Seasonal removal of herbicides in urban runoff

The occurrence of two herbicides (diuron and simazine) in receiving surface waters is related to their seasonal applications within an urban catchment. Comparisons of herbicide concentrations within baseflow and during rainfall conditions provide an insight into pollutant transport processes following application to urban surfaces. Two storm events, with different hydrological characteristics, are described. The maximum recorded herbicide concentrations reached 238.4 and 2.23 μg/l for diuron and simazine, respectively, with the former corresponding to an application loss of 45.1% with respect to the diuron recently applied to the urban catchment. The factors influencing the extent of application losses to receiving waters of herbicides applied to urban substrates are discussed.