The presence of micropollutants, particularly pesticides, in surface waters across Canada has been of concern not only for their environmental impact, but also for their potential effects on human health and recalcitrant nature to conventional water treatment methods. Although ozone has been mainly applied for disinfection of drinking water, oxidation of trace organics by ozonation has been considered potentially effective. In an effort to meet increasingly stringent drinking water regulations, different solid catalysts have been used to enhance the removal of water contaminants by ozonation. In spite of the increasing number of data demonstrating the effectiveness of heterogeneous catalytic ozonation, the influence of different factors on the efficiency of micropollutants oxidation is still unclear.<p> In the present work, application of three solid catalysts in ozonation of two model micropollutants in pure water was examined using a laboratory-scale reaction system over a range of operating conditions. The three catalysts investigated were activated carbon, alumina, and perfluorooctyl alumina, and the two model micropollutants were the pesticides atrazine and 2,4-dichlorophenoxyactic acid. The effects of solution pH, presence of a radical scavenger, pesticide adsorption on catalyst, and catalyst dose on micropollutant removal were investigated. Solution pH was found to significantly influence the catalyst ability to decompose ozone into free hydroxyl radicals. The effect of these free radicals was markedly inhibited by the radical scavenger resulting in a negative impact on pesticides degradation. In general, the removal rate of pesticides was found to increase with increasing doses of catalyst.<p> In the ozonation process in the presence of activated carbon, atrazine removal rates increased four and two times when using a catalyst dose of 0.5 g L-1 at pH 3 and 7, respectively, whereas observed reaction rates for 2,4-D increased over 5 times in the presence of 1 × 10-4 M tert-butyl alcohol at pH 3. In the ozonation system catalyzed by 8 g L-1 alumina, the observed reaction rate constant of atrazine removal notably improved at neutral pH by doubling the micropollutant removal rate. For the pesticide 2,4-D in the presence of 1 × 10-4 M tert-butyl alcohol at pH 5, the observed removal rate was over ten times higher than that for the non-catalytic ozonation process using also using a catalyst dose of 8 g L-1. Modification of alumina to produce perfluorooctyl alumina resulted in a material able to significantly adsorb atrazine, while not exhibiting affinity for adsorption of 2,4-D. In spite of its adsorptive properties, perfluorooctyl alumina was found to enhance neither molecular ozone reactions nor ozone decomposition into hydroxyl radicals. Thus, the observed removal rates for atrazine and 2,4-D by ozonation in the presence of perfluorooctyl alumina did not increase significantly.

The presence of micropollutants, particularly pesticides, in surface waters across Canada has been of concern not only for their environmental impact, but also for their potential effects on human health and recalcitrant nature to conventional water treatment methods. Although ozone has been mainly applied for disinfection of drinking water, oxidation of trace organics by ozonation has been considered potentially effective. In an effort to meet increasingly stringent drinking water regulations, different solid catalysts have been used to enhance the removal of water contaminants by ozonation. In spite of the increasing number of data demonstrating the effectiveness of heterogeneous catalytic ozonation, the influence of different factors on the efficiency of micropollutants oxidation is still unclear.<p> In the present work, application of three solid catalysts in ozonation of two model micropollutants in pure water was examined using a laboratory-scale reaction system over a range of operating conditions. The three catalysts investigated were activated carbon, alumina, and perfluorooctyl alumina, and the two model micropollutants were the pesticides atrazine and 2,4-dichlorophenoxyactic acid. The effects of solution pH, presence of a radical scavenger, pesticide adsorption on catalyst, and catalyst dose on micropollutant removal were investigated. Solution pH was found to significantly influence the catalyst ability to decompose ozone into free hydroxyl radicals. The effect of these free radicals was markedly inhibited by the radical scavenger resulting in a negative impact on pesticides degradation. In general, the removal rate of pesticides was found to increase with increasing doses of catalyst.<p> In the ozonation process in the presence of activated carbon, atrazine removal rates increased four and two times when using a catalyst dose of 0.5 g L-1 at pH 3 and 7, respectively, whereas observed reaction rates for 2,4-D increased over 5 times in the presence of 1 × 10-4 M tert-butyl alcohol at pH 3. In the ozonation system catalyzed by 8 g L-1 alumina, the observed reaction rate constant of atrazine removal notably improved at neutral pH by doubling the micropollutant removal rate. For the pesticide 2,4-D in the presence of 1 × 10-4 M tert-butyl alcohol at pH 5, the observed removal rate was over ten times higher than that for the non-catalytic ozonation process using also using a catalyst dose of 8 g L-1. Modification of alumina to produce perfluorooctyl alumina resulted in a material able to significantly adsorb atrazine, while not exhibiting affinity for adsorption of 2,4-D. In spite of its adsorptive properties, perfluorooctyl alumina was found to enhance neither molecular ozone reactions nor ozone decomposition into hydroxyl radicals. Thus, the observed removal rates for atrazine and 2,4-D by ozonation in the presence of perfluorooctyl alumina did not increase significantly.

