Aplicação de SPME (Solid Phase Micro-Extraction) na análise de águas potáveis de três localidades do estado de São Paulo

The technique of solid phase microextraction (SPME) was used for the extraction of halogenated contaminants of water samples from three cities of the State of São Paulo and the extracts were submitted to gas chromatographic analysis with electron capture detection (GC-ECD). In the samples of water collected at the city of São Paulo the detected level of trihalomethanes (THM) expressed as the sum of chloroform, dibromochloromethane and dichlorobromomethane, were higher than the permissible limit established by the Brazilian regulation. In the samples collected at the two other cities the level of any of the three THM remained below the sensitivity of the ECD.

Contaminação por crômio de águas de rios proveniente de curtumes em Minas Gerais

In order to evaluate the chromium contamination from tannery discharges into rivers in the State of Minas Gerais, samples of water and suspended material were collected and submitted to chemical analysis. The total content of chromium in the samples was measured by flame atomic absorption spectrophotometry. Water samples were analysed by standard addition method, while chromium concentration in suspended materials was determined by calibration curves. Localities investigated were Ipatinga, Matias Barbosa, Dores de Campo, Ressaquinha, Ubá and Juiz de Fora. Samples from a not-industrialized area were also analysed to obtain regional background values. Metal inputs were related to effluent discharges into the rivers. Suspended material transported Cr downriver. Chromium concentration in river water exceeded 656 times the value of the Brazilian Environmental Standards, while its concentration in suspended material ranged from 15 to 11066 µg g-1.

Determinação de resíduos de organoclorados em águas fluviais do município de Viçosa - MG

In this work the contamination, by organochlorinated, of a drinking water source located in the region of Viçosa, MG, was evaluated. The identification and quantification of the analytes was carried out using a gas-chromatograph equipped with an electron capture detector after liquid-liquid extraction and concentration. Four insecticides, Aldrin, Epoxy heptachloride, Endrin and op'- DDT were detected in concentrations that are higher than the safety limits established in the Brazilian legislation.

Eletrocatálise e poluição ambiental

This work considers mainly the problem of environmental pollution due to the production of energy by burning fossil fuels, particularly in urban vehicles. Electrochemical energy conversion is proposed as a partial solution to this problem, through the use of hydrogen in fuel cells. In both the production of hydrogen by electrolysis and in the electrochemical processes in fuel cells, the key factor is electrocatalysis. The concept of electrocatalysis, the production of catalysts and supported catalysts and their use in practical systems for the conversion of energy is discussed.

Contaminação do ambiente aquático por pesticidas. Estudo de caso: águas usadas para consumo humano em Primavera do Leste, Mato Grosso - análise preliminar

A preliminary analyses of the possible contamination of superficial and underground water by the active ingredients of the pesticide products used in the surroundings of the urban area of Primavera do Leste, Mato Grosso, Brazil, was carried out. A description of the study region and of its environmental characteristics, which can favor the contamination of the local aquatic environment, was presented. The EPA screening criteria, the groundwater ubiquity score (GUS) and the criteria proposed by Goss were used to evaluate which pesticides might contaminate the local waters. Among the active ingredients studied, several present risks to the local aquatic environment.

Distribuição de coprostanol (5beta(H)-colestan-3beta-ol) em sedimentos superficiais da Baía de Guanabara: indicador da poluição recente por esgotos domésticos

A critical evaluation is presented on the use of faecal sterols for the identification of sewage contamination in Guanabara Bay. Sediments were collected from 8 stations in the bay selected as representative of different contamination levels. GC/MS determination of faecal sterols gave: coprostanol, 335 - 40000 ng g-1; coprostanone, 112-4136 ng g-1; cholesterol, 1407-7800 ng g-1; cholestanol, 2011 - 10900 ng g-1 and cholestanone, 655-7954 ng g-1. The observed concentration is in accordance with the presence of known pollution sources, however, concentration ratios of different sterols species produced unclear results evidently influenced by primary production and microbial processes.

Construção e otimização de um reator de baixo custo para a fotodegradação da matéria orgânica em águas naturais e sua aplicação no estudo da especiação do cobre por voltametria

This work describes the construction of a home-made low-cost reactor, using easily available materials, capable of destroying efficiently dissolved organic matter. Just 30 minutes of irradiation were sufficient to destroy more than 99% of the humic acids present in a solution of 4 mg C L-1. Copper speciation was evaluated in natural waters of different salinities to test the reactor's efficiency in destroying organically complexed metal species. The effect of the organic matter concentration, salinity, dissolved oxygen and temperature in the photo-oxidation process is discussed.

Determinação de baixas concentrações de cobre em águas naturais por espectrofotometria de absorção atômica em chama usando um sistema SIA com uma coluna de poli(etilenimina)

This paper describes a sequential injection analysis (SIA) set-up coupled to a flame atomic absorption spectrometer (FAAS) to accomplish the determination of low concentrations of copper in drinking waters. Copper is first retained under neutral media in an on-line 29x1.6 mm column filled with poly(ethylenimine) immobilised on silica gel. The retained analyte is then eluted by flowing through the column 250 mL of a nitric acid solution. The selection of 3.85 ml of sample enabled to obtain a detection limit of 0.27 mug/L and a sampling rate of about 24 samples/h. There was a good agrement between the results of 12 samples furnished by the proposed procedure and by electrothermal atomic absorption spectrometry. Repeatability assessment gave a relative standard deviation of 1.3 % after ten replicate analysis of a sample containing about 70 mug/L in copper..

