Chemical synthesis is not complete without waste treatment. There is no chemical process that does not produce waste. The untreated effluent discharged by chemical industries poses a major environmental concern. This dissertation describes the results of an investigation carried out on the formation of by-products (impurities) during the synthesis of atrazine by neutralization of the reaction mixture during the actual synthesis procedure, and prior to disposal using carbon dioxide or hydrochloric acid. The main objectives for the said investigation were: {u100083} To optimise the reaction parameters to obtain a higher yield and purity of atrazine. {u100083} To evaluate the use of carbon dioxide and hydrochloric acid to neutralise the reaction mixture. {u100083} To study the solids present in the effluent. Synthetic reactions were carried out in the presence of an organic solvent, methyl isobutyl ketone (MIBK). The synthesis of atrazine was optimised in terms of addition sequence and rates of amine reagents and base (proton acceptor) additions by means of bench scale reactions. It was found that addition of a neutralising step (hydrochloric acid or carbon dioxide) to neutralise the basic reaction mixture prior to and after addition of the secondary amine and the base minimizes the formation of by-products. Of particular importance in ensuring high yields and selectivity to the atrazine product was temperature control, pH control, reagent ratios, addition rates and mixing. The latter was important in view of the rapid reaction of amine/NaOH with cyanuric chloride, as well as the possible reaction of mono-i, the reaction intermediate, with IPA in cases of excesses of reagent. Under optimum conditions, an atrazine composition of >97% was achieved where the resultant product was well within stipulated product specifications.

Bioremediation was studied in soils containing high concentrations of formulated chlorpyrifos (5 mg kg-1 Dursban® 4E) and atrazine (5 mg kg-1 AAtrex® 4L) using amendments including lignocellulosic sorbents, microbial nutrients (vegetable oil, corn meal and fertilizers), and microbial extracts from organic media previously exposed to these pesticides (chlorpyrifos and atrazine, respectively). Radiolabeled atrazine was used to examine the various dissipation routes in contaminated soil, also amended with lignocellulosic sorbents and microbial nutrients. Both chlorpyrifos and atrazine dissipation from contaminated soils was enhanced by organic-based material amendments. The half-lives of chlorpyrifos based on extractability for soils unamended and amended with vegetable oil and peat moss were 87 and 52 days, respectively. The half-lives of atrazine in unamended and amended soil (vegetable oil, peat moss and fertilizers) were 175 and 40 days, respectively. The leachability of chlorpyrifos from contaminated soil was dramatically reduced by 82% during the first 30 days of incubation in treatments amended with vegetable oil and peat moss while only a 28% of reduction in leachability occurred in the corresponding unamended controls. Only a slight reduction of atrazine leachability was detected in amended treatments after 120 days of incubation. Differences were found in the leachability of chlorpyrifos and atrazine when they were applied to soil either as technical grade or formulated material. The presence of surfactants and other adjuvants in formulated chlorpyrifos (Dursban® 4E) reduced chlorpyrifos leachability in contaminated soil. Chlorpyrifos leachability was reduced by 43% in the formulated chlorpyrifos treatments, whereas there was a negligible decrease in technical chlorpyrifos treated soil during the first 3 days after contamination. Atrazine extractability and leachability was not affected by its formulation (AAtrex® 4L). Amendments with lignocellulosic sorbents and nutrients decreased atrazine®s volatility from contaminated soils. After 16 weeks of incubation, less than 1% of 14C-atrazine was volatilized from incubated soils. Overall, after 16 weeks of incubation less than 4% of 14C-atrazine was mineralized and more radioactivity was recovered from amended treatments than unamended treatments as 14CO2. The major portion of radioactivity (62%) was associated with physisorbed atrazine represented by the ethylacetate extract I from unamended treatments while only 28% of initial applied radioactivity was recovered in the corresponding amended treatments. Based on the sum of radioactivity in humic and fulvic acids, approximately 14% of radioactivity was incorporated or chemisorbed atrazine and its metabolites in both unamended and amended treatments. Forty-five percent of the initially applied radioactivity was associated with alkali insoluble fraction in amended treatments but only 17% of the initially applied radioactivity was detected in the corresponding unamended treatments. Less than 2 % of initial activity associated with physisorbed portions of fulvic acids and alkaline insoluble fraction indicated as the radioactivity in methylene chloride and ethylacetate extract II . Over time, more radioactivity was associated with polar atrazine hydroxylated degradation products. / Ph. D.

