<p> Supercapacitors have occupy an indispensable role in today's energy storage systems due to their high power density and long life. The introduction of car- bon nanotube (CNT) forests as electrode offers the possibility of nano-scale design and high capacitance. We have performed molecular dynamics simulations on a CNT forest-based electrochemical double-layer capacitor (EDLC) and a widely used electrolyte solution (tetra-ethylammonium tetra-fluoroborate in propylene carbonate, TEABF₄ /PC) </p><p> We compare corresponding primitive model and atomically detailed model of TEABF₄ /P, emphasizing the significance of ion clustering in electrolytes. The molecular dynamic simulation results suggests that the arrangement of closest neigh- bors leads to the formation of cation-anion chains or rings. Fuoss's discussion of ion-pairing model provides the approximation for a primitive model of 1-1 electrolyte is not broadly satisfactory for both primitive and atomically detailed cases. A more general Poisson statistical assumption is shown to be satisfactory when coordina- tion numbers are low, as is likely to be the case when ion-pairing initiates. We examined the Poisson-based model over a range of concentrations for both models of TEABF₄ /P, and the atomically detailed model results identified solvent-separated nearest-neighbor ion-pairs. </p><p> Large surface areas plays an essential role in nanomaterial properties, which calls for an accurate description of interfaces through modeling. We studied propylene carbonate, a widely used solvent in EDLC systems. PC wets graphite with a contact angle of 31&deg;. The MD simulation model reproduced this contact angle after reduction 40% of the strength of graphite-C atom Lennard-Jones interactions with the solvent. The critical temperature of PC was accurately evaluated by extrapolating the PC liquid-vapor surface tensions. PC molecules tend to lie flat on the PC liquid-vapor surface, and project the propyl carbon toward the vapor phase. Liquid PC simulations also provide basic data for construction of accurate information to assist in device- level modeling of EDLCs. </p><p> The most serious uncertainty with previous simulations of CNT based EDLCs was definition of the actual composition of the pores. Therefore, direct simulations of filling of CNT forest based electrochemical double-layer capacitors with TEABF₄ /P solution was performed. Those calculation characterize the charging and discharg- ing process, including rates of charging responses, the possibility of bubble forma- tion, and kinetic properties with confinement. The mobilities of ions and solvent was investigated through mean square displacement (MSD) and velocity autocorrela- tion functions (VACF). The memory kernel was extracted from VACF by discretized linear-equation solving and a specialized Fourier transform method, results implies the existence of dielectric friction. </p><p> With the interest in chemical features of EDLCs, a multi-scale theory was de- veloped to embed high resolution ab <i>initio</i> molecular dynamics (AIMD) methods into studies of EDLCs. This theory was based on McMillan-Mayer theory, potential dis- tribution approach, and quasi-chemical theory. The quasi-chemical theory allow us to break-up the free energies into <i> packing, outer-shell</i> and <i>chemical</i> contributions, where the last part can be done by AIMD directly. For the primitive model of TEABF₄ /P, Gaussian statistical models are effective for these <i> outer-shell</i> contributions. And the Gaussian approximation is more efficient than the Bennett method in achieving an accurate mean activity coefficient. </p>

No description available.

Thesis (Ph. D.)--University of Illinois at Urbana-Champaign, 2008. / Source: Dissertation Abstracts International, Volume: 69-11, Section: B, page: 6874. Adviser: Kenneth S. Schweizer. Includes bibliographical references. Available on microfilm from Pro Quest Information and Learning.

