SOIL BACTERIA SENSITIVITY TOWARDS HEAVY-METALS - EXPERIMENTAL SYSTEM OPTIMIZATION USING CHEMICAL SPECIATION CALCULATIONS

The ecotoxicological relevance of many laboratory studies on soil bact eria sensitivity towards heavy metals is limited because culture condi tions are chosen which do not adequately represent field conditions. T he influence of the composition of culture media on the speciation of copper in an oligotrophic model soil system has been investigated. The expected chemical speciation has been calculated to obtain informatio n on the concentration of the bioavailable fraction and the totally di ssolved copper. For control measurements of totally dissolved copper, vacuum filtration has been used. The results of the measurements are i n a good agreement with the calculations. Therefore, the use of specia tion calculations is postulated as a useful tool for the assessment of free metal concentrations at higher pH, where the concentrations of d issolved metals are too low to be measured by simple methods.