Thesis (Ph. D.)--Ohio State University, 2008. / Title from first page of PDF file. Includes bibliographical references (p. 96-107).

FundaÃÃo Cearense de Apoio ao Desenvolvimento Cientifico e TecnolÃgico / BactÃrias do gÃnero Burkholderia possuem a capacidade de biodegradar inÃmeros compostos considerados poluentes. Mediante o exposto, este trabalho visou a identificaÃÃo molecular do isolado SMF042 oriundo de uma coleÃÃo de espÃcies de Burkholderia, verificar sua capacidade biodegradar o herbicida Ãcido 2,4-diclorofenoxiacÃtico (2,4-D), identificar as enzimas envolvidas neste processo por eletroforese bidimensional (2D) e a analisar a expressÃo dos genes tfdA e tfdB da via TFD de biodegradaÃÃo do 2,4-D. A fim de fazer a extraÃÃo de RNA e proteÃnas foi realizado o crescimento bacteriano em dois meios de cultivo BH (meio mineral), um controle, suplementado com glicose (600 mg/L), e outro suplementado com 2,4-D (600 mg/L). A extraÃÃo de RNA foi realizada na fase logarÃtmica enquanto a extraÃÃo de proteÃnas foi feita no inicio da fase estacionÃria de crescimento bacteriano. A partir das proteÃnas extraÃdas foi determinado o mapa bidimensional de referÃncia para cada condiÃÃo. O ajuste das imagens dos gÃis bidimensionais, a detecÃÃo de spots protÃico e a avaliaÃÃo dos dados para determinar variaÃÃes quantitativas e qualitativas, massa molecular (MW) e ponto isoelÃtrico (pI) dos spots foi feito pelo programa ImageMaster e a anÃlise da expressÃo dos genes, foi realizado por qRT-PCR empregando o mÃtodo da expressÃo relativa 2-&#916;&#916;CT. Por meio da anÃlise do gene 16S rRNA o isolado SMF042 foi identificado como Burkholderia phymatum. No tocante a abordagem proteÃmica, o nÃmero mÃdio de spots das rÃplicas dos gÃis foi de 535 (controle) e 705 (tratado). A maior abundÃncia de proteÃnas foi observado nos gÃis na faixa de MW 20 e 40 KDa e pH 5-6. Enzimas envolvidas na biodegradaÃÃo do 2,4-D foram identificadas utilizando os valores de pI e MW do spot em comparaÃÃo com o banco de dados de proteÃnas no ExPASy, foram elas: 2,4-D alfa KG-dependente dioxigenase (tfdA) e clorocatecol 1,2-dioxigenase (tfdC) pertencentes a via TFD e 2,4-D oxigenase da via cadRABK, ambas de biodegradaÃÃo do 2,4-D. ProteÃnas envolvidas na resistÃncia ao estresse quÃmico, tambÃm foram identificadas, sendo elas: proteÃna GrpE e chaperona DnaK. O nÃvel de expressÃo do gene tfdA aumentou cerca de 23 vezes em relaÃÃo ao controle. Pelo exposto, o isolado SMF042 foi capaz de crescer em um meio contendo 2,4-D como Ãnica fonte de carbono, expressou proteÃnas de vias de biodegradaÃÃo do 2,4-D, resistÃncia ao estresse quÃmico e aumentou a expressÃo gÃnico de tfdA, o que indica a importÃncia desta bactÃria na biodegradaÃÃo deste poluente. / Burkholderia bacteria it has ability to biodegrade pollutants considered numerous compounds. By the above, this study aimed to identify molecular SMF042 come from an isolated collection of Burkholderia species, verify their ability to biodegrade the herbicide 2,4-dichlorophenoxyacetic acid (2,4-D), to identify the enzymes involved in this process by electrophoresis two-dimensional (2D) and to analyze the expression of genes and TFDA tfdB track TFD biodegradation of 2,4-D. In order to make the extraction of RNA and protein bacterial growth was performed in two culture media BH (mineral medium), a control supplemented with glucose (600 mg / L) and another supplemented with 2,4-D (600 mg / L). RNA extraction was performed in the logarithmic phase while protein extraction was done at the beginning of the stationary phase of bacterial growth. The extracted proteins from two-dimensional map was determined for each reference condition. The adjustment of images of two-dimensional gels, the protein spot detection and evaluation of data to determine quantitative and qualitative changes, molecular weight (MW) and isoelectric point (pI) of the spots was made by the ImageMaster software and analysis of gene expression was qRT-PCR performed by using the method of relative expression 2-&#916;&#916;CT. Through the analysis of the 16S rRNA isolate SMF042 was identified as Burkholderia phymatum. Regarding proteomics approach, the average number of spots of the replicas of the gels was 535 (control) and 705 (treated). The most abundant protein in the gels was observed in the range of 20 and 40 MW kDa and pH 5 and 6. Enzymes involved in the