Spatial and temporal variations of herbicide (triazines and phenylureas) concentrations in the catchment basin of the Marne river (France)

Triazine and phenylurea concentrations were investigated in four sub-basins of the Marne river (France) in 1992 and 1993. The peak concentrations of a trazine, simazine and isoproturon occurred between March and July. In the f our basins, the peaks were in relation with the herbicide application perio ds and with the important rainfalls, except for the isoproturon. The peaks of terbutryne and ametryne came later in the year, due to their use for wee d control on post-emergent corn. For the phenylureas, the peak concentratio ns were observed in March-April next to the spraying period on winter cerea ls. The fast transfer of those herbicides was related to their high water s olubility. In all the samples, the deethylatrazine (DEA) was detected 1 mon th after the atrazine due to its degradation within the soils which is of m inor importance as compared to its transport by surface waters and also, to interactions between the silt sheet and the stream itself. The DAR evoluti on showed that the atrazine residence time depends both on the run-off in t he first centimetres of the soil and on the treatment periods, particularly in the Grand Morin. The Marne river contamination level was similar to tha t of the Melarchez and of the Grand Morin. The minor pollution of the Orgev al was related to minor cultivated areas. (C) 1998 Elsevier Science B.V. Al l rights reserved.