Submitted by Victor Hugo Sant Ana Bomfim null (victorhugorex@hotmail.com) on 2018-03-29T14:26:47Z No. of bitstreams: 1 Disssertação de Mestrado - Bomfim, Victor Hugo Santana.pdf: 1752737 bytes, checksum: 3590d7ae4906fc8090c9b08cf8f32419 (MD5) / Approved for entry into archive by Elza Mitiko Sato null (elzasato@ibilce.unesp.br) on 2018-03-29T15:02:41Z (GMT) No. of bitstreams: 1 bomfim_vhs_me_sjrp.pdf: 2124719 bytes, checksum: eae3b7818f7a91da6ad5998675a30905 (MD5) / Made available in DSpace on 2018-03-29T15:02:41Z (GMT). No. of bitstreams: 1 bomfim_vhs_me_sjrp.pdf: 2124719 bytes, checksum: eae3b7818f7a91da6ad5998675a30905 (MD5) Previous issue date: 2018-02-23 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Os reservatórios são ecossistemas artificiais, que apesar de constituírem uma fonte significativa de recurso hídrico para a população em várias cidades, estão, muitas vezes, sujeitos a impactos ambientais. A urbanização e a poluição por matéria orgânica são fatores que podem comprometer a qualidade da água, alterando também a biota ali presente. Torna-se assim necessário um monitoramento biológico para avaliar as condições desses reservatórios. Uma das maneiras de se fazer esse monitoramento é através das análises dos organismos do zooplâncton, sendo que vários pesquisadores já comprovaram que esta comunidade pode ser um bom bioindicador pois apresenta alta sensibilidade a alterações nos recursos ou nas condições do ambiente aquático. O objetivo deste estudo foi descrever as variações na composição e densidade do zooplâncton na Represa Municipal e verificar quais fatores ambientais apresentam maior influência sobre tais variações. O que se espera com os dados adquiridos é que diferenças de densidade e diversidade ao longo do ano sejam causadas por alterações nos fatores da água provocadas por impactos antrópicos, podendo estar ligados à eutrofização. A Represa Municipal de São José do Rio Preto está localizada na região urbana da cidade e foi formada com o represamento do Rio Preto. É dividida em três lagos, sendo responsável pelo abastecimento de 30% a 40% da água que chega à população. As amostragens foram realizadas trimestralmente ao longo de um ano em seis pontos distribuídos na zona limnética do Lago 3. As coletas dos organismos foram realizadas por meio de arrastos verticais com rede de plâncton de 45 µm de malha. Nos mesmo pontos foram avaliados os fatores físicos e químicos, tais como profundidade e transparência por meio de um disco de Secchi, temperatura, ph, condutividade e oxigênio dissolvido por meio da sonda multiparâmetros YSI 556, além de clorofila-a e material em suspensão. Por meio dos dados de clorofila foi calculado o Índice do Estado Trófico. A comunidade zooplanctônica foi analisada segundo a composição de espécies de Cladocera e de Copepoda. Além destas espécies, Rotifera e Tecameba foram avaliados quantitativamente para determinação das abundâncias dos grupos. Por meio de medidas do comprimento do corpo, as classes de tamanho – micro, meso e macrozooplâncton – foram determinadas e suas abundâncias estimadas. Índices de diversidade de espécies de microcrustáceos foram determinados utilizando a riqueza de espécies, diversidade de Shannon~Winer, dominância de Simpson e equabilidade de Jaccard. Por meio de análise de variância, os dados, tanto dos 2 parâmetros físicos e químicos quanto os da comunidade, foram comparados entre os meses para detectar variações significativas. A correlação de Spearman foi realizada para verificar quais fatores ambientais poderiam estar relacionados com variações na comunidade. Os fatores físicos e químicos apresentaram variações significativas ao longo do ano e a represa pôde ser classificada como mesotrófica na maioria dos meses. Foram encontradas 11 espécies de cladóceros e 2 de copépodos, dando um total de 15 táxons registrados, contando com rotífero e tecameba. As densidades variaram ao longo do ano (p<0,05), exceto para rotíferos, sendo que o mês de novembro foi o mais abundante. Copepoda foi o grupo com os maiores valores de densidade, tendo a forma de náuplio como a mais numerosa. Dentre os cladóceros, Daphnia gessneri foi a espécie mais abundante, seguida de Moina micrura. Quanto às classes de tamanho, macrozooplâncton foi a mais numerosa, principalmente nos meses de agosto e novembro. A presença de espécies de cladóceros de tamanho grande como as do gênero Daphnia em elevadas densidades sugere que o ambiente não oferece condições de elevada eutrofização, como confirmado pelo Índice do Estado Trófico. As condições ambientais, mesmo apresentando variações ao longo do ano não demonstraram ser impróprias para o desenvolvimento da comunidade