Fate of dichlobenil in the River Ivel. 1: Determination of the residues of dichlobenil in sediment and water

Abstract

A section of river was treated with the slow release formulation of dichlobenil, Casoron GSR, at a dose rate equivalent to just over 1 mg/l. Water and sediment samples were taken at various points over a 1.75 km section downstream of the treated section for up to 84 d to determine residue concentrations. Residues in the water reached a peak 3 h after application of just over 5000 ng/l and then declined but were still detectable after 84 d. Sediment residues were higher than the water residues but had declined close to the limit of detection after 84 d. The residue data derived from this experiment were used by Makepeace & Glaisher (1999) to show that lettuces, grown hydroponically and irrigated with water containing residues of dichlobenil similar to those found in the river, were damaged or killed if exposed to flowing, but not in static, water.