Global ETD Search

131	Herbicides, Reservoirs, and Daphnia Reproduction: Is There a Cost to Male Production? Stoeckel, James A. 03 August 2007 (has links) No description available. Daphnia parvula atrazine Acton lake reservoir herbicide retention cost of male production timing of sexual reproduction
132	Impact of an atrazine-based herbicide on an agrobiont wolf spider Godfrey, Jake A. 29 September 2017 (has links) No description available. Biology Ecology Toxicology Agricultural Chemicals
133	PHOTOLYTIC DEGRADATION OF ENVIRONMENTALLY IMPORTANT ORGANIC CONTAMINANTS IN NOVEL ROOM TEMPERATURE IONIC LIQUIDS YANG, QIAOLIN 31 March 2004 (has links) No description available. chlorophenols PAHs atrazine environmental ionic liquids photolysis photodegradation UV hydrogen peroxide purification recycling
134	BACTERIAL COMMUNITIES CAPABLE OF ENHANCED EPTC AND ATRAZINE DEGRADATION IN OHIO SILT LOAM AND SILTY CLAY LOAM SOILS Bardhan, Sougata 09 September 2010 (has links) No description available. Agronomy Environmental Science Microbiology Soil Sciences EPTC atrazine enhanced degradation PCR DGGE bacterial community bioremediation
135	Anaerobic degradation of cyanuric acid, cysteine and atrazine by a facultative anaerobic bacterium Jessee, Joel Allen January 1982 (has links) A facultative anaerobic bacterium that rapidly degrades cyanuric acid (CA) was isolated from sediment of a stream that received industrial waste water effluent. CA decomposition was measured throughout the growth cycle by using a High Performance Liquid Chromatography assay while also measuring the concomitant production of ammonia. This bacterium used CA or cysteine as a major, if not sole, carbon and energy source under anaerobic, but not aerobic conditions in a defined medium. The cell yield was greatly enhanced by the simultaneous presence of cysteine and CA in the medium. Cysteine was preferentially used rather than CA early in the growth cycle, but all the CA was used without an apparent lag after the cysteine was metabolized. Atrazine was also degraded by this bacterium under anaerobic conditions in a defined medium. / Master of Science LD5655.V855 1982.J477 Anaerobic bacteria Atrazine -- Biodegradation Cyanuric acid -- Biodegradation Cysteine -- Biodegradation
136	THE EFFECT OF DEVELOPMENTAL ATRAZINE EXPOSURE ON KEY NEUROENDOCRINE AND NEUROTRANSMISSION PATHWAYS Sydney Christine Stradtman (20348625) 10 January 2025 (has links) <p dir="ltr">Atrazine is an herbicide used to control broadleaf and grassy weeds on agricultural fields in the US and other global regions, but this herbicide has been banned from use in the European Union since 2003, based mainly on risk of contamination of surface and groundwater. Atrazine is categorized as an endocrine disrupting chemical (EDC) but the specific mechanism that leads to this disruption is not yet clearly defined. This study investigated the hypothesis that the main target of neuroendocrine atrazine toxicity is the kisspeptin system, which then leads to multiple adverse health outcomes that are seen affecting multiple endocrine axes. Furthermore, an embryonic atrazine exposure was expected to result in adverse effects on neurohormones and associated gene expression along the endocrine axes into adulthood. Using the zebrafish model, concentrations of estradiol, dopamine, kisspeptin, and luteinizing hormone were measured in atrazine exposed larvae as well as male and female adult brains using ELISA. Adult wild type zebrafish were bred to obtain embryos, collected at 1 hour post fertilization (1 hpf), and randomly assigned to 0, 0.3, 3, or 30 ppb (µg/L) atrazine treatment, surrounding the current US EPA regulatory level in drinking water of 3 ppb. Exposure ceased at the end of embryogenesis (72 hpf) and fish placed in filtered aquaria water for continued development. Zebrafish were either collected for larval evaluation [72, 120, 144, or 168 hpf] or grown to different timepoints in adulthood for collection of brains [6 months post fertilization (mpf), 2 years post fertilization (ypf), or 2.5 ypf]. Gene expression of neuroendocrine molecular targets was examined to determine if an