The Corda river is the main source of fresh water for recreation, leisure, supply and irrigation to the municipality of Barra do Corda - MA. The objective of the present study was to evaluate the physicochemical parameters of Corda river’s water using the methodology described by the American Public Health Association. The water samples were collected in the seasonal period spanning between February and September of the year of 2018. The parameters which were analyzed during the study were pH, conductivity, turbidity, total dissolved solids and salinity, besides concentrations of nitrite, nitrate, and total phosphorus. Three principal components were identified during the PC Analysis. Those components explain more than 74% of the total variance observed during the rainy and dry season. Axis 1and 2 included variables which were related to quality of water and could be affected by the change in seasons. The results indicated that pH (7.11), P (2,82 mg L-1), NO3- (3,23 mg L-1), turbidity (35.82 NTU) and conductivity (35.83 µS/cm) parameters were most affected by changing from rainy to dry season.

No abstract

Population growth has led to occupation and housing near rivers and lakes. This contributes to the increase of water pollution. The industrial laundry sector, for example, consumes a large quantity for its processes and pollutes water bodies due to the improper disposal of its effluents which contain numerous harmful compounds. This study employed electroflocculation in effluent treatment and evaluated its efficiency by analyzing turbidity, chemical oxygen demand, and pH levels. It used aluminum and zinc plates as sacrificial electrodes and principal component analysis (PCA) as a statistical tool. A maximum electroflocculation time of 40 min was utilized in order to obtain efficient results from the study. The experiment showed significant improvement in the water quality in the physicochemical aspects, primarily concerning the reduction of organic matter in the effluent. The efficiency of this treatment increased with higher current; however, both the aluminum and zinc plates reacted differently to pH, COD, and turbidity. Two principal components were generated to explain 86.90% of the data variance in the experiment. The principal component analysis indicated that the aluminum electrode showed the best correlation (|>0.5|) for pH, COD, and turbidity in the effluent treatment.

No abstract

The objective of this study was to optimize the operational conditions of the Microwave-Assisted Extraction (MAE) of Canavalia ensiformis leaves by Response Surface Methodology (RSM), based on analysis of phenolic compounds obtained from the aqueous extracts. Optimal conditions for MAE were temperature of 100°C, extraction time of 10 min and ramp of temperature of 5 min, using approximately 2 g of dry plant material and 30 mL of water. The extracts obtained were determined by HPLC-UV. Among the phenolic compounds present in plant leaves, ferulic acid was selected as reference in all analyzes of the extracts. The results showed that the developed model was able to describe the effects and the relationship between them in the performance of the extraction, taking full advantage of all the limitations of the equipment.

Thus, the analytical methodology satisfies the minimum requirements for control of residues of such insecticides in rice samples destined for human consumption.

A água potável é um dos principais meios para preservação da saúde humana, entretanto, a água que não possui o tratamento adequado pode servir como um potencial veículo para transmissão de doenças, pois é capaz de veicular inúmeras enfermidades a partir de falhas no controle de qualidade dos mananciais e reservatórios que fornecem água para população, seja por ingestão ou por contato da pele e mucosas com a água contaminada. O aumento da demanda por água potável e os riscos de contaminação dos poços subterrâneos por se encontrarem próximos a fossas e depósitos inadequados de lixo são alguns dos problemas enfrentados pelo Serviço Autônomo de Água e Esgoto (SAAE) do município de Raposa.  Com o auxílio de Análises das Componentes Principais, foram geradas três Componentes Principais (CP) explicando mais de 75% da variância total entre os períodos estudados. Nas CP1, CP2 e CP3 foram enquadradas as variáveis pH, turbidez, condutividade, sólidos totais dissolvidos, teor de nitrato e nitrito relacionadas a variação em períodos sazonais.

An alternative and fast method for the analysis of a mixture of nine triazines herbicides in soil is presented. The method is based on MAE (microwave-assisted extraction) of herbicides using ethyl acetate as extractant. The economy in the use of solvents coupled with the decrease in extraction time and lower power consumption make MAE a technique that meets the principles of green chemistry. MAE operational parameters, extraction time, mass of the sample and extraction temperature, were optimized by RSM (response surface methodology). Determination of analytes was completed using gas chromatograph coupled to mass spectrometry detection. The selected triazines could be efficiently extracted by the solvent at 80 °C for 10 min, with 80% output of maximum power. When the optimized method was applied to analysis samples, the recoveries of analytes ranged from 81.8 to 106.0% and relative standard deviations were lower than 8.41%. The method is stable and reasonable, which can be used for the determination of ninetriazine herbicides residues in soil.