Greenhouse gas emissions (CO2, CH4 and N2O) from perialpine and alpine hydropower reservoirs
Other literature type
Schubert, C. J.
(issn: 1726-4189, eissn: 1726-4189)
In eleven reservoirs located at different altitudes in Switzerland depth
profiles of greenhouse gas (CO<sub>2</sub>, CH<sub>4</sub>, and N<sub>2</sub>O) concentrations
were measured several times during spring and summer. Trace gas emissions
were calculated using surface concentrations, wind speeds and transfer
velocities. Additionally we assessed methane loss at the turbine and the
methane input by inflowing water. All reservoirs were net emitters of
CO<sub>2</sub> with an average of 1030±780 mg m<sup>−2</sup> d<sup>−1</sup> and of
methane with an average of 0.20±0.15 mg m<sup>−2</sup> d<sup>−1</sup>. One
reservoir (Lake Wohlen) emitted methane at a much higher rate (160±110 mg m<sup>−2</sup> d<sup>−1</sup>),
most of which (>98%) was due to
ebullition. Only lowland reservoirs were sources for N<sub>2</sub>O (72±22 μg m<sup>−2</sup> d<sup>−1</sup>),
while the subalpine and alpine reservoirs seem
to be in equilibrium with atmospheric concentrations. Methane loss at the
turbine was as large as the diffusive flux from the surface for two
subalpine reservoirs and around five times smaller for a lowland reservoir.
The available data suggests greenhouse gas emissions from reservoirs in the
Alps are minor contributors to the global greenhouse gas emissions.