Water-soluble organic nitrogen in fine aerosols over the Southern Ocean

Shipboard measurements of the water-soluble organic nitrogen (WSON) in the aerosols over the remote ocean in the Indian sector of the Southern Ocean were conducted during three summer seasons. The aims of this study were to improve our understanding of the spatiotemporal distributions and potential sources of the WSON over this oceanic region. The average concentration of the WSON in the PM2.5 obtained in this study was 4.7 ng m−3, which was within the reported values from a previous study over the Southern Ocean and lower than the reported over the lower latitude remote oceans. The average concentration ratio of the WSON/WSTN was 0.20. The WSON was an important piece of bioavailable nitrogen in the fine aerosols. The primary emission of sea salt particles was a principal source of the WSON. The temporal changes of the WSON concentrations were explained by the differences in the primary emission of sea salt particles.