Degradation and Migration of Vinclozolin in Sand and Soil

The migration of the dicarboximide fungicide vinclozolin and its principal degradation products through porous media was experimentally determined by simulating pesticide applications to a 23-30 mesh Ottawa sand and a North Carolina Piedmont aquic hapludult soil in laboratory columns. The mass of vinclozolin and its degradates were measured in the porous media 24, 168, and 504 h after fungicide application, varying pore fluid pH and size of simulated rain events. Degradation in the soil was near detection limits under all experimental scenarios. In sand at pH 8.8, vinclozolin degraded along two pathways. The degradation to the butenoic acid degradate was faster than the degradation to vinclozolinʹs enanilide degradate. The presence of the enanilide pathway had not previously been observed in solutions with pH > 7, indicating that the presence of particles plays a role in the rate and pathway of vinclozolin degradation. Thus, the direct extrapolation of dicarboximide chemistry from solution studies to agricultural field conditions is not possible without consideration of the soil matrix characteristics.