Les résidus d'antibiotiques et de psychotropes sont déversés dans l'environnement, en conséquence d'une utilisation massive et souvent inadaptée de ces substances dans les domaines médicaux et vétérinaires et d’une métabolisation incomplète dans l’organisme. Les eaux de surface et les eaux souterraines sont les réceptacles majeurs de ces polluants et représentent également les sources d'eau utilisées pour la consommation humaine. Notre recherche s’est focalisée sur la phototransformation et l’oxydation par le chlore et le peroxyde d’hydrogène de quatre composés : deux antibiotiques et deux psychotropes : sulfaméthazine, sulfaméthoxypyridazine, amitriptyline et clomipramine). Ces deux derniers processus sont utilisés fréquemment dans les filières de traitement de l’eau.D’abord, une étude cinétique nous a permis à déterminer des constantes cinétiques. Pour chaque composé, une dégradation plus ou moins rapide a été observée suivant le procédé de photolyse ou d’oxydation employé. L’étude cinétique a été appliquée également sur des eaux naturelles pour prévoir le devenir des composés pharmaceutiques et estimer leur dégradation après photoréaction et chloration. Puis, de nombreux sous produits de chloration et de photolyse ont été identifiés par LC/MS/MS et des mécanismes réactionnels ont été proposés. / Antibiotics and psychiatrics residues are dumped into the environment due to their massive and inappropriate use in human and veterinary medicine either to an incomplete metabolism into organism. Surface waters and ground waters are the major receptacles of these pollutants and also represent sources of water used for human consumption. This study was specifically focused on photolysis of four pharmaceuticals compounds: two antibiotics and two psychiatrics (sulfamethazine, sulfamethoxypyridazine, amitriptyline and clomipramine) also on their oxidation by chlorine and hydroxyl radicals, two processes mainly used in water treatment.First, kinetic studies were conducted and rate constants were determined. For each pharmaceutical, different rates of degradation were observed depending on photolysis or oxidation process. To better assess pharmaceutical removal under water treatment conditions, an estimation of pharmaceutical removal in natural water was undertaken. Secondly, several degradation products formed during chlorination and photolysis were identified by LC/MS/MS and degradation pathways were proposed

La microscopie de super-résolution PALM (microscopie de localisation après photo-activation) est un outil performant pour l'étude des cellules à l'échelle nanométrique. Dans ses applications avancées, la microscopie PALM permet l'étude quantitative et dynamique des objets et événements biologiques. Ces applications sont cependant limitées par le comportement photophysique complexe des protéines fluorescentes photoconvertibles vert à rouge (PCFPs) utilisées comme marqueurs. En particulier, les transitions répétées et stochastiques des PCFPs entre un état sombre et un état fluorescent (scintillement) ainsi que l'incomplétude de photoconversion compliquent l'extraction d'informations quantitatives.Nos travaux combinant cristallographie aux rayons X des protéines et microscopie de localisation ont permis de mettre en évidence le rôle central d'un acide aminé conservé au sein des PCFPs, l'arginine 66, dans le contrôle du scintillement et du photoblanchiment de la forme rouge de deux PCFPs populaires: mEos2 et Dendra2.D'autre part, des résultats préliminaires suggèrent que dans leur formes vertes et dans les conditions d'illumination classiques PALM, les PCFPs entrent dans un état sombre de long temps de vie ce qui ralentit la photoconversion.Nos résultats ouvrent la porte à la conception raisonnée de nouvelles PCFPs optimisées pour les applications quantitatives et dynamiques du PALM. / Super-resolution PALM microscopy (photoactivated localization microscopy) is a powerful tool to investigate the cells with nanoscopic accuracy. Advanced PALM microscopy allows to quantitatively and dynamically study biological objects and events. These applications are nevertheless limited by the complex photophysical behavior of the green-to-red photoconvertible fluorescent proteins (PCFPs) used as markers. In particular, PCFPs red forms repeated and stochastic transitions between a fluorescent and a dark state (blinking) as well as photoconversion uncompleteness complicate the extraction of quantitative information.Our study, by combining X-ray crystallography and localization microscopy, evidences that a single aminoacid well conserved among PCFPs, the arginine 66, controls the blinking and photobleaching behavior of two popular PCFPs: mEos2 and Dendra2.Preliminary results suggest that in their green forms and under PALM classical illumination conditions, PCFPs switch to a long-lived dark state resulting in a photoconversion slowing down.Our results open the door to future rational engineering of enhanced PCFPs for quantitative and dynamic PALM.

