Dissolved organic carbon (DOC) makes up the majority of marine organic carbon. Understanding its source and sink processes is of great significance to the global carbon cycle and will provide insights in achieving carbon neutrality. How do different physical and biogeochemical processes interact to contribute to the budgets of DOC and particulate organic carbon (POC)? Are there unique dynamics in different regions? The journal Science China Earth Sciences published online a carbon cycle study in the South China Sea led by Dr. Peng Xiu (South China Sea Institute of Oceanology, Chinese Academy of Sciences) and Dr. Wentao Ma (Second Institute of Oceanography, Ministry of Natural Resources). The purpose of this study is to quantitatively evaluate processes of carbon fixation, sequestration, and the interaction between the biological carbon pump and the microbial carbon pump.