A comparison of predicted and measured levels of runoff-related pesticide concentrations in small lowland streams on a landscape level

The predicted concentrations were compared with measured concentrations obtained by runoff-triggered sampling. Fungicides, insecticides and herbicides were detected in 17 streams, with max. concentrations measuring up to 29.7 μg/l for the fungicide azoxystrobin and 0.3 μg/l for the insecticide parathion-ethyl. Herbicides were detected in 16 streams, with max. concentrations between 13.7 and 1.2 μg/l. The linear regression between the predicted and measured concentrations (log-values) shows significant correlations for the following pesticides: azoxystrobin: r2=0.43; p=0.03; epoxiconazole: r2=0.71; p⩽0.01; tebuconazole: r2=0.77; p⩽0.01. The present model successfully explains the pesticide concentrations associated with single entry events caused by runoff, especially at concentration levels above (⩾0.5 μg/l).