Conazole fungicides are currently used pesticides with considerable chronic toxicity and ecotoxicity that are also on EU list for substitution. They enter the soil forming short- or long-term residues. In this study two of their representatives, epoxiconazole (EPC) and tebuconazole (TBC), have been tested with 20 soils from the Czech Republic for their adsorption. Adsorption, by means of Kd coefficients, was compared to "basic" (TOC, pH, clay …) and "advanced" (surface area, minerals ..) soil properties. After doing multivariate analysis of the variables it was apparent that adsorption of both pesticides was highly associated with pH (negatively correlated), and less associated with soil organo-mineral complex (TOC, clay and surface area) and C and N in soil organic matter (OM). Particle sizes or cation exchange capacity (CEC) did not show correlation with adsorption, but showed an association in multidimensional space in factor analysis (FA). Some correlations were revealed between EPC adsorption and soil organic matter parameters. Recalculating Kd to Koc and to Gibb's free energy (ΔG) and its values indicated that the adsorption of EPC and TBC is mainly weak physical adsorption - partitioning. Also, ΔG values gave better correlation with pH(H2O) than Kd. Surface area impacted EPC adsorption. From the several soil minerals, kaolinite showed EPC and TBC adsorption. EPC adsorption was not highly influenced with pH changes compared to TBC. The number and types of H-bonds with molecular geometry govern the sorption, which might crucially affect leachibility in soil, and this may indicate that TBC is more leachable than EPC for the same soil.

Institute for Environmental Biotechnology Department for Agrobiotechnology Konrad Lorenz Strasse 20 A 3430 Tulln Austria

Materials Research Centre Brno University of Technology Purkyňova 464 118 612 00 Brno Czech Republic

Research Centre for Toxic Compounds in the Environment Faculty of Science Masaryk University Kamenice 753 5 Brno 625 00 Czech Republic

Research Centre for Toxic Compounds in the Environment Faculty of Science Masaryk University Kamenice 753 5 Brno 625 00 Czech Republic; Department of Agrochemistry Soil Science Microbiology and Plant Nutrition Faculty of Agronomy Mendel University in Brno Zemědělská 1 1665 613 00 Czech Republic

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