Avaliando a contaminação por elementos traço em atividades de maricultura: resultados parciais de um estudo de caso realizado na ilha de Santa Catarina, Brasil

Adopting the perspective of human health risk assessment, an interdisciplinary research group has been investigating since 1998 the quality of mussels and oysters cultivated in coastal zones of Santa Catarina State. Evaluation of physico-chemical parameters considered relevant in measuring the degree of eutrophication showed values compatible with the dynamics of well balanced environmental systems. Concentrations of metallic and semi-metallic elements in seawater and bivalves were found to be similar to or lower than those found in Chile, Greenland and the USA. Further investigations focusing upon sediments will provide new and useful data for the management of sustainable mariculture strategies in Brazil.

Desempenho físico-químico de metais e estruturas de concreto de redes de distribuição de energia: estudo de caso na região de Manaus

The influence of natural aging furthered by atmospheric corrosion of parts of electric transformers and materials, as well as of concrete poles and cross arms containing corrosion inhibitors was evaluated in Manaus. Results for painted materials, it could showed that loss of specular gloss was more intensive in aliphatic polyurethane points than in acrylic polyurethane ones. No corrosion was observed for metal and concrete samples until 400 days of natural aging. Corrosion in steel reinforcement was noticed in some poles, arising from manufacturing faults, such as low cement content, water/cement ratio, thin concrete cover thickness, etc. The performance of corrosion inhibitors was assessed by many techniques after natural and accelerated aging in a 3.5% saline aqueous solution. The results show the need for better chemical component selection and its concentration in the concrete mixture.

Avaliação da composição química de águas do Sistema Guarapiranga: estudo de caso nos anos de 2002 e 2003

The supply of drinking water in the Metropolitan Area of São Paulo City has been a great and serious challenge in the latest years. This work demonstrates the viability of the evaluation of the degree of contamination of the water reservoirs using analytical procedures, which allow the analysis of several compounds at relatively low cost: stripping square wave voltammetry (SSWV) and capillary zone electrophoresis with contactless conductivity detection (CZE-CCD). The results of ionic composition indicated significant contamination of the Guarapiranga water system by human activities on the reservoir banks. In fact, the Guavirutuba and Itupu streams presented high concentrations of phosphate and ammonium ions. This can be directly related to misuse and unruled occupation of the soil and precarious sanitary infrastructure.

Contaminação de aqüífero por hidrocarbonetos: estudo de caso na Vila Tupi, Porto Velho - Rondônia

Underground storage tanks (UST) are widely used in the Porto Velho area. A large number of these USTs are in bad condition due to corrosion processes causing groundwater contamination. A large number of these leaking underground fuel tanks (LUFT) are in urban areas but due to the lack of water quality monitoring, they are only detected when there is a high contamination level. This study identified petroleum hydrocarbons, derived from a LUFT, by a silica gel/petroleum ether partitioning gravimetric method and by gas chromatographic analysis of samples collected in wells dug in a gas station and in houses in the aforementioned neighborhood.

Avaliação da qualidade de sedimentos - estudo de caso: sub-bacia do Ribeirão Espírito Santo, afluente do Rio São Francisco

This study evaluated the environmental impact resulting from surface water and sediment contamination by metals in a watershed affected by a tailing basin that controls effluents coming from a zinc-ore beneficiation plant. The studies combined assessments of sediment chemistry (exceedances of sediment quality guidelines), benthic assemblage structure and acute and chronic ecotoxicity. The results showed that the levels of metal contamination in sediments are not yet enough to cause deleterious effects to the biota. However, the ecotoxicity tests indicated the occurrence of chronic effects, demonstrating that other factors, as the use of fertilizers, could also be a source of contamination.

Avaliação e identificação de parâmetros importantes para a qualidade de corpos d'água no semiárido baiano. Estudo de caso: bacia hidrográfica do rio Salitre

Objective of this work was identifying superficial water quality parameters, significant to semi-arid hydrographic basins, minimizing costs of water monitoring. The Salitre river basin, an important sub-basin of the São Francisco river, was used as a case study. STD, Cl-, DO, BOD, pH, NO3-, PO4(3-), Al, Cu, Fe, Mn, Ni and Pb were considered the most significant parameters, with concentration levels found in some stretches of the basin not compliant with the current legislation. Some of the Salitre river basin sediments may represent a risk to the quality of the water body in relation to levels of nickel and zinc.

Validação de metodologia analítica para determinação de mercúrio total em amostras de urina por espectrometria de absorção atômica com geração de vapor frio (CV-AAS): estudo de caso

Mercury is a toxic metal used in a variety of substances over the course history. One of its more dubious uses is in dental amalgam restorations. It is possible to measure very small concentrations of this metal in the urine of exposed subjects by the cold vapor atomic absorption technique. The present work features the validation as an essential tool to confirm the suitability of the analytical method chosen to accomplish such determination. An initial analysis will be carried out in order to evaluate the environmental and occupational levels of exposure to mercury in 39 members of the auxiliary dental staff at public consulting rooms in the city of Araguaína (TO).

