| Autor: |
Berg, F., Smelt, J. H., Boesten, J. J. T. I, Teunissen, W. |
| Zdroj: |
Journal of Environmental Quality; May 1999, Vol. 28 Issue: 3 p918-928, 11p |
| Abstrakt: |
The large‐scale use of soil fumigants results in substantial emissions into the air. To describe the fate of these chemicals in soil, the PEST‐icide Leaching and Accumulation (PESTLA) model was extended to include the diffusion of pesticides through the gas phase and their volatilization at the soil surface. The model was tested against measurements of methyl isothiocyanate after injection of metam‐sodium into the soil at 0.19‐m depth with a blade injector and after injection at 0.10‐m depth followed by rototillage. For both techniques, the fumigant behavior in soil was described reasonably well. The volatilization rates measured in the field corresponded roughly to the rates computed. After injection with the blade injector at 0.19‐m depth, the initial volatilization rates measured were higher than those computed. This is possibly the result of rapid diffusion of fumigant through large voids in the topsoil. Such heterogeneities were not accounted for in the model. For shallow injection followed by rototillage, the volatilization rates were high from the start, both in the computations and measurements. The cumulative volatilization of methyl isothiocyanate when injecting metam‐sodium at 0.19‐m depth was computed to range up to a few percent of the dosage. When shallow injection was followed by rototillage, the computed cumulative emission ranged between 17 and 34% of the dosage. The model can be used to evaluate the effect of different factors on the volatilization of fumigants and that of other, soil‐incorporated pesticides from homogeneous noncracking soils, but for the evaluation of tillage factors model development is needed. |
| Databáze: |
Supplemental Index |
| Externí odkaz: |
|
Plný text