Amphibian populations are in mass decline on a global scale. Various explanations have been considered, including harmful effects from exposure to toxicants. Using Xenopus laevis adults and tadpoles, potential sublethal effects of atrazine, a herbicide, were investigated in this thesis. I also investigated the toxicity of an organic herbicide compared this with the toxicity of a synthetic herbicide, using LC50 values. Whether X. laevis adult frogs could communicate chemically was tested experimentally. The results suggest that adult female X. laevis communicate chemically, but there was no evidence that male individuals did so. For testing tadpoles I used a kin-preference assay. An encouraging trend for kin preference was evident, for both an outbred and an inbred line. Tadpoles changed their behaviour after exposure to l0μg/L of atrazine for 24 hr. Kin preferences in the control tests were reversed after exposure. A hypothesis of altruistic kin avoidance was suggested by these results. However, when individuals were isolated and then exposed, these individuals had more pronounced preference for kin compared to controls. X. laevis tadpoles exposed to Organic Interceptor (organic herbicide) had a LC50 that was more than 7000 times lower than the 20% recommended dose, whereas Roundup Renews' (a synthetic herbicide) LC50 was around 8 times lower than the 1% recommended dose. This research adds to evidence that toxicants have a negative impact on amphibian populations, and suggests that more research needs to be conducted to identify other sublethal effects of toxicants and to clarify the implications these effects might have for the amphibian populations in nature.

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).

Contaminants in aqueous environments exist in phases that are sorbed to suspended or colloidal material and that are dissolved in solution. Polymer flocculants can be used to remove suspended or colloidal material along with sorbed contaminants, but they remove little of the dissolved contaminants. In the study presented here, development of polymers to sorb contaminants from aqueous solution during the flocculation process was investigated. Atrazine and phosphate (H₂PO₄ ̄) were chosen as test contaminants. For a given test contaminant, multiple copies of a functional group that interacted with that contaminant were inserted into the polymer backbone of a polyacrylamide flocculant. The functional groups inserted into the polymer structure acted as a trap for the dissolved contaminant. The traps were a cyclic secondary amine that interacted with atrazine, and a thiourea that interacted with phosphate. Modified flocculants with different configurations and densities of trapping groups were made and evaluated for removal of the test contaminants from aqueous suspensions. The suspensions consisted of bentonite or kaolinite in water with a known concentration of a test contaminant. The atrazine source was labeled with ¹⁴C and concentrations were measured using a scintillation counter. The source of phosphate used was NaH₂PO₄ and ion chromatography was used to measure the aqueous concentrations of phosphate. In general, the modified polymer flocculants containing trapping groups removed significantly more atrazine and phosphate from suspension compared to the control polymer flocculants ([alpha] =0.05). While the amount of modified polymers needed to achieve significant removal of the test contaminant were higher than the Environmental Protection Agency limit for concentration of polyacrylamide flocculants in water, it was possible to enhance the polymers sorbtion and removal of contaminants from solution during the flocculation process.

