title: Dynamics of transformation of the veterinary antibiotic sulfadiazine in two soils.
abstract: Veterinary antibiotics administered to livestock can be unintentionally released into the environment, for example by the application of manure to soils. The fate of such antibiotics in soils is mostly determined by sorption and degradation processes, including transformation. There is a need to further examine the combined transformation and sorption behavior of these emerging pollutants in soils. Long-term batch sorption experiments with the (14)C-radiolabeled antibiotic sulfadiazine enabled us to simultaneously trace the sorption and transformation dynamics of sulfadiazine. The parent compound and the transformation products were analyzed in the liquid phase and in the extracts from the solid phase after a sequential extraction. We found that of up to six transformation products were formed during degradation and that these products exhibited quite different dynamics in the two soils. Transformation products were formed rapidly and were extractable from the solid phase. We observed identical sets of the transformation products in both phases. The input concentration influenced the course of transformation of the parent substance. We present a detailed analysis including a mathematical description and derive regulatory kinetic endpoints for predicting environmental concentrations.
authors.affiliation: Agrosphere Institute, IBG-3, Forschungszentrum Jülich GmbH, Leo-Brandt-Strasse, D-52425 Jülich, Germany. Electronic address: sittig.stephan@t-online.de.
authors.forename: Stephan
authors.initials: S
authors.lastname: Sittig
authors.forename: Roy
authors.initials: R
authors.lastname: Kasteel
authors.forename: Joost
authors.initials: J
authors.lastname: Groeneweg
authors.forename: Diana
authors.initials: D
authors.lastname: Hofmann
authors.forename: Björn
authors.initials: B
authors.lastname: Thiele
authors.forename: Stephan
authors.initials: S
authors.lastname: Köppchen
authors.forename: Harry
authors.initials: H
authors.lastname: Vereecken
mesh_terms: D000327:Adsorption; D000900:Anti-Bacterial Agents / Q000032:analysis*; D007700:Kinetics; D008956:Models, Chemical; D012987:Soil / Q000737:chemistry*; D012989:Soil Pollutants / Q000032:analysis*; D013411:Sulfadiazine / Q000032:analysis*; D019155:Veterinary Drugs / Q000032:analysis*
chemical_list: D000900:Anti-Bacterial Agents; D012987:Soil; D012989:Soil Pollutants; D019155:Veterinary Drugs; D013411:Sulfadiazine
keywords: Kinetic endpoints; Numerical studies; Sorption and sequestration; Sulfadiazine; Transformation in soils