Determination of insecticide contamination in agricultural headwater streams

A headwater stream in an agricultural catchment in Northern-Germany was int ensively monitored for insecticide occurrence (lindane, parathion-ethyl, fe nvalerate). Brief insecticide inputs following precipitation with subsequen t surface runoff result in high concentrations in water and suspended matte r (e.g. fenvalerate: 6.2 mu g l(-1) 302 mu g kg(-1)). These transient insec ticide contaminations are typical for headwater streams with an agricultura l catchment area, but have been rarely reported in such extent. Event contr olled sampling methods for the determination of this runoff related contami nation with a time resolution of up to 1 h are introduced. The temporal dis tribution of the insecticide concentration is shown on different time scale s (years, months, hours) over a period of 4 years. The measured concentrati ons are compared with other references. Insecticide losses due to surface w ater runoff were calculated between 0.01-0.07% of the applied insecticide. (C) 1998 Elsevier Science Ltd. All rights reserved.