Ces travaux s’inscrivent dans une problématique actuelle de compréhension des effets, encore peu connus, des mélanges de pesticides dans le sol. Les formulations d’herbicides S-métolachlore (Dual Gold Safeneur®), mésotrione (Callisto®) et nicosulfuron (Milagro®) ont été appliquées en mélanges et à la dose agronomique recommandée. Les molécules formulées sont plus toxiques que les molécules actives seules (Microtox®) et aucun effet synergique ou antagoniste des mélanges n’a été observé. Cependant, ces mélanges impactent transitoirement et à court terme les communautés microbiennes du sol de Limagne, sans modifier les paramètres généraux de structure et d’abondance. Toutefois, des effets ont été mis en évidence sur des communautés sensibles telles que les phototrophes ou celles impliquées dans les processus de nitrification et de dénitrification. De plus, une comparaison des effets des mélanges sur les communautés phototrophes de deux sols souligne l’importante toxicité du Dual Gold Safeneur® et remet en cause son utilisation d’un point de vue écotoxicologique. / These experiments are part of the actual problematic of understanding the poorknown effects of pesticides mixtures in soil ecosystem. The herbicidal commercial formulations of S-metolachlor (Dual Gold Safeneur®), mesotrione (Callisto®) and nicosulfuron (Milagro®) were applied in mixtures at the recommended field rate. Formulated compounds are more toxic than active ingredients alone (Microtox®) and no synergistic or antagonistic effects were recorded. However, these mixtures impaired rapidly and transitory the Limagne soil microbial communities, without modifying the global parameters of structure and abundance. Effects were also recorded on sensitive communities, such as phototrophic, nitrifying and denitrifying communities. A comparison of mixtures effects on phototrophic communities from two soils underlined the high toxicity of Dual Gold Safeneur® and challenged its use from an ecotoxicological point of view..

<p>U okviru ove doktorske disertacije, razvijene su elektroanalitičke metode za određivanje odabranih pesticida primenom hronopotenciometrije. Ispitana je mogućnost primene elektrode od staklastog ugljenika i tankoslojne živine elektrode kao radnih elektroda za određivanje insekticida imidakloprida i herbicida metamitrona i metribuzina. U cilju optimizacije uslova hronopotenciometrijske tehnike, za svaki ispitivani sistem (pesticid/radna elektroda) ispitan je uticaj najznačajnijih eksperimentalnih parametara na analitički signal pesticida, uključujući mehanizam generisanja analitičkog signala na radnoj elektrodi (oksidacija/redukcija), optimalnu metodu za uklanjanje rastvorenog kiseonika iz analiziranog rastvora, kao i vrstu, pH i koncentraciju pomoćnog elektrolita. Nakon toga definisan je optimalni opseg potencijala i struje redukcije. Pored toga, u okviru validacije metode za svaki ispitivani sistem, ispitan je i definisan opseg linearnosti, određena granica detekcije i granica kvantifikacije, ispitana preciznost, tačnost, robusnost i selektivnost metode. Dobijeni analitički signal za ispitivane pesticide bio je posledica ireverzibilne redukcije analita na radnoj elektrodi, a za svaki analit dobijen je jedan redukcioni pik. U slučaju određivanja metribuzina eksperimenti su pokazali da se analitički signal ne može detektovati na elektrodi od staklastog ugljenika uz kori&scaron;ćenje dostupne instrumentacije. Ispitivanja u model-rastvorima za svaki ispitivani sistem pokazala su dobre karakteristike u pogledu preciznosti, tačnosti, selektivnosti i robusnosti metode. Najveća osetljivost za sva tri pesticida postignuta je uz primenu tankoslojne živine elektrode, a vrednosti granice detekcije iznosile su 0,17 mg/l za imidakloprid, 0,07 mg/l za metamitron i 0,04 mg/l za metribuzin. Nakon optimizacije i validacije, razvijene hronopotenciometrijske metode primenjene su na komercijalne formulacije pesticida i uzorke vode. U cilju dodatne potvrde hronopotenciometrijskih rezultata na uzorcima vode izvedena su komparativna merenja uz primenu hromatografske LC-MS/MS analize.</p> / <p>Within this doctoral dissertation, electroanalytical methods for the determination of selected pesticides using chronopotentiometry are developed. The possibility of using glassy carbon electrode and thin film mercury electrode as a working electrode for determination of insecticide imidacloprid and herbicides metamitron and metribuzin is investigated. In order to optimize the conditions of the chronopotentiometric technique for each tested system (pesticide/working electrode), the influence of the most important experimental parameters on the analytical signal of the pesticides is investigated, including the generating mechanism of the analytical signal on the working electrode (oxidation/reduction), the optimal method for removal of dissolved oxygen from the analyzed solution, as well as type, pH, and concentration of the supporting electrolyte. Afterwards, the optimal range of potential and reduction current is defined. Additionally, within the validation of the method for each tested system, the linearity range is determined and defined, limit of detection and quantification are determined, and precision, accuracy, robustness and selectivity of the method are tested. The obtained analytical signal for the investigated pesticides is the result of irreversible reduction of the analyte on the working electrode, and for each analyte one reduction peak is obtained. In the case of metribuzin determination, the experiments have shown that by using the available instrumentation the analytical signal can not be detected on the glassy carbon electrode. Investigation in model solutions for each tested system shows good characteristics in terms of precision, accuracy, selectivity and robustness of the method. The highest sensitivity for all three pesticides was achieved by using thin film mercury electrode, and values of detection limit were 0.17 mg/l for imidacloprid, 0.07 mg/l for metamitron and 0.04 mg/l for metribuzin. After optimization and validation, the developed chronopotentiometric methods are applied to commercial pesticide formulations and water samples. In order to further confirm the chronopotentiometric results on the water samples, comparative measurements are performed using chromatographic LC-MS/MS analysis.</p>