: The ability of the white rot basidiomycete Phanerochaete chrysosporium to transform s-triazine herbicides has been investigated in laboratory experiments. The chlorinated metabolites formed during atrazine Ndealkylations were not further transformed by the fungus, whereas hydroxyatrazine was converted to an unknown product. P. chrysosporium was also able to carry out the N-dealkylation of the herbicides simazine, propazine and terbuthylazine. Herbicide metabolism was not supported by puriÐed peroxidases. The highest rates of herbicide N-dealkylation were obtained in liquid cultures maintained under moderate temperature allowing a long mycelium growing phase. Atrazine transformation was found to be supported by the mycelium, which contained signiÐcant amounts of microsomal cytochrome P450. Herbicide N-dealkylation was decreased in the presence of 1-aminobenzotriazole, in agreement with the involvement of P450 monooxygenases in atrazine metabolism.
Retention processes play a major role in the fate and impact of organic contaminants in soils. The main goal of this study was to determine the influence of soil hydrophobic properties on the retention of diuron by using plots of a long-term experiment in Versailles. We selected seven plots with pH 3.4 to 8.2 and low organic content. Sorption isotherms were obtained on soil slurries and kinetic measurements of diuron sorption were performed on undisturbed soil samples. The results showed that the Freundlich coefficient k f decreased as pH increased and that the K oc coefficient, k f /TOC, was linearly related to the contact angle measured on the clay fraction over a wide range of pH. A low initial adsorption rate and low adsorption equilibrium were observed for the plot treated with NaNO 3 . In this case, the structure in micro-aggregates was assumed to limit the accessibility of adsorption sites. The CaCO 3 and CaO treated plots had similar organic matter contents, pHs, CECs and bulk densities, although their < 2 mm:C ratio differed. The higher retention of diuron in the CaCO 3 plot is attributed to the higher hydrophobicity of the < 2 mm fraction, probably masking part of the permanent clay negative charges. Thus, in addition to the different treatments, organic matter composition and distribution should also be included as specific soil properties. We conclude that the sorption properties of pesticides such as diuron can be a good tool to obtain greater understanding of soil properties and the degree of soil hydrophobicity/hydrophilicity in particular.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.