34 The effectiveness of a 6m-wide vegetative buffer strip for reducing runoff of S-metolachlor, 35 terbuthylazine and desethyl-terbuthylazine was studied in 2007-2008 in Northern Italy. Two 36 cultivated fields, with and without the buffer strip, were compared. Residues of the chemicals were 37 investigated in runoff water collected after runoff events and their dissipation in the soil was 38 studied. The highest concentration of the chemicals in water occurred in samples collected from the 39

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... nbuffered field at the first runoff events. Losses of terbuthylazine and S-metolachlor in runoff 40 waters were particularly high in 2007 (2.6% and 0.9% of the amount applied, respectively). Soil 41 half-life of terbuthylazine and S-metolachlor ranged between 13.5 and 8.9 days and 16 and 7 days, 42 respectively. Presence of desethyl-terbuthylazine was related to parent compound degradation. The 43 buffer strip allowed important reduction of chemicals content in water (>90%), in particular during 44 the first runoff events. 45