Thesis (Ph. D.)--University of Washington, 1996. / Vita. Includes bibliographical references (leaves [127]-142).

Inúmeros pesticidas são usados na agricultura, para controle de pragas e ervas daninhas. Dentre eles destaca-se o herbicida atrazina, intensivamente utilizado nas culturas de cana-de-açúcar, milho e sorgo, que ocupam extensas áreas no estado de São Paulo. Grande parcela do herbicida, que é aplicado na agricultura, entra em contato com o solo, podendo ser lixiviado, atingindo as águas superficiais. Neste sentido, alguns animais como, por exemplo, moluscos bivalves, podem ser utilizados como monitores biológicos do ambiente aquático e auxiliar no estudo da ecotoxicologia. Considerando o risco de contaminação do ambiente aquático pela atrazina, propõe-se, no presente trabalho, desenvolver uma metodologia de análise daquele herbicida nos tecidos nas espécies de bivalves límnicos Anodontites trapesialis (LAMARCK, 1819) e Corbicula fluminea (Muller, 1789), validar esse método e, finalmente, verificar se ocorre a bioacumulação do herbicida nas partes moles dessas duas espécies. Como técnica de extração utilizou-se a extração líquido- líquido e como técnica de análise, a cromatografia líquida de alta eficiência (CLAE). / Large amount of pesticides have been used for the control of agriculture pests and weeds. Particularly important among herbicides is atrazine, extensively employed in cultures of sugar cane, corn and sorghum, that occupies an extensive area in São Paulo state. Large portions of atrazine, applied in the agricultural fields, leaches from the soil to surface water systems. In this way, some organisms such as fresh- water mollusks bivalves, can be used as biological monitors of aquatic environments, contributing for ecotoxicology studies. Considering the existence of risk of contamination by atrazine of the aquatic environment, the purpose of this work was, (i) to develop a method for the analysis of atrazine in the fresh- water bivalves species Anodontites trapesialis (LAMARCK, 1819) and Corbicula fluminea (MULLER, 1789), (ii) to validate such method and, (iii) to detect if these organisms can bioaccumulate atrazine in their tissues. This method involved a simple liquid-liquid extraction procedure, followed by high- performance liquid chromatographic analysis (HPLC).

Recent reports of damage to maize seedlings where atrazine or atrazine/terbuthylazine was applied post-emergence again raised the issue of maize tolerance to triazines. The potential of atrazine or atrazine/terbuthylazine to injure maize when applied post¬emergence was investigated under controlled conditions. Factors considered were growth stage, surfactants, cultivar tolerance, temperature and crop recovery from herbicide injury. The first experiment was conducted to determine the effect of atrazine and terbuthylazine on maize seedlings, and the second one was carried out to identify whether stage of maize development has an influence on atrazine or terbuthylazine phytotoxicity. In Experiment 1, herbicide treatments were applied at the 2-leaf stage of cultivar PAN 6043, and in Experiment 2 at the 2-leaf and 4-leaf stages. The third experiment was carried out to determine cultivar tolerance to atrazine or atrazine/terbuthylazine. The three cultivars used were CG 4526, PAN 6043 and PAN 6140. The fourth and fifth experiments were carried out in growth chambers where the role of temperature and cultivars were investigated. The temperature levels were 20/15 and 30/25°C (day/night). Herbicide and temperature treatments were applied at the 2-leaf stage of cultivars CG 4526, CAN 3891, PAN 6043 and PAN 6140. Finally, an experiment was conducted to investigate the recovery of maize seedlings from the initial atrazine/terbuthylazine phytotoxicity. The cultivar PAN 6043 was used and the herbicide rates were the recommended and double the recommended rate. The rates of the herbicides and associated activity enhancers were 2.5 L ha-1and 1 L ha-1 respectively. The following products were used: Atrazine 500 SC (485 g L-1 atrazine) + BP Agripon (940 g L-1 mineral oil); Gesaprim Super 600 SC (291 g L-1 atrazine and 291 g L-1 terbuthylazine) + AG Penetrex (363 g L-1); Gesaprim Super 600 SC (291 g L-1 atrazine and 291 g L-1 terbuthylazine) + Complement (363 g L-1). Maize seedlings were tolerant when atrazine or atrazine/terbuthylazine was applied at the 4-leaf stage, but significant damage was caused when application was done at the 2-leaf stage. No significant differences were found between surfactants. Significant differences occurred with cultivars at specific temperatures. At the low temperature regime (20/15°C), CG 4526 showed shoot dry mass (SDM) reduction of > 40 %, while the growth of PAN 6140 was reduced by less than 10 % by both herbicides. However, with an increase in temperature, CG 4526 was the most tolerant. It showed <17 % reduction in SDM while others showed >30 % reduction. It is suggested that the tolerance of maize (specifically at the two-leaf stage) to atrazine or atrazine/terbuthy1azine is dependent on cultivar and temperature. Although initial phytotoxic symptoms were visible several weeks after spraying, the growth inhibition of the atrazine/terbuthylazine-treated maize plants was transient. At five weeks after application, leaf area index (LAI) had recovered 100% and 95% at the recommended and double the recommended rate, respectively. Recovery in SDM and root dry mass (RDM) were similar, with 100% recovery reached after eight weeks following application. It was found that although growth stage plays an important role in the tolerance of maize seedlings when atrazine or atrazine/terbuthylazine is applied post-emergence, surfactants, cultivars, and temperature also have an influence on the tolerance of maize seedlings towards these herbicides. / Dissertation (M Inst Agrar (Weed Science))--University of Pretoria, 2006. / Plant Production and Soil Science / unrestricted

