Sediment phosphorus fractions in an urban lake and its usability for predicting of the internal loading phenomenon

The object of present study was Sukiel Lake (area 20.8 ha, max. depth 25 m), localised in north-eastern Poland (Mazurian Lake District), in Olsztyn city. The aim of this study was to analyse the phosphorus fractions in the sediments of two lake bottom zones - profundal (25 m) and sublittoral (7 m). Observed high P concentrations in the deposits of Sukiel Lake and quantitative domination of hard mobile P fractions (NaOH-TP, HCl-P and res-P) suggest that the sediments of Sukiel Lake are the effective trap for phosphorus and that limits excessive internal loading in this lake.