Cette étude s’inscrit dans le cadre de la dépollution de l’eau, elle a eu pour but d’examiner la dégradation photocatalytique d’herbicides phénylurées en solution aqueuse à pH acide, en présence d’un oxyde de fer naturel et d’acides carboxyliques. L’oxyde de fer naturel a été caractérisé par spectroscopie Raman, l’identification des produits de dégradation du fénuron et la proposition d’un mécanisme de dégradation ont été réalisées. Deux types d’irradiation ont été utilisés, i.e. l’irradiation solaire naturelle et l’irradiation par des UV générés par des lampes à vapeur de mercure. La photodégradation du fenuron en présence d’oxyde de fer naturel et l'acide oxalique obéit à une loi du premier ordre, les conditions expérimentales optimales pour ce système étaient [acide oxalique]0 = 10-3 M, [Hématite naturelle] = 0.1 g L-1 ; pH = 3. Le temps de demi-vie du fenuron est court (60 32 min) mais les résultats sont meilleurs sous irradiation solaire naturelle (30 15 min). L'acide oxalique est l’acide carboxylique le plus efficace en photodégradation du fénuron (disparition totale), l’ordre d’efficacité varie ainsi : acide oxalique > acide citrique > acide tartrique > acide malique. L’étude analytique de la dégradation du fénuron par ce procédé a permis l’identification de huit photoproduits aromatiques, de trois acides carboxyliques à courte chaîne de carbone et des ions inorganiques. Ce travail a permis de mettre en évidence le rôle de l’oxygène dissous dans le processus de dégradation du fenuron par le procédé de photo-Fenton-like, le processus ne peut pas avoir lieu en milieu désoxygéné car aucune production de H2O2 n’a été observée sous irradiation UV. L’oxygénation du milieu permet d’améliorer la capacité oxydative du procédé et d’augmenter le taux de minéralisation du carbone organique totale. En effet l’oxygénation du milieu augmente indirectement la production des radicaux hydroxyles par augmentation de la production de H2O2. Il a été mis en évidence pendant l’étude quantitative que l’oxygène était le réactif le plus consommé par ce procédé. Le traitement de la solution contenant 10-4 M de fenuron et 10-3 M d’oxalate a permis de réduire significativement la toxicité de la solution initiale après 360 minutes d’irradiation. / The photodegradation of the herbicide phenylurea by using a natural iron oxide (NIO) α-Fe2O3 in aqueous solution at acidic pH has been undertaken. The NIO was characterized by the Raman spectroscopy method. The degradation pathways and the formation of by-products were studied. A high-pressure mercury lamp and sunlight were employed as light source. Fenuron photodegradation using NIO with oxalic acid followed the pseudo-first order kinetics, the optimal experimental conditions were [oxalic acid]0 = 10−3 M and [NIO] = 0.1 g L−1 at pH 3. NIO/oxalic acid/UV system led to a low fenuron half-life (32 min). The results were even better when solar light is used (15 min). The effect of four carboxylic acids; oxalic, citric, tartaric and malic acids on the degradation efficiency was studied. Oxalic acid was the most effective carboxylic acid used on the fenuron photodegradation with NIO at pH 3. The analytical study showed many aromatic intermediates, short-chain carboxylic acids and inorganic ion.The role of dissolved oxygen (DO) in degradation and mineralization of fenuron in the photo-Fenton-like system by using the NIO was also studied; the NIO was used as an iron source. The DO effect has been elucidated by carrying out experiments with and without oxygen, it has been found that the degradation and mineralization rate were strongly affected by change in DO concentration. In absence of oxygen, there is no photo-Fenton-like because of the lack of hydrogen peroxide, the degradation was caused only by the photo-reduction of Fe(III) complex in this case. Oxygenation improved the hydrogen peroxide production under irradiation. The mass balance of the reactive species showed that dissolved oxygen was the main reactive consumed during the process. The toxicity decrease with irradiation time proves that the intermediates generated during photo-oxidation by the photo-Fenton-like system by using a NIO are less toxic than fenuron.

