Environmental Fate of Trifloxystrobin in Soils of Different Geographical Origins and Photolytic Degradation in Water
Kaushik Banerjeea, Axel Patrick Ligonb and Michael Spitellerb
aNational Research Centre for Grapes, Pune 412 307, India bInstitute of Environmental Research (INFU), University of Dortmund, Otto-Hahn-Strasse 6, 44221 Dortmund, Germany
Received 19 July 2006
Revised 7 September 2006
Accepted 7 September 2006
In vitro biodegradation of trifloxystrobin (TFS) under darkness could best be explained by two-compartment first + first-order rate kinetics with half-lives ranging between 1.8 and 2.3 days. Hydrolysis was found to be the major pathway of degradation resulting in the formation of the acid metabolite, TFS-acid, with an EE conformation. The adsorption rate kinetics of both TFS and TFS-acid followed linear and Freundlich isotherms. The extent of adsorption was directly correlated with organic matter and clay contents, whereas desorption had a negative correlation. The high partition coefficients (KD) indicate strong adsorption of TFS on all of the test soils without any appreciable risk of groundwater contamination. In case of the TFS-acid, however, the adsorption was weaker; hence, if its further degradation is slow, it may contaminate lower soil horizons under worst case conditions. TFS did not cause any adverse effect on the soil microbial population. TFS was susceptible to aquatic photolysis in summer with an environmental half-life of 0.7-1.3 days irrespective of the latitudes.
Keywords: Trifloxystrobin; soils; biodegradation; half-life; adsorption; desorption