embryonic atrazine exposure perturbed neuroendocrine development using qPCR. Behavior analysis was conducted on larvae and in adults to assess downstream functional changes related to dopaminergic signaling. Significant findings in gene expression, neurohormone and protein concentration, and behavior were observed and a CRISPR-Cas9 knockdown model was designed to further investigate the kisspeptin system as a viable target of atrazine toxicity in connection with the multitude of adverse effects. Studies to further examine perturbations along the pathways associated with these biomarkers are necessary to elucidate the mechanism of atrazine and further characterize the role of the kisspeptin system in atrazine toxicity.</p> Toxicology (incl. clinical toxicology) atrazine reproductive developmental zebrafish neuroendocrine kisspeptin signaling system
137	Étude de l'hydrolyse acide des herbicides atrazine, simazine et diuron en solution dans l'eau et à la surface de minéraux argileux déshydratés à l'air libre, au voisinage de 0 et 22 C Couture, Geneviève 17 April 2018 (has links) Ces travaux voulaient démontrer que l'hydrolyse d'herbicides dans le sol, l'hiver comme l'été, est catalysée par l'acidité de surface des minéraux argileux. Le manque d'eau pouvant limiter la réaction, l'hydrolyse a d'abord été étudiée dans l'eau. La demi-vie d'hydrolyse acide du diuron dans l'eau a été estimée à 320 et 5,2 ans, à 0 et 22 °C respectivement, entre pH 1 et -1 où la vitesse de la réaction plafonne. Par contre en 16 semaines, la quantité initiale d'atrazine ou de simazine dans l'eau est réduite de 20 % à pH 2,0 à 0 °C, et 3,3 à 22 °C. Une nouvelle équation, basée sur la fonction acide Ho plutôt que le pH, impliquant les triazines neutre, mono-, di- et triprotonées, a été proposée pour prédire la demi-vie en solutions très acides. Deux pellicules plastiques, l'une en polyethylene basse densité (LDPE), l'autre en chlorure de polyvinyle (PVC) plastifié, ont été testées comme support transparent dans l'UV-Visible de films minces d'argile imprégnés d'herbicide. Le LDPE absorbe moins dans cette région spectrale. Sa faible polarité entraîne toutefois de sérieux problèmes d'étalement et d'adhésion de l'argile. Le PVC libère du HCl(g), mais en quantité négligeable et limitée à 21 °C. L'hydrolyse acide de l'atrazine et du diuron à la surface de films d'argile supportés par la pellicule de PVC, a été étudiée à -4 et 21 °C, par spectroscopie UV-Visible de transmission. Les formes -K, -Ca, -Mg, -Zn, -Fe, -Al et -H de deux smectites et d'une vermiculite ont été préparées. Les argiles homoioniques déshydratées à l'air libre n'ont montré aucune activité catalytique vis-à-vis des herbicides en 16 semaines, à l'exception de la montmorillonite-H où l'atrazine est protonée au-dedans de 24 heures. Cette réactivité s'explique seulement par l'accessibilité de l'atrazine neutre à l'espace interfoliaire de la montmorillonite-H, et l'acidité de surface particulièrement élevée de celle-ci. L'atrazine n'est pas hydrolysée sur la montmorillonite-H en raison de l'insuffisance d'eau disponible. L'absence de protonation de l'atrazine sur les autres argiles, lorsque l'ouverture des feuillets permet son accès, découle de leur trop forte teneur en eau résiduelle. Le diuron ne pénètre pas dans l'espace interfoliaire des argiles. S 405 UL 2010 C872 Atrazine Simazine Diuron Hydrolyse Herbicides -- Aspect de l'environnement
138	Avaliação da qualidade da água do rio Piracicaba (SP) e efeito da vinhaça para os organismos aquáticos antes e após a correção do pH / Assessment of water quality of the Piracicaba River (São Paulo, Brazil) and effects of vinasse to aquatic organisms before and after pH correction Botelho, Rafael Grossi 13 September 2013 (has links) A avaliação da qualidade da água do rio Piracicaba foi realizada utilizando diferentes metodologias e organismos teste, e para tanto, de fevereiro de 2011 a janeiro de 2012 amostras de água foram coletadas em seis locais de amostragens ao longo do rio Piracicaba. Parâmetros físicos e químicos da água foram mensurados e de acordo com a condutividade elétrica e demanda bioquímica de