[n the paper the cationic equilibrium in the leaves of aquatic plants Nymphaea alba L. and Nuphar lutea (L.) Sibith. & Sm. was studied according lo Czarnowski method. Plant material was collected in 25 sites from littoral of fourteen eutrophic lakes of Pojezierze Leszczyńskie in West Poland. After the leaves had been cleaned, dryed and pulverized, the concentrations of N, P, K, Ca, Mg, Na, S, Fe, Sr, V, Cu, Cr, Mn, Ni, Cd, Al, Co, Pb, Zn, and Ba in them were determined. Next, the relative concentrations of the examined elements (concentration of each element in relation to the sum of all elements) and their relationships were calculated. The values of weighed sums of square roots of the relative cation concentrations in Nymphaea alba L. and Nuphar lutea (L.) Sibith. & Sm. varied from 13.2 to 13.8 and from 13.5 to 14.0, respectively. These values were higher than 12.5 given by Czarnowski because of high calcium and sodium concentrations. Significant positive correlations between relative concentrations of potassium and nitrogen, magnesium and zinc, cadmium and lead, iron and copper, iron and aluminium, aluminium and manganese, cadmium and manganese, cadmium and nickel, cadmium and zinc, as well as nickel and zinc were found, which proves the evidence for existence of synergism between these ions. However, substantial negative correlation between potassium and calcium testified to antagonism between these cations.

The contents or Cd, Pb. Cu, Mn, Zn, Ni and Fe in different organs or Typha latifolia L., coming from six sites selected within Jezioro Wielkie (Leszczyńskie Lakeland in western Poland), were determined. Three groups or metals, cach with a different accumulation pattern within the plant were distinguished in this study. Pb, Zn and Cu were found to be the least mobile and shown the following accumulation scheme: roots> rhizomes> lower leave part> top leave part. 13y contrast, Mn, a metal which is both easily transported in plants and accumulated in green plant organs, exhibited the following accumulation scheme: roots> top leave part> lower leave part> rhizomes. Ni, Cd and re were accumulated by the cattail as follows: roots> rhizomes> top leaf part> lower leaf part. The fact that Tvpha tatifol io L. had the highest proportion 01· all the metals studied in its roots can suggest that some kind of protection barrier exists which prevents toxic compounds permeating from that part or this plant to its rhizomes and its aerial parts. The confirmation or this thesis requires some further research.