Most new fields in chemistry usually began as a curiosity by the researchers, followed by an intrinsic interest in basic biological, physical and chemical properties of reactions, interactions, structural features, and response to external stimuli by chemical elements and/or chemical compounds. If the “curiosity” has appealing bio-physico-chemical properties this trend is followed by studies on the possible applications of such new fields. As a result, is it expected that these curiosities develop or give insights into new technologies. The development of the field of dendrimer chemistry is no different. In fact, dendrimer chemistry illustrates this trend fittingly. The research in this dissertation follows a similar trend. First, the synthesis of a melamine-based dendrimer is achieved. The synthesis illustrates the concept of using triazines as building blocks in dendrimer synthesis. The characterization of this molecule was followed by a basic inquiry of the properties that were unique relative to its composition. This dendrimer is compared against a small library of similar dendrimers in a structure-activity relationship (SAR) study. From the basic concept of an SAR, we moved toward more applied studies of these molecules. The grafting of organic molecules onto inorganic supports has had influences in the fields of catalysis, separations, and sensors. We developed protocols for the grafting of melamine-based molecules onto hydroxyl rich surfaces. After extensive characterization using solution and surface analyses, we tested the sequestration abilities of these new materials toward the separation of molecules of environmental importance from water. Following the data collected in these experiments, we moved toward a different type of applied technology. The use of linear polymers for separations instead of dendrimers is more attractive from an engineering perspective. We then used what was learned from the study of the separations performed by dendrimers and applied it to the design of linear polymers. We take advantage of a latent solid phase response to external stimuli to remove the herbicide atrazine from aqueous solution to the limit of detection.

Thesis (Ph. D.)--University of Washington, 2003. / Vita. Includes bibliographical references (leaves 91-106).

Soil samples were collected from several corn fields with history of atrazine (herbicide) application. Samples were inoculated into Erlenmeyer flasks each containing 50m1 of minimal basal salts medium amended with 100 ppm atrazine as sole nitrogen source. Flasks were shaken at 200 rpm at ambient temperature and were examined daily for one week for microbial growth and/or disappearance of atrazine. Promising consortia were subcultured for further additional enrichments before characterization of potentially active protein (enzyme)fractions. Proteins from cell-free and cellbound fractions were compared for ability to denature atrazine. Following gel permeation chromatography, isolated protein fractions were examined for atrazinefound in the cell-bound fractions capable degrading degradation. Two were found in the cell-free fractions (approx. Mol. wts. 55kDa and 180kDa) and one (55 kDa) atrazine to hydroxyatrazine. Atrazine and its breakdown products (hydroxyatrazine in particular) were detected via HPLC using C18 and C8 columns with absorbance at 229 nm. / Department of Biology

Amphibian populations are in mass decline on a global scale. Various explanations have been considered, including harmful effects from exposure to toxicants. Using Xenopus laevis adults and tadpoles, potential sublethal effects of atrazine, a herbicide, were investigated in this thesis. I also investigated the toxicity of an organic herbicide compared this with the toxicity of a synthetic herbicide, using LC50 values. Whether X. laevis adult frogs could communicate chemically was tested experimentally. The results suggest that adult female X. laevis communicate chemically, but there was no evidence that male individuals did so. For testing tadpoles I used a kin-preference assay. An encouraging trend for kin preference was evident, for both an outbred and an inbred line. Tadpoles changed their behaviour after exposure to l0μg/L of atrazine for 24 hr. Kin preferences in the control tests were reversed after exposure. A hypothesis of altruistic kin avoidance was suggested by these results. However, when individuals were isolated and then exposed, these individuals had more pronounced preference for kin compared to controls. X. laevis tadpoles exposed to Organic Interceptor (organic herbicide) had a LC50 that was more than 7000 times lower than the 20% recommended dose, whereas Roundup Renews' (a synthetic herbicide) LC50 was around 8 times lower than the 1% recommended dose. This research adds to evidence that toxicants have a negative impact on amphibian populations, and suggests that more research needs to be conducted to identify other sublethal effects of toxicants and to clarify the implications these effects might have for the amphibian populations in nature.

Thesis (Ph.D.)-- University of Adelaide, Dept. of Agricultural Biochemisty, 1979.