Evaluation of some alternative guidelines for risk assessment of various habitats.

Recently, some relatively inexpensive and simple methods suitable for classification of dangerous wastes and pollution of surface water have been developed. In order to compare the performance of the various alternative bioassays a series of examinations have been carried out with Thamnotox kits and Daphnia heart test. In addition, duckweed, as a relatively new bioindicator has been used. The alternative methods have been used for the monitoring of river Tisza, and for detection of the pollution of some watersheds. The results revealed that the alternative tests are sensitive to indicate the combined effect of various pollutants in aquatic ecosystems. It seems to be that the tests using crustacean species would give realistic results in well-defined point sources, but they can be accepted somewhat more sceptic way when comparing samples taken from different habitats. Daphnia heart rate were specific only to a limited number of compounds like pyrethroid type pesticides. For some mixtures of pollutants there was a correlation between Thamnotox and Daphnia heart data. In the case of Lemna minor at some sites instead of growth inhibition a stimulation can be detected. The toxicity estimation with Lemna strains will give us a habitat-specific indication of the pollution. An important conclusion of the results is that there is no universal bioassay available for detection of all types of pollution. The best results can be obtained with employment of a battery of bioassays.