Floating aquatics plants, duckweed (Lemna minor) ar liverwort (Riccia fluitans), were examd. as mineral-carrying components of animal diet. The plants were rinsed, dried at 60 degrees C, and suspended in solutions contg. (a) Cr (III) 20 (b) Cr(III) 20, Cu 2, Mn(II) 20, Zn(II) 20, and Fe(III) 20 mg 20 degrees C, pH 5. With either plant, the (b) metal-binding capacities followed the descending order: Fe > Cr > Zn > Mn Cu and the molar ratio of the sorbed ions was 17:34:3:2: The total sorption capacities were (a) 1.75 and 1.63; 2.26 and 1.87 meq/g, resp. L. minor sorbed 48 mg/g - 5 dry cell wt., (Fe 17, Cr 15, Zn 9.4, Mn 4.9, Cu 1.6 mg/g), ar R. fluitans 38 mg/g - 4% dry cell wt. (Fe 17, Cr 12, Zn 4. Mn 2.4, and Cu 1.6 mg/g).