A model study on carbon cycle and phytoplankton dynamical processes in the Bohai Sea

The carbon cycle of lower trophic level in the Bohai Sea is studied with a three-dimensional biological and physical coupled model.The influences of the processes(including horizontal advection,river nutrient load,active transport etc.) on the phytoplankton biomass and its evolution are estimated.The Bohai Sea is a weak sink of the CO₂ in the atmosphere.During the cycle,13.7% of the gross production of the phytoplankton enter the higher trophic level and 76.8% of it are consumed by the respiration itself.The nutrient reproduction comes mainly from the internal biogeochemical loop and the remineralization is an important mechanism of the nutrient transfer from organic form to inorganic.Horizontal advection decreases the total biomass and the eutrophication in some sea areas.Change in the nutrient load of a river can only adjust the local system near its estuary.Controlling the input of the nutrient,which limits the alga growth,can be very useful in lessening the phytoplankton biomass.