ATMOSPHERIC TRANSPORT OF PESTICIDES ADSORBED ON AEROSOLS .1. PHOTODEGRADATION IN SIMULATED ATMOSPHERE

Eight pesticides (Alachlor, Pendimethalin, Trifluralin, Malathion, Ter buthylazine, Atrazine, Isoproturon and Fenithrothion), adsorbed on kao lin and fly ash are submitted to irradiation (wavelength above 290 nm) for 40 or 80 min. The first four compounds photodegrade when they are adsorbed on fly ash. The presence of metals and metal oxides in the f ly ash seem to be responsible for this rapid degradation (up to 70% in 40 min). They do not degrade, however, when they are adsorbed on kaol in. Terbuthylazine and Atrazine do not degrade significantly, at least during this short irradiation time. Weakening of the pesticide-suppor t bonds after irradiation, promoting the extraction by organic solvent s, is important for several pesticides, particularly for Alachlor and Atrazine. Isoproturon and Fenithrothion do not adsorb significantly on these two atmospheric supports and cannot be successfully submitted t o irradiation. These results are used to predict the possibility of th e meso-scale atmospheric transport of the pesticides from agricultural regions to non polluted areas, like alpine regions.