Differential sensitivity of the Lemnaceae species to chromium and zinc

The aim of study was to optimize alternative acute toxicity tests involving toxic compounds of Cr(VI) and Zn(II) and two representatives of the Lemnaceae species ( Lemna gibba and Spirodela polyrhiza ) as testing organisms and to compare their relative sensitivity with Lemna minor and Daphnia magna . The most sensitive organism to both metals was D. magna . The highest duckweed sensitivity to Cr(VI) and Zn (II) was determined for S. polyrhiza and L. gibba , respectively. The compound of Cr(VI) provided sig nificantly higher toxicity effect towards the testing organisms than Zn(II). L. gibba proved the most suitability for assessment of envi ronmental quality due to the highest duckweed sensitivity. In contrast, L. minor and S. polyrhiza showed the lowest sensitivity to Cr(VI) and Zn(II), respectively. It was probably caused by their antioxidant ability, a nd thus they may be the most effective for removal of metals fro m water environment.