biodegradation of 2,4-D were identified using the values of pI and MW of spot against a database of proteins at ExPASy, they were: 2,4-D alpha KG-dependent dioxygenase (TFDA) and chlorocatechol 1 ,2-dioxygenase (tfdC) belonging saw PDT and 2,4-D oxygenase pathway cadRABK, both biodegradation of 2,4-D. Proteins involved in resistance to chemical stress, have also been identified, which are: protein chaperone DnaK and GrpE. The level of gene expression TFDA increased about 23 times compared to control. As shown, the isolated SMF042 was able to grow on a medium containing 2,4-D as sole carbon source expressed protein degradation pathways of 2,4-D, resistance to chemical stress and increased expression of gene TFDA, which indicates the importance of this bacterium in this pollutant biodegradation.

The potential human health issues resulting from the continuous consumption of drinking water containing low concentration levels of persistent emerging pollutants has raised some concerns. The presence of emerging pollutants in surface water bodies and ground-water in Canada together with absence of proper drinking water treatment processes in remote places has created the need for an effective and simple process for removal of emerging pollutants from drinking water. Low seasonal temperatures in regions such as Saskatchewan demand a removal process that is effective at temperatures lower than room temperature. Adsorption with granular activated carbon is a well-established and effective method for removal of organic compounds from drinking water. There are a large number of reports on removal of organic compounds by activated carbon in literature however, the effectiveness of adsorption of emerging pollutants with granular activated carbon is not clear. Effectiveness of ozone treatment for oxidation of emerging pollutants is reported in literature however, effectiveness of regeneration of adsorbents saturated with emerging pollutants with ozone has not been investigated extensively. In the present work, effectiveness of adsorption with granular activated carbon for removal of emerging pollutants is investigated. Three model compounds of Ibuprofen, 2,4-dichlorophenoxyacetic acid, and Bisphenol A reported at considerable concentration levels in Saskatchewan water bodies were selected as model compounds. Bituminous coal based and coconut shell based granular activated carbons with basic point of zero charge were selected as adsorbents. Isotherm adsorption of model compounds on adsorbents was conducted at 280, 288, and 296 K. The Gibbs free energy, enthalpy, and entropy of adsorption were calculated using isotherm model parameters. Nitric acid pre-treatment was applied to reduce the point of zero charge of adsorbents. Adsorption isotherms were conducted with the acid treated adsorbents. Adsorption removal of model compounds in tap water was studied. Effectiveness of regeneration of saturated adsorbents with ozone was investigated. In terms of quality of fit to the isotherm adsorption data, Langmuir model was better than Freundlich model indicating monolayer adsorption of model compounds in all experiments. Higher Langmuir monolayer adsorption capacity (Qmax) of bituminous coal based adsorbent than coconut shell adsorbent for adsorption of model compounds was attributed to the higher porosity of bituminous coal based adsorbent. Adsorption of model compounds (i.e. IBP and BPA) present in molecular form in the pH condition of the experiments were more dependent on adsorbent surface functional groups e.g. carboxyl and carbonyl groups. The Qmax of adsorption of 2,4-D present in anionic form was proportional with the specific surface area of adsorbent. Adsorption at temperatures lower than room temperature was effective. Adsorbent with acidic point of zero charge was more effective in removal of model compounds than adsorbent with basic point of zero charge. Adsorption of BPA was higher in tap water in comparison to Millipore water due to the more neutral surface of adsorbent in tap water. Higher pH of tap water than Millipore water and the ionic interaction between the adsorbent and dissolved solids present in tap water caused the more neutral surface of adsorbent. Regeneration of adsorbents with ozone failed in restoration of adsorption capacity of adsorbents and excessive ozonation destroyed the pore structure of adsorbents.

