Formation and bioavailability of soil-bound-[14c]-pyrethroid residues

Abstract

¹⁴C-cypermethrin and ¹⁴C-permethrin degraded in Humic Gley and Red-Yellow Latosol soil samples were observed under laboratory conditions. Degradation to ¹⁴CO₂ was mainly biological, as it was very reduced in sterile soil samples. The formation of non-extractable ¹⁴C-cypermethrin residues or its metabolites represented after 120-day incubation 47% of the recovered radiocarbon in Humic Gley soil and 91% in Red-Yellow Latosol. These residues were liberated as ¹⁴CO₂ after addition of non-treated soil, as inoculum source, indicating bioavailability of the bound residue by soil microorganisms action.