Fate of ¹⁴C-Deltamethrin applied to Chickpea in a Model Terrestrial Agroecosystem

Fate of ¹⁴C (cyclopropyl)-deltamethrin sprayed on chickpea was studied using a model terrestrial agroecosystem. About 30.4% of the applied chemical was deposited on soil surface. Deltamethrin was dissipated from soil with a half-life of 9.4 days. The radioactive residues in soil after 30 d consisted of 13.1% deltamethrin and 6.5% Br₂CA in addition to 30.5% other degradation products and 49.9% bound residues. Forty seven % of the radiocarbon that was deposited on the soil was retained by the top 0.5 cm layer of soil, 43.3% by the 0.5–7.5 cm layer and only 9.5% moved to the 7.5–15 cm layer. The half-life of deltamethrin on cotton foliage was 23.2 days. The radiolabeled residues at the close of 30 d consisted of 21.5% cis-deltamethrin, 9.4% trans-deltamethrin, 26.3% metabolites, 33.2% conjugates and 9.5% bound residues. Only about 6.9% of the applied activity was detected in air over a period of 30 days. The concentration of residues in air was very high during the 24 h period following spray application. Almost 97.9% of the applied activity was recovered from different components of the ecosystem.