Characterization of non-extractable residues of the fungicide dithianon in soil using 13C/14C-labelling techniques.
The fate of the (14)C-labelled fungicide dithianon in soil is characterized by the formation of non-extractable, "bound" residues of approximately 63% of applied amount in 64 d. Humic acids containing these "bound" residues were isolated after conducting degradation studies of the active ingredient in an orthic luvisol under standardized conditions. In the same way, (13)C-labelled dithianon was incubated in an artificial soil which was produced by humification of (13)C-depleted straw in an incinerated soil. The "bound" residues of the (13)C-labelled dithianon in the humic acid fraction of the artificial soil were analyzed using (13)C-NMR techniques. There was no evidence of a covalent bonding of the residues to the humic substances. Results of polarity gradient high performance thin layer chromatography (AMD-HPTLC) of "bound" residues of the (14)C-labelled dithianon in the humic acid fraction indicate a sequestration process of metabolites into the humic substance as a possible binding mechanism.
Institute of Chemistry and Dynamics of the Geosphere, Institute IV: Agrosphere, Forschungszentrum Jülich GmbH, D-52425 Jülich, Germany.
Uwe
U
Wanner
Fritz
F
Führ
Albert A
AA
DeGraaf
Peter
P
Burauel
D000880:Anthraquinones / Q000032:analysis* / Q000737:chemistry; D002250:Carbon Radioisotopes; D002851:Chromatography, High Pressure Liquid; D005659:Fungicides, Industrial / Q000032:analysis* / Q000737:chemistry; D006812:Humic Substances; D007553:Isotope Labeling; D010573:Pesticide Residues / Q000737:chemistry*; D012989:Soil Pollutants / Q000032:analysis*
D000880:Anthraquinones; D002250:Carbon Radioisotopes; D005659:Fungicides, Industrial; D006812:Humic Substances; D010573:Pesticide Residues; D012989:Soil Pollutants; C018529:dithianone