THE POLLUTION OF WATER BY PESTICIDES - STATE AND ORIGIN

In Europe, monitoring campaigns of surface and groundwaters used for drinking water frequently show pollution by pesticides, above the EU specification. This situation is due to intensive agriculture, non-respect of good agricultural practices, non-agricultural uses and the existence of especially vulnerable sites (eg, thick and diffuse hydrological system, broken relief, filtering or cracked soils, water table lying near the surface). The assessment of the pollution can be conducted at different levels. However, local study appears to be the only satisfactory method. Indeed, it allowed us to focus on some pesticides, sampling dates and water supplies, in relation to the local characteristics. In France, few pesticides are involved in water pollution: atrazine, simazine, lindane, carbofuran and phenylureas. However, this list would be different if practices carried out locally or degradation products (deethylatrazine) were taken into account. The pollution of surface water can reach a high level but for a small time. It is closely related to the ability of pesticides to be transported by runoff, and the dilution with water from untreated areas. In contrast, groundwater is weakly but, in some instances, continuously polluted. This depends on the leaching processes, and, hence, on the availability of pesticides and the wafer dynamics. In the case of pesticides with high persistance and relatively good mobility, the storage of pesticides in soil sustains the groundwater pollution.