HYDROTHERMAL METHANE FLUXES FROM THE SOIL AT SOUSAKI (GREECE)

Thessaloniki, Greece

Methane soil flux measurements have been made in 38 sites at the geothermal system of
Sousaki (Greece) with the closed chamber method. Fluxes range from –47.6 to 29,150 mg m-2 d-1 and
the diffuse CH4 output of the system has been estimated in 19 t/a. Contemporaneous CO2 flux measurements
showed a fair positive correlation between CO2 and CH4 fluxes but the flux ratio evidenced
methanotrophic activity within the soil. Laboratory CH4 consumption experiments confirmed the presence
of methanotrophic microorganisms in soil samples collected at Sousaki. These results further confirm
recent studies on other geothermal systems that revealed the existence of thermophilic and acidophilic
bacteria exerting methanotrophic activity also in hot and acid soils thereby reducing methane
emissions to the atmosphere.