zooplanctônica. / Reservoirs are artificial ecosystems, which, while constituting a significant source of water resources for the population in several cities, are often subject to environmental impacts. Urbanization and pollution by organic matter are factors that can compromise the water quality, also altering the biota present there. Biological monitoring is therefore necessary to evaluate the conditions of these reservoirs. One of the ways to do this monitoring is through the analysis of zooplankton organisms, and several researchers have already proven that this community can be a good bioindicator because it has high sensitivity to changes in conditions of the aquatic environment. The objective of this study was to describe the variations in the composition and density of the zooplankton in the Represa Municipal de São José do Rio Preto and to verify which environmental factors present greater influence on such variations. What is expected from the data is that differences in density and diversity throughout the year are caused by changes in water factors caused by anthropic impacts and may be linked to eutrophication. The Represa Municipal of São José do Rio Preto is located in the urban area of the city and was formed with the impoundment of the rio Preto. It is divided into three lakes, being responsible for the supply of 30% to 40% of the water that reaches the population. Samplings were performed quarterly over a year at six points distributed in the limnetic zone of Lake 3. The organisms were collected by vertical trawls with 45 μm mesh of plankton. In the same points, the physical and chemical factors such as depth and transparency were evaluated by means of a Secchi disc, temperature, pH, conductivity and oxygen dissolved by means of the YSI 556 multiparameter probe, as well as chlorophyll-a and suspended material. Through the data of chlorophyll was calculated the Index of the Trophic State. The zooplankton community was analyzed according to the composition of Cladocera and Copepoda species. In addition to these species, Rotifera and Tecameba were evaluated quantitatively to determine the abundances of the groups. By means of body length measurements, size classes - micro, meso and macrozooplankton - were determined and their abundances estimated. Diversity indexes of microcrustaceans species were determined using species richness, Shannon-Winer diversity, Simpson dominance and Jaccard equability. By means of analysis of variance, the data of both the physical and chemical parameters as well as those of the community were compared between the months to detect significant variations. Spearman correlation was performed 4 to verify which environmental factors could be related to variations in the community. The physical and chemical factors presented significant variations throughout the year and the dam could be classified as mesotrophic in most months. Eleven species of cladocerans and two species of copepods were found, giving a total of 15 registered taxa, with rotifer and tecameba. The densities varied throughout the year (p <0.05), except for rotifers, and November was the most abundant. Copepoda was the group with the highest values of density, having the form of nauplio as the most numerous. Among the cladocerans, Daphnia gessneri was the most abundant species, followed by Moina micrura. As for size classes, macrozooplankton was the most numerous, especially in the months of August and November. The presence of large cladocera species such as those of the Daphnia genus at high densities suggests that the environment does not offer conditions of high eutrophication as confirmed by the Trophic State Index. Environmental conditions, even showing variations throughout the year, have not been shown to be unfit for the development of the zooplankton community.

No / The present study demonstrates the application of decision tree algorithms to the co-crystallization process. Fifty four (54) batches of carbamazepine–salicylic acid co-crystals embedded in poly(ethylene oxide) were manufactured via hot melt extrusion and characterized by powder X-ray diffraction, differnetial scanning calorimetry, and near-infrared spectroscopy. This dataset was then applied in WEKA, which is an open-sourced machine learning software to study the effect of processing temperature, screw speed, screw configuration, and poly(ethylene oxide) concentration on the percentage of co-crystal conversion. The decision trees obtained provided statistically meaningful and easy-to-interpret rules, demonstrating the potential to use the method to make rational decisions during the development of co-crystallization processes.

