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This item was digitized as part of the Million Books Project led by Carnegie Mellon University and supported by grants from the National Science Foundation (NSF). Cornell University coordinated the participation of land-grant and agricultural libraries in providing historical agricultural information for the digitization project; the University of Arizona Libraries, the College of Agriculture and Life Sciences, and the Office of Arid Lands Studies collaborated in the selection and provision of material for the digitization project.

This item was digitized as part of the Million Books Project led by Carnegie Mellon University and supported by grants from the National Science Foundation (NSF). Cornell University coordinated the participation of land-grant and agricultural libraries in providing historical agricultural information for the digitization project; the University of Arizona Libraries, the College of Agriculture and Life Sciences, and the Office of Arid Lands Studies collaborated in the selection and provision of material for the digitization project.

Made available in DSpace on 2014-06-11T19:26:10Z (GMT). No. of bitstreams: 0 Previous issue date: 2013-09-18Bitstream added on 2014-06-13T18:29:36Z : No. of bitstreams: 1 rolisola_amcm_me_rcla.pdf: 1132649 bytes, checksum: 427d7970dd28e9d0c7190b92e04de416 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / A técnica de difusão em filmes finos por gradiente de concentração (DGT - diffusive gradients in thin films) está entre as ferramentas analíticas usadas para análise de especiação de metais e semimetais. Esta técnica é capaz de fornecer as concentrações médias por tempo, pré-concentração do elemento e amostragem in situ. Nesta pesquisa, a determinação de As(V) pela técnica DGT foi realizada usando a resina de troca aniônica fortemente básica Amberlite IRA 910, seletiva para a retenção do mesmo; enquanto que o hidróxido férrico foi utilizado para a determinação do arsênio total. A concentração de As(III) foi obtida pela diferença entre ambos. Foram também avaliadas, a membrana de troca aniônica fracamente básica DE81 e a resina de troca aniônica fortemente básica Amberlite IRA 410. A resina de troca aniônica fortemente básica Amberlite IRA 910 apresentou melhor desempenho nas condições testadas. O DAs(V) em agarose 1,5 % (m/v), na presença de cloreto de sódio obtido por curva de imersão foi de 4,59 ± 0,43 x 10-6 cm2 s-1 e, o obtido pela câmara de difusão foi de 6,33 ± 0,21 x 10-6 cm2 s-1. A retenção de As(V) pela resina Amberlite IRA 910, apresentou melhor linearidade para um tempo de imersão de 8 h. Do mesmo modo, a melhor retenção de As(V) foi observada na faixa de pH entre 5,0 e 9,0 e, força iônica entre 0,001 mol L-1 a 0,05 mol L-1. Dentre os potenciais interferentes aniônicos, o sulfato demonstrou ser o ânion que mais interferiu na retenção de As(V), enquanto o carbonato apresentou menor interferência. A metodologia desenvolvida foi aplicada para análise de especiação de arsênio inorgânico em amostras sintéticas com diferentes concentrações de As(III) e As(V) e os resultados obtidos pela DGT ficaram próximos aos valores esperados. Para a análise de amostras coletadas no Córrego Furnas, a recuperação... / The diffusive gradients in thin films (DGT) technique is among the analytical tools used for speciation analysis of metals and semimetals. The DGT is able to provide average concentrations by time, pre-concentration of the element and in situ sampling. In this research, the determination of As(V) by DGT technique was possible using a strongly basic anion exchange resin, Amberlite IRA 910, selective for accumulating As(V), while ferrihydrite was used for measuring the total arsenic. The As(III) concentration was obtained by the difference between both. The DE81 weakly basic anion exchange membrane and strongly basic anion exchange resins Amberlite IRA 410 were also investigated for selective sampling of As (V). The resin Amberlite IRA 910 has shown the best performance. Diffusion coefficients of the As(V) obtained by immersion curves and diffusion cell were 4.59 ± 0.43 x 10-6 cm2 s-1 e 6.33 ± 0.21 x 10-6 cm2 s-1 respectively. Both experiments were carried out using 1.5 % m/v agarose as diffusive layer and sodium chloride as ionic strength electrolyte. The As(V) accumulated by IRA 910 shown the best linear range for immersion times of up to 8 hours. While the range of pH 5.0 – 9.0 and ionic strength from 0.001 mol L-1 to 0.05 mol L-1 were the best working conditions. These rates are among the common values found in surface water. Among the potential interfering anions, the sulfate anion interfere the most in the As(V) retention while carbonate showed the least interference. The proposed methodology was applied to speciation analysis of inorganic arsenic on synthetic samples with different concentrations of As(III) and As(V), and the obtained results by DGT were close to expected values. For the analysis of spiked samples collected in Furnas Stream, the recoveries for total arsenic were between 103.9 % and 118.8 %... (Complete abstract click electronic access below)

