This award supports a two year effort to develop a membrane inlet system for mass spectrometry and to use it in preliminary measurements of oxygen flux during phytoplankton photosynthesis. The initial photosynthetic studies are a novel approach to phytoplankton photosynthesis and respiration and in addition, the membrane inlet system can be used for a variety of marine studies of biologically active gases. These latter applications include carbon dioxide so that a small portion of the award will be made as part of the Global Ocean Flux Study (GOFS).