Soil bacteria sensitivity towards heavy metals – Experimental system optimisation using chemical speciation calculations

Abstract

The ecotoxicological relevance of many laboratory studies on soil bacteria sensitivity towards heavy metals is limited because culture conditions are chosen which do not adequately represent field conditions. The 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 information on the concentration of the bioavailable fraction and the totally dissolved copper. For control measurements of totally dissolved copper, vacuum filtration has been used. The results of the measurements are in a good agreement with the calculations. Therefore, the use of speciation calculations is postulated as a useful tool for the assessment of free metal concentrations at higher pH, where the concentrations of dissolved metals are too low to be measured by simple methods.