In-situ mätning av gasutbytet över sjösediment - en förutsättning för ökad kunskap om en betydande växthusgaskälla i det skogslandskap
Tidsperiod: 2012-01-01 till 2015-12-31
Projektledare: Sebastia Sobek, Sebastian Sobek
Budget: 3 000 000 SEK
The degradation of organic matter in the sediments of boreal lakes contributes greatly to the significant emissions of the greenhouse gases carbon dioxide and methane from boreal lakes to the atmosphere. However, current sediment gas release estimates are probably biased low, because they are derived from measurement methods that inhibit turbulent water movements, which exert a strong physical control on sediment gas exchange. We therefore plan to join our expertise in aquatic biogeochemistry and turbulent flux measurement for an interdisciplinary research project on turbulent gas exchange in boreal lake sediments. We will apply the novel subaqueous eddy covariance (EC) technique for in-situ measurement of oxygen exchange at natural turbulence conditions, coupled to acoustic doppler current profiler suveys of water turbulence, conventional measurements of carbon dioxide and methane release from sediment cores, and atmospheric EC measurements of lake carbon dioxide and methane emission. Based on these data, we will be able to calculate the first estimates of lake sediment carbon dioxide and methane release at natural turbulence conditions, and to compare the sediment release to atmospheric emission. The proposed research will take our understanding of lake sediments as greenhouse gas sources to the next level, and will enable us to better account for potential climate change effects on the role of lake sediments in the carbon cycle of boreal landscapes.