This thesis aimed to reveal seawater effects on peat soil processes using different laboratory flow-through experiments. The results show that the effects depend on the environmental conditions, which are in turn affected by the peatland’s land-use history. The interaction of geochemical and hydrophysical soil properties determines the mobility of solutes. Initial leaching and desorption processes and, later on, an enhanced, sulfate-related decomposition of organic matter may lead to nutrient emission into adjacent aquatic ecosystems.