Orientador: Rodnei Bertazzoli / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecanica / Made available in DSpace on 2018-08-07T06:34:47Z (GMT). No. of bitstreams: 1 Badellino_Carla_M.pdf: 4439168 bytes, checksum: 0e434b627394c712d54234bcc01ad717 (MD5) Previous issue date: 2006 / Resumo: Nest trabalho foi investigada a desempenho do peróxido de hidrogênio eletrogerado a partir de redução do oxigênio na superfície de um catodo de carbono vítreo reticulado para a oxidação do herbicida ácido 2,4-diclorofenoxiacético. Inicialmente, foram feitas voltametrias cíclicas para verificar se o 2,4-D para verificar a existência de pares redox. O eletrólito suporte usado foi o K2SO4 0,3 mol L-1, pH 10, em meio saturado de N2. Após a verificação da ausência de reação redox para o 2,4-D, fez-se a otimização da eletrogeração de peróxido de hidrogênio. Usando como catodo um eletrodo rotatório cilíndrico de carbono vítreo reticulado de 60 ppi e um anodo de platina, em meio de K2SO4 0,3 mol L-1, pH 10, saturado com O2 e 900 rpm, determinou-se que o melhor potencial para eletrogeração de H2O2 foi de ¿ 1,6 V vs. ECS a uma temperatura de 8 0C. Em etapa subseqüente, verificou-se a degradação do herbicida 2,4-D em solução, na concentração de 100 mg L-1 por diferentes três processos: H2O2 eletrogerado, UV/H2O2, e fotoeletro-Fenton, este último realizado em pH 2,5. Para tanto foram feitas injeções no Cromatógrafo Líquido de Alta Eficiência, além de análise de Carbono Orgânico Total e Demanda Química de Oxigênio. Dos processos estudados, o mais vantajoso foi o catalisado com radiação UV e sais de Fe2+ (Reagente de Fenton), com uma redução do COT de 69 % do valor inicial. Dando continuidade os estudos, foi construído um reator em escala piloto do tipo filtro prensa com fluxo transversal para eletrogeração de peróxido de hidrogênio. Composto por dois compartimentos anódicos e um catódico, separado por membranas catiônicas Nafion ®N242, o reator foi otimizado em três diferentes parâmetros: o potencial de trabalho, a velocidade de vazão do fluido e a vazão de oxigênio. Os valores ótimos encontrados para eletrogeração de H2O2 em eletrólito suporte de K2SO4 0,3 mol L-1 foram: potencial de -1,6 V vs. Pt, velocidade do fluido de 500 L h-1 e vazão de oxigênio de 6 L s-1. Com o reator otimizado e acumulando cerca de 1100 mg L-1 de H2O2 em 5 horas de processo, foram feitos ensaios de degradação do 2,4-D em seis deferentes métodos: dois ensaios em meio básico com e sem incidência de radiação ultravioleta, e em seguida, mais quatro ensaios em meio ácido, também com e sem a incidência de radiação ultravioleta, na presença do reagente de Fenton, e por fim, um ensaio catalisado com radiação ultravioleta e na presença do reagente de Fenton. Os ensaios em meio ácido e catalisado, mais uma vez se mostraram mais eficientes e a remoção do COT seguiu uma cinética de pseudo-primeira ordem. Mesmo não havendo muita variação no tempo de degradação o gráfico de ln[C(t)/C(0)] vs. tempo, mostra que o processo mais vantajoso é aquele catalisado com UV/Fenton, com uma constante de redução do COT uma ordem de grandeza maior do que para o processo apenas com incidência de radiação UV. Os valores foram, respectivamente, 9,4x10-5 s-1 e 1,75x10-4 s / Abstract: In this work, the performance of the H2O2 electrogeneration process from O2 reduction on a reticulated vitreous carbon cathode was investigated. The process was also use for the oxidation of the herbicide 2,4-dichlorophenoxyacetic acid. Firstly, cyclic voltammetries were used for the identification of possible reduction reactions of the herbicide. The supporting electrolyte used was a 0,3 mol L-1 K2SO4, pH 10, nitrogen saturated solution. Then, the optimization of hydrogen peroxide electrogeneration it was carried out. As a cathode, a reticulated vitreous carbon-rotating cylinder, shaped from a 60 ppi RCV plate was used. A platinum foil was used as anode and a saturated calomel electrode was used