The Volgermeerpolder, located near Amsterdam in the Netherlands, is a toxic waste site that was capped with foil and an artificial wetland on top.
According to researchers at Radboud University, six years after the opening of the wetland, it appears that the new site is already forming peat, which can capture and store carbon.
How does this work? Peat contains high levels of carbon, which binds pollutants. There is already a large layer of peat beneath the toxic landfill, which is preventing toxins from leaking from the landfill into the groundwater. That layer of peat has eliminated the need to dig up the entire toxic site at the Volgermeer. Instead, authorities were able to cap the site with a layer of foil.
If the foil were to tear, another protective layer of peat is forming on top of that protective barrier. Growing peat from scratch has never been attempted before, but it appears to be working.
Peat grows at a very slow pace—only about 1 millimeter per year on average—and researcher Sarah Faye Harpenslager says this growth is something that can’t be measured directly.
“That one millimeter falls outside of the margin of error,” she said. “But we can measure whether carbon is being captured and stored by determining the difference in carbon dioxide levels by taking the amount of carbon dioxide that is captured by plants and then subtracting the carbon dioxide that is released when those plans decompose. The less plants decompose, the more peat that is formed. The Volgermeer is indeed capturing and storing carbon, so peat is clearly being formed even though you can’t see it.”
Harpenslager and her colleagues also compared peat formation in ponds with different bottoms—sand, clay, or a layer of organic topsoil. The topsoil was shown to be the more fertile. “In ponds with a thin layer of topsoil, peat-forming plants grow most prolifically and capture the most carbon,” Harpenslager said. “For peat o form, it is essential that peat-forming plants such as common reed, cattail, and water soldiers start to grow here.”
According to the researchers, the results of their study are not just applicable to capping of polluted land. Their research shows that peat could also be important for the capture and storage of greenhouse gases through need peat formation and preventing subsidence.