The thesis presents the evaluation of polysulfone sorbents for solid phase extraction (SPE) and the development of colorimetric probes for pesticides analysis in water. Through electrospraying and electrospinning techniques, different morphologies of sorbents (particles, beaded fibers and bead-free fibers) were fabricated. The sorbents were morphologically characterized by scanning electron microscopy. Adsorption capacities of sorbents were evaluated by conducting recoveries studies for model pesticides; atrazine, chlorpyrifos and DDT using batch and column SPE modes. Better recovery results were achieved by employing the batch mode of fibers, as values ranged from 98 to 105percent. Further sorbent evaluation was conducted using breakthrough experiments and static experiments. The breakthrough studies indicated that 1700 μL was the sample volume that could be percolated with no breakthrough of the analyte that correspond to a concentration of 150 mg/g of sorbent that can be extracted without any loss of analyte. From static studies, quantities of each model compound adsorbed into the fiber at the equilibrium time were evaluated. The adsorbed atrazine was 65, chlorpyrifos 250 and DDT 400 mg/g of sorbent. Kinetic studies suggested retention mechanism following pseudo first and second order model observed by high correlation coefficients (> 0. 96), demonstrating the fiber affinity to retain both polar and non-polar compounds opening a possibility to be used as sorbent for sample preparation of different classes of pesticides in water. For the second part of the study simple strategies for colorimetric sensing based on silver nanoparticles and polivinylpyrrolidone capped nanoparticles were developed, respectively for atrazine and chlorpyrifos detection. The limits of detection of the methods were 3.32 and 0.88 mg/L for atrazine and chlorpyrifos respectively. The applicability of the probe in real samples was demonstrated by the recoveries studies of tap water varying from 94 to 104 percent. The versatility of the probe was demonstrated by affording a simple, rapid and selective detection of atrazine and chlorpyrifos in the presence of other pesticides by direct analysis without employing any sample handling steps. Attempt to incorporate the probes in a solid support was achieved by using nylon 6 as solid support polymer proving to be fast and useful for on-site detection.

[Truncated abstract] Pesticides are often transported to streams and/or groundwater as a result of the occurrence of rainfall events which trigger surface runoff or rapid preferential flow through the unsaturated zone. Much of the theory of solute transport has been derived assuming steady state or slowly varying upper boundary conditions and continuous, averaged process descriptions. However, a review of pesticide dynamics reveals that pesticides are episodically transported, predominantly through discrete flow pathways and this transport is often initiated as a near surface process, driven by naturally variable and intermittent rainfall intensities. The objective of the thesis is to better understand how the structure of natural variability of rainfall intensities impacts upon pesticide transport by these fast flow processes. We first conducted an analysis of a lysimeter leaching experiment that was aimed at identifying the rainfall controls on herbicide transport. Multivariate analyses revealed that average water balance behaviour at low temporal resolution controlled water and bromide transport while extreme rainfall events and rainfall event frequency controlled herbicide transport. A minimalist event based modelling approach was able to simulate the observed herbicide transport without or with only minor calibration. ... Finally we conduct a climate based regional risk assessment of pesticide leaching for the Wheatbelt region of the south-west of Western Australia. This is done for a suite of pesticides on a single soil to evaluate the impact of rainfall variability alone. Moderately sorbing, slowly degrading solutes have a greater regional potential for rapid leaching than both strongly and weakly sorbing solutes. High leaching potentials are found along the western and southern coast and in the far-east, with a band of low leaching potential through the central Wheatbelt. This is despite higher annual rainfall in the central areas compared to the east, and it is found that this occurs because of a change in the dominant fast flow triggers from frequent low intensity rainfall on the coasts to high intensity infrequent storms in the east. The coefficient of variation of annual leaching loads is similarly distributed. Spatial patterns of leaching potential depend upon chemical properties and application time. Peak loads of chemicals to fast flow pathways are found to converge to mid-winter, indicating periods of high loads of multiple pesticides may be an unavoidable consequence of the seasonality of storm properties.

