Nutrient mobilisation and losses related to the groundwater level in low peat soils

The changes in dissolved organic carbon (DOC), N-NO₃, N-NH₄ and P-PO₄ concentrations in response to fluctuations in the groundwater table were investigated in the peatlands of Biebrza National Park and some of its surrounding sites. The lowering of the groundwater table during summer time was accompanied by an increase in P-PO₄ and N-NH₄ concentrations, and in some cases they were exceptionally high compared with undisturbed water. Concentrations of both nutrients correlated with groundwater levels. Decreasing the groundwater level promoted higher concentrations of both nutrients. Nevertheless, elevated concentrations of P-PO₄ and N-NH₄ occurred in groundwater during the summer months when the outflow of water from peatland was slow. The N-NO₃ and DOC concentrations did not change markedly with the lowering of groundwater table or during different seasons.