title: Dissipation and mobility of permethrin in the field with repeated applications under tropical conditions.
abstract: Studies on persistence, mobility and the effect of repeated application of permethrin on its half-life were carried out under field conditions. The half-life of permethrin in the top 20 cm of the soil increased from 11.5 to 23.6 days as the application rates increased from 35 to 140 g ha(-1). Induced by heavier rainfall, more residues moved downward in trial 2 than in trial 1. Repeated applications enhanced degradation rates and mobility of permethrin in the soil. The residue level in the 0-5-cm layer was reduced at day 28 after 17 consecutive applications to a level lower than after 5 applications. The half-life of permethrin was reduced from 15.9 days to 11.2 days after 5 and 17 applications, respectively. The residue reached the 15-20 cm layer much earlier (approximately 3 days after treatment) in soil that received 17 applications as compared to those with two applications.
authors.affiliation: School of Environmental and Natural Resource Sciences, Universiti Kebangsaan Malaysia, Bangi, Selangor, Malaysia. ismail@pkrisc.cc.ukm.my
authors.forename: B S
authors.initials: BS
authors.lastname: Ismail
authors.forename: K
authors.initials: K
authors.lastname: Kalithasan
mesh_terms: D002851:Chromatography, High Pressure Liquid; D006207:Half-Life; D007306:Insecticides / Q000032:analysis / Q000378:metabolism*; D026023:Permethrin / Q000032:analysis / Q000378:metabolism*; D010573:Pesticide Residues / Q000032:analysis / Q000378:metabolism*; D011891:Rain; D012987:Soil / Q000032:analysis*; D012989:Soil Pollutants / Q000032:analysis / Q000378:metabolism*; D013997:Time Factors
chemical_list: D007306:Insecticides; D010573:Pesticide Residues; D012987:Soil; D012989:Soil Pollutants; D026023:Permethrin