Capes / O presente estudo objetivou a determinação de pesticidas organoclorados (OCP, do inglês Organochlorine Pesticides) em águas superficiais do rio Taquara por meio da otimização da técnica de extração USAEME (do inglês Ultrasound - Assisted Emulsification Microextraction) e análise por Cromatografia Gasosa Acoplada à Espectrometria de Massas (CG-EM). A extração foi otimizada para determinação 16 pesticidas organoclorados simultaneamente (α-BHC, γ-BHC, β-HC, δ-BHC, heptacloro, aldrin, heptacloro epóxido, γ-clordano, endosulfan I, α-clordano, 4,4’-DDE, dieldrin, endrin, endosulfan II, 4,4’-DDD, endrin aldeído, endosulfan sulfato, 4,4’-DDT, endrin cetona e metoxicloro). Para isso, foi proposto um planejamento experimental do tipo DCCR (Delineamento Composto Central Rotacional), no qual foram avaliados os seguintes fatores: volume de solvente extrator (clorofórmio), tempo de agitação manual e tempo de exposição ao ultrassom, no total de 20 ensaios. Dentre as variáveis, o volume de clorofórmio foi o mais significativo para todos os 16 pesticidas, principalmente pelo fato que seu volume influencia diretamente o fator diluição do extrato, sendo o valor ótimo de 122 µL. Para a agitação manual, tempos maiores que 1 segundo, não se apresentaram significativos para o processo de extração. Na etapa do ultrassom, tempos maiores que 14 minutos influenciaram negativamente para a extração, principalmente devido à elevação da temperatura do sistema. O aumento da temperatura acabava provocando uma maior solubilização do clorofórmio na fase aquosa, com isso diminuindo a eficiência da extração. Já o percentual de recuperação, realizada a partir de amostras reais com adição de padrão em três níveis (0,5, 1,0 e 2,0 µg L-1), variaram entre 65,35 a 127,14%, valores considerados adequados por se tratarem de análises ambientais. Os valores dos limites de detecção, LOD (Limit of Detection) e de quantificação, LOQ (Limit of Quantification) variaram de 0,13 à 0,50 e 0,39 à 1,52 µg L-1 respectivamente. Quanto a presença dos OCP nas águas superficiais, verificou-se a presença da série do endosulfan em 78% dos pontos amostrados. Foi apontado a presença do DDT e seus metabólitos DDD e metoxicloro exclusivamente no ponto 3, e nas coletas de maio, junho e novembro apenas. Fatos que reforçam o rótulo de poluentes persistentes, principalmente em relação ao DDT, que mesmo após décadas da sua proibição, ainda são encontrados no ambiente. / The main goal of this study was to determine organochlorine pesticides (OCP) concentrations from Taquara River using optimized USAEME extraction technique ((Ultrasound - Assisted Emulsification Microextraction) and analysis by GC-MS (Gas Chromatography-MassSpectrometry). The extraction process was optimized on the determination of 16 organochlorine pesticides simultaneously (α-BHC, γ-BHC, β-HC, δ-BHC, heptacloro, aldrin, heptacloro epóxido, γ-clordano, endosulfan I, α-clordano, 4,4’-DDE, dieldrin, endrin, endosulfan II, 4,4’-DDD, endrin aldeído, endosulfan sulfato, 4,4’-DDT, endrin cetona e metoxicloro). Therefore, the influence a DCCR design (Delineation Central Composite Rotational) with 20 experiments was proposed, in which the following factors were evaluated: extractor solvent volume (chloroform), manual agitation time and time of ultrasound exposure. Among the factors, solvent volume was the most significant parameter to all 20 pesticides, mainly for the fact that its volume influenced directly the extract dilution factor, with the optimum value 122 µL. For manual agitation, time superior to 1 second were not significant to enhance extraction. For ultrasound assisted phase, time superior to 14 minutes negatively influenced the extraction due to elevation on system temperature. Higher temperatures promote higher solubilization of chloroform in the aqueous phase, diminishing extraction efficiency. Percentage of recovery of the compounds in real samples fortified in three different levels (0.5, 1.0 and 2.0 µg L 1) varied from 65,35 to 127,14%, which can be considered adequate for environmental analysis. Limit of Detection (LOD) and Limit of Quantification (LOQ) varied from 0.13 to 0.50 and 0.39 to 1.52 µg L-1, respectively. As for the presence of the OCP in real samples, it was detected the endosulfan family in 78% of the samples. DDT and its metabolites, DDD and metoxiclor, were found, exclusively on site 3, and for May, June and November samples only. Those facts reinforce that even after decades of the prohibition of use of these pesticides, mostly for DDT, they are still found in the environment.