oxigênio, baixa qualidade foi observada em locais próximos a Americana e Piracicaba. Efeitos sobre a reprodução de Ceriodaphnia dubia e Ceriodaphnia silvestrii foram observados em fevereiro e março de 2011 e janeiro de 2012, e ocorreram em amostras coletadas próximas às cidades de Americana e Piracicaba. A avaliação das brânquias do peixe Danio rerio mostrou que para todos os meses, exceto fevereiro, setembro e outubro para alguns pontos, as alterações não foram significativas. Amostras de água coletada em todos os locais, assim como em todos os meses apresentaram valores de clorofila a abaixo do estabelecido pela legislação ambiental brasileira. A água coletada nos meses de outubro e novembro e aquelas amostradas à montante e à jusante de Piracicaba apresentaram maiores valores de índice de estado trófico comparado aos outros pontos e meses do ano, no entanto, não foram classificadas como eutrofizadas. Concentrações dos herbicidas atrazina e ametrina também foram determinadas na água do rio Piracicaba e variaram de 0,11 a 1,92 \'mü\'g L-1 e 0,25 a 1,44 \'mü\'g L-1, respectivamente, e mostraram ter potencial mutagênico e genotóxico para D. rerio. Um estudo avaliando a toxicidade da vinhaça antes e após a correção do pH também foi realizado já que o rio Piracicaba está localizado em uma região influenciada por plantações de cana-de-açúcar. Os resultados apresentados confirmam que a vinhaça possui alta toxicidade aguda para organismos aquáticos, no entanto, esta pode ser reduzida através da correção do seu pH para 6,5 / An assessment of water quality of the Piracicaba River was performed using different methodologies and organisms, and therefore, from February 2011 to January 2012 water samples were collected at six sampling sites along the Piracicaba River. Physical chemical parameters of the water were measured and demonstred low water quality according to the conductivity and biochemical oxygen in places close to Americana and Piracicaba. Effects on the reproduction of Ceriodaphinia dubia and Ceriodaphnia silvestrii were observed in February and March 2011, and January 2012 and occurred in samples collected close to Americana and Piracicaba cities. Evaluation of the gills of Danio rerio showed no significant difference during all months, except in February, September and October for some locations. During the study period, water samples collected in all sampling sites and months presented values of chlorophyll a below the limit set by the Brazilian environmental law. Water collected in October and November and those sampled upstream and downstream of Piracicaba presented higher values of throfic state index than the other sites and months, however, were not classified as euthrofic. Concentrations of atrazine and ametrine during the sampling period were also measured and ranged from 0.11 to 1.92 \'mü\'g L-1 and from 0.25 to 1.44 \'mü\'g L-1, respectively, and showed genotoxic and mutagenic potentials to D. rerio. A study evaluating the acute toxicity of vinasse before and after the pH correction was conducted due to the influence of sugar cane cultures on the Piracicaba River area. The results confirmed the high acute toxicity of vinasse to aquatic organisms, however, this can be reduced by correcting its pH to 6.5 Ametrina Ametrine Atrazina Atrazine Biomonitoramento Biomonitoring Brânquias Genotoxicity Genotoxidade Gills Microcrustaceans Microcrustáceos Mutagenicidade Mutagenicity Toxicidade Toxicity Vinasse Vinhaça
139	Degradação eletroquímica dos herbicidas atrazina e alaclor utilizando ânodo dimensionalmente estável comercial / Electrochemical degradation of atrazine and alachlor herbicides using dimensionally stable commercial anode Sousa, Rafaely Ximenes de 19 February 2016 (has links) A presença de defensivos agrícolas no meio ambiente, mesmo que em baixas concentrações (ng L-1/ μg L-1), representa uma potencial fonte de perturbação endócrina para os seres vivos. Neste cenário, destacam-se os herbicidas alaclor e atrazina, que são amplamente utilizados no combate a ervas daninhas. Entretanto, a Agência de Proteção Ambiental dos Estados Unidos (EPA) classifica como carcinogênicos, desreguladores