The transfer and resulting negative effects of nano- and micro-plastics through the aquatic trophic web—A discreet threat to human health

The ubiquitous occurrence of plastic nano- and micro-particle contamination has raised concerns about its potential risks and impacts on the global environment, especially in aquatic ecosystems. Hundreds of aquatic species, from different trophic levels, have been affected by this “new” contaminant, which has been reported mainly in their digestive tracts. Consequently, current knowledge about plastic nano- and micro-particle spread and the potential impact on aquatic biota is growing rapidly. However, there is a significant lack of understanding of the trophic spread of microplastic contamination and integration of knowledge derived from laboratory assays with that from field research is difficult. Field experiments are unable to deal with differentiating between directly and indirectly ingested plastic microparticles. On the other hand, laboratory assays evaluating the influence of plastic microparticles and of their adhered or constitutive toxins on representative species cannot satisfactorily simulate the real environment. As a result, little is known about the effective transfer of plastic particles through the trophic net and the resulting human health risks. The present review seeks to gather information that can give a more accurate idea of the current situation and future challenges to be faced in mitigating the environmental and human effects of plastic particle pollution in aquatic, particularly estuarine, ecosystems

Recent advances in the study of biocorrosion: an overview Avanços recentes no estudo da biocorrosão: uma revisão

Biocorrosion processes at metal surfaces are associated with microorganisms, or the products of their metabolic activities including enzymes, exopolymers, organic and inorganic acids, as well as volatile compounds such as ammonia or hydrogen sulfide. These can affect cathodic and/or anodic reactions, thus altering electrochemistry at the biofilm/metal interface. Various mechanisms of biocorrosion, reflecting the variety of physiological activities carried out by different types of microorganisms, are identified and recent insights into these mechanisms reviewed. Many modern investigations have centered on the microbially-influenced corrosion of ferrous and copper alloys and particular microorganisms of interest have been the sulfate-reducing bacteria and metal (especially manganese)-depositing bacteria. The importance of microbial consortia and the role of extracellular polymeric substances in biocorrosion are emphasized. The contribution to the study of biocorrosion of modern analytical techniques, such as atomic force microscopy, Auger electron, X-ray photoelectron and Mössbauer spectroscopy, attenuated total reflectance Fourier transform infrared spectroscopy and microsensors, is discussed.<br>Processos de biocorrosão na superfície de metais são associados com microrganismos ou com os seus produtos metabólicos, tais como: enzimas, exopolímeros, ácidos orgânicos e inorgânicos, e compostos voláteis como amônio ou sulfeto de hidrogênio. Todos estes produtos podem afetar reações catódicas e/ou anódicas, alterando processos eletroquímicos na interface biofilme/metal. Esta revisão discute diversos mecanismos de biocorrosão causados pelos diferentes atividades fisiológicas associadas com microrganismos e os conhecimentos mais recentes. Estudos modernos da corrosão microbiologicamente influenciada focalizam problemas em ligas de ferro e de cobre. Microrganismos especialmente enfocados são as bactérias redutoras de sulfato e bactérias que depositam metais, destacando aquelas que depositam manganês. A importância de consórcios microbianos e o papel de substâncias poliméricas extracelulares na biocorrosão são enfatizados nesta revisão. Considera-se a contribuição de técnicas analíticas modernas, tais como microscopia de força atómica, espectroscopia Auger, espectroscopia de raio-X, espectroscopia Mössbauer, espectroscopia de infra-vermelho de reflectância total com transformação de Fourier e microsensores