Capes / O presente estudo objetivou a determinação de pesticidas organoclorados (OCP, do inglês Organochlorine Pesticides) em águas superficiais do rio Taquara por meio da otimização da técnica de extração USAEME (do inglês Ultrasound - Assisted Emulsification Microextraction) e análise por Cromatografia Gasosa Acoplada à Espectrometria de Massas (CG-EM). A extração foi otimizada para determinação 16 pesticidas organoclorados simultaneamente (α-BHC, γ-BHC, β-HC, δ-BHC, heptacloro, aldrin, heptacloro epóxido, γ-clordano, endosulfan I, α-clordano, 4,4’-DDE, dieldrin, endrin, endosulfan II, 4,4’-DDD, endrin aldeído, endosulfan sulfato, 4,4’-DDT, endrin cetona e metoxicloro). Para isso, foi proposto um planejamento experimental do tipo DCCR (Delineamento Composto Central Rotacional), no qual foram avaliados os seguintes fatores: volume de solvente extrator (clorofórmio), tempo de agitação manual e tempo de exposição ao ultrassom, no total de 20 ensaios. Dentre as variáveis, o volume de clorofórmio foi o mais significativo para todos os 16 pesticidas, principalmente pelo fato que seu volume influencia diretamente o fator diluição do extrato, sendo o valor ótimo de 122 µL. Para a agitação manual, tempos maiores que 1 segundo, não se apresentaram significativos para o processo de extração. Na etapa do ultrassom, tempos maiores que 14 minutos influenciaram negativamente para a extração, principalmente devido à elevação da temperatura do sistema. O aumento da temperatura acabava provocando uma maior solubilização do clorofórmio na fase aquosa, com isso diminuindo a eficiência da extração. Já o percentual de recuperação, realizada a partir de amostras reais com adição de padrão em três níveis (0,5, 1,0 e 2,0 µg L-1), variaram entre 65,35 a 127,14%, valores considerados adequados por se tratarem de análises ambientais. Os valores dos limites de detecção, LOD (Limit of Detection) e de quantificação, LOQ (Limit of Quantification) variaram de 0,13 à 0,50 e 0,39 à 1,52 µg L-1 respectivamente. Quanto a presença dos OCP nas águas superficiais, verificou-se a presença da série do endosulfan em 78% dos pontos amostrados. Foi apontado a presença do DDT e seus metabólitos DDD e metoxicloro exclusivamente no ponto 3, e nas coletas de maio, junho e novembro apenas. Fatos que reforçam o rótulo de poluentes persistentes, principalmente em relação ao DDT, que mesmo após décadas da sua proibição, ainda são encontrados no ambiente. / The main goal of this study was to determine organochlorine pesticides (OCP) concentrations from Taquara River using optimized USAEME extraction technique ((Ultrasound - Assisted Emulsification Microextraction) and analysis by GC-MS (Gas Chromatography-MassSpectrometry). The extraction process was optimized on the determination of 16 organochlorine pesticides simultaneously (α-BHC, γ-BHC, β-HC, δ-BHC, heptacloro, aldrin, heptacloro epóxido, γ-clordano, endosulfan I, α-clordano, 4,4’-DDE, dieldrin, endrin, endosulfan II, 4,4’-DDD, endrin aldeído, endosulfan sulfato, 4,4’-DDT, endrin cetona e metoxicloro). Therefore, the influence a DCCR design (Delineation Central Composite Rotational) with 20 experiments was proposed, in which the following factors were evaluated: extractor solvent volume (chloroform), manual agitation time and time of ultrasound exposure. Among the factors, solvent volume was the most significant parameter to all 20 pesticides, mainly for the fact that its volume influenced directly the extract dilution factor, with the optimum value 122 µL. For manual agitation, time superior to 1 second were not significant to enhance extraction. For ultrasound assisted phase, time superior to 14 minutes negatively influenced the extraction due to elevation on system temperature. Higher temperatures promote higher solubilization of chloroform in the aqueous phase, diminishing extraction efficiency. Percentage of recovery of the compounds in real samples fortified in three different levels (0.5, 1.0 and 2.0 µg L 1) varied from 65,35 to 127,14%, which can be considered adequate for environmental analysis. Limit of Detection (LOD) and Limit of Quantification (LOQ) varied from 0.13 to 0.50 and 0.39 to 1.52 µg L-1, respectively. As for the presence of the OCP in real samples, it was detected the endosulfan family in 78% of the samples. DDT and its metabolites, DDD and metoxiclor, were found, exclusively on site 3, and for May, June and November samples only. Those facts reinforce that even after decades of the prohibition of use of these pesticides, mostly for DDT, they are still found in the environment.