Substitutos do " novo" mundo para as antigas plantas raras: um estudo de caso dos bálsamos

Convinced that the " true balsam" was lost forever, Conrad Gesner described other substances with similar healing virtues. However, he was not the only one in the 16th to search for other varieties of balsamic oleoresins. The arrival of the Europeans to the Americas allowed the finding of native plants with properties similar to those of the original balsam, including Balsam of Peru, Balsam of Tolu and particularly in the Brazilian area, Balsam of Copaiba. Focusing on the Brazilian context, this paper analyzes two different moments in the transit of the newly found varieties of balsams to the pharmacopeia and materia medica.

Processo de transferência de tecnologia da universidade para a indústria: estudo de caso envolvendo a conversão de glicerol

Currently, public policy has encouraged innovation in universities and also transference of technology to the industry. Another important stage to be considered would be the registration or filing of a patent and the economical viability study. Government programs, such as the innovation incentive program, among others, should facilitate popularization and promote interest by industry. In this work we described the steps, from the conception of the idea to the scale up going through its interest by the industry. The case study is about the glycerol conversion utilizing modified niobia as catalysts.

Estimativa da incerteza de medição: estudo de caso no ensaio de migração de ε-caprolactama com determinação por CG-DIC

The estimation of measurement uncertainty of an analytical result is an important tool to be applied for compliance to ISO IEC 17025. Through the available guides it is possible to establish procedures and criteria for the estimation of measurement uncertainty. This paper presents a case study on the estimation of measurement uncertainty in migration the test of ε-caprolactam from the polyamide 6 packages to fatty foods with determination by GC-FID. The calculation methodology used for the estimation of measurement uncertainty for the migration test was developed based on the guides EURACHEM / CITAC and ISO GUM, taking into account relevant aspects of the migration test. The expanded uncertainty estimated was approximately 23% of the concentration of migration.

Desenvolvimento sustentável e pensamento complexo: estudo de caso: o uso de argilas como catalisadores

Use of clays as catalyzers in heterogeneous processes has increased significantly given their low cost, safety and commercial availability. However, interconnected political, economic, social, environmental, geological, and chemical aspects should be considered for chemical processes to satisfy sustainable development concepts. This concept requires complex thinking involving different areas of knowledge in dialogue, contrasting with classical thought, which is linear and Cartesian. Thus, this paper discusses the principles of complex thought in the concept of sustainable development exemplified by use of clay as a clean technology in organic synthesis.

Fatores químicos e físicos que afetam a contaminação por chumbo e cobre em água potável: uma abordagem para o estudo de caso em química analítica

Lead and copper concentrations in drinking water increase considerably on going from municipality reservoirs to the households sampled in Ribeirão Preto (SP-Brazil). Flushing of only 3 liters of water reduced metal concentrations by more than 50%. Relatively small changes in water pH rapidly affected corrosion processes in lead pipes, while water hardness appeared to have a long-term effect. This approach aims to encourage University teachers to use its content as a case study in disciplines of Instrumental Analytical Chemistry and consequently increase knowledge about drinking water contamination in locations where no public monitoring of trace metals is in place.

Métodos para análises de HPA e BTEX em águas subterrâneas de postos de revenda de combustíveis: um estudo de caso em Campo Grande, MS, Brasil

Two methods using headspace solid-phase microextraction and gas chromatography - mass spectrometry were developed for the determination of polycyclic aromatic hydrocarbons (PAH) and BTEX. Best results were obtained using DVB/CAR/PDMS fiber, with 10 min extraction at 25 °C and 0.15 min desorption at 260 °C (BTEX), and PDMS/DVB fiber, with 60 min extraction at 90 °C, 10% NaCl and 5 min desorption at 270 °C (PAH). LOD intervals were 3x10-2 - 5x10-2 µg L-1 (BTEX) and 1.6x10-3 - 1.4 µg L-1 (PAH). The methods were applied to forty-five groundwater samples from monitoring wells of gas stations and only benzene level exceeded the limit established by Brazilian regulations.

Separação e determinação quantitativa dos alcanos lineares e dos cíclicos/ramificados em petróleos brasileiros por aduto de ureia e cromatografia gasosa: um estudo de caso revisitado

A complete analysis of oils and their fractions allows correlations to be defined between their composition and derivatives or related geological materials. This work focused on optimization and implementation of a method for separation and quantification of n-alkanes in Brazilian oil samples by urea adduction and GC-FID techniques. Ten samples with different ºAPI were analyzed in triplicate to quantify individual n-alkanes and cyclic/branched alkane fraction. For individual quantification of n-alkanes, internal standardization with deuterated n-tetracosane was used. The use of urea adduction for the separation and quantification of n-alkanes was highly effective, with recovery values of above 80%.