The belief that salt marshes export organic materials has been central to the description of these ecosystems as well as a prime argument for the conservation.  However, there is very limited information about the controls of carbon dynamics within and across marshes.  In this research, the concentrations of CO2, O2, and chlorophyll were monitored, as well as other necessary parameters in a tidal gate of a small salt marsh to address the pattern of carbon dynamic transportation in the water flux of tide.  Among the organic carbon transferred by the tidal cycle twice a day, chlorophyll is considered to be a proxy for the standing stock of primary producers.  Initial results from samples collected during August 2007-October 2007, indicate that overall the marsh is a source of CO2 and a sink of O2.  Interactions of the tidal cycle with the light field are a large source of variation in daily CO2/O2/chl data.