Stream samples were tested at 18 sites in three subwatersheds of the Upper White River for ammonia, nitrate, orthophosphate, atrazine, and diazinon. Nutrient results were tested with a general linear model and in linear regressions with selected landuse characteristics. A critical areas index for surface runoff of pollutants was created using a geographic information system. Comparisons were made between results obtained by Ball State University and by the Muncie Bureau of Water Quality and other outside laboratories. Most mean concentrations of nutrients were likely related to combinations of agricultural and residential landuse factors. Only concentrations of ammonia and orthophosphate were significantly related (a = 0.05) to any landuse characteristics. Atrazine levels were high in the spring, but decreased in the fall. Results suggest that improved or increased best management practices should be implemented in these subwatersheds to control non-point source pollution of the streams. / Department of Natural Resources and Environmental Management

The increased use of pesticides has resulted in a corresponding increase in concern for the effect they may have on the health of humans and other non-target organisms. The two main areas of concern are the toxicological effects that mixtures of pesticides may have as well as the endocrine disrupting effects. Although the individual pesticides may be present at concentrations below the levels deemed to be detrimental to health, it has been argued that their combined effect may still result in elevated health risks. Another important aspect of pesticide risk assessment requires a consideration of the breakdown products of pesticides and their effect on human health. There has been very little research into the effects of degradation products and this issue should be addressed as these could potentially pose a higher risk than their parent compounds. One of the most important bio-markers available for use is the ubiquitous enzyme acetylcholinesterase (AChE). This enzyme is responsible for one of the most important functions in the body; namely nerve impulse transmission, upon which all life depends. The inhibition of this enzyme indicates toxicity and as a subsequence, a threat to the organism’s well-being. Bioassays have also recently been developed to test chemicals for endocrine disrupting effects. These tests rely on a dose response equivalent to that of the most potent well known estrogen 17-β estradiol. Any chemical that has a measurable response is deemed to display endocrine disrupting effects. This first aim of this study was to investigate the toxicological and endocrine disrupting effects of three organophosphorus pesticides; aldicarb, parathion and demeton-S-methyl, in addition to two breakdown products; aminophenol and p-nitrophenol. Two carbamate pesticides; carbaryl and carbofuran were also analysed. The toxicological effects of mixtures of the parent pesticide compounds were tested to assess if any antagonistic, additive or synergistic effects were observed. This data was then used in conjunction with an artificial neural network to assess if individual pesticides could be distinguished from mixtures of pesticides. A final objective was to sample various Eastern Cape water sources, utilising the enzymatic assay to determine the presence of any of these pesticides in these samples. There were several conclusions drawn from this study. AChE was successfully used as an assay to test the toxicity of the pesticides under investigation, based on their inhibition of this enzyme. An important factor for