Interaction of aquatic humic substances with anilazine and its derivatives: The nature of the bound residues

This study is focused on the binding behaviour of the triazine fungicide anilazine and its main metabolites such as dihydroxyanilazine in aquatic ecosystems. For this purpose anilazine and its derivatives were incubated with ultrafiltrated dissolved organic matter (DOM) and isolated fulvic and humic acids, respectively and the adsorption isotherms according to Freundlich were determined. More than 90% bound residues were formed and up to 60% of anilazine metabolites were released with a recently developed silylation method. The study of the reactivity of metabolites and model compounds as well as our NMR investigations showing ether bondings led to a suggested binding scheme of anilazine to humic substances. To have more realistic conditions the behaviour of anilazine and dihydroxyanilazine in aquatic model ecosystems with water and sediment from a river was also part of this study. Furthermore the release of active ingredients or derivatives from sediment by different extraction methods was examined. (C) 1998 Elsevier Science Ltd. All rights reserved.