Main content area

Peat capping: Natural capping of wet landfills by peat formation

Harpenslager, Sarah F., Overbeek, Ciska C., van Zuidam, Jeroen P., Roelofs, Jan G.M., Kosten, Sarian, Lamers, Leon P.M.
Ecological engineering 2018 v.114 pp. 146-153
Typha latifolia, basins, biomass production, bioremediation, clay, constructed wetlands, landfills, landscapes, net ecosystem exchange, organic soils, peat, sand, topsoil, vegetation types, water quality
Given the bioremediation potential of peat, natural capping of landfills in wetlands with a “peat cap” could provide a sustainable addition to regular capping methods using basal liners with limited life-spans and sand. It is unknown, however, which initial conditions optimise growth of this “peat cap” on top of a sand layer. Here, we tested the combined effects of topsoil addition (clay or organic soil) and vegetation type (Typha latifolia, T. angustifolia, Stratiotes aloides and submerged spp.) on net ecosystem C exchange and water quality in 18 sandy basins situated in a constructed wetland on top of a landfill. Although the highest net C sequestration rates occurred in Typha stands on sand, due to lower decomposition-related C losses as compared to clay and organic topsoils, vegetation development was slow and its cover was very low (15%) compared to clay (40%) and organic topsoils (70%). As this strongly impeded the build-up of a uniform peat layer, we conclude that, within a restricted time frame, the application of nutrient-rich topsoils is still necessary for sufficient biomass production to accumulate organic material. By recycling local soils, the accompanying initial C loss becomes negligible on a landscape scale.