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(M/EH089) Atmospheric contamination by pesticides : a review on French studies. Millet, Maurice 1,3, Bedos, Carole2, Briand, Olivier1, Cellier, Pierre2, Barrusio, Enrique2, Mirabel, Philippe3, Seux, René1, 1 3 2 ABSTRACT- Pesticides can be transported to the atmosphere during (drift) and after treatment (volatilization from treated surfaces, wind erosion) leading thus to an atmospheric pollution, whatever the phases considered : gaseous, liquid (in cloud / fog droplets, rainwater) and solid (aerosol particles mostly). The assessment of pesticides concentrations requires specific experimental development since : concentrations are low, pesticides may be chemically instable, and no sensors exist nowadays allowing a direct concentration measurements. After a presentation of the different methods of measurements, the first part deals with the state of knowledge of the atmospheric contamination in France. Various experimental studies carried out since almost ten years in some French regions, have been devoted to the assessment of the concentrations for several molecules (atrazine, isoproturon, lindane, ...). Results in remote and urban areas showed a spatial variability as well as a chronic contamination throughout the year, showing sometimes a seasonal pattern. It is striking that pesticides which could be expected to be little volatile based on their physico-chemical characteristics are found in the atmosphere as well as molecules which have been banned. In a second part, another theme of research also developed in France will be presented : the study of the magnitude and the determinism of the processes involved in the transfer of pesticides to the atmosphere. Examples of experimental results dealing with the processes of spray drift and volatilization from soil will be presented here to illustrate the order of magnitude of these processes and the approach adopted. The presentation will finish giving some elements on the numerical approach selected to describe the volatilization process, together with the further works going on. Key words: Pesticides, Atmospheric contamination, Sampling and chemical analysis, Mass transfer and Modelling |