In light of the world‟s growing demand for energy that is environmentally friendly and sustainable, energy sources such as hydrogen have been considered potential contenders. Hydrogen, which can be used for energy storage, can be produced efficiently by the membrane based Hybrid Sulfur (HyS) thermo-chemical process consisting of a decomposition and an electrolysis step. During the HyS electrolysis step, SO2 and H2O are converted to H2 and H2SO4, which implies that the proton exchange membranes (PEMs) to be used for this process should have a high proton conductivity, limited SO2 cross-over and good H2SO4 stability. In order to find alternatives to the costly and high-temperature unstable Nafion®, the aim of this study was to evaluate the H2SO4 stability of various novel membranes. To structure the study, the novel PEM materials were grouped according to the PBI-type base component within the blend membranes, resulting in three groups comprising non-PBI based membranes, PBIOO based membranes and F6-PBI based membranes. Nafion®212 was included as reference PEM. By repeating the H2SO4 treatment with three different Nafion®212 samples, the obtained Nafion® data was also used to determine the experimental and analytical error margins for the study. The stability of all membranes was determined by submerging the membrane samples in 80 wt% H2SO4 at 80 °C for 120 hours. To determine the influence of the acid on the membranes, all samples were characterised before and after the H2SO4 treatment and compared in terms of their acid stability. Physical characterisation of the PEMs included the evaluation of weight and thickness changes, while IEC, SEM-EDX, FTIR and TGA were used to elucidate possible chemical changes due to the H2SO4 treatment. According to the Nafion®212 data, which had been obtained in triplicate for each of the analytical techniques, the experimental error of both the analytical and H2SO4 treatment remained below 10 %, except for the SEM-EDX sulfur-content where significantly larger errors were observed. In spite of the high error margins of the SEM-EDX data (S-content), its results, combined with the results from the other analytical techniques, resulted in a better understanding (both physical and chemical) of the effect the H2SO4 had on the membrane. This further facilitated the evaluation and comparison of the various blended PEM materials in terms of their H2SO4 stability, and the subsequent relation obtained between the observed stability and the chemical constitution and cross-linking of the membranes. After the 80 wt% H2SO4 treatment, significant weight losses were reported for the non-PBI based and PBIOO based membrane groups in comparison with the minimal changes noted for the F6-PBI based group and Nafion®212. Furthermore, significant thickness changes were reported for most of the PBIOO based membranes. The small weight and thickness changes observed for the F6-PBI confirmed the improved stability of this group of membranes in an H2SO4 environment, most likely due to the protective role of the partially fluorinated basic polymer and the known strength of the C-F bonds present. The results showed a clear correlation between the H2SO4 stability and the specific polymers present in the PEM blends investigated. Specific effects found included sulfonation, salt formation, hydrolysis and the accompanied dissolution of membrane fragments. Significant physical changes, for example ascribed to sulfonation of the concerned polymers, were supported by increased IEC measurements and peak intensities of the FTIR spectra, corresponding to the additional –SO3H groups present, while a variation in TGA signals served to further support the altered membrane composition and structure due to the H2SO4 treatment. In the case of dissolution, the corresponding chemical changes (analytical techniques) were supported by the decreased peak intensities of FTIR spectra, IEC measurements and TGA signals associated with degradation of the polymer backbone. It was shown that the stability of the blended membranes depended on the composition (blend components) of the membrane and the effective cross-linking (interaction) between the blend components. For all three groups examined, it became apparent that blend components sFS and sPSU were, for example, more stable than sPEEK and that ionical cross-linking seemed more effective than covalent cross-linking of blend components. When considering all membranes tested, the non-PBI based blend membranes consisting of (s)PSU and PFS copolymers in the presence of fluorinated cross-linkers and the PBIOO-sPSU blended membranes including most of the F6-PBI based membranes showed sufficient stability to be recommended for SO2 electrolysis. / MSc (Chemistry), North-West University, Potchefstroom Campus, 2014

In light of the world‟s growing demand for energy that is environmentally friendly and sustainable, energy sources such as hydrogen have been considered potential contenders. Hydrogen, which can be used for energy storage, can be produced efficiently by the membrane based Hybrid Sulfur (HyS) thermo-chemical process consisting of a decomposition and an electrolysis step. During the HyS electrolysis step, SO2 and H2O are converted to H2 and H2SO4, which implies that the proton exchange membranes (PEMs) to be used for this process should have a high proton conductivity, limited SO2 cross-over and good H2SO4 stability. In order to find alternatives to the costly and high-temperature unstable Nafion®, the aim of this study was to evaluate the H2SO4 stability of various novel membranes. To structure the study, the novel PEM materials were grouped according to the PBI-type