title: Mitigation of dimethazone residues in soil and runoff water from agricultural field.
abstract: Dimethazone, also known as clomazone [2-[(2-chlorophenyl) methyl]- 4,4-dimethyl-3-isoxaolidinone] is a pre-emergent nonionic herbicide commonly used in agriculture. A field study was conducted on a silty-loam soil of 10 % slope to monitor off-site movement and persistence of dimethazone in soil under three management practices. Eighteen plots of 22 x 3.7 m each were separated using stainless steel metal borders and the soil in six plots was mixed with municipal sewage sludge (MSS) and yard waste (YW) compost (MSS+YW) at 15 t acre⁻¹ on dry weight basis, six plots were mixed with MSS at 15 t acre⁻¹, and six unamended plots (NM) were used for comparison purposes. The objectives of this investigation were to: (i) monitor the dissipation and half-life (T₁/₂) of dimethazone in soil under three management practices; (ii) determine the concentration of dimethazone residues in runoff and infiltration water following natural rainfall events; and (iii) assess the impact of soil amendments on the transport of NO₃, NH₄, and P into surface and subsurface water. Gas chromatography/mass spectrometery (GC/MS) analyses of soil extracts indicated the presence of ion fragments at m/z 125 and 204 that can be used for identification of dimethazone residues. Intitial deposits of dimethazone varied from 1.3 μg g⁻¹ dry native soil to 3.2 and 11.8 μg g⁻¹ dry soil in MSS and MSS+YW amended soil, respectively. Decline of dimethazone residues in the top 15 cm native soil and soil incorporated with amendments revealed half-life (T₁/₂) values of 18.8, 25.1, and 43.0 days in MSS+YW, MSS, and NM treatments, respectively. Addition of MSS+YW mix and MSS alone to native soil increased water infiltration, lowering surface runoff water volume and dimethazone residues in runoff following natural rainfall events.
authors.affiliation: Department of Plant and Soil Science, Kentucky State University, Frankfort, Kentucky 40601, USA. george.antonious@kysu.edu
authors.forename: George F
authors.initials: GF
authors.lastname: Antonious
mesh_terms: D000383:Agriculture; D052918:Environmental Restoration and Remediation / Q000379:methods*; D008401:Gas Chromatography-Mass Spectrometry; D006207:Half-Life; D006540:Herbicides / Q000032:analysis*; D007555:Isoxazoles / Q000032:analysis*; D023303:Oxazolidinones / Q000032:analysis*; D010573:Pesticide Residues / Q000032:analysis; D012722:Sewage / Q000737:chemistry; D012987:Soil / Q000737:chemistry; D012989:Soil Pollutants / Q000032:analysis*; D014874:Water Pollutants, Chemical / Q000032:analysis*
chemical_list: D006540:Herbicides; D007555:Isoxazoles; D023303:Oxazolidinones; D010573:Pesticide Residues; D012722:Sewage; D012987:Soil; D012989:Soil Pollutants; D014874:Water Pollutants, Chemical; C095255:clomazone