as reference. Supporting electrolyte was always K2SO4 0,3 mol L-1, in an O2 saturated solution. The experiments were run in a 150 mL electrode cell, with a water jacket to keeping temperature in the range from 8 0C. The best potential to produce hydrogen peroxide in these conditions was -1,6 V vs. SCE. In following stage, the degradation of 2,4-D was investigated by tree different process: H2O2 electrogenerated, H2O2/UV and photo electro-Fenton being the last at pH 2,5. The degradation of 2,4-D was followed by HPLC, moreover TOC and COD analyses. The most efficient process was the catalyzed UV/Fe2+ process that presented a TOC reduction of 69 %. In a sequence, a pilot scale reactor was mounted for hydrogen peroxide electrogeneration. The reactor is formed by two anolytes and one catholyte compartments, separated by a N424 Nafion® membrane. The reactor was optimized considering three different parameters: the applied potential, oxygen flow and the electrolyte flow. Best operational parameters electrogeneration rate of hydrogen peroxide in a K2SO4 0,3 mol L-1 electrolyte support were: -1,6 V vs. Pt, 500 L h-1 of electrolyte flow and 6 L s-1 of oxygen flow. Considering these results, the experiments for the degradation of 2,4-D were conducted with the optimized reactor. In this new series of experiments, six different processes were tested. In alkaline medium, the degradation occurred only with H2O2 and H2O2, catalyzed by UV radiation. Four processes were used in acidic medium: H2O2, H2O2 catalyzed by UV radiation, Fe2+ (electro Fenton process) and H2O2 with Fe2+ catalyzed by UV radiation (photo-electro Fenton process). In catalyzed experiments in acidic medium, degradation rates were higher TOC decay presented a pseudo-first order kinetic. The differences between electro Fenton and photo-electro Fenton processes appeared only when TOC reduction was considered. A greater degree of organics combustion was observed for the last process, with 95 % of TOC was eliminated. / Mestrado / Engenharia de Materiais / Mestre em Engenharia Mecânica

The teratogenic potential of commercial formulations of atrazine (40.8%) and 2,4-D was evaluated using FETAX (frog embryo teratogenic assay--Xenopus). Because these herbicides have been detected in ground and surface water, this study was designed to determine the adverse effects in buffer and natural water for both herbicides. All treatments showed a significant concentration-response effect on exposed embryos, except for the 2,4-D natural water sample. Atrazine (solubility of the commercial formula used 70 mg/L at 20 degrees C), compared to 2,4-D (solubility = 311 mg/L at pH = 1 and 25 degrees C), had a significantly greater teratogenic effect in both the buffer (atrazine EC50 = 33 mg/L, LC50 = 100 mg/L, TI = 3.03; 2,4-D EC50 = 245 mg/L, LC50 = 254 mg/L, TI = 1.04) and natural water samples (atrazine EC50 < 8 mg/L, LC50 = 126 mg/L; 2,4-D EC50 and LC50 > 270 mg/L). The 2,4-D EC50 and LC50 values for the buffer were similar at 245 mg/L and 254 mg/L. These similar values and the teratogenic index (TI) of 1.04 suggested that 2,4-D was more embryotoxic than teratogenic to frog embryos at high concentrations. Atrazine in natural water demonstrated a significantly greater EC50 (100% abnormality at 8 mg/L, the lowest test concentration) to frog embryos than the buffer experiment (EC50 = 33 mg/L). The extrapolated lowest observable adverse effect concentration (LOAEC) for the natural water experiment was 1.1 mg/L. These results suggest that atrazine toxicity is enhanced by the synergistic or additive effects of some component of the water or atrazine was already present in the sample. In contrast to atrazine, 2,4-D was less toxic in natural water than buffer. These results suggest that both atrazine and 2,4-D pose little threat, since their embryotoxicity and teratogenicity to frog embryos occur at high concentrations approaching their maximum solubility levels in water.

