mass absorption efficiency (MAE365) of water-soluble organic carbon (WSOC) in the marine aerosols correlated well with absorption Ångström exponent (AAE), but with the lowest response of MAE365 to AAE when compared to those of continental sites, owing to the difference in aromatic compound contents derived from combustion sources. Our observations imply that a better control of ship emission and biomass burning in the region would contribute to climate change mitigation by reducing the direct atmospheric radiative forcing from BC and BrC.