base component within the blend membranes, resulting in three groups comprising non-PBI based membranes, PBIOO based membranes and F6-PBI based membranes. Nafion®212 was included as reference PEM. By repeating the H2SO4 treatment with three different Nafion®212 samples, the obtained Nafion® data was also used to determine the experimental and analytical error margins for the study. The stability of all membranes was determined by submerging the membrane samples in 80 wt% H2SO4 at 80 °C for 120 hours. To determine the influence of the acid on the membranes, all samples were characterised before and after the H2SO4 treatment and compared in terms of their acid stability. Physical characterisation of the PEMs included the evaluation of weight and thickness changes, while IEC, SEM-EDX, FTIR and TGA were used to elucidate possible chemical changes due to the H2SO4 treatment. According to the Nafion®212 data, which had been obtained in triplicate for each of the analytical techniques, the experimental error of both the analytical and H2SO4 treatment remained below 10 %, except for the SEM-EDX sulfur-content where significantly larger errors were observed. In spite of the high error margins of the SEM-EDX data (S-content), its results, combined with the results from the other analytical techniques, resulted in a better understanding (both physical and chemical) of the effect the H2SO4 had on the membrane. This further facilitated the evaluation and comparison of the various blended PEM materials in terms of their H2SO4 stability, and the subsequent relation obtained between the observed stability and the chemical constitution and cross-linking of the membranes. After the 80 wt% H2SO4 treatment, significant weight losses were reported for the non-PBI based and PBIOO based membrane groups in comparison with the minimal changes noted for the F6-PBI based group and Nafion®212. Furthermore, significant thickness changes were reported for most of the PBIOO based membranes. The small weight and thickness changes observed for the F6-PBI confirmed the improved stability of this group of membranes in an H2SO4 environment, most likely due to the protective role of the partially fluorinated basic polymer and the known strength of the C-F bonds present. The results showed a clear correlation between the H2SO4 stability and the specific polymers present in the PEM blends investigated. Specific effects found included sulfonation, salt formation, hydrolysis and the accompanied dissolution of membrane fragments. Significant physical changes, for example ascribed to sulfonation of the concerned polymers, were supported by increased IEC measurements and peak intensities of the FTIR spectra, corresponding to the additional –SO3H groups present, while a variation in TGA signals served to further support the altered membrane composition and structure due to the H2SO4 treatment. In the case of dissolution, the corresponding chemical changes (analytical techniques) were supported by the decreased peak intensities of FTIR spectra, IEC measurements and TGA signals associated with degradation of the polymer backbone. It was shown that the stability of the blended membranes depended on the composition (blend components) of the membrane and the effective cross-linking (interaction) between the blend components. For all three groups examined, it became apparent that blend components sFS and sPSU were, for example, more stable than sPEEK and that ionical cross-linking seemed more effective than covalent cross-linking of blend components. When considering all membranes tested, the non-PBI based blend membranes consisting of (s)PSU and PFS copolymers in the presence of fluorinated cross-linkers and the PBIOO-sPSU blended membranes including most of the F6-PBI based membranes showed sufficient stability to be recommended for SO2 electrolysis. / MSc (Chemistry), North-West University, Potchefstroom Campus, 2014

This thesis is concerned with the study of electrode kinetics, which we shall examine via comparison between theory with experiment. As such the first two chapters outline the basic principles of electrochemical experiments and their simulation. First, we examine the properties of voltammetry at porous electrodes by means of both simulations and experiments. We then introduce the symmetric Marcus-Hush (SMH) model of electrode kinetics as an alternative to the empirical Butler-Volmer model. First, we examine different methods for modeling the voltammetry of kinetically inhomogeneous electroactive monolayers. Next, we perform a critical evaluation of the SMH model for solution-phase systems through extensive comparison to experiments under diffusion-only and convective mass transport conditions using both cyclic and square wave voltammetry. The model is compared with the Butler-Volmer model throughout and is ultimately found to be poorly suited to the parameterisation of electrode kinetics, despite its foundations in the microscopic Marcus theory. We then introduce the asymmetric Marcus-Hush model, which removes the assumption that the Gibbs energy curves for reactant and product have the same curvature. This modification results in an additional parameter which quantifies the asymmetry of the system. A similar evaluation of this model is then undertaken for both surface-bound and solution phase systems and the asymmetric model is found to be a great deal more successful than its symmetric predecessor. Finally we outline a novel technique for extracting kinetic information directly from experimental cyclic voltammetry. The method is simple to implement and is general to all electrode geometries with one-dimensional symmetry.