Afin de comprendre, caractériser et prédire l’évolution des cycles biogéochimiques océaniques face au changement climatique global, il est nécessaire d’appréhender au mieux la dynamique de la matière organique (MO) au niveau des interfaces « terre/océan ». Dans ce contexte, l’objectif général de cette thèse était d’améliorer les connaissances sur la dynamique de la fraction dissoute chromophorique de la MO (CDOM) des eaux de surface côtières méditerranéennes et arctiques, et d’en déterminer l’impact sur l’atténuation du rayonnement UV (UVR) et visible (PAR) sous-marin. Pour cela, l’étude des propriétés optiques d’absorbance et de fluorescence de la CDOM, couplée à des mesures radiométriques atmosphériques et sous-marines, ont été réalisées lors d’un cycle saisonnier en Baie de Marseille (station SOFCOM), et lors d’une mission océanographique en Mer de Beaufort durant l’été 2009. La Baie de Marseille est caractérisée par des quantités de CDOM faibles (aCDOM(350) = 0,10 ± 0,02 m-1), particulièrement à la fin de la période estivale de stratification, à cause de l’intensité de l’éclairement solaire, enrichi en UVR-B, qui dégrade et blanchie cette CDOM (SCDOM = 0,023 ± 0,003 nm-1). Dans cette zone côtière fortement urbanisée, la dynamique de la CDOM est pilotée par des processus biotiques (production biologique in situ et induite par les intrusions épisodiques du panache du Rhône) et abiotiques (photo-blanchiment et brassage). La CDOM est essentiellement d’origine autochtone, même lors d’événements d’intrusion du panache du Rhône (photo-dégradation de la CDOM terrestre durant son transit). Lors des périodes d’efflorescences algales, la CDOM se compose principalement de matériel récent, de type protéique (pic T), qui absorbe préférentiellement les courts UVR. Ces pulses de CDOM récente se superposent à un persistent signal de fond de CDOM composé majoritairement de matériel âgé, de type humique (pics M et C), qui absorbe les UVR et également le PAR. Au niveau du plateau Canadien de la Mer de Beaufort, la CDOM est très abondante (aCDOMmax(350) = 6,36 m-1), fortement influencée par les apports allochtones du Mackenzie (pics A-C et M) et décroit de manière conservatrice avec la salinité. Dans les eaux marines (salinité >25), la CDOM, qui présente de plus faibles concentrations (aCDOM(350) = 0,21 ± 0,13 m-1), provient d’une production biologique in situ récente favorisée par des upwellings ainsi que d’injections de CDOM (pics B-T et M) lors de la formation/fonte de la glace de mer. Etonnamment, la source principale du composé « humique marin » (pic M) n’est pas autochtone. Elle est issue d’apports allochtones provenant du Mackenzie. Celui-ci draine en effet de nombreux lacs qui sont le siège d’une intense activité biologique, et il est proposé dans cette thèse que les macrophytes qui s’y développent seraient à l’origine du pic M. Cette source de CDOM biologique allochtone, couplée aux processus de photo-blanchiment et d’absorption sur les particules de la CDOM terrestre, pourraient expliquer les valeurs élevées de SCDOM (≈ 0,020 nm-1) du Mackenzie en été. / To understand, characterize, and predict the evolution of oceanic biogeochemical cycles in relation to the global climate change, it is necessary to better understand the dynamics of organic matter (OM). In this context, the overall objective of this thesis was to get more insights chromophoric dissolved fraction of OM (CDOM) dynamics in surface Mediterranean and Arctic coastal waters and to determine the impact on attenuation of ultraviolet (UVR) and visible (PAR) underwater radiation. For this, the study of optical properties of absorbance and fluorescence of CDOM, coupled with atmospheric and underwater radiometric measurements, were made during a seasonal cycle in the Bay of Marseille (SOFCOM station), and in the Beaufort Sea during summer 2009. The Bay of Marseilles is characterized by low amounts of CDOM (aCDOM(350) = 0.10 ± 0.02 m-1), particularly in end summer stratification period due to the intensity of the solar irradiance, enriched in UVR-B, which degrades and bleaches CDOM (SCDOM = 0.023 ± 0.003 nm-1). In this highly urbanized coastal area, the dynamics of CDOM are driven by biotic processes (in situ biological production and within the Rhône River plume) and abiotic (photo-bleaching and mixing). Our results showed that CDOM is mostly of autochthonous origin, even during Rhône plume intrusion events (photo-degradation of terrestrial CDOM during the transit). During bloom periods, the CDOM consists mainly of a recent type protein (peak T), which preferentially absorbs in the short UVR. These pulses of recent CDOM are superimposed on a persistent background of CDOM mainly composed of aged material, humic-type (peaks M and C), which absorbs UVR and PAR. Over the Canadian shelf of the Beaufort Sea, CDOM is highly abundant (aCDOMmax (350) = 6.36 m-1) and strongly influenced by allochthonous inputs from the Mackenzie (peaks A-C and M) decreasing conservatively with salinity. In marine waters (salinity> 25), CDOM had lower concentrations (aCDOM(350) = 0.21 ± 0.13 m-1) and originated from a recent in situ biological production favored by upwelling and brine injections (peaks B-T and M). Surprisingly, the main source of the marine humic-like component (peak M) was not autochthonous. This material originates from allochthonous inputs from the Mackenzie River, which traverses numerous lakes where intense biological activity occurs. We suggest that this activity is mainly due to the macrophytes development, which may in part explain the origin of the peak M. This source of organic allochthonous CDOM coupled to other processes such as photobleaching and absorption on the particles of terrestrial CDOM, could explain the high values of SCDOM (≈ 0.020 nm-1) recorded in the Mackenzie during summertime.