Uncertainty is pervasive in risk assessment. In ecotoxicological risk assessments, it arises from such sources as a lack of data, the simplification and abstraction of complex situations, and ambiguities in assessment endpoints (Burgman 2005; Suter 1993). When evaluating and managing risks, uncertainty needs to be explicitly considered in order to avoid erroneous decisions and to be able to make statements about the confidence that we can place in risk estimates. Although informative, previous approaches to dealing with uncertainty in ecotoxicological modelling have been found to be limited, inconsistent and often based on assumptions that may be false (Ferson & Ginzburg 1996; Suter 1998; Suter et al. 2002; van der Hoeven 2004; van Straalen 2002a; Verdonck et al. 2003a). In this thesis a Generalised Linear Modelling approach is proposed as an alternative, congruous framework for the analysis and prediction of a wide range of ecotoxicological effects. This approach was used to investigate the results of toxicity experiments on the effect of 2,4-Dichlorophenoxyacetic Acid (2,4-D) formulations and 4-Chlorophenol (4-CP, an associated breakdown product) on Daphnia carinata. Differences between frequentist Maximum Likelihood (ML) and Bayesian Markov-Chain Monte-Carlo (MCMC) approaches to statistical reasoning and model estimation were also investigated. These approaches are inferentially disparate and place different emphasis on aleatory and epistemic uncertainty (O'Hagan 2004). Bayesian MCMC and Probability Bounds Analysis methods for propagating uncertainty in risk models are also compared for the first time. For simple models, Bayesian and frequentist approaches to Generalised Linear Model (GLM) estimation were found to produce very similar results when non-informative prior distributions were used for the Bayesian models. Potency estimates and regression parameters were found to be similar for identical models, signifying that Bayesian MCMC techniques are at least a suitable and objective replacement for frequentist ML for the analysis of exposureresponse data. Applications of these techniques demonstrated that Amicide formulations of 2,4-D are more toxic to Daphnia than their unformulated, Technical Acid parent. Different results were obtained from Bayesian MCMC and ML methods when more complex models and data structures were considered. In the analysis of 4-CP toxicity, the treatment of 2 different factors as fixed or random in standard and Mixed-Effect models was found to affect variance estimates to the degree that different conclusions would be drawn from the same model, fit to the same data. Associated discrepancies in the treatment of overdispersion between ML and Bayesian MCMC analyses were also found to affect results. Bayesian MCMC techniques were found to be superior to the ML ones employed for the analysis of complex models because they enabled the correct formulation of hierarchical (nested) datastructures within a binomial logistic GLM. Application of these techniques to the analysis of results from 4-CP toxicity testing on two strains of Daphnia carinata found that between-experiment variability was greater than that within-experiments or between-strains. Perhaps surprisingly, this indicated that long-term laboratory culture had not significantly affected the sensitivity of one strain when compared to cultures of another strain that had recently been established from field populations. The results from this analysis highlighted the need for repetition of experiments, proper model formulation in complex analyses and careful consideration of the effects of pooling data on characterising variability and uncertainty. The GLM framework was used to develop three dimensional surface models of the effects of different length pulse exposures, and subsequent delayed toxicity, of 4-CP on Daphnia. These models described the relationship between exposure duration and intensity (concentration) on toxicity, and were constructed for both pulse and delayed effects. Statistical analysis of these models found that significant delayed effects occurred following the full range of pulse exposure durations, and that both exposure duration and intensity interacted significantly and concurrently with the delayed effect. These results indicated that failure to consider delayed toxicity could lead to significant underestimation of the effects of pulse exposure, and therefore increase uncertainty in risk assessments. A number of new approaches to modelling ecotoxicological risk and to propagating uncertainty were also developed and applied in this thesis. In the first of these, a method for describing and propagating uncertainty in conventional Species Sensitivity Distribution (SSD) models was described. This utilised Probability Bounds Analysis to construct a nonparametric 'probability box' on an SSD based on EC05 estimates and their confidence intervals. Predictions from this uncertain SSD and the confidence interval extrapolation methods described by Aldenberg and colleagues (2000; 2002a) were compared. It was found that the extrapolation techniques underestimated the width of uncertainty (confidence) intervals by 63% and the upper bound by 65%, when compared to the Probability Bounds (P3 Bounds) approach, which was based on actual confidence estimates derived from the original data. An alternative approach to formulating ecotoxicological risk modelling