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Year‐Round Measurements of Dissolved Black Carbon in Coastal Southeast Asia Aerosols: Rethinking Its Atmospheric Deposition in the Ocean
Author(s) -
Geng Xiaofei,
Zhong Guangcai,
Liu Junwen,
Sun Yue,
Yi Xin,
Bong Chui Wei,
Zakaria Mohamad Pauzi,
Gustafsson Örjan,
Ouyang Yan,
Zhang Gan
Publication year - 2021
Publication title -
journal of geophysical research: atmospheres
Language(s) - English
Resource type - Journals
eISSN - 2169-8996
pISSN - 2169-897X
DOI - 10.1029/2021jd034590
Subject(s) - dbc , carbon black , environmental science , deposition (geology) , biomass (ecology) , carbon fibers , environmental chemistry , combustion , aerosol , atmospheric sciences , chemistry , meteorology , geology , materials science , oceanography , sediment , geomorphology , geography , natural rubber , optoelectronics , organic chemistry , composite number , composite material , cmos
Dissolved black carbon (DBC) is an important recalcitrant fraction of marine dissolved organic matter. Riverine discharge is the largest known source of oceanic DBC; however, the significance of atmospheric deposition as a source of oceanic DBC remains poorly understood. In this study, year‐round aerosol sampling was carried out at a rural coastal site in Southeast Asia for DBC analysis using the benzene polycarboxylic acid (BPCA) method. The results revealed the uncertainty of an earlier estimate of the atmospheric deposition flux of DBC to the global ocean (F DBC ), which assumed a linear correlation between DBC and water‐soluble organic carbon (WSOC). The correlation between DBC and WSOC depended on the sources of carbonaceous aerosols. The DBC/WSOC ratios were higher for the biomass burning aerosols. DBC was linearly correlated with black carbon (BC) for biomass or fossil fuel combustion aerosols. However, the DBC/BC ratios were higher for biomass burning aerosols (0.41 ± 0.22), whereas lower for fossil fuel combustion aerosols (0.04 ± 0.03). F DBC was revisited based on the relationship between DBC and BC. F DBC is primarily contributed by biomass burning aerosols and maybe previously underestimated. In this study, the DBC in aerosols had less condensed aromatic structures than the DBC present in the major rivers of the world, as shown by the BPCA compositions. This indicated that oceanic DBC sourced from atmospheric deposition was less likely to be removed by photodegradation and sedimentation, as compared to the DBC sourced from riverine discharge.