Neste trabalho realizou-se estudos comparativos da fototransformação da protoporfirina IX (PpIX) sintética e endógena, extraída de glândulas Harderianas dos ratos da espécie Rattus Novergicus Albinus, quando irradiada pela luz visível. A fototransformação foi analisada através de monitoramento dos espectros de absorção ótica e de fluorescência em soluções aquosas homogêneas de tampão fosfato e na presença de micelas e albumina de soro bovino (ASB) e em soluções não aquosas de Acetonitrila e Dimetilsulfóxido na proporção 3:1 e em acetona, todos na presença e ausência de oxigênio. Além disso, foram obtidos através de técnica de flash fotólise as curvas cinéticas da absorção do Tripleto da PpIX e da fosforescência do oxigênio singleto. Observamos que sob ação de luz visível, a PplX sobre fototransformação cujas características dependem tanto da natureza da PplX qunto do ambiente onde a PplX se encontra. Devido a sua alta hidrofobicidade a PplX sintética em solução aquosa está presente em forma de agregados o que diminui a velocidade da sua fototransformação. Já a PplX endógena, quando em soluções aquosas, não sofre agregação, pois continua ligada com algumas estruturas biológicas de natureza anfifílica, que sobraram após sua extração de glândulas, e sua velocidade de fototransformação é elevada. A ligação com essas estruturas aumenta a afinidade da PplX endógena com micelas e dificulta sua ligação com a ASB. Os processos de fototransformação de ambas as PplX na interação com as micelas, com ASB e em tecidos glandulares in vivo são semelhantes. Isso mostra que o processo de fototransformação em meio micelar e na interação com ASB modela com sucesso o processo dentro de tecidos.Baseando-se nos fatos que a taxa de fototransformação da PplX aumenta na presença do oxigênio e que foi observada a formação do oxigênio singleto pela transferência de energia do estado tripleto da PplX para o oxigênio molecular, podemos dizer que o mecanismo tipo II contribui na fototransformação da PplX e esse mecanismo é responsável pela formação de fotoproduto, caracterizado pelos novos picos nos espectros de absorção óptica e de fluorescência. Entretanto, a existência de fototransformação da PplX na ausência do oxigênio mostra a participação de outros mecanismos de fototransformação. / In this work we carried out comparative studies of phototransformation of protoporphyrin IX (PpIX) both synthetic and endogenous, extracted from the Harderian glands of the Rattus Novergicus Albinus, when irradiated by visible light. The phototransformation was analyzed by monitoring the PpIX optical absorption and fluorescence spectra in homogeneous aqueous solution (phosphate buffer) and in the presence of bovine serum albumin (BSA), micelles, formed from different surfactants, in non-aqueous acetonitrile and dimethyl sulfoxide 3:1 solutions, and in acetone, both in the presence and absence of oxygen. Besides, the kinetic curves of the PpIX Triplet state absorption and the singlet oxygen phosphorescence were obtained using the flash photolysis technique. It was observed that when irradiated with visible light PplX suffers phototransformation with characteristics depending on its nature and on the environment. Due to high hydrophobicity the synthetic PplX forms aggregates, which reduces its phototransformation rate, while the endogenous PplX is not aggregated due to its interaction with the residues of some biological amphiphilic structures, which continue after it extraction from glands, and its phototransformation rate is elevated. Besides, the interaction with these structures increases the endogenous porphyrin affinity with micelles and reduces that with BSA. The characteristics of both PplX phototransformation in micellar media, at the interaction with BSA and in the gland tissues in vivo are similar. This demonstrates that the phototransformation process in micellar media and at the interaction with BSA may successfully simulate the process in the tissue.Basing on the facts that the phototransformation rate increases in the presence of molecular oxygen and that the singlet oxygen formation due to energy transfer from the PplX triplet state to oxygen was observed we can conclude that the type II mechanism contributes on the PplX phototransformation and is responsible on the formation of a photoproduct with observed new optical absorption and fluorescence peaks. At the same time, the PplX phototransformation in the oxygen absence shows the participation of other mechanisms on the PplX phototransformation.

