Fate and effects of esfenvalerate in agricultural ponds

The fate of esfenvalerate was investigated by sampling and chemical analysi s after spraying of an artificial pond (25 g a.i./ha) and in the laboratory with [C-14]esfenvalerate by trapping of (CO2)-C-14 and fractionation of th e sediment. The effects were investigated on pelagic communities in enclosu res in a natural lake and in the laboratory on surface (Cymatia coleoptrata ) and sediment (Chironomus riparius) insects. The latter were used in sedim ent-plus-water and in water-only tests, measuring effects on emergence and mortality. The measurements in the artificial pond indicated exposure conce ntrations in the surface microlayer, water column, and sediment of 0.4 mug/ L. 0.05 mug/L, and 9 mug/kg dry weight, respectively, two weeks after appli cation. The degradation studies showed a limited mineralization (26.5%) of [chlorophenyl-C-14]esfenvalerate during 112 d. Part of the substance was tr ansformed to water-soluble compounds (18.1%) or compounds attached to fulvi c acids (26.2%), humic acids (14.28), or nonextractable sediment constituen ts (8.8%). The formulated product Sumi-Alpha 5 FW (R) caused 100% mortality to Cymatia coleoptrata after surface application of 0.13 g a.i./ha. Effect s on zooplankton were recorded at 0.005 mug/L of esfenvalerate. The 96-h me dian lethal concentration for first-instar larvae of Chironomus riparius wa s 0.13 mug/L, whereas the delayed emergence lowest-observed-effect concentr ation was 0.8 mug/L.