title: Persistence of spiromesifen in soil: influence of moisture, light, pH and organic amendment.
abstract: Persistence of spiromesifen in soil as affected by varying moisture, light, compost amendment, soil sterilization and pH in aqueous medium were studied. Degradation of spiromesifen in soil followed the first-order reaction kinetics. Effect of different moisture regimes indicated that spiromesifen dissipated faster in submerged soil (t 1/2 14.3-16.7 days) followed by field capacity (t 1/2 18.7-20.0 days), and dry soil (t 1/2 21.9-22.9 days). Dissipation was faster in sterilized submerged (t 1/2 17.7 days) than in sterilized dry (t 1/2 35.8 days). Photo spiromesifen metabolite was not detected under different moisture regimes. After 30 days, enol spiromesifen metabolite was detected under submerged condition and was below detectable limit (<0.001 μg g(-1)) after 90 days. Soil amendment compost (2.5 %) at field capacity enhanced dissipation of the insecticide, and half-life value was 14.3 against 22.4 days without compost amendment. Under different pH condition, residues persisted in water with half-life values 5.7 to 12.5 days. Dissipation in water was faster at pH 9.0 (t 1/2 5.7 days), followed by pH 4.0 (t 1/2 9.7 days) and pH 7.2 (t 1/2 12.5 days). Exposure of spiromesifen to different light conditions indicated that it was more prone to degradation under UV light (t 1/2 3-4 days) than sunlight exposure (t 1/2 5.2-8.1 days). Under sunlight exposure, photo spiromesifen metabolite was detected after 10 and 15 days as compared to 3 and 5 days under UV light exposure.
authors.affiliation: Division of Agricultural Chemicals, Indian Agricultural research Institute, New Delhi, 110012, India.
authors.forename: Ch Jamkhokai
authors.initials: ChJ
authors.lastname: Mate
authors.forename: Irani
authors.initials: I
authors.lastname: Mukherjee
authors.forename: Shaon Kumar
authors.initials: SK
authors.lastname: Das
mesh_terms: D004784:Environmental Monitoring; D006207:Half-Life; D006863:Hydrogen-Ion Concentration; D007306:Insecticides / Q000032:analysis* / Q000737:chemistry; D007700:Kinetics; D008027:Light; D008956:Models, Chemical; D012987:Soil / Q000737:chemistry; D012989:Soil Pollutants / Q000032:analysis* / Q000737:chemistry; D013141:Spiro Compounds / Q000032:analysis* / Q000737:chemistry; D014466:Ultraviolet Rays
chemical_list: D007306:Insecticides; D012987:Soil; D012989:Soil Pollutants; D013141:Spiro Compounds; C521569:spiromesifen