Metofluthrin [2,3,5,6-tetrafluoro-4-(methoxymethyl)benzyl (1R,3R)-2,2-dimethyl-3-((1EZ)-prop-1-enyl)cyclopropanecarboxylate] was rapidly degraded in two aerobic US soils with first-order half-lives of 2.3-3.5 days primarily via ester cleavage to give the corresponding acid and alcohol without any epimerization and geometrical isomerization. The rapid oxidation proceeded either at the prop-1-enyl group of the acid to moiety form the diacid derivative or the benzyl carbon to finally give the terephthalic acid derivative. These metabolites were finally mineralized to carbon dioxide with partial formation of bound residues. The soil adsorption coefficients (K oc ) of the Z isomer, the main component of metofluthrin, in three German soils were determined to be 3553-6124 (ml/g o.c.) by the batch equilibrium method. The screening groundwater simulation model SCI-GROW using the metabolic half-lives and K oc values clearly indicates that metofluthrin is most unlikely to contaminate groundwater even in the unrealistic worst case.

The aerobic aquatic soil metabolism of esfenvalerate [(2S,aS)-a-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 a-cyanobenzyl carbon significantly proceeded to form the corresponding [2S,aR] 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.

Aerobic soil metabolism of uniconazole-P ([S]-E-1-[4-chlorophenyl]-4,4-dimethyl-2-[1,2,4-triazole-1-yl]-penten-3-ol) and the effect of illumination on metabolic profiles were studied in the water-sediment system when spiked to water. Uniconazole-P was gradually partitioned to the sediment with an aquatic half-life of 6.9 d in darkness with formation of bound residues. Illumination of the system from a xenon lamp (>290 nm) greatly accelerated the degradation of uniconazole-P via photoinduced isomerization between E- and Z-isomers with a subsequent intramolecular cyclization, and its aquatic half-life was greatly reduced to 0.6 d. Kinetic analysis based on compartment models suggested the possible contribution of photodegradation at the water-sediment interface, leading to more formation of the cyclized derivative in the sediment.

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