|Berglof, Tomas - SWEDISH UNIV UPPSALA SW|
|Kylin, Henrik - SWEDISH UNIV UPPSALA SW|
Submitted to: International Association of Environmental and Analytical Chemistry
Publication Type: Abstract Only
Publication Acceptance Date: April 4, 1997
Publication Date: N/A
Technical Abstract: Pesticide sorption coefficients (Kds) are generally obtained using the batch slurry method or other methods requiring separation of soil and soil solution before analysis. As a consequence, the results may not adequately reflect sorption processes in field-moist or unsaturated soil. The objective of this study was to use supercritical fluid extraction (SFE) for rdetermining metsulfuron methyl sorption-desorption in field-moist soils. Experiments were performed with low density (i.e. 0.3 g/mL) SF-CO2 to remove metsulfuron methyl from the soil water phase only, thus allowing calculation of sorption coefficients at low water contents. Influence of water content and soil properties on the Kds was determined. Kds for sandy loam, silt loam, and clay loam soils at 11 percent water content were 120, 180, and 320 mL/g, respectively. Sorption on the silt loam soil was greater at 17 percent water content than at 11 percent. These Kds are a hundred times greater than Kds obtained using the batch slurry technique. Solute transport models would overpredict leaching of these chemicals if slurry Kds were used rather than field-moist Kds.