Pesticides monitoring in Brest bay

Abstract

Brest Bay Contract's main objective : achieving restoration, management and protection of the environmental quality of Brest bay and its waterheds. Some objectives are : - ensure environmental monitoring : follow-up changes in environmental states, identify sensitive areas, reinforce monitoring networks. · ensure monitoring of the effects of environmental policies or programmes : monitoring and measuring the relevance of actions and programmes undertaken within the Bay contract framework. In Britanny, the nitrate and pesticide content in surface and underground waters has constantly increased over the past fifteen years. The Brest bay catchment area is a very agricultural region with particulary an intensive corn agriculture. Large amounts of herbicides are applied, atrazine is the main one. The analysis of pesticides in Brest Bay show that even at high salinity the pesticides are present. Desethylatrazine (DEA) and desisopropylatrazine (DIA), atrazine degradation products, are also present and the ratio between atrazine DEA ou DIA is much more important in May, that represent the back-ground of atrazine from the year before. In the same time other pesticides also arrive to Brest Bay (metolachlor, alachlor, diuron, isoproturon.).