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Sorption of isoxaflutole diketonitrile degradate (DKN) and dicamba in unsaturated soil
- Source :
- Journal of environmental science and health. Part. B, Pesticides, food contaminants, and agricultural wastes. 41(7)
- Publication Year :
- 2006
-
Abstract
- When analyzing the sorption characteristics of weakly sorbing or labile pesticides, batch methods tend to yield a high margin of error attributable to errors in concentration measurement and to degradation, respectively. This study employs a recently developed unsaturated transient flow method to determine the sorption of isoxaflutole's herbicidally active diketonitrile degradate (DKN) and dicamba. A 20-cm acrylic column was packed with soils with varied texture that had been uniformly treated with 14C-labeled chemical. The antecedent solution herbicide in equilibrium with sorbed phase herbicide was displaced by herbicide-free water, which was infiltrated into the column. Sorption coefficients, Kd, were obtained from a plot of total herbicide concentration in the soil versus water content in the region where the antecedent solution accumulated. DKN Kd values were approximately 2-3 times (average Kd = 0.71 L kg-1) greater using the unsaturated transient flow method as compared to the batch equilibration method in clay loam (Kd = 0.33 L kg-1), but similar for the two methods in sand (0.12 vs 0.09 L kg-1) soils. Dicamba Kd values were 3 times greater using the unsaturated transient flow method as compared to the batch equilibration method in the clay loam soil (0.38 vs 0.13 L kg-1), however, the Kd values were the same for the two methods in the sand (approximately 0.06 L kg-1). This demonstrates that to determine sorption coefficients for labile hydrophilic pesticides, an unsaturated transient flow method may be a suitable alternative to the batch method. In fact, it may be better in cases where transport models have overpredicted herbicide leaching when batch sorption coefficients have been used.
- Subjects :
- Chromatography
Herbicides
Dicamba
Lessivage
Reproducibility of Results
Sorption
General Medicine
Isoxazoles
Pollution
chemistry.chemical_compound
chemistry
Loam
Alfisol
Soil water
Nitriles
Soil Pollutants
Adsorption
Carbon Radioisotopes
Sulfones
Leaching (agriculture)
Water content
Food Science
Environmental Monitoring
Subjects
Details
- ISSN :
- 03601234
- Volume :
- 41
- Issue :
- 7
- Database :
- OpenAIRE
- Journal :
- Journal of environmental science and health. Part. B, Pesticides, food contaminants, and agricultural wastes
- Accession number :
- edsair.doi.dedup.....f005aa8e55787e5e01918c8c013576be