was also proposed and was based on a Binomial GLM. In this formulation, the model is first fit to the available data in order to derive mean and uncertainty estimates for the parameters. This 'uncertain' GLM model is then used to predict the risk of effect from possible or observed exposure distributions. This risk is described as a whole distribution, with a central tendency and uncertainty bounds derived from the original data and the exposure distribution (if this is also 'uncertain'). Bayesian and P-Bounds approaches to propagating uncertainty in this model were compared using an example of the risk of exposure to a hypothetical (uncertain) distribution of 4-CP for the two Daphnia strains studied. This comparison found that the Bayesian and P-Bounds approaches produced very similar mean and uncertainty estimates, with the P-bounds intervals always being wider than the Bayesian ones. This difference is due to the different methods for dealing with dependencies between model parameters by the two approaches, and is confirmation that the P-bounds approach is better suited to situations where data and knowledge are scarce. The advantages of the Bayesian risk assessment and uncertainty propagation method developed are that it allows calculation of the likelihood of any effect occurring, not just the (probability)bounds, and that the same software (WinBugs) and model construction may be used to fit regression models and predict risks simultaneously. The GLM risk modelling approaches developed here are able to explain a wide range of response shapes (including hormesis) and underlying (non-normal) distributions, and do not involve expression of the exposure-response as a probability distribution, hence solving a number of problems found with previous formulations of ecotoxicological risk. The approaches developed can also be easily extended to describe communities, include modifying factors, mixed-effects, population growth, carrying capacity and a range of other variables of interest in ecotoxicological risk assessments. While the lack of data on the toxicological effects of chemicals is the most significant source of uncertainty in ecotoxicological risk assessments today, methods such as those described here can assist by quantifying that uncertainty so that it can be communicated to stakeholders and decision makers. As new information becomes available, these techniques can be used to develop more complex models that will help to bridge the gap between the bioassay and the ecosystem.

The ubiquitous presence of anthropogenic chemicals and their transformation products in surface water represents a toxicological concern from both an ecological standpoint and a human perspective as many of these chemicals are capable of altering hormonal function. Endocrine disrupting compounds can be traced back to numerous sources and may fall under the class of pesticide, industrial chemical, pharmaceutical, personal care product, and/or heavy metals. The adrenal gland is the most common target for endocrine disruptors, although in comparison to the sex steroids, this system has received much less attention in published research. Corticosteroids play a pivotal role in many physiological processes, including immunity, cognitive function, growth, metabolism, reproduction, mineral balance, and blood pressure. A primary cell culture of rainbow trout adrenocortical cells was used to investigate the endocrine disrupting activity of two commonly detected water-borne toxicants, a personal care product, triclosan (TCS), a pesticide, dichlorophenoxyacetic acid (2,4-D), and their transformation products, methyl-triclosan (M-TCS) and dichlorophenol (DCP). Previously, it has been shown that TCS, 2,4-D, and DCP exhibit a potential for endocrine disruption, although it is currently unknown if these chemicals are capable of affecting corticosteroid balance. In this study, all four chemicals showed significant inhibitory effects on corticosteroid synthesis, even though there were considerable differences in their activity. The chemical that exhibited the highest toxicity was 2,4-D, followed by TCS, DCP, and M-TCS. Both parent-compounds proved to be more toxic than their degradation products. More research with suitable test systems is needed to determine the mechanism(s) of action of these corticosteroid disruptors and the health risk that they may present. / ix, 139 leaves : ill. ; 29 cm

Aujourd'hui, avec l'augmentation de la population, la consommation de médicaments et de produits phytosanitaires dans l'agriculture a considérablement augmenté. Cela devient inquiétant car une grande partie de ces molécules, rejetée dans l'environnement, ne sont pas bien éliminées par les stations d'épuration (lorsqu'elles existent). En trop grande quantité, ces produits deviennent des poisons pour tous les organismes vivants, y compris l’Homme.Des méthodes analytiques classiques pour la mesure de ces produits chimiques existent déjà (méthodes séparatives classiques telles que la chromatographie en phase gazeuse, la chromatographie liquide à haute performance, éventuellement couplée à la spectrométrie de masse, etc.). Cependant, même si elles sont extrêmement précises et fiables, ces techniques sont difficiles à appliquer pour la surveillance sur site et sont généralement coûteuses. Pour cette raison, ma thèse se concentre sur de nouvelles approches analytiques pour détecter de petites molécules