The objective of this study was to evaluate the concentration of Cu, Zn, Cr and Pb in different species of fish collected in the estuarine and limnic regions of the São Gonçalo channel, located in the Patos-Mirim lagoon complex in the coastal plain of Rio Grande do Sul State (Southern Brazil) during 2013 (autumn, winter and spring) and 2014 (summer). Fish samples were decomposed in a digester block with a reflux system under conditions optimized using a central composite design as it follows: 250 mg of fish sample, 5 mL HNO 3 , 2 mL H 2 O 2 during 2 h at 150 °C. The concentrations obtained ranged from 6.7 to 12.0 mg kg-1 for Cu; 1.8 to 23.6 mg kg-1 for Zn; 37 to 487 µg kg-1 for Pb; and 40 to 1268 µg kg-1 for Cr. The highest concentrations of Cu, Zn and Pb, were observed in fishes collected at locations in the estuarine region and Cr showed high levels, especially in the limnic region. The samples of the species Loricariichthys anus (viola) showed the highest concentrations of all analytes investigated.

O texto objetiva apresentar uma proposta que busca auxiliar professores de Pedagogia e/ou de Ciências a introduzir modos de pensar e entender a temática da COVID-19 na ótica da Ciência, sobretudo por meio de atividades que permitem introduzir alguns conceitos de Química desde o Ensino Fundamental. A proposta didática se fundamenta na perspectiva da alfabetização científica e nos três momentos pedagógicos, organizada em uma sequência de atividades de ensino com metodologias que envolvem, por exemplo, aulas expositivo-dialogadas, atividades experimentais e lúdicas, leitura e interpretação. As atividades possibilitam problematizar o papel da Ciência no contexto da temática da COVID-19 e se apropriar de palavras e significados com origem na cultura da Ciência e da Química, com vistas a viabilizar o pensar e o agir de modo mais consciente e responsável, em especial, sobre as diferentes formas de higienização das mãos que ajudam no combate da transmissão e do contágio do vírus. Palavras-chave: COVID-19; alfabetização científica; três momentos pedagógicos; ensino de Ciências.

This study evaluated the total concentrations of Cd, Cr, Cu, Pb and Zn in sediments samples from the São Gonçalo channel, Patos-Mirim lagoon complex, RS state, Southern Brazil during 2013 autumn, winter and spring, and 2014 summer. Ultrasound-assisted extraction method was employed to extract metals from the sediment samples. The sample powder was mixed with HNO3 and HF in an ultrasonic bath during 60 minutes at 25 oC. The limits of detection were 0.002; 0.026; 0.83; 0.386 and 0.44 mg kg-1 for Cd, Cr, Cu, Pb and Zn, respectively. The accuracy of the method was confirmed by analysis of two sediment certified reference materials and its precision was determined by the values of relative standard deviation lower than 9.1%. The concentrations obtained ranged from 0.11 to 0.58 mg kg-1 for Cd; 14.7 to 38.4 mg kg-1 for Cr; 3.9 to 102.0 mg kg-1 for Cu; 1.6 to 3.11 mg kg-1 for Pb; and 29.3 to 126 mg kg-1 for Zn. These values did not exceed the probable effect levels (PEL). Simplicity, low cost and high efficiency are some of the qualities of the method, making it adequate for routine analysis.