Neste trabalho realizou-se estudos comparativos da fototransformação da protoporfirina IX (PpIX) sintética e endógena, extraída de glândulas Harderianas dos ratos da espécie Rattus Novergicus Albinus, quando irradiada pela luz visível. A fototransformação foi analisada através de monitoramento dos espectros de absorção ótica e de fluorescência em soluções aquosas homogêneas de tampão fosfato e na presença de micelas e albumina de soro bovino (ASB) e em soluções não aquosas de Acetonitrila e Dimetilsulfóxido na proporção 3:1 e em acetona, todos na presença e ausência de oxigênio. Além disso, foram obtidos através de técnica de flash fotólise as curvas cinéticas da absorção do Tripleto da PpIX e da fosforescência do oxigênio singleto. Observamos que sob ação de luz visível, a PplX sobre fototransformação cujas características dependem tanto da natureza da PplX qunto do ambiente onde a PplX se encontra. Devido a sua alta hidrofobicidade a PplX sintética em solução aquosa está presente em forma de agregados o que diminui a velocidade da sua fototransformação. Já a PplX endógena, quando em soluções aquosas, não sofre agregação, pois continua ligada com algumas estruturas biológicas de natureza anfifílica, que sobraram após sua extração de glândulas, e sua velocidade de fototransformação é elevada. A ligação com essas estruturas aumenta a afinidade da PplX endógena com micelas e dificulta sua ligação com a ASB. Os processos de fototransformação de ambas as PplX na interação com as micelas, com ASB e em tecidos glandulares in vivo são semelhantes. Isso mostra que o processo de fototransformação em meio micelar e na interação com ASB modela com sucesso o processo dentro de tecidos.Baseando-se nos fatos que a taxa de fototransformação da PplX aumenta na presença do oxigênio e que foi observada a formação do oxigênio singleto pela transferência de energia do estado tripleto da PplX para o oxigênio molecular, podemos dizer que o mecanismo tipo II contribui na fototransformação da PplX e esse mecanismo é responsável pela formação de fotoproduto, caracterizado pelos novos picos nos espectros de absorção óptica e de fluorescência. Entretanto, a existência de fototransformação da PplX na ausência do oxigênio mostra a participação de outros mecanismos de fototransformação. / In this work we carried out comparative studies of phototransformation of protoporphyrin IX (PpIX) both synthetic and endogenous, extracted from the Harderian glands of the Rattus Novergicus Albinus, when irradiated by visible light. The phototransformation was analyzed by monitoring the PpIX optical absorption and fluorescence spectra in homogeneous aqueous solution (phosphate buffer) and in the presence of bovine serum albumin (BSA), micelles, formed from different surfactants, in non-aqueous acetonitrile and dimethyl sulfoxide 3:1 solutions, and in acetone, both in the presence and absence of oxygen. Besides, the kinetic curves of the PpIX Triplet state absorption and the singlet oxygen phosphorescence were obtained using the flash photolysis technique. It was observed that when irradiated with visible light PplX suffers phototransformation with characteristics depending on its nature and on the environment. Due to high hydrophobicity the synthetic PplX forms aggregates, which reduces its phototransformation rate, while the endogenous PplX is not aggregated due to its interaction with the residues of some biological amphiphilic structures, which continue after it extraction from glands, and its phototransformation rate is elevated. Besides, the interaction with these structures increases the endogenous porphyrin affinity with micelles and reduces that with BSA. The characteristics of both PplX phototransformation in micellar media, at the interaction with BSA and in the gland tissues in vivo are similar. This demonstrates that the phototransformation process in micellar media and at the interaction with BSA may successfully simulate the process in the tissue.Basing on the facts that the phototransformation rate increases in the presence of molecular oxygen and that the singlet oxygen formation due to energy transfer from the PplX triplet state to oxygen was observed we can conclude that the type II mechanism contributes on the PplX phototransformation and is responsible on the formation of a photoproduct with observed new optical absorption and fluorescence peaks. At the same time, the PplX phototransformation in the oxygen absence shows the participation of other mechanisms on the PplX phototransformation.

