Modeling dissolved organic carbon exchange across major straits and shelf breaks in the South China Sea

•Seasonal variability of dissolved organic carbon (DOC) transport through major straits of the South China Sea (SCS) is largely controlled by the East Asian monsoon.•Cross-isobath transport is determined by both the pressure gradient along the isobath and the Ekman transport, with the contribution of the latter increasing shoreward.•DOC is transported into the SCS via the Luzon Strait and out via the Taiwan, Karimata and Mindoro straits.•A net export of labile and semilabile DOC from the SCS is quantified.