Methane and Carbon Dioxide Fluxes at the Sediment-Water Interface in Reservoirs

Methane (CH4) and carbon dioxide (CO2) fluxes at the sediment-water interface were studied during autumn in three reservoirs in Poland. The theoretical diffusive fluxes of dissolved pore-water carbon gases to the overlying water ranged from 0.16 mg.m(-2)d(-1) to 3.84 mg.m(-2)d(-1) and from 20.68 mg.m(-2)d(-1) to 99.88 mg.m(-2)d(-1) for methane and carbon dioxide, respectively. The comparison between the diffusive fluxes of methane at the sediment-water interface and its fluxes at the water-atmosphere interface showed that an ebullition is probably the major pathway for CH4 transport from the sediment to the atmosphere. The fluxes of CO2 at the sediment-water interface were considerably lower than its fluxes at the water-atmosphere interface. This indicates that most CO2 is generated in the water column, whereas only a small portion originates from sediments.