Microbiological, chemical and toxicological characterization of contaminated sites in Czechoslovakia

We investigated the contaminated area near the wood-preserving factory at the town Sobĕslav in South Bohemia. The factory has been working for approximately 90 years. The soils of this area are extremely contaminated with the polyaromatic hydrocarbons (PAHs) derived from the creosote oils and heavy metals (predominantly Zn, Cu, Hg). The biological activities of sample contaminated soils are very low compared with unpolluted soil. The comparison of actual and potential activity between samples is evaluated for the prediction of the efficiency of application of a bioremediation processes. The testing of frequency of occurrence of a bacterium resistant to heavy metals (Zn and Cu) is used for prediction of possible negative effects on the biodegradation of organic pollutants at the concentrations of heavy metals in soils. A concentration of 2 mmol/l zinc in medium (according Houba-Remarcle) does not negatively influence the number of bacteria. A concentration of 2 mmol/l copper practically does not influence the number of bacteria. Several bacterial strains are able to survive concentrations of 20 mmol/l zinc, 8.5 mmol/l copper and 2 mmol/l cadmium. The preliminary results show that practically all strains which are resistant to heavy metals are able to degrade fluoranthene, as a representative PAH. The real concentrations of heavy metals in soils are below the levels where heavy metals negatively influence the growth of bacteria.