Distribution and importance of microplastics in the marine environment: A review of the sources, fate, effects, and potential solutions

Heavy metals in soils

Human populations are using oceans as their household dustbins, and microplastic is one of the components which are not only polluting shorelines but also freshwater bodies globally. Microplastics are generally referred to particles with a size lower than 5 mm. These microplastics are tiny plastic granules and used as scrubbers in cosmetics, hand cleansers, air-blasting. These contaminants are omnipresent within almost all marine environments at present. The durability of plastics makes it highly resistant to degradation and through indiscriminate disposal they enter in the aquatic environment. Today, it is an issue of increasing scientific concern because these microparticles due to their small size are easily accessible to a wide range of aquatic organisms and ultimately transferred along food web. The chronic biological effects in marine organisms results due to accumulation of microplastics in their cells and tissues. The potential hazardous effects on humans by alternate ingestion of microparticles can cause alteration in chromosomes which lead to infertility, obesity, and cancer. Because of the recent threat of microplastics to marine biota as well as on human health, it is important to control excessive use of plastic additives and to introduce certain legislations and policies to regulate the sources of plastic litter. By setup various plastic recycling process or promoting plastic awareness programmes through different social and information media, we will be able to clean our sea dustbin in future.

Microplastic pollution, a threat to marine ecosystem and human health: a short review

Microplastic contamination of the oceans is one of the world’s most pressing environmental concerns. The terrestrial component of the global microplastic budget is not well understood because sources, stores and fluxes are poorly quantified. We report catchment-wide patterns of microplastic contamination, classified by type, size and density, in channel bed sediments at 40 sites across urban, suburban and rural river catchments in northwest England. Microplastic contamination was pervasive on all river channel beds. We found multiple urban contamination hotspots with a maximum microplastic concentration of approximately 517,000 particles m−2. After a period of severe flooding in winter 2015/16, all sites were resampled. Microplastic concentrations had fallen at 28 sites and 18 saw a decrease of one order of magnitude. The flooding exported approximately 70% of the microplastic load stored on these river beds (equivalent to 0.85 ± 0.27 tonnes or 43 ± 14 billion particles) and eradicated microbead contamination at 7 sites. We conclude that microplastic contamination is efficiently flushed from river catchments during flooding.

Microplastic contamination of river beds significantly reduced by catchment-wide flooding

The qualitative and quantitative composition of biofilms on microplastic surfaces is widely unknown. A previous study (Zettler et al., 2013; EST) reports the presence of potentially pathogenic bacteria (Vibrio spp.) on floating microplastic particles. Hence microplastics could function as vectors for the dispersal of microorganisms to new habitats. Several Vibrio species are serious human pathogens. Contact with contaminated water and consumption of raw seafood are the main infection factors for Vibrio associated diseases. On research cruises to the North- and Baltic Sea, microplastic particles were collected and subjected to APW (alkaline peptone water) enrichment. Growth on selective CHROMagar™ Vibrio and further identification of isolates by MALDI-TOF (matrix assisted laser desorption/ionization time-of-flight) clearly indicate the presence of potentially pathogenic Vibrio spp. on microplastics. Our results highlight the urgent need for detailed microbiological analyses of floating microplastic particles in the future.

Dangerous hitchhikers? evidence for potentially pathogenic vibrio spp. on microplastic particles

A poluição de sistemas aquáticos com contaminantes emergentes é uma crescente preocupação. Dentre estes, os desreguladores endócrinos (DE) são substâncias que podem alterar o sistema endócrino de seres vivos até em baixas concentrações. Suas características físico-químicas indicam afinidade com matéria orgânica, sendo relevante o estudo de sedimentos. A atividade estrogênica pode ser avaliada pelo ensaio in vitro YES, porém matrizes ambientais complexas podem apresentar citotoxicidade e interferir no resultado do ensaio. Este estudo objetivou avaliar métodos de preparo de amostras de sedimento utilizando extração em fase sólida para remoção de compostos citotóxicos no ensaio in vitro YES. O uso isolado de EDTA para remoção de metais não foi eficiente para reduzir a citotoxicidade, enquanto a remoção foi completa com o cartucho SAX. Conclui-se que o uso combinado de cartuchos foi a técnica mais viável para a avaliação da atividade estrogênica de amostras de sedimento com ensaio YES.
Palavras-chave: Sedimento. Atividade estrogênica. Efeito matriz. Citotoxicidade. Ensaio YES.

