Cold-climate vegetative buffer zones as pesticide-filters for surface runoff

Abstract

Vegetative buffer zones adjacent to watercourses can be effective filters for diffuse pollution from agriculture. Several investigations, even during snowmelt season, have shown that retention of sediments and sediment-bound nutrients in runoff water has been high through buffer zones (BZ). It is likely that BZ also can be effective filters for sediment-bound pesticides. The retention of glyphosate, propiconazole, fenpropimorph and soil particles was studied in surface runoff experiments with 5 m wide buffer zones. Volume proportional samples were collected after each runoff episode (1999-2002). The distribution coefficient (Kd) shows moderate to high adsorption of the pesticides to the experimental soil. Results show average retention efficiency of about 51%, 48%, 85% and 34% for particles, glyphosate, propiconazole and fenpropimorph, respectively. The amount of AMPA (which is a degradation product of glyphosate), entering the BZ was high; approximately the same amount as for glyphosate. The retention efficiency through the BZ for AMPA was about 67%. There were no significant differences in removal efficiency (in %) between winter with snowmelt and summer. This is possibly due to detachment of coarser aggregates during winter, which trap more easily in the BZ. The conclusion based on this study suggests BZ to be contributors to reduced pesticide input to surface waters.