Cette thèse porte sur l’étude de la transformation de polluants organiques à la surface du sol sous l’effet de la lumière. Deux principaux composés organiques ont été utilisés : une molécule modèle, la phénylbenzo-quinone (PhQ) ; et un pesticide de la famille des carbamates, le carbaryl. Nous avons travaillé sur différents supports : trois supports modèles (silice, sable de Fontainebleau et kaolinite) et sur un sol de la région d’Orange. La phototransformation a été réalisée en utilisant un dispositif qui simule le rayonnement solaire (l>300nm). L’étude des propriétés spectroscopiques de PhQ sur support solide a permis de montrer un élargissement de la bande d’absorption et des effets bathochrome et hyperchrome. Lors de l’irradiation, la concentration et l’épaisseur des films se sont avérés être des paramètres importants à considérer afin de tenir compte respectivement l’effet d’écran et le phénomène de diffusion. Une valeur limite de l’épaisseur égale à 100 μm a été déterminée afin de s’affranchir du processus de diffusion. Le mécanisme de transformation de PhQ s’est avéré être identique à celui observé dans l’eau avec la formation d’un unique produit, la 2-hydroxydibenzofuranne, et la mise en évidence de l’état excité triplet de PhQ. La présence d’eau influence la phototransformation du composé en augmentant la vitesse de transformation. Ceci s’explique par une modification des propriétés d’absorption du support humide qui favorise la pénétration de la lumière. Suite à cette première étude, un travail plus complexe a été entrepris sur la photodégradation du carbaryl à la surface de supports modèles. Le coefficient d’absorption molaire sur la kaolinite et le rendement quantique de transformation ont pu être déterminés pour le carbaryl et d’autres composés organiques. Ceci nous a permis de confirmer l’effet bathochrome, l’effet hyperchrome, ainsi que l’augmentation du rendement quantique : augmentation d’un facteur 10 pour le carbaryl. Les études cinétiques ont montré que la dégradation du carbaryl est effective sur tous les supports. A l’aide des propriétés physico-chimiques des supports, nous avons pu émettre l’hypothèse que la taille des particules contrôle la photodégradation. Celle-ci est plus efficace avec des particules de grande taille, du fait de la meilleure pénétration des photons. Enfin à l’aide d’une étude analytique poussée et de la mise en évidence de la formation de HO• et 1O2, nous avons proposé un mécanisme de photodégradation impliquant des réactions de PhotoFries, de photohydrolyse, de dimérisation et d’hydroxylation. Dans la deuxième partie des travaux sur le sol réel, un protocole original a été mis en oeuvre. Il consiste en un fractionnement préalable du sol suivi d’un traitement chimique afin d’atténuer l’impact de la matière organique. Il a été montré que la dégradation sur le sol et ses fractions est efficace et que la matière organique a un effet bénéfique, à faible concentration, et inhibiteur, à forte concentration, sur la transformation du carbaryl. De plus, le fractionnement a révélé que la photodégradation est d’autant plus importante que les fractions sont constituées de particules de grande taille. Enfin, la formation d’espèces réactives (HO• et 1O2) a été observée systématiquement et plus efficacement pour les fractions sans matière organique suggérant des processus de transformation attribuables à la partie minérale des supports. / This study focuses on the transformation of organic pollutants on soil surface under the influence of the light excitation. Two main organic compounds were used as model molecules, phenylbenzoquinone (PhQ) and a carbamate pesticide, carbaryl. We used several supports : three model supports (silica, sand of Fontainebleau and kaolinite) and a real soil of the region of Orange (France). The phototransformation was carried out using a device that simulates the solar radiation (l > 300 nm). The study of the spectroscopic features of PhQ on solid support shows a broad band of absorption that presents bathochromic and hyperchromic effects. During irradiation, the concentration and the thickness of film were found to be important parameters to be considered in order to avoid the screen as well as diffusion effect. The optimal value of the thickness was determined roughly to 100 μm in order to minimise the diffusion effect. The mechanism of transformation of PhQ is similar to that observed in aqueous solution with the formation of the unique photoproduct 2-hydroxybenzofuran. The process involves the triplet excited state of PhQ. After this work, the first studies are on the phototransformation of carbaryl and other pesticides on model supports. Furthermore, the molar absorption coefficient and quantum yield have been determined in order to confirm the bathochromic and hyperchromic effect and also the increase of the quantum yield (10 times for carbaryl). The degradation process was most effective when the particle size increases. Moreover, from the analytical studies the photodegradation mechanism was suggested involving several reactions such as photofries, photohydrolyse, dimerisation and hydroxylation. The second part of the present work was dedicated to the study on real soil. An original protocol had to be set up. It consisted on a prefractionation of soil followed by a chemical treatment to minimise the impact of organic matter. Concerning the phototransformation of carbaryl, it was shown that the degradation at the surface of soil and its fractions is effective and that the organic matter has a beneficial effect at low concentrations and inhibition effect at high concentrations. Furthermore, fractionation revealed that photodegradation is more important when the fractions are composed of large particles. Finally, the formation of reactive species (HO• and 1O2) was observed consistently and efficiently for fractions without organic matter suggesting transformation processes induced by the mineral part of the supports.