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Remoção da citotoxicidade no ensaio de atividade estrogênica (YES) para amostras de sedimento lagunar: Métodos de extração e efeito matriz

Aim: Tyre wear particles (TWPs) have been indicated as one of the main sources of microplastics (MPs) in aquatic environments, yet they receive little attention in the published literature. They have never been reported in Guanabara Bay in spite of several published analyses of the abundance, distribution, type, chemical composition and color of MPs in this area. We aimed to develop a method to allow ready detection of these particles in sediments. Methods: Nine sediment samples were taken from locations over a wide geographic cover of the bay. They were collected from different depths using a Van Veen grab sampler. MPs were separated using peroxide degradation of organic matter followed by floatation and filtration. TWPs were identified using a binocular stereo microscope,Scanning Electron Microscopy (SEM) and Fourier transformed infrared spectroscopy. Results: The combined use of these MP detection methods allowed the visualization and identification of high numbers of TWPs in the bay. Exact quantification was impossible because of the large size range of the particles and the use of a sedimentation system already shown to be sub-optimal. Conclusion: High levels of TWPs were detected in Guanabara Bay sediments. Future studies to quantify these particles in coastal environments will necessitate the development of more robust methods, possibly using specific TWP markers. Various options are discussed.

Occurrence of microplastics derived from tyres in bottom sediments of Guanabara Bay, Brazil: a form of pollution that is neglected or difficult to detect?

Studies assessing the presence of endocrine disrupting compounds in marine environments have increased in the last decades. In Brazil, the combination of poor sanitation conditions and low investment in sewage treatment plants leads to significant contamination of receiving waters. The risks of these micropollutants in the aquatic biota include biochemical and histopathological alterations of the liver, gonads, and kidneys, as well as, reproductive process and development modifications, and behavioral changes, among others. The aim of this study was to evaluate the quality of the surface and deep waters of Guanabara Bay, southeastern Brazil, regarding the presence of estrogenic substances. Acute toxicity assays were also conducted employing Vibrio fischeri. The estrogenic activity of the water samples was determined by Yeast Estrogen Screen assay and the quantification of the Bisphenol A, estriol, 17β-estradiol, and 17α-ethinylestradiol by high-performance liquid chromatography, using fluorescence and diode array detectors. Estrogenic activity ranged from 9 to 77 ng L-1 of estradiol equivalents. The highest micropollutants concentrations were detected for bisphenol A (298.5 and 465.5 ng L-1), followed by 17α-ethinylestradiol (248 and 256.9 ng L-1), estriol (70.7 and 179.6 ng L-1), and 17β-estradiol (167 and 174.8 ng L-1) for surface and deep waters, respectively. The findings indicate significant risks for the Guanabara Bay ecosystem. No acute toxicity effects were observed in the V. fisheri assay. These data reflect the current environmental degradation situation of the bay’s waters and highlight the need for the systematic monitoring of this important estuary. 

Estrogenic Activity and Endocrine Disruptor Compounds Determined in Guanabara Bay (Brazil) by Yeast Estrogen Screen Assays and Chemical Analyses

Afloramentos de granitos e gnaisses nas praias de Niteroi (RJ) apresentam morfologias desenvolvidas em decorrencia do intemperismo da acumulacao de sal na superficie da rocha. Pequenas depressoes e bacias e, de modo mais organizado, morfologias denominadas alveolos e tafoni, sao frequentemente encontradas na superficie das rochas. Este trabalho apresenta uma descricao dessas morfologias com enfase na praia de Itacoatiara onde os melhores exemplos sao encontrados. Nessa praia, 12 amostras foram analisadas (MEV, IC, AAS) permitindo a identificacao de halita, gipsita, silvita, bischofita, mirabilita, thenardita e kieserita. Em funcao dos ciclos de cristalizacao desses sais durante periodos de seca e posterior dissolucao, ocorre a desintegracao das rochas e formacao dessas morfologias. A frequencia desses ciclos promove o rompimento das ligacoes entre os cristais e a fadiga das rochas gerando as morfologias com aspectos cavernosos. Caracteristicas geologicas, tais como, planos de esfoliacao, contatos litologicos, composicao e textura das rochas, entre outras, apresentam papel importante no tipo de morfologia desenvolvida durante o intemperismo de sal.