endócrinos e seu limite, em água, não pode ultrapassar 2 e 3 μg L-1, respectivamente. O objetivo deste trabalho foi estudar a degradação eletroquímica do alaclor e atrazina, utilizando uma célula do tipo filtro-prensa, e um ânodo dimensionalmente estável (ADE) de composição nominal Ti/Ru0,3Ti0,7O2, pH inicial fixo em 3 e a temperatura em 25 ºC, uma vez que, os métodos convencionais de tratamento não são totalmente eficientes na remoção destes compostos orgânicos nos sistemas aquosos. Inicialmente realizou-se apenas a degradação eletroquímica do herbicida alaclor (100 mg L-1) via planejamento fatorial de ponto central do tipo 32, tendo como variáveis, a concentração do eletrólito suporte cloreto de sódio (0,05, 01 e 0,15 g L-1) e a densidade de corrente (10, 30 e 50 mA cm-2), obtendo como melhor resposta, 93,45 % de remoção e 71,6 % de mineralização, ao usar CNaCl de 0,15 g L-1 e 50 mA cm-2. Porém, a CNaCl de 0,15 g L-1 e densidade de 30 mA cm-2 foi escolhida como a melhor condição estudada, em virtude do seu menor valor de consumo energético e por apresentar a taxa de remoção (93,6%) e mineralização (71,24%) próximas ao uso da maior densidade de corrente. Só então, na melhor condição, obtida previamente a partir dos experimentos de degradação do alaclor, que realizou-se a oxidação de 100 mg L-1 de atrazina e da mistura dos herbicidas. Também foi observado uma cinética de pseudo primeira ordem na oxidação dos herbicidas, e, além disso, foi realizada a identificação dos intermediários e/ou produtos de degradação do alaclor e atrazina através da técnica de CLAE acoplada a um espectrômetro de massas. / The pesticides presence in environment represents a potential endocrine disturbance source for the living beings, even in low concentrations (ng L-1/ μg L-1). The herbicides alachlor and atrazine are important to highlight, these herbicides are widely used to combat weeds herbs. However, the Environmental Protection Agency (EPA) classifies alachlor and atrazine as carcinogens, endocrine disruptors and their water limit may not exceed 2 and 3 μg L-1, respectively. The aim of this work was to study the electrochemical degradation of alachlor and atrazine, using a filter-press cell, and a dimensionally stable anode (DSA) with a nominal composition Ti/Ru0.3Ti0.7O2, fixed initial pH of 3 and temperature of 25ºC. The conventional treatment methods are not completely effective to remove these organic compounds in aqueous systems. Initially, only an electrochemical degradation of alachlor (100 mg L-1) was made by factorial design center point type 32, considering as variables: the supporting electrolyte sodium chloride concentration (0.05, 0.1 and 0.15 g L-1) and current density (10, 30 and 50 mA cm-2). In this initial degradation was obtained as better result: 93.45% of removal and 71.6% of mineralization of alachlor, using CNaCl of 0.15 g L-1 and 50 mA cm-2. However, CNaCl of 0.15 g L-1 and a density of 30 mA cm-2 was chosen as the best condition studied, in the reason of its lower energy consumption value and presents a removal rate (93.6%) and the mineralization (71.24%) closer to the use of higher current density. The electrolyses of 100 mg L-1 of atrazine and the herbicides mixture were performed only in the best condition, previously obtained with alachlor degradation experiments. In addition, a kinetic of pseudo first order for both herbicides and their mixture oxidation was observed, and besides, the identification of intermediates and/or degradation products of alachlor and atrazine was performed by liquid chromatography coupled to mass spectrometry (LC-MS). ADE Alachlor Alaclor Atrazina Atrazine Degradação eletroquímica DSA Electrochemical degradation Herbicides Hercidas LC-MS LC-MS Ti/Ru0,3Ti0,7 Ti/Ru0,3Ti0,7