La phototransformation des matières actives à la surface des plantes après pulvérisation a une influence considérable sur l’efficacité des traitements. Dans ce travail, l’ensemble des réactions photochimiques se produisant sur des supports modèles des cires végétales dans des conditions proches des conditions environnementales ont été étudiées dans le cas d’un fongicide (le chlorothalonil) et d’un herbicide (la cycloxydime). Nous avons considéré les réactions photochimiques induites par l’absorption de lumière par les composés eux-mêmes et celles faisant intervenir des sensibilisateurs comme les métabolites secondaires des plantes. Dans chacun des cas, des études mécanistiques détaillées ont été conduites. Nous montrons que le chlorothalonil possède la capacité remarquable de produire de l’oxygène singulet avec un rendement quantique proche de l’unité. En parallèle, la réactivité de la cycloxydime avec l’oxygène singulet a été montrée. De ce fait, la phototransformation de la cycloxydime sur film de cire est accélérée lorsque des sensibilisateurs naturels, tels que les phytoalexines sont ajoutés à la cire, ou lorsque des traces de chlorothalonil sont présents à la surface du modèle foliaire. Ce travail a permis 1) de comprendre le mécanisme de phototransformation par excitation directe et sensibilisées du chlorothalonil et de la cycloxydime, 2) de mesurer de nombreuses données physico-chimiques (constantes de vitesse de réaction, rendements quantiques, durées de vie, caractéristiques spectrales des transitoires) et 3) de mettre au point un protocole expérimental permettant d’étudier la photochimie de molécules à l’état solide incluses dans des films de cire. / The phototransformation of active ingredients on plant surfaces after spraying has a significant impact on the treatment efficiency. In this work, the photochemical reactions taking place on leaf models and environmental conditions close to real ones have been overviewed for two pesticides: chlorothalonil and cycloxydim. We considered the photochemical reactions induced by light absorption by the compounds themselves and the reactions involving natural sensitizers such as plants secondary metabolites. Detailed mechanistic studies were conducted. We show that chlorothalonil has a noteworthy capacity to produce singlet oxygen with a quantum yield close to unity. Besides, the reactivity of cycloxydim towards singlet oxygen was demonstrated. Hence, the phototransformation of cycloxydim deposited on wax films is accelerated when natural sensitizers, such as phytoalexins, are included in the wax, or when chlorothalonil traces are present on the leaf model. This work allowed 1) to understand the mechanism of phototransformation by direct excitation and sensitization of chlorothalonil and cycloxydim, 2) to measure many physicochemical data (reaction rate constants, quantum yields, lifetime, spectral characteristics oft ransients and 3) to put in work an experimental protocol for the photochemical study of organic compounds in solid state and included in wax films.

Les pesticides appliqués par pulvérisation dans les cultures sont dispersés à la surface des plantes où ils peuvent être transformés sous l'effet de la lumière solaire. Nous avons montré dans ce travail que les herbicides mésotrione et sulcotrione, et les insecticides cypermétrine et deltaméthrine sorbés à la surface des cires cuticulaires, sont photosensibles. Cette propriété est modifiée par l'ajout d'additifs présent dans les formulation commerciales ? Ces derniers peuvent accélèrer ou ralentir la photolyse des principes actifs. Cependant, il ne semble pas y avoir de règle générale permettant de prévoir l'importance de la phototransformation pour chaque matière active. D'autre part, alors qu'en laboratoire la dissipation des pesticides étudiés est uniquement due à la phototranformation ; sur les plantes entières, d'autres phénomènes interviennent. La diffusion dans la cuticule et les pertes dues au lessivage par la pluie ou la rosée peuvent devenir prépondérantes devant la phototransformation.

