The intensive use of pesticides in agriculture has prompted researchers to develop new methods for identifying these pollutants in water. This study sought to validate a high performance liquid chromatography (HPLC) method to determine the concentration of the pesticide glyphosate in groundwater samples by using solid-phase extraction (SPE) filters after derivatization with chloroformate 9-fluorenylmethoxycarbonyl (FMOC-Cl). For the HPLC method, we evaluated the following main validation parameters: linearity, specificity, precision, accuracy, robustness, and limits of detection and quantification. After validation of the method, we determined the concentration of glyphosate in samples from thirteen deep, tubular wells distributed in urban and rural areas in Chapecó, SC, Brazil. The solvent used in the extraction of excess FMOC-Cl was dichloromethane and subsequently filtration was performed on C18 SPE, and injected into the chromatograph column in amino polymer with fluorescence detection. The analytical curve made in ultrapure water was linear, with a correlation coefficient of 0.99. The limits of detection and quantification were 0.24 and 0.07 µg L-1 , respectively. Recovery tests in natural waters ranged from 90.37 to 101.70%. Glyphosate was detected in 5 of the thirteen wells evaluated. The highest concentration of glyphosate (6.80 µg L-1) was detected in a countryside well, near the municipal water supply. Despite the low levels of glyphosate detected in our study, any amount present in groundwater samples is worrisome, as these molecules have low ground mobility.
Resumo: No ensino de Biologia, os conteúdos são bastante diversos e relacionados ao cotidiano dos estudantes, possibilitando a relação entre a teoria e a prática. O conteúdo sobre os anfíbios apresenta grande potencial para ser trabalhado de maneira dinâmica e alternativa no ambiente escolar, pois muitos aspectos interessantes sobre o grupo podem ser abordados.Neste contexto, este estudo teve como objetivo conhecer como a temática anfíbios é trabalhada no ensino médio. A pesquisa foi realizada no ano de 2007, de maneira qualitativa em 20% das escolas estaduais do município de Chapecó, estado de Santa Catarina, sendo entrevistados dez professores da disciplina de Biologia atuantes no ensino médio destas escolas.Palavras-chave: Biologia. Ensino médio. Métodos de ensino. Anfíbios.
The objective of this work was to evaluate the groundwater quality of the Guarani/Serra Geral Integrated Aquifer System (GAIS / SGAIS) in a region located in the western part of the state of Santa Catarina. A total of 105 water wells were selected which five are exploring water from the Guarani Aquifer and 100 from the Serra Geral Aquifer. A sample of each well was submitted to microbiological (total coliforms and Escherichia coli) and physicochemical analyzes (dissolved oxygen, pH, turbidity, electrical conductivity, alkalinity, chlorides, fluorine, sulfates, potassium, sodium, calcium, magnesium, iron, manganese, nitrate). For analyze possible contamination by BTEX hydrocarbons (benzene, toluene, ethyl benzene, xylenes) the water of 25 wells in the urban environment was analyzed in strategic points close to possible risk of risk contamination agents. In another 25 wells in the rural area the water was collected for analyze the presence of glyphosate. Some groundwater with turbidity, pH, iron, manganese, total and thermotolerant coliforms were found in disagreement with Ministry of Health Ordinance 2914/2011. Furthermore, there was no BTEX and glyphosate contamination detected in any of the wells.
Analysing which environmental features influence structure of communities is important to establish management and conservation priorities for regional biodiversity. In this study, we analysed the structure of amphibian larval assemblages in southern Brazilian streams and their relationships with local and landscape factors. We sampled tadpoles in 18 streams between November 2014 and February 2015. We collected pH, electric conductivity, temperature and dissolved oxygen in streams, and performed laboratory analyses to estimate metal concentrations in water samples. We collected metrics describing landscape factors, such as the land cover classification of a set of buffers around the streams. We found eight amphibian species in total. Tadpole richness was higher in streams with greater cover of agriculture in the 50 and 100 m buffers, but it was also lower in streams with greater cover of buildings in the 100 m buffer. Highest abundance was also found in streams with greater dissolved oxygen and larger areas of dams in the 250 m buffer, but it was lower in streams with larger areas of forests in the 500 m buffer. The presence of agriculture in the immediate surroundings of streams can increase richness of amphibians due to the occupation by open‐habitat species. On the other hand, the low number of rheophilic species suggests that soil use may restrict permanence of these species.Abstract in Portuguese is available with online material.
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