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The widespread use and subsequent release of pesticides into aquatic environments have sparked concerns about how organisms within these aquatic systems are affected by pesticide pollution. While many studies have examined the effects of pesticides on individual organisms, in a series of experiments, I investigated the effects of a pesticide mixture on members of a complex host-parasite system and on host susceptibility to infection. In my first experiment in the laboratory, I examined changes in survivorship when trematode parasites (Echinostoma trivolvis) and their first intermediate host, Planorbella trivolvis snails, were exposed to a low concentration (10 ppb: 15 ppb) and high concentration (85 ppb: 100 ppb) mixture of atrazine and metolachlor, respectively. There was a significant decline in parasite survivorship in the high concentration treatment at 14 hours, while snail survivorship was unaffected across all treatments. In my second experiment, prior to infection, I exposed the parasites and/or second intermediate hosts, Rana clamitans and Rana sylvatica tadpoles, to the pesticide mixtures and examined subsequent infection levels in the tadpoles. The atrazine and metolachlor mixtures had no significant effects on parasite load in the laboratory. Newly shed parasites were more likely than 10 hours old parasites to infect tadpoles, regardless of pesticide exposure. In my final experiment, I utilized outdoor mesocosms to expose parasites, snail hosts, and Rana sylvatica tadpoles to the pesticide mixture, and I examined differences in parasite load within the tadpoles after two weeks. The pesticides had no significant effect on parasite loads in the field. Overall, my findings suggest the atrazine and metolachlor mixtures used in this study had no significant effects on disease dynamics in a system involving Echinostome parasites, snails, and tadpoles. / Master of Science

The decline of honey bee (Apis mellifera) colony numbers in recent years presents an economic and ecological threat to agriculture. One outstanding threat to honey bees is the unintended exposure to agricultural pesticides. Previous studies report that acute exposures to the common-use herbicide atrazine elicit oxidative stress in non-target insects; however, little information is currently available on the exposure risk of atrazine to honey bees. This project examined biochemical and molecular oxidative stress response markers of honey bees following laboratory and field treatments of atrazine. Laboratory experiments were conducted with honey bees exposed to increasing concentrations of atrazine for 24 h whereas hive experiments were conducted with bees exposed to one sub-lethal concentration of atrazine for 28 d. The overall antioxidant enzyme activities of atrazine-treated honey bees were decreased compared to the untreated honey bees in both the laboratory and hive experiments. After exposure to atrazine in the laboratory and field, semi-quantitative RT-PCR analysis of antioxidant-encoding genes reveals the differential expression of genes in atrazine-treated bees that are important for oxidative stress tolerance in the laboratory and field experiments. Here, we provide evidence that the laboratory and hive exposure of honey bees to the common-use herbicide atrazine results in oxidative stress responses that can compromise the health of bee colonies. The data will be discussed with regard to the protection of these pollinators against the untended exposure of agricultural pesticides. / Master of Science in Life Sciences

Thesis (Ph. D.)--West Virginia University, 2007. / Title from document title page. Document formatted into pages; contains vi, 183 p. : ill. (some col.). Includes abstract. Includes bibliographical references.