en milieu aqueux, telles que ces polluants. Dans une première partie de mon travail, j’ai développé un immunocapteur basé sur une complexation compétitive originale et sur une transduction électrochimique (ampérométrique), pour la détection du diclofénac, un anti - inflammatoire non stéroïdien généralement utilisé pour réduire l’inflammation et soulager la douleur. L'électrode de travail a été fonctionnalisée par deux sels de diazonium, l'un utilisé comme sonde moléculaire (un dérivé du diclofénac couplé à une arylamine) et l'autre comme sonde redox (une quinone) également couplée à une arylamine, capable de transduire l'association haptène-anticorps par une variation de son électroactivité ; en particulier, la transduction a été conçue pour délivrer une augmentation de courant lors de la détection du diclofénac (soit une détection « signal-on »). J’ai montré une limite de détection d’environ 20 fM dans l'eau du robinet, ce qui rend ce type de capteur très compétitif. Dans la suite de mon travail, j'ai conservé la même approche de transduction originale (immunoreconnaissance compétitive) mais appliquée à un transistor à effet de champ organique à grille électrolytique (EGOFET) dont le semiconducteur est le poly (N-alkyldiketopyrrolo-pyrrole dithiénylthiéno [3,2-b ] thiophène) (DPP-DTT) et dont l'électrode de grille a été fonctionnalisée par électrogreffage d'un sel de diazonium fonctionnel capable de lier un anticorps spécifique de l'acide 2,4-dichlorophénoxyacétique (2,4-D), un herbicide courant. Le design de la sonde moléculaire a été rationalisée par modélisation moléculaire afin d’optimiser la capture de l’anticorps en surface de grille. Dans la dernière partie de mon travail, je propose une approche qui met à profit à la fois le couplage capacitif de l'EGOFET mais aussi sa sensibilité aux charges électrostatiques accumulées en surface de grille. J'ai immobilisé en surface de grille un peptide court (Gly-Gly-His) connu pur avoir une forte affinité envers les ions cuivre Cu2+. Le peptide a été immobilisé par électro-oxydation directe de l'amine primaire du premier fragment glycine. J’ai démontré que les dispositifs EGOFET, modifiés par GGH, peuvent transduire la complexation de Cu2+ par des variations significatives de leurs caractéristiques de sortie et de transfert, en particulier par un décalage de la tension de seuil (VTh). / Today, with the increase of population, the consumption of drugs and of chemicals in agriculture has dramatically increased. It becomes a worrisome issue because a large amount of these molecules, excreted to the environment, are not well eliminated by water-treatment plants (when they exist) and are therefore released without control into the ecosystem. In too large quantities, these drugs are poisons for living organisms, including humans. Classical analytical methods for the measurement of these chemicals already exist (classical separative methods such as gas chromatography, high-performance liquid chromatography, possibly coupled with mass spectrometry, etc). However, even if extremely precise and reliable, these techniques are difficult to apply for on-site monitoring and are usually costly. For this reason, my thesis focuses on novel analytical approaches to detect small organic molecules such as these pollutants. In a first part of my work, I developped an original immunosensor based on a competitive complexation and on an electrochemical (amperometric) transduction, for detection of diclofenac, which is a non – steroidal anti – inflammatory drug generally employed to protect patients from inflammation and relieve pain. The working electrode was electrografted with two functional diazonium salts, one as molecular probe (a diclofenac derivative coupled with an arylamine) and the other as redox probe (a quinone) also coupled with an arylamine, able to transduce the hapten-antibody association into a change in electroactivity. The transduction was designed to deliver a current increase upon detection of diclofenac (“signal-on” detection). The detection limit is ca. 20 fM in tap water, which is competitive compared to other label-free immunosensors. In the following part of my thesis, I kept the same original transduction approach (competitive immunoassay) but applied to an Electrolyte-Gated Organic Field-Effect Transistor (EGOFET) based on poly(N-alkyldiketopyrrolo-pyrrole dithienylthieno[3,2-b]thiophene) as organic semiconductor whose gate electrode was functionalized by electrografting a functional diazonium salt capable to bind an antibody specific to 2,4-dichlorophenoxyacetic acid (2,4-D), an herbicide well-known to be a soil and water pollutant. Molecular docking computations were performed to design the functional diazonium salt to rationalize the antibody capture on the gate surface. In the last part of my work, I propose an approach which takes profit not only of the capacitive coupling of the EGOFET but also on its sensitivity to electrostatic charges accumulated on the gate surface. To illustrate this in the field of sensors, I used a short peptide (Gly-Gly-His), known to selectively bind copper ions Cu2+. The peptide was immobilized by direct electrooxidation of the primary amine of the first glycine moiety. I demonstrated that GGH-modified EGOFETs can transduce Cu2+ complexation through significant changes of their output and transfer characteristics, in particular their threshold voltage (VTh).