consideration throughout the study was the need to establish basal and monitor AChE activity (i.e. the need to monitor AChE activity in the absence of any pesticide). This ensured accurate comparison of the results obtained. It was found that demeton-S-methyl was the most potent of these pesticides followed by carbaryl, parathion, aldicarb and finally carbofuran, and that carbofuran could potentiate AChE. The results indicated that pesticide mixtures generally exhibited an additive inhibitory effect on AChE, although at some concentrations of pesticides, synergistic and antagonistic effects were noted. From the data using mixtures of pesticides, a feed forward neural network was created that was successfully able to distinguish individual pesticides from mixtures within its training parameters. None of the pesticides tested displayed endocrine disrupting properties in the Yeast Estrogen Screen (YES), T47D-KBluc and MDA-kb2 bio-assays. Other studies reported mixed results in this regard and thus no final conclusions could be drawn. The Blaauwkrantz River, Kariega River, Sundays River, Swartkops River and Kowie River were all tested for pesticides and although positive results were recorded, conventional methods indicated that there were no pesticides in the rivers. There were, however, trace metals present which are known to inhibit AChE, thus causing a false positive result. These results indicated that AChE can be used as a high throughput initial pre-screening tool, but that it cannot serve as a substitute for more accurate conventional testing methods.

This thesis presents an evaluation of the dispersive solid-phase extraction (d-SPE) method referred to as the quick, easy, cheap, effective, rugged and safe (QuEChERS) method for the determination of four organochlorine pesticide residues in fish samples. The pesticides investigated in this study were o, p′-DDT, p, p′-DDE, aldrin and dieldrin. The combined use of Gas Chromatography with an Electron Capture Detector (GC-ECD) and sensitive Time of Flight (TOF) mass detector facilitated the identification of the target analytes. In the absence of certified reference material, the overall analytical procedure was validated by systematic recovery experiments on spiked samples at three levels of 2, 5 and 10 ng/g. The targeted compounds were successfully extracted and their recovery ranged from 76 to 96% with relative standard deviations of less than 13%. The optimum QuEChERS conditions were 2g of fish powder, 10 ml acetonitrile and 1 min shaking time. The optimal conditions were applied to assess the levels of chlorinated pesticides in blunt-tooth catfish (Clarias ngamensis), tigerfish (Hydrocynus vittatus), Oreochromis andersonii and red-breasted tilapia (Tilapia rendalli) from the Okavango Delta, Botswana. Dieldrin, p, p′-DDE and aldrin were detected in all the analysed samples with a concentration range of 0.04 – 0.29, 0.07 – 0.33, 0.04 – 0.28 and 0.03 – 0.24 ng/g per dry weight in O. andersonii, C. ngamensis, T. rendalli and H. vittatus respectively. These concentrations were below the US-EPA 0.1 μg/g allowable limit in edible fish and the Australian Maximum Residue Limit (MRL) of 50 - 1000 ng/g in fresh fish. DDT was not detected in all the fish species investigated. The mean lipid content recorded in the fish samples were 1.24, 2.16, 2.18 and 4.21% for H. vittatus, T. rendalli, O. andersonni and C. ngamensis respectively. No systematic trend was observed between fish age and pesticide levels in fish. Acetylcholinesterase (AChE) activity assays were performed to assess the effects of organochlorine pesticides in Clarias ngamensis. The enzyme activity recorded in Clarias ngamensis from the Okavango Delta and the reference site was 12.31 μmol of acetylcholine iodide hydrolysed/min/g brain tissue. The enzyme activity remained the same indicating no enzyme inhibition. The conclusions drawn from this study are that the QuEChERS method is applicable for the determination of organochlorine pesticide residues in fish matrices. The fish from the Okavango Delta are safe for human consumption.