La conception, la synthèse et l’étude des propriétés photophysiques de sondes fluorescentes d’espèces moléculaires ou de cations présente beaucoup d’intérêt dans des domaines aussi divers que l’environnement et la biologie. En particulier, les cations polluants (cations d’aluminium, cations de potassium) et les résidus de pesticides (tels que le glyphosate ou l’atrazine) qui n’étant pas dégradés par le métabolisme, ils se retrouvent dans les eaux de boissons à des concentrations délétères pour l’environnement. Les méthodes analytiques actuelles telles que la spectroscopie d'absorption atomique, la spectroscopie de masse sont coûteuses et ne peuvent être utilisées que pour les déterminations à l'intérieur. Inversement, l'utilisation de la technique de fluorescence offre des avantages distincts en termes de sensibilité, de sélectivité et de développement potentiel d'appareils portables.Dans cette thèse, des sondes fluorescentes efficaces pour la détection de l'aluminium, du potassium, du glyphosate et de l'atrazine ont été ciblées. Pour l'aluminium, une nouvelle sonde hydrosoluble (PSSA) a été synthétisée, reconnaissant les cations d'aluminium sur la base du mécanisme d'amélioration de l'émission induisant une agrégation. Avec une limite de détection de 153 nM et une bonne propriété de sélectivité, le PSSA a également été intégré avec succès dans un système PDMS / verre afin de permettre l’utilisation d’un dispositif portable pour la détection de l’aluminium.Ensuite, deux sondes synthétisées différentes de notre laboratoire (Calix-Rhod-aza et DMAP-BARB) ont été considérées dans cette thèse. Ces sondes ont été développées pour la détection de potassium et d'atrazine, respectivement. Pour les deux molécules, la photophysique et la complexation vis-à-vis d'espèces ciblées ont été étudiées, et deux configurations différentes de microfluidique capillaire en PTFE ont été réalisées pour leur détection, avec des limites de détection très satisfaisantes (qui bien conformes à la gamme des normes réglementaires).Enfin, des efforts ont été consacrés à la conception et à la synthèse de nouveaux capteurs pour le glyphosate. Quatre sondes différentes ont été conçues (GlyP-a, GlyP-b, GlyP-c, GlyP-d). GlyP-a a été faite, alors que les autres étaient à deux pas de la réalisation. En effet, ce projet est toujours en cours dans notre laboratoire, en prenant les résultats préliminaires de ce travail. / The design, synthesis and photophysical studies of fluorescent sensors of neutral molecules or cations are of great interest in environment and biology. In particular, metal-based pollutants (aluminium cations, potassium cations) and pesticide residues (such as glyphosate or atrazine) which are not degraded by the metabolism can be found in drinking water at harmful concentrations to the environment. Actual analytical methods such as atomic absorption spectroscopy, mass spectroscopy are expensive and can only be used for indoor determinations. Conversely, the use of fluorescence technique offers distinct advantages in terms of sensitivity, selectivity with a potential development of portable devices.In this thesis, efficient fluorescent probes for the sensing of aluminium, potassium, glyphosate and atrazine were targeted. For aluminium, a novel water-soluble probe (PSSA) was synthesized, which recognize aluminium cations based on aggregation-induce emission enhancement mechanism. With a detection limit of 153 nM and good selectivity property, PSSA was also successfully incorporated onto a PDMS/glass system for enabling a portable device for aluminium detection.Next, two different synthesized probes from our laboratory (Calix-Rhod-aza and DMAP-BARB) were considered in this thesis. These probes were developed for potassium and atrazine sensing, respectively. For both molecules, the photophysical and complexation towards targeted species were studied, and two different PTFE capillary microfluidics set-ups were realized for their detection, with highly satisfactorily detection limits (well in accordance with the range of the regulation standards).Finally, efforts were given on the design and synthesis of new sensors for glyphosate. Four different probes were designed (GlyP-a, GlyP-b, GlyP-c, GlyP-d). GlyP-a has been made, while the others were just one step away from realization. Indeed, this project is still under progress in our laboratory, taking the preliminary results from this work.