A Terapia Fotodinâmica (TFD) é um método de tratamento do câncer e de outras doenças baseado no efeito conjunto de um composto fotoativo, luz da região visível ou infravermelho próximo e oxigênio molecular. O diagnóstico por fluorescência (DF) é uma técnica para o diagnóstico precoce de diversas doenças que consiste em utilizar algum composto fluorescente para distinguir tecido tumoral de tecido saudável. As porfirinas são amplamente utilizadas como fotossensibilizadores (FS) na TFD e como fluoróforos (FF) no DF. Os pontos quânticos (PQ) são novas nanoestruturas que possuem intenso e largo espectro de absorção na região espectral UV e visível, espectro de luminescência muito intenso e estreito e são fotoestáveis. Isso os torna promissores para o uso em TFD ou em DF, competindo com FS e FF orgânicos. A interação entre PQ e FS orgânicos pode aumentar a eficiência de ambos, devido aos processos de transferência de energia e/ou de carga. Durante o fototratamento os FS podem sofrer fototransformações, perdendo sua fotoatividade e formando produtos estáveis tóxicos. Isso torna importante o estudo da fototransformação dos FS. Neste trabalho, estudou-se, através da espectroscopia de absorção óptica, da fluorescência com resolução temporal e de flash-fotólise, a interação das porfirinas meso-tetrametil piridil (TMPyP) e meso-tetrasulfonatofenil (TPPS4) com o PQ de Telureto de Cádmio (CdTe) encapsulado com ácido 3-mercaptopropiônico (MPA) e sua fotólise individual e em conjunto. Os experimentos entre a TMPyP e o PQ mostraram que existe a formação de um complexo de transferência de carga entre a porfirina e o PQ. Verificou-se que a formação do complexo TMPyP-PQ aumenta a eficiência do processo de fotólise. A interação entre a p TPPS4 e o PQ em pH 4,0 (TPPS4 biprotonada) induz a transferência dos prótons para o PQ. A porfirina TPPS4 em pH 7,0 com adição de PQ não apresentou mudanças espectrais. Entretanto, em ambos os pHs, o PQ causava o aumento da velocidade de fotólise da TPPS4, sendo que o efeito do PQ foi maior em pH 4,0. Os resultados obtidos mostraram a importância da carga dos componentes, tanto na sua interação, como na eficiência de fotólise, devido à sua interação eletrostática. Também foi observado um aumento da intensidade da fluorescência de sistemas porfirina-PQ durante a fotólise. Esse efeito pode ser explicado pela redução da supressão da fluorescência devido à diminuição das concentrações dos componentes durante a fotólise. / The Photodynamic Therapy (PDT) is a method of treatment of cancer and other diseases based on combined effects of a photoactive compound, visible or near infrared light and molecular oxygen. The diagnosis by fluorescence (DF) is a technique for diagnostics of disease that consists in utilizing fluorescence compound to discern tumor tissue from a healthy one. Porphyrins are widely used as photosensitizer (PS) in PDT and as fluorophore (FP) in DF. Quantum dots (QD) are new nanostructures, which have intense and broad absorption spectrum in the UV and visible light region, intense and narrow luminescence spectrum and possess high photostability. They are considered promising for clinical application in PDT and/or DF, competing with organic PS and FP. Interaction between QD and organic PS can increase the efficiencies of both, due to the energy and/or charge transfer processes. The PS phototransformation during phototreatment may lead to loss of the PS photoactivity and formation of toxic products, that is important to study the processes of the PS phototransformation. In this work, with the support of absorption spectroscopy, steady state and time resolved fluorescence and flash-photolysis, we study interaction of meso-tetramethyl pyridyl (TMPyP) and meso-tetrakis sulfonatofenyl (TPPS4) porphyrins with CdTe QD functionalized with 3-mercaptopropionic acid (MPA) and their photolysis individual and in mutual. Experiments with TMPyP and QD demonstrate formation of a charge transfer complex between the porphyrin and the QD. We have verified that TMPyP-QD complex increases the efficiency of the porphyrin photolysis. The photolysis of the proper complex has been observed, as well. The interaction between TPPS4 and QD at pH 4.0 (biprotonated TPPS4) provokes deprotonation of the porphyrin via the proton transfer to QD. At pH 7.0 (deprotonated TPPS4) interaction of the porphyrin with the QD does not change TPPS4 spectral characteristics. Nevertheless, at both pHs QD cause increase in the TPPS4 photolysis rate, the effect being higher at pH 4.0. The observed results demonstrate the importance of the component charges both at their interaction and in photolysis efficiency, associated with their electrostatic interaction. The fluorescence intensity of the porphyrin-QD systems is enhanced during photolysis. This effect may be explained as the fluorescence quenching reduction due to decrease of the compound concentrations in the photolysis process.