The fugacity of CO2 and abundance of chlorophyll a (Chla) were determined in two long transects from the Polar Front to the Antarctic Continent in austral summer, December 1995 to January 1996. Large undersaturations of CO2 in the surface water were observed coinciding with high Chla content. In the major hydrographic regions the mean air-sea fluxes were found to range from -3 to +7 mmol m-2 d-1 making these regions act a sink as well as a source for CO2. In the total 40-dayperiod the summation of the several strong source and sink regions revealed an overall modest net source of 0.3 mmol m-2d-1, this based on the Wanninkhof (1992) quadratic relationship at in situ windspeed. A simple budget approach was used to quantify the role of phytoplankton blooms in theinorganic carbonate system of the Antarctic seas in a time frame spanning several weeks. The major controlling physical factors such as air-sea flux, Ekman pumping and upwelling are included. Net community production varies between -9 mmol m-2d-1 and +7 mmol m-2 d-1, because of to large oscillations in the dominance of autotrophic (CO2 -fixation) versus heterotrophic (CO2 respiration) activity. Here the mixed layer depth is the major controlling factor. When integrated over time the gross influx and efflux of CO2 from air to sea is large, but the net residual air/sea exchange is a modest efflux from sea to atmosphere.