EN
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⁻²d⁻¹ to 3.84 mg・m⁻²d⁻¹ and from 20.68 mg・m⁻²d⁻¹ to 99.88 mg・m⁻²d⁻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.