Elucidating the role of cyanobacteria in the biotransformation of arsenic (As) oxyanions is crucial to understand the biogeochemical cycle of this element and indicate species with potential for its bioremediation. In this study, we determined the EC50 for As(III) and As(V) and evaluated the biotransformation of As by Synechococcus sp. through high-performance liquid chromatography hyphenated to inductively coupled plasma mass spectrometry (HPLC-ICP-MS) and X-ray absorption fine structure spectroscopy (XAFS). Synechococcus sp. exhibited higher sensitivity to As(III) with an EC(50, 96 h) of 6.64 mg L(-1) that was approximately 400-fold lower than that for As(V). Even though the cells were exposed to concentrations of As(III) (6 mg L(-1)) approximately 67-fold lower than those of As(V) (400 mg L(-1)), similar intracellular concentrations of As (60.0 μg g(-1)) were observed after 30 days. As(V) was the predominant intracellular As species followed by As(III). Furthermore, organic As species such as monomethylarsonic acid (MMA) and dimethylarsinic acid (DMA) were observed in higher proportions after exposure to As(III). The differential toxicity among As oxyanions indicates that determining the redox state of As in the environment is fundamental to estimate toxicity risks to aquatic organisms. Synechococcus sp. demonstrated potential for its application in bioremediation due to the high accumulation of As and production of As organic compounds notably after exposure to As(III).

ResumoA telefonia celular pela sua modernidade e múltiplas facetas de produção de conhecimento é uma temática que carece de estudos teórico-práticos no ambiente escolar, principalmente interligada à visão realista do movimento CTS (Ciência, Tecnologia e Sociedade). Sendo assim, esta pesquisa teve por objetivo desenvolver a temática: "Telefonia celular na atualidade" de forma integrada entre os conteúdos curriculares das Ciências da Natureza e embasada na abordagem CTS. Para isso, foram planejadas, executadas e avaliadas sequências de atividades diferenciadas para 40 adolescentes do 1º ano do Ensino Médio de uma escola pública. Os resultados mostraram que a didática interdisciplinar apoiada na tríade CTS proporciona aos estudantes maior facilidade em entender os aspectos relacionados à telefonia móvel, provocando refl exões sobre os benefícios e malefícios da mesma. Os docentes envolvidos perceberam a importância e a necessidade de maximizar atividades articuladas nos seus planejamentos. Palavras-chave:Telefonia celular, Ciências naturais, CTS.

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Cyanobacteria possess metallic ion interaction properties that should be explored with the aim of recovering arsenic (As) contaminated areas. Contamination of As is an issue of worldwide concern due to the risk of human chronic intoxication and negative environmental health effects. In this study the potential decontamination of As (III) and As(V) using cyanobacteria cultures was assessed. Microcystis novacekii (Komárek-Compere, 1974) showed normal growth in concentrations of As(V) similar to those found in natural environments contaminated with As, demonstrating its resistance to As(V). Growth rates gradually decreased upon exposure to high As(V) concentrations from 600 to 5630 mg.L -1 while As(III) affected growth from 14.7 -85.7 mg.L -1 . The As(III) EC50 value (41.0 mg.L -1 ) was 140-fold lower possibly due to differences in As(III) and As(V) absorption pathways. Upon exposure to 14.7 mg.L -1 As(III), 21.2% of As was removed from culture medium. The absorption capacity (12000 mg.kg -1 ) remained constant with increasing As(III) concentrations in a dose independent effect. The potential of M. novacekii for As decontamination was demonstrated in this study. This microorganism is recommended in As bioremoval studies due to its autotrophicmixotrophic growth, low nutritional requirements and high As(III) absorption capacity. Biological and Applied SciencesFerreira, FAG et al.Braz. Arch. Biol. Technol. v.61: e18160644 2018 . The risk of As exposure is an issue of worldwide concern 1, 4 . Chronic intoxication by this element has been reported in several countries (e. g. Bangladesh, Vietnam, China, Argentina, Chile) where As in water exceeds safety limits in some localities 5, 6, 7 . On the aquatic ecosystem As pollution can affect the equilibrium and coexistence of aquatic organisms. Furthermore, the capacity of As accumulation by aquatic primary producers is determinant for its biomagnification in the trophic chain 8 . Using microorganisms as a tool for removal of contaminants such as metals and metalloids is a low-cost process known as bioremediation 9 . Bioremediation technologies have a promising potential to contribute eco-friendly manner. These comprise high-efficiency techniques for heave metal removal in from dilute solutions, in addition, they could provide metal recovery 10 . The accumulation and concentration of pollutants from aqueous solutions by the use of biological materials [such as aquatic macrophytes biomass 11,12,13 or microbial biomass 14,15,16 ], facilitating the recovery and/or environmentally acceptable disposal of the pollutant is termed as "bioremoval" 17 . The possibility of using clean technologies for environmental decontamination has spurred the search for resistant organisms that are capable of biotransforming toxic elements such as As. The possibility of using clean technologies for environmental decontamination has spurred the search for resistant organisms that are capable of biotransforming toxic elements such as As 18 . Arsenic metabolism by cyanobacteria has mainly been studi...

Este livro reúne trabalhos que possuem, como eixo norteador, saberes e possibilidades de estudos em Educação Ambiental. Os seis capítulos que compõem a obra foram inspirados por uma EA entendida a partir das relações do indivíduo com o mundo em que vive e sua responsabilidade sobre ele, de forma que é percebida como um processo que educa para uma compreensão/posicionamento sobre a complexidade das questões ambientais.