We conducted a WSOC-specific 13
C analysis of submicron marine aerosols over the eastern equatorial Pacific for the first time. The analysis of 13
C combined with monosaccharides provides evidence of a significant contribution of marine dissolved organic carbon (DOC) to submicron particles in the MBL regardless of the oceanic area. The study demonstrates that DOC is closely correlated with the submicron WSOC and implies that it may characterize background OA in the MBL over the study region.