Abstract EN:

This work aims to quantify pesticide residues on tomato and pepper and study of the degradation of difenoconazole as a result of atmospheric photo-oxidants at the interface solid / gaz. The results show that: - From the 96 tomato samples analysed in the monitoring study 2006-2007 of the souss ,it appears that some chemicals are more persistent than others. The most frequently found compounds included endosulfan (32%), dicofol (25%), difenoconazole (22%). -From 86 number of pepper samples analysed in the monitoring 2006-2007 of the souss, indicate that the compounds frequently found in the samples are azoxystrobin,chlorothalonil and endosulfan respectively at a rate of 26%,24% and 20%. - Residue levels in tomato samples were between 1. 54 and 0. 31 mg/kg for dicofol and between 2. 00 and 0. 28 mg/kg for difenoconazole. - The time to harvest for dicofol is 12 days whereas that of difenoconazole is 15 days in the tomato. - Residue levels in pepper samples were between 1. 14 and 0. 02 mg/kg for azoxistrobin and between 0. 55 and 0. 04 mg/kg for chlorothalonil. - The application of an intensive washing process to the pepper samples did not lead to a significant reduction of the residue level of azoxystrobin and chlorothalonil. Likewise, no significant differences were found between the residue levels in the “edible” and “inedible” parts of the peppers. - The kinetic results of the photochemical degradation of difenoconazole adsorbed on quartz surface by atmospheric oxidants, namely ozone and OH-radicals. Show that the life-time of difenoconazole with respect to both oxidants is in the order of several months, meaning that this pesticide is relatively persistent, and may be transported over long distances