SEDIMENT CARBON SEQUESTRATION IN VEGETATED AREAS OF FINNISH LAKES: FIRST RESULTS FROM THE BLUE LAKES PROJECT

Aquatic vegetated ecosystems play an important role in global carbon sequestration. Although coastal marine environments have been relatively more studied in the past decades, vegetated shorelines in freshwater ecosystems can also bury significant amounts of carbon. This is especially relevant in boreal landscapes, which often show high densities of small, shallow lakes. In Finland, for example, it has been suggested that lakes may host nationally significant carbon stocks. Given this context, one goal of the Blue Lakes project is to understand drivers of sedimentary carbon burial along vegetated shorelines of boreal lakes. We took sediment cores from three large lakes in Finland with sites chosen based on previous satellite data of macrophyte presence. At each site, sediment cores were sampled in a transect through macrophyte zones, from the landside towards the waterside. Sedimentary carbon stocks (mass of carbon per area) showed a large spatial variability regarding lakes, zones and type of vegetation. However, grain size was the most significant parameter explaining variability in the magnitude of large C stocks. Sites dominated by silts and with large C stocks were found in sheltered embayments, regardless of proximity to rivers, density of vegetation or slope of the shoreline, implying a strong control of exposure on C accumulation. Refining C stock estimates according to the shoreline exposure degree will allow to more precise upscaling when combining these data with macrophyte vegetation surface area coverage in Finnish lakes.

Presentation Preference: Oral

Primary Presenter: Ana Lúcia Lindroth Dauner, University of Helsinki (ana.lindrothdauner@helsinki.fi)

Authors:

Ana Lúcia Lindroth Dauner, Department of Geosciences and Geography, Faculty of Science, University of Helsinki, Helsinki, Finland  (anadauner@gmail.com)

Max Kankainen, Department of Geosciences and Geography, Faculty of Science, University of Helsinki, Helsinki, Finland  (max.kankainen@helsinki.fi)

Karoliina Koho, Geological Survey of Finland, Espoo, Finland  (karoliina.koho@gtk.fi)

Tom Jilbert, Department of Geosciences and Geography, Faculty of Science, University of Helsinki, Helsinki, Finland  (tom.jilbert@helsinki.fi)