Contamination of aquatic ecosystems by runoff events - comparison of small and large plot experiments

The transport of the herbicides Dichlorprop-p, Isoproturon, and Bifenox via surface runoff was investigated on small and large field plots with simulated rainfall. Dichlorpop-p and Isoproturon were transported mainly in the runoff water phase. Total Dichlorprop-p and Isoproturon losses in runoff mainly depend on the time of runoff initiation. Concentrations in early runoff samples at a precipitation of about 5 mm may lead to herbicide concentrations above 1 mg/l. The concentration of Dichlorprop-p and Isoproturon in the runoff of the large plot were below 200 myg/1 with a total loss of 0.02 percent of the applied herbicides during a 30 mm rainfall event.