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Intemperismo decorrente da acumulação de sal e a formação de alvéolos e tafoni nos afloramentos das praias de niterói (rio de janeiro, brasil)

A Baia de Guanabara, um dos mais importantes sistemas costeiros do sudeste brasileiro, com os seus primeiros rasgos estruturais durante o pre-cambriano e instalacao definitiva durante o Cenozoico, tem vindo a ser modelada por processos relacionados com alteracoes climaticas e mais recentemente pela forte atividade antropica, na regiao. Este trabalho pretende efetuar uma sintese de registros sedimentares historicos relacionados com a acao antropica no entrono da Baia de Guanabara e definir o inicio do Antropoceno neste sistema costeiro.Em adicao, os resultados desta investigacao permitem a  divisao do Antropoceno em quatro periodos de sedimentacao na Bia da Guanabara. A documentacao e os dados analisados permitem considerar que a camada sedimentar que marca o inicio do Antropoceno, na Baia de Guanabara foi depositada em 1502 ( Ano Domine ), no decurso da “Pequena Idade do Gelo”, ano a partir do qual teve inicio o processo de ocupacao colonialista dos Portugueses. Esforcos de ocupacao e defesa local apos o descobrimento, em 1502, culminou com a criacao da cidade do Rio de Janeiro, em 1565.A partir de entao observam-se no registro sedimentar a reducao granulometrica dos sedimento, em plena Pequena Idade do Gelo, aumento progressivo dos teores de materia orgânica mudancas polinicas resultantes do desmatamento para extracao do pau-brasil, para a cultura da cana-de-acucar, que se estendeu dos seculos XVI ao XIX, e do cafe nos seculos XVIII e XIX. De meados do sec. XVIII ao inicio do sec. XX inicia o ciclo da mineracao, seguida do comeco do ciclo da industrializacao e principia de forma incipiente a poluicao danosa na Baia de Guanabara. O desenvolvimento industrial, a partir da invencao da maquina a vapor, associado a necessidade de materia-prima, conseguida a baixo custo nos paises colonizados a epoca, marcou a segunda fase do Antropoceno na Baia de Guanabara, a partir de meados do seculo XVIII e que tera durado ate ao inicio do seculo XX. Esta fase e identificada em registros sedimentares onde ocorre aumento expressivo de metais. Inicio do sec. XX ao inicio dos anos 50 a alteracao de mais de 10 Km da orla ocidental da baia proxima a desembocadura causa a alteracao do padrao hidrodinâmico dando lugar a um aumento acentuado da acumulacao de sedimentos finos em vastas areas da Baia de Guanabara A quarta fase do Antropoceno, apos meados do seculo XX, teve lugar num cenario de grande crescimento demografico e industrial. A Baia de Guanabara passou a recolher o excedente sedimentar provocado pelas intervencoes antropicas acrescido do aumento dos residuos domesticos (lixo em geral e esgoto) e industriais (oleo, metais pesados, substâncias toxicas e carga orgânica) oriundos da expansao das atividades no seu entorno, acarretando a aceleracao da perda de sua area de superficie e de profundidade.

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José Antônio Baptista Neto

Papers

Remoção da citotoxicidade no ensaio de atividade estrogênica (YES) para amostras de sedimento lagunar: Métodos de extração e efeito matriz

Occurrence of microplastics derived from tyres in bottom sediments of Guanabara Bay, Brazil: a form of pollution that is neglected or difficult to detect?

Estrogenic Activity and Endocrine Disruptor Compounds Determined in Guanabara Bay (Brazil) by Yeast Estrogen Screen Assays and Chemical Analyses

Intemperismo decorrente da acumulação de sal e a formação de alvéolos e tafoni nos afloramentos das praias de niterói (rio de janeiro, brasil)

O histórico das intervenções humanas na baía de guanabara (brasil) e o registro do antropoceno em quatro unidades sedimentares