OBJECTIVES: An enhanced worldwide application of platinum group elements (PGE), in particular platinum, has been observed during recent decades. An increased concentration of PGE was determined in collected samples of great amount of aqueous ecosystems.The aim was to compare phytotoxic effect of platinum (PtCl4) by performing two different bioassays on green algae Pseudokirchneriella subcapitata and macrophyte duckweed, Lemna minor. MEDTHODS: The algal experiment (Pseudokichneriella subcapitata) followed OECD 201, the concentration row for PtCl4 was: 0.05; 0.01; 0.25; 0.5; 1 µM. The duckweed (Lemna minor) experiment was conducted according to OECD 221, employed PtCl4 concentrations were: 5; 10; 25; 50; 100 µM. Plants were cultivated as a microbiotest, using micro-volumes.
RESULTS: The results of the algal test showed significant growth inhibition of the final biomass. The values of 72hEC5(µ), 72hEC10(µ), 72hEC20(µ) counted on a basis of average specific growth rate (µ) were 0.31 µM, 0.58 µM and 1.12 µM of PtCl4, respectively. The values, obtained on a basis of the area under the growth curves (A), were 0.04 µM (72hEC5(A)), 0.24 µM (72hEC10(A)) and 0.64 µM (72hEC20(A)). The experiment with duckweed showed 50% of growth inhibition and the values of 168hEC50(µ) were 19.55 µM and 168hEC50(A) 13.63 µM of PtCl4.
CONCLUSION: The fronds of duckweed showed strong adverse effect of platinum influence (chlorosis, necrosis). The algal test and the estimation of 72hEC5(A) appears to be the most sensitive.