COMPARATIVE SENSITIVITY OF 20 BIOASSAYS FOR SOIL QUALITY

Increasing evidence suggests that the use? of a single bioassay will n ever provide a full picture of the quality of the environment. Only a test battery, composed of bioassays of different animal and plant spec ies from different trophic levels will reduce uncertainty allowing an accurate assessment of the quality of the environment. III the present study a test battery composed of 20 bioassays of varying biological e ndpoints has been compared. Apart from lethality and reproductive fail ure in earthworms, springtails, nematoda, algae and vascular plants, t hese endpoints also included bioavailibility of metals (bacteria), hea t-shock induction (nematodes, algae), DNA damage (bacteria, earthworm, vascular plants), beta-galactosidase (Daphnia) and esterase activity (algae) and a range of immunological parameters (earthworm). Four chem icals (cadmium, phenol, pentachlorophenol and trifluralin) - each repr esenting a different toxic mode of action - were applied in a dilution series (from 1 mg/kg up to 1000 mg/kg) onto OECD standard soil. The t ests have been performed both on these artificially contaminated soil samples and on aqueous extracts subsequently obtained from these soils . The results show that the immunological parameters and the loss of w eight in the earthworms were among the most sensitive solid-phase assa ys. Esterase inhibition and heat-shock induction in algae were shown t o be extremely sensitive whet? applied to soil extracts As previously shown at the species level, Ilo single biological endpoint was shown t o be the most sensitive for all four modes of toxic action.