Climate gases

Methane in alpine hydroelectric reservoirs

As measurements in hydroelectric reservoirs in African and temperate climates showed reservoirs acting as sources for atmospheric methane, the question arose, whether the alpine reservoirs in Switzerland also contain methane and act as a methane source?

Preliminary measurements showed that alpine reservoirs can be split in two main groups, those dominated by glacial waters that have milky water representing extreme environments and those with little or no direct water from glaciers, who can maintain primary production. The glacial reservoirs contain methane, but it is not produced inside the reservoirs, which mainly act as a store for methane.
Additional measurements of the carbon and hydrogen isotope ratios should be able to distinguish between biogenic or thermogenic methane and facilitate the search for the methane source.
In the other group of lakes the sediment acts as a methane source and methane is microbially oxidized in the water column. Here the interest lies in factors like height above sea level, agricultural influence, etc., controlling the amount of methane produced in the reservoir and the amount of methane oxidized in the water column.

Funding

• Eawag
  

Publications

• Schubert, C.J., Durisch-Kaiser, E., Wehrli, B., Holzner, C.P., Kipfer, R., Schmale, O., Greinert, J., and Kuypers, M.M.M. (2006) Recent studies on sources and sinks of methane in the Black Sea. – In: Neretin, L. N., Jørgensen, B. B. and Murray, J. W. [eds.], Past and Present Marine Water Column Anoxia, Nato Science Series: Earth and Environmental Sciences, Kluwer-Springer, Vol. 64. pp. 419-441.
  
  
• Diem, T., Koch, S., Schwarzenbach, S., Wehrli, B., Schubert, C.J. Greenhouse gas emissions (CO2, CH4, and N2O) from perialpine and alpine hydropower reservoirs - Biogeosciences, in review.