Measurements of surface total carbon dioxide (TCO2), alkalinity, and calculated pCO2, along with water column nutrients and hydrography, were made on two cruises to the Ross Sea polynya (NBP 94-6, November-December 1994 and NBP 95-8, December 1995 to January 1996). The polynya experiences an intense phytoplankton bloom during a short period of open water conditions from mid-December to mid-February each year. Our biogeochemical observations were used to determine the temporal variability of CO2, fluxes of carbon within the ocean, and rates of air-sea exchange of CO2. Depletions of TCO2, pCO2, and nitrate+nitrite were considerable (~70--150 μmol kg-1, 80--150 μatm, and 10--20 μmol kg-1, respectively) and associated primarily with biological uptake during Phaeocystis and diatom blooms. Alkalinity was a conservative tracer of salinity and nitrate+nitrite. Surface pCO2 was undersaturated by ~50--150 μatm, and air-sea gas exchange of CO2 during open water conditions was directed from atmosphere to ocean. Observed surface stoichiometric C:N ratios were 6.66:1 and 6.77:1 for the 2 years, consistent with global Redfield ratios, while C:P and N:P ratios were variable (75--141:1, 12--18:1). Estimates of net community production (NCP) rates were made using in situ changes in TCO2 and nitrate+nitrite across repeated transects along 76¿30'S. Mean NCP rates across the polynya ranged from 0.86 to 0.98 g C m-2 d-1. These values may be underestimated by 5--25% because of the contribution of atmospheric CO2 to the surface layer through gas exchange. Export of carbon from the surface to depth was at least 55--60% of NCP rates. ¿ 1998 American Geophysical Union