Emprego de reagente em suspensão em sistema de injeção em fluxo: determinação espectrofotométrica de sulfato em águas naturais

This paper presents an automatic procedure employing a reagent in the form of a slurry in a flow-injection system. The feasibility of the proposal is demonstrated by sulphate determination in water using the Barium Chloranilate method, which is based on the precipitation of barium sulphate. The release of a stoichiometric amount of highly colored chloranilic ions is monitored at 528 nm. The reaction is carried out in alcoholic medium in order to reduce the solubility of the reagent. A considerable improvement in the sensitivity is attained by adding ferric ions to the released chloranilic ions. An on-line filtration step to separate the excess reagent from the released chloranilic ions was necessary. In addition, a column containing a cation exchange resin was included in the manifold to remove potentially interfering ions. The proposed procedure is suitable for 30 determinations per hour and the relative standard deviation is less than 2%. The analytical curve is linear between 0.0 and 40 mg L-1 and the determination limit is about 2.0 mg L-1SO4(2-). Accuracy was confirmed by running several samples already analysed by a standard turbidimetric procedure.

Alternativa analítica para especiação físico-química de mercúrio em águas costeiras tropicais

The determination of the physical-chemical mercury speciation in tropical coastal waters using the derivatization technique with CVAFS detection was optimized. This methodology is able to separate the elementary, reactive, organic and total mercury phases with low operational costs. The importance of bromide chloride solution, the diluted aqua regia, used as the oxidative solution, and different compositions of the reductive solution of stannous chloride were tested and the better results for coastal waters are presented. The recuperation of the sum of the different phases ranges from 80 to 94% of the total Hg content in duplicates of different marine samples. The optimized methodology permits important studies on the mercury cycle in the coastal environment.

Métodos de baixo custo para purificação de reagentes e controle da contaminação para a determinação de metais traços em águas naturais

Probably one of the most difficult and challenging aspects of measuring trace metals in natural waters is to avoid contamination during sampling, manipulation and analysis. This work discusses how to avoid contamination using simple procedures, and considers alternative methods to purify deionised water and low grade reagents to enable accurate determination of trace metals in natural waters in a common laboratory. Measurements were performed by cathodic stripping voltammetry and copper was used as a model metal to test the procedures. It was possible to evaluate copper speciation in natural waters even when total dissolved copper concentration was as low as 1.5 nmol L-1. The methods' accuracy was confirmed by analysis of certified seawater.

Influência da mineralogia dos sedimentos das bacias hidrográficas dos rios Mogi-Guaçu e Pardo na composição química das águas de abastecimento público

This work studied bottom sediment from catchment area of 13 stations of water treatment of Mogi-Guaçu and Pardo river basins, through identification of mineralogical matrix and its correlation with potential bioavailable metal concentrations. The main clay minerals present were kaolinite and illite. The values of iron and manganese grades were derived from reddish-purple soil, which is rich of such elements. They had higher values on areas with weak vegetation cover compared with other areas linked with more vegetation density. Higher values of calcium at Campestrinho station (IG 69) were associated to occurrence by weathering of calcium feldspars markedly present on regional porphiritic acid rocks. The concentrations of phosphorous are characteristically high on areas near urbanized regions.

Avaliação de poluição do ar por chumbo particulado: uma abordagem geoquímica

High lead concentrations up to 5478 mg kg-1 were detected in dry atmospheric precipitations in Rio Grande city and adjacent area. Lead anomalies cover up to 30% of the study area. Lead concentration measurement in dry atmospheric precipitation and suspended particulate matter provides a possibility to detect concentrations above lead threshold in the air. The most impacted areas are fishermen's villages. The most possible source of lead in the air is uncontrolled sub industrial activity of local population

Poluição química relacionada ao ar de interiores no Brasil

During the last two decades there has been increasing concern within the scientific community related to the effects of indoor air quality on health. Changes in building design devised to improve energy efficiency and new synthetic building materials have contributed to increase pollutant concentrations. These factors have generated poor air quality and caused the development of a lot of symptoms known as Sick Building Syndrome (SBS). In Brazil, there are few studies in this area, collected in this review to support researches and awareness of the need to adopt preventive measures to reach a better quality for the Indoor Environment.

Gerenciamento de resíduos químicos e águas servidas no laboratório de isótopos estáveis do CENA/USP

A system for disposal and recovery of the main effluents and chemical waist from isotope separation plants and enriched compounds-15N and 34S production has been carried out at the Stable Isotope Laboratory (LIE) of the CENA/USP. Around four hundred thousand liters of effluents has been recovered yearly. Among the recovered chemical wastes, the more relevant are: ammonia; brome; ammonium and sodium sulfate; sodium hydroxide; sulfur dioxide; and hydrochloric acid. Chemical wastes containg recoverable heavy metals (Ag, Cr and Cu) and solvents (methanol, ethanol and acetone) are processed and recovered. Gaseous emissions, mainly H2S are used for recovery of heavy metals solutions. The minimization of the residues waters, as well the reduction of electric energy consume was established using a water deionization system. A cost/effect balance of the process is reported.