Orientador: Amauri Antonio Menegário / Banca: Joaquim de Araújo Nóbrega / Banca: Didier Gastmans / Resumo: A técnica de difusão em filmes finos por gradiente de concentração (DGT - diffusive gradients in thin films) está entre as ferramentas analíticas usadas para análise de especiação de metais e semimetais. Esta técnica é capaz de fornecer as concentrações médias por tempo, pré-concentração do elemento e amostragem in situ. Nesta pesquisa, a determinação de As(V) pela técnica DGT foi realizada usando a resina de troca aniônica fortemente básica Amberlite IRA 910, seletiva para a retenção do mesmo; enquanto que o hidróxido férrico foi utilizado para a determinação do arsênio total. A concentração de As(III) foi obtida pela diferença entre ambos. Foram também avaliadas, a membrana de troca aniônica fracamente básica DE81 e a resina de troca aniônica fortemente básica Amberlite IRA 410. A resina de troca aniônica fortemente básica Amberlite IRA 910 apresentou melhor desempenho nas condições testadas. O DAs(V) em agarose 1,5 % (m/v), na presença de cloreto de sódio obtido por curva de imersão foi de 4,59 ± 0,43 x 10-6 cm2 s-1 e, o obtido pela câmara de difusão foi de 6,33 ± 0,21 x 10-6 cm2 s-1. A retenção de As(V) pela resina Amberlite IRA 910, apresentou melhor linearidade para um tempo de imersão de 8 h. Do mesmo modo, a melhor retenção de As(V) foi observada na faixa de pH entre 5,0 e 9,0 e, força iônica entre 0,001 mol L-1 a 0,05 mol L-1. Dentre os potenciais interferentes aniônicos, o sulfato demonstrou ser o ânion que mais interferiu na retenção de As(V), enquanto o carbonato apresentou menor interferência. A metodologia desenvolvida foi aplicada para análise de especiação de arsênio inorgânico em amostras sintéticas com diferentes concentrações de As(III) e As(V) e os resultados obtidos pela DGT ficaram próximos aos valores esperados. Para a análise de amostras coletadas no Córrego Furnas, a recuperação... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The diffusive gradients in thin films (DGT) technique is among the analytical tools used for speciation analysis of metals and semimetals. The DGT is able to provide average concentrations by time, pre-concentration of the element and in situ sampling. In this research, the determination of As(V) by DGT technique was possible using a strongly basic anion exchange resin, Amberlite IRA 910, selective for accumulating As(V), while ferrihydrite was used for measuring the total arsenic. The As(III) concentration was obtained by the difference between both. The DE81 weakly basic anion exchange membrane and strongly basic anion exchange resins Amberlite IRA 410 were also investigated for selective sampling of As (V). The resin Amberlite IRA 910 has shown the best performance. Diffusion coefficients of the As(V) obtained by immersion curves and diffusion cell were 4.59 ± 0.43 x 10-6 cm2 s-1 e 6.33 ± 0.21 x 10-6 cm2 s-1 respectively. Both experiments were carried out using 1.5 % m/v agarose as diffusive layer and sodium chloride as ionic strength electrolyte. The As(V) accumulated by IRA 910 shown the best linear range for immersion times of up to 8 hours. While the range of pH 5.0 - 9.0 and ionic strength from 0.001 mol L-1 to 0.05 mol L-1 were the best working conditions. These rates are among the common values found in surface water. Among the potential interfering anions, the sulfate anion interfere the most in the As(V) retention while carbonate showed the least interference. The proposed methodology was applied to speciation analysis of inorganic arsenic on synthetic samples with different concentrations of As(III) and As(V), and the obtained results by DGT were close to expected values. For the analysis of spiked samples collected in Furnas Stream, the recoveries for total arsenic were between 103.9 % and 118.8 %... (Complete abstract click electronic access below) / Mestre

Excessive nutrient loading of natural and artificial lakes has led, in some systems, to plethoric algal and aquatic macrophyte growth which can result in aesthetic degradation and undesirable tastes and odors. It would be advantageous to have some indication of the potential trophic status of a reservoir before it is filled. An objective of this study was to assess the water quality and nutrient loading potential of the tributaries entering Ray Roberts Lake, a large reservoir located in north central Texas. Samples from a maximum of thirteen sites were collected on the Elm Fork, Trinity River, Isle duBois Creek, and five additional tributaries. Data were also collected during six storms, from atmospheric deposition collectors, and from soil-water microcosms. The relationship between watershed landuse and mean water nutrient concentrations was evaluated. Significant differences will exist between the two major arms of Ray Roberts Lake: Elm Fork, Trinity River and Isle duBois Creek. While the majority of the annual phosphorus and nitrogen load entering both tributaries is coming from overland flow, the proportion is higher in Isle duBois Creek. Point sources in the Elm Fork contribute a larger percentage of the bioavailable phosphorus, which is significantly greater than in Isle duBois Creek. The water quality of Isle duBois Creek, especially nitrogen, is affected to a greater degree by the landuses in its watershed. Predictive regression models made accurate estimations of stream nutrient concentrations in Isle duBois Creek. The entire reservoir, upon reaching equilibrium conditions, will be classified as a eutrophic lake. The Trinity arm, with a higher phosphorus load, will display a higher trophic status. The Isle duBois arm has a lower phosphorus load which will give it a lower trophic status. The long hydraulic residence time of the two arms of the reservoir will remove nutrients upstream of the main body, thus contributing to overall better water quality in the main body of the reservoir.

Two years before impoundment, the trophic status of Lake Ray Roberts was predicted by applying the total phosphorus input into the Organization for Economic Cooperation and Development (OECD) eutrophication model. Predicted mean summer epilimnetic (MSE) chlorophyll a of Elm Fork arm, Isle duBois arm and Main Body were in the eutrophic category of the OECD model. Observed MSE chlorophyll a two years after impoundment of Elm Fork arm, Isle duBois and Main Body had not reached their predicted means and were at the mesotrophic-eutrophic boundary of the OECD model. Six years after impoundment, observed MSE chlorophyll a for Main Body, was closer to its predicted mean and in the eutrophic category of the OECD model. Six years after impoundment, Elm Fork arm was the most productive area of Lake Ray Roberts. Observed means of chlorophyll a, total phosphates, suspended solids and turbidity were often highest in the Elm Fork arm. Wastewater effluent from Gainesville and Valley View, TX, had an impact on productivity in Elm Fork arm.