Degradation of esfenvalerate in illuminated water-sediment system

The aerobic aquatic soil metabolism of esfenvalerate [(2S,αS)-α-cyano-3-phenoxybenzyl 2-(4-chlorophenyl)-3-methylbutyrate] was examined in two Japanese pond water-sediment systems in relation to the effects of illumination and formulation on degradation profiles. Esfenvalerate was rapidly partitioned from the water phase to the bottom sediments with dissipation half-lives of less than 1 day and either the application of formulation or illumination slightly accelerated the partition. The main degradate of esfenvalerate was 3-phenoxybenzoic acid via ester cleavage both under dark and light conditions. The epimerization at the α-cyanobenzyl carbon significantly proceeded to form the corresponding [2S,αR] isomer in both water and sediment. The possible degradate via photo-induced decarboxylation was scarcely detected in the water phase of the illuminated water-sediment systems.