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.

The journal Science China Earth Sciences published online a carbon cycle study in the South China Sea led by Dr. Peng Xiu and Dr. Wentao Ma. 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.

“The South China Sea (SCS) is the largest semi-enclosed marginal sea in the western Pacific. We know that the alternation of northeast winter monsoon and southwest summer monsoon makes the distribution of phytoplankton chlorophyll concentration show clear seasonal pattern according to satellite products” Dr. Ma says.

The team used an eddy-resolving marine physical-biogeochemical model to analyze the seasonal changes in phytoplankton photosynthesis and the storage of these fixed carbon in the SCS.

The numerical simulations reported fluxes of carbon fixation by phytoplankton, export of particulate organic carbon (POC) by gravity, and Dissolved organic carbon (DOC) production and transformation by microbes. The production of refractory DOC (RDOC) reaches 26% of the carbon sequestration rate of the biological carbon pump, and its contribution to carbon storage cannot be ignored.

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> Source: https://phys.org/news/2022-01-dissolved-carbon-south-china-sea.html