140	Degradação eletroquímica dos herbicidas atrazina e alaclor utilizando ânodo dimensionalmente estável comercial / Electrochemical degradation of atrazine and alachlor herbicides using dimensionally stable commercial anode Rafaely Ximenes de Sousa 19 February 2016 (has links) A presença de defensivos agrícolas no meio ambiente, mesmo que em baixas concentrações (ng L-1/ μg L-1), representa uma potencial fonte de perturbação endócrina para os seres vivos. Neste cenário, destacam-se os herbicidas alaclor e atrazina, que são amplamente utilizados no combate a ervas daninhas. Entretanto, a Agência de Proteção Ambiental dos Estados Unidos (EPA) classifica como carcinogênicos, desreguladores endócrinos e seu limite, em água, não pode ultrapassar 2 e 3 μg L-1, respectivamente. O objetivo deste trabalho foi estudar a degradação eletroquímica do alaclor e atrazina, utilizando uma célula do tipo filtro-prensa, e um ânodo dimensionalmente estável (ADE) de composição nominal Ti/Ru0,3Ti0,7O2, pH inicial fixo em 3 e a temperatura em 25 ºC, uma vez que, os métodos convencionais de tratamento não são totalmente eficientes na remoção destes compostos orgânicos nos sistemas aquosos. Inicialmente realizou-se apenas a degradação eletroquímica do herbicida alaclor (100 mg L-1) via planejamento fatorial de ponto central do tipo 32, tendo como variáveis, a concentração do eletrólito suporte cloreto de sódio (0,05, 01 e 0,15 g L-1) e a densidade de corrente (10, 30 e 50 mA cm-2), obtendo como melhor resposta, 93,45 % de remoção e 71,6 % de mineralização, ao usar CNaCl de 0,15 g L-1 e 50 mA cm-2. Porém, a CNaCl de 0,15 g L-1 e densidade de 30 mA cm-2 foi escolhida como a melhor condição estudada, em virtude do seu menor valor de consumo energético e por apresentar a taxa de remoção (93,6%) e mineralização (71,24%) próximas ao uso da maior densidade de corrente. Só então, na melhor condição, obtida previamente a partir dos experimentos de degradação do alaclor, que realizou-se a oxidação de 100 mg L-1 de atrazina e da mistura dos herbicidas. Também foi observado uma cinética de pseudo primeira ordem na oxidação dos herbicidas, e, além disso, foi realizada a identificação dos intermediários e/ou produtos de degradação do alaclor e atrazina através da técnica de CLAE acoplada a um espectrômetro de massas. / The pesticides presence in environment represents a potential endocrine disturbance source for the living beings, even in low concentrations (ng L-1/ μg L-1). The herbicides alachlor and atrazine are important to highlight, these herbicides are widely used to combat weeds herbs. However, the Environmental Protection Agency (EPA) classifies alachlor and atrazine as carcinogens, endocrine disruptors and their water limit may not exceed 2 and 3 μg L-1, respectively. The aim of this work was to study the electrochemical degradation of alachlor and atrazine, using a filter-press cell, and a dimensionally stable anode (DSA) with a nominal composition Ti/Ru0.3Ti0.7O2, fixed initial pH of 3 and temperature of 25ºC. The conventional treatment methods are not completely effective to remove these organic compounds in aqueous systems. Initially, only an electrochemical degradation of alachlor (100 mg L-1) was made by factorial design center point type 32, considering as variables: the supporting electrolyte sodium chloride concentration (0.05, 0.1 and 0.15 g L-1) and current density (10, 30 and 50 mA cm-2). In this initial degradation was obtained as better result: 93.45% of removal and 71.6% of mineralization of alachlor, using CNaCl of 0.15 g L-1 and 50 mA cm-2. However, CNaCl of 0.15 g L-1 and a density of 30 mA cm-2 was chosen as the best condition studied, in the reason of its lower energy consumption value and presents a removal rate (93.6%) and the mineralization (71.24%) closer to the use of higher current density. The electrolyses of 100 mg L-1 of atrazine and the herbicides mixture were performed only in the best condition, previously obtained with alachlor degradation experiments. In addition, a kinetic of pseudo first order for both herbicides and their mixture oxidation was observed, and besides, the identification of intermediates and/or degradation products of alachlor and atrazine was performed by liquid chromatography coupled to mass spectrometry (LC-MS). ADE Alaclor Atrazina Degradação eletroquímica Hercidas LC-MS Ti/Ru0,3Ti0,7 Alachlor Atrazine DSA Electrochemical degradation Herbicides LC-MS Ti/Ru0,3Ti0,7

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