Buried carbon at the shore
Jonathan Ardenstedt and Esra Reichert taking samples from the bottom sediment in the littoral zone of Lake Alsta. Photo: Marcus Holmqvist, Uppsala University
Lake shores with a lot of reeds and other vegetation may not be tempting for swimmers. However, Sebastian Sobek and his colleagues have discovered that such environments can be important for the climate. Littoral zones store carbon that would otherwise seep into the atmosphere and contribute to global warming.
“What we have now realised is that there is a great deal of biological activity in the littoral zones, with both greenhouse gas emissions, especially of methane, and carbon storage in the lakebed,” says Sebastian Sobek, Professor of Limnology at the Department of Ecology and Genetics.
He has travelled to Lake Alsta in Uppland, where on this very day doctoral student Esra Reichert, research assistant Fredrik Wikström and Master’s student Jonathan Ardenstedt are taking sediment samples in the reeds. Back in the laboratory, they will then analyse the carbon content to find out how much carbon has been stored. They are also measuring how much methane is released into the atmosphere.
“The reeds absorb carbon dioxide from the air as they grow, of course. And then, when the reeds die in the autumn, much of this is broken down by microbes. The dead plant material may then be returned to the atmosphere as carbon dioxide or methane. But part of the reed’s mass is not broken down by the microbes. It lies there for a long time, hundreds, thousands of years,” Sobek explains.
In this way, the littoral zone becomes a carbon sink.
Åsa Malmberg and Marcus Holmqvist