https://www.ukm.my/ipi/wp-content/uploads/2013/07/25.2010Climate-impacts-on-European-agriculture-and-water-management-in-the-context-of-adaptation-and-mitigation.pdf

Climate impacts on European agriculture and water management in the context of adaptation and mitigation—The importance of an integrated approach

The build-up of methane in the hypolimnion of the eutrophic Lake Rotsee (Lucerne, Switzerland) was monitored over a full year. Sources and sinks of methane in the water column were characterized by measuring concentrations and carbon isotopic composition. In fall, high methane concentrations (up to 1 mM) were measured in the anoxic water layer. In the oxic layer, methane concentrations were much lower and the isotopic composition shifted towards heavy carbon isotopes. Methane oxidation rates peaked at the interface between oxic and anoxic water layers at around 8–10 m depth. The electron balance between the oxidants oxygen, sulphate, and nitrate, and the reductants methane, sulphide and ammonium, matched very well in the chemocline during the stratified season. The profile of carbon isotopic composition of methane showed strong indications for methane oxidation at the chemocline (including the oxycline). Aerobic methane oxidizing bacteria were detected at the interface using fluorescence in situ hybridization. Sequencing the responsible organisms from DGGE bands revealed that aerobic methanotrophs type I closely related to Methylomonas were present. Sulphate consumption occurred at the sediment surface and, only towards the end of the stagnation period, matched with a zone of methane consumption. In any case, the flux of sulphate below the chemocline was not sufficient to oxidize all the methane and other oxidants like nitrate, iron or manganese are necessary for the observed methane oxidation. Although most of the methane was oxidized either aerobically or anaerobically, Lake Rotsee was still a source of methane to the atmosphere with emission rates between 0.2 mg CH4 m−2 day−1 in February and 7 mg CH4 m−2 day−1 in November.

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Oxidation and emission of methane in a monomictic lake (Rotsee, Switzerland)

Greenhouse Gas Emissions from Hydroelectric Reservoirs: What Knowledge Do We Have and What is Lacking?

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Purpose
Sediments are significant methane (CH4) sources of the atmosphere. However, the mechanisms of CH4 generation remain unclear in sediments of shallow urban lakes. The aims of this investigation were to study the characterization of environmental parameters, CH4 generation, and methanogen populations in Wulongtan Lake, China, which is affected solely by nonpoint pollution.

Detection of methane biogenesis in a shallow urban lake in summer

CO2 emissions from German drinking water reservoirs.

. In eleven reservoirs located at different altitudes in Switzerland depth profiles of greenhouse gas (CO2, CH4, and N2O) 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 CO2 with an average of 1030±780 mg m−2 d−1 and of methane with an average of 0.20±0.15 mg m−2 d−1. One reservoir (Lake Wohlen) emitted methane at a much higher rate (160±110 mg m−2 d−1), most of which (>98%) was due to ebullition. Only lowland reservoirs were sources for N2O (72±22 μg m−2 d−1), 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.

/pdf/greenhouse-gas-emissions-co-2-ch-4-and-n-2-o-from-perialpine-2iau1vvssk.pdf

C. J. Schubert

Papers

Greenhouse gas emissions (CO 2 , CH 4 and N 2 O) from perialpine and alpine hydropower reservoirs

Greenhouse-gas (CH4, N2O and CO2) emissions from hydroelectric reservoirs in Switzerland