Variability of cation-exchange capacity (CEC) of fen peats in vertical profiles from eastern and central Poland in relation to function of peatlands as natural geological barriers

An analysis of cation-exchange capacity (CEC) variability of peats is presented in vertical profiles from eastern and central Poland. CEC values were compared with ash content (Ac), pH and CaCO3 content. Eight peatlands were selected for research in the following areas: Warsaw Plateau (2 objects), Siedlce Plateau (2 objects), Lubartów Plateau (2 objects), Nałęczów Tableland (1 object) and Dobrohusk Depression (1 object). The peatlands represented a fen peat type of similar botanic compositions of sediments, but they differed in the area, peat thickness and drainage conditions. Characteristic regularities in CEC variability were noted in the peatlands and there were three types of CEC variability in vertical profiles. Carbonate peats (types 1 and 2) had the highest pH and definitely the highest values of CEC. In vertical profiles, there was also a zonation, but the regularities similar to non-carbonate peats were not observed. Different distribution of physical and chemical parameters were established in vertical profiles in partly drained peatlands (with a muck layer on top) with non-carbonate peats (type 3) and there were three distinct zones in vertical profiles, with different Ac and CEC. Determination of the vertical CEC variability and other physical and chemical parameters in peatlands made it possible to distinguish zones with potentially most beneficial isolation conditions.