Abstract: A simple food web,including plankton(phytoplankton,zooplankt on and bacteria) and non-living nitrogen (detritus,dissolved organic nitro gen,nit rate and am monium),is used to describe the biological processes taking placing in the upper layer of the ocean.This biological model is respectively applied in a fixed position and a parcel of water moving from the Strait of Florida (24°N,80°W) to the Norwegian Sea (68°N,10°E) in the Extended Gulf Stream System (EGSS) to investigate the influence of the biological processes on the uptake of atmospheric carbon dioxide by the parcel.The results from the parcel model apparently gives the spring bloom,in which the peak is sharper than that from the model including phytoplankton-zooplnakt on and nitrate.The resutls are more reasonable.A mean net primary production of 43g Cm-2a-1is obtained,which is smaller than the observed one.The simulated total alkalinity,total carbon dioxide and p CO2 are in the range of observations.The contribution of biological pumpis about 16% of the amount of carbon dioxide taken up by the parcel.