Forest areas are particularly susceptible to fires, which are often manmade. Too-frequent fires are likely to adversely affect the soil properties as well as vegetation composition, and possibly lead to soil erosion and desertification. One of the most fire affected forest regions in the world is the Mediterranean. Libya, in the Mediterranean region, has soils that are considered to be arid except in a small area called Aljabal Alakhdar (Green mountain), which is the geographic area covered by this study. It is the wettest part of Libya, and has an extensive forest and many agricultural crops. Like other forests in the Mediterranean it has suffered extreme degradation. This is mainly due to people removing fire wood, or sometimes converting forested areas to agricultural use, as well as fires which may alter several soil chemical and physical properties. The purpose of this research was to evaluate the effects of fires on the physical and chemical properties of soil of Aljabal Alakhdar forest in the north-east of Libya. The physical and chemical properties of soil following fire in two geographic areas have been determined, with those subjected to the fire compared to those in adjacent unburned areas in one coastal and one mountain site. Physical properties studied were: soil particle size, soil water content, soil porosity and soil particle density; and chemical properties studied were: soil electrical conductivity (EC), soil pH, soluble and exchangeable Na, K, Ca and Mg, cation exchange capacity (CEC), soluble Cl, CO3 and HCO3, SO4, organic matter, total N and total P. For the first time in Libyan soils, the effect of burning on the magnetic susceptibility properties of soils was also tested. The results showed that except for the soil water content and magnetic susceptibility, fire has not had a clear effect on the soils' physical properties, while there has been a strong impact of fire on most of the studied chemical properties. These results have been used to create an index of burning for such soils in each of the geographic areas, as a step towards creating a model which will enable a subset of soil parameters to be used to estimate how recently a site was burned, as well as defining fire severity at a site.

A água é um recurso natural essencial para a vida, sendo sua qualidade, uma característica extremamente importante para avaliar as possibilidades de seu uso. O presente estudo teve como objetivo avaliar a qualidade da água do complexo de represas Paraibuna-Paraitinga, classificado como corpo dágua Classe 2, localizadas na Bacia do Rio Paraíba do Sul, no Estado de São Paulo. Foram apresentados os resultados das análises dos parâmetros limnológicos: temperatura do ar, temperatura da água, condutividade elétrica, oxigênio dissolvido, pH, transparência, turbidez e sólidos totais; das concentrações dos ânions: nitrato, fluoreto, sulfato, fosfato e cloreto; e das concentrações de elementos-traço: Hg, Se, As, Sb, Pb, Cd, Ag, Al, B, Ba, Be, Co, Cr, Ca, Cu, Fe, K, Li, Mg, Mn, Mo, Na, Ni, P, Si, Sn, Sr, Ti, V e Zn, obtidos a partir das amostras de água de superfície, meio e fundo da coluna dágua, representativas de oito estações de amostragem. Os resultados foram comparandos com os limites estabelecidos na Resolução CONAMA 357/2005. Dos 30 elementos analisados, somente Alumínio, Ferro, Fósforo, Prata e Manganês apresentaram concentrações acima dos padrões legais, principalmente nos períodos chuvosos. Os paramêtros limnológicos ficaram dentro dos padrões para ambientes oligotróficos, como as represas são classificadas. As espécies iônicas apresentaram a maioria dos resultados abaixo dos limites de quantificação e abaixo da legislação. A partir dos resultados obtidos, infere-se que as represas Paraitinga e Paraibuna encontram-se preservadas, e estão isentas de contaminação por metais e elementos-traço, associando as concentrações de Al, Fe, P, Ag e Mn à característica geológica da região. / Water is a natural resource, essential to life, and its quality, an important feature to evaluate the possibilities of its use. This study aimed to evaluate the water quality of the Complex Paraibuna-Paraitinga, classified as Class 2 water body, located in the basin of Paraíba do Sul River, State of Sao Paulo. In order to analyze the water quality of these reservoirs, this paper presents an analysis of some limnological parameters: air temperature, water temperature, electrical conductivity, dissolved oxygen, pH, transparency, turbidity and total solids; the concentrations of anions: nitrate, fluoride, sulfate, phosphate and chloride; and concentrations of trace elements: Hg, Se, As, Sb, Pb, Cd, Ag, Al, B, Ba, Be, Co, Cr, Ca, Cu, Fe, K, Li, Mg, Mn, Mo, Na, Ni, P, Si, Sn, Sr, Ti, V and Zn, obtained from samples of surface water, middle and bottom of water column, representing eight sampling stations. The results were compared with the limits established by CONAMA Resolution 357/2005. From the 30 elements analyzed, only aluminum, iron, phosphorus, silver and manganese concentrations were above the legal standards, especially in rainy periods. The limnological parameters were within the standards for oligotrophic environments, such as these reservoirs are classified. The ionic species present most results below the quantification limits and under the legislation. From the results obtained, it appears that the reservoirs Paraibuna and Paraitinga are preserved, and are free of contamination by metals and trace elements, suggesting that the concentrations of Al, Fe, P, Ag and Mn are linked to the geological feature of the region.