Air bubble curtains have been applied to a wide range of situations, from the attenuation of underwater noise, debris control, and containment of suspended sediment to the reduction in saltwater intrusion. This work conducts a preliminary numerical study on the influence of a bubble curtain device on microplastic dynamics. Simulations are conducted with a two-phase unsteady model, and the trajectories of the microplastic particles are computed with the Discrete Phase Model (DPM). Particles are injected upstream of the bubble curtain, and their transport is analyzed under different flow conditions. Results show that the ratio between the water velocity and the air injection velocity can significantly impact the efficiency of the device in directing the particles toward the surface. Furthermore, a higher degree of turbulent mixing is seen for lower water velocities. This study highlights the intricate flow behavior, and the need for a deeper understanding of other variables such as the microplastic size and concentration and the geometry of the air injection system.

A crescente urbanização do litoral tem causado, com frequência diversos impactos provenientes do descarte de resíduos sólidos, poluentes domésticos e industriais, culminando no desequilíbrio dos ecossistemas lagunares e prejudicando atividades importantes como à pesca artesanal e o turismo local. O Sistema lagunar Maricá-Guarapina, localizado no município de Maricá (RJ), vem apresentando problemas relacionados à poluição devido à ocupação de suas áreas marginais nas últimas décadas. Diante do exposto, o conhecimento sobre a poluição por resíduos sólidos neste ambiente, assim como, os processos responsáveis pela origem e distribuição destes materiais, são de grande relevância para a análise da qualidade ambiental dessas lagunas. Estudos dessa natureza permitem identificar os impactos causados pelas atividades desenvolvidas no entorno desse ambiente e o estado de poluição por resíduos sólidos no sistema lagunar. Este estudo objetivou estabelecer um diagnóstico acerca da poluição por resíduos sólidos nas Lagoas de Maricá e Guarapina utilizando os microplásticos como indicador. Foram realizados trabalhos de campo para a coleta de 16 amostras de água na superfície, 16 amostras de sedimentos de fundo e 13 de margem lagunar, para a extração e classificação de microplásticos. Os procedimentos laboratoriais incluem a pesagem das amostras secas, peneiramento, extração de microplásticos através do método de separação por densidade e identificação dos microplásticos encontrados com o auxílio de uma lupa binocular. Os resultados permitiram identificar a presença de 5.339 microplásticos nas lagunas estudadas, com as maiores concentrações na margem lagunar (40,4%), seguida pela superfície da água (39%) e nos sedimentos de fundo (20,60%). Esse valor representa uma média de 165,92 MPs/kg–1para sedimentos de margem, 68,75 MPs/kg–1 para os sedimentos de fundo e 11,93 MPs/m–3 para a água superficial. Os tipos de microplásticos identificados foram: fragmentos (36,09%), fibras (29,96%), filmes (26,72%), pellets (4,46%), espumas (2,29%) e isopor (0,48%). Um total de 98,89% dos microplásticos analisados aparentavam uma superfície desgastada, indicando atrito ou deterioração pela ação dos processos intempéricos. Entre as cores do material analisado predominou o azul para fragmentos (34,22%), fibras (26,83%) e filmes (52,52%), bronze para pellets (29,41%), e branco para espumas (36,07%) e isopor (96,43%). As possíveis fontes de microplásticos para as lagunas de Maricá e Guarapina podem estar relacionadas com o processo de expansão urbana, as atividades de lazer e turismo, com expressiva contribuição dos rios, do escoamento superficial urbano e do mar. Por ser uma laguna do tipo confinada e de baixa troca com o mar, o tempo de permanência de materiais em disponibilidade na superfície d’água é maior na laguna de Maricá. Em Guarapina, o Canal de Ponta Negra permite a troca constante de água entre o a laguna e o mar, o que favorece também a remobilização de microplásticos para foram deste ambiente. Por outro lado, a entrada de água através do canal possibilita a entrada de microplásticos na laguna, principalmente durante eventos de tempestade, como constatado neste estudo.

As partículas de plástico menores que 5 mm são classificadas como microplásticos (MP), e representam a categoria numericamente mais abundante nos ambientes marinhos devido a constante fragmentação das partículas depois de liberadas no meio ambiente. Uma vez liberados nos corpos hídricos, os polímeros sintéticos são rapidamente colonizados por microrganismos incrustantes e/ou formadores de biofilme que secretam substâncias poliméricas extracelulares na superfície do plástico possibilitando a agregação de partículas e outros microrganismos. A formação de biofilmes pode acarretar o aumento da palatabilidade, assim como interferir na densidade e consequentemente na flutuabilidade das partículas de MP. As comunidades microbianas colonizadoras de MP divergem das comunidades de microrganismos formadores de biofilmes em substratos naturais, assim como destoam dos microrganismos que não formam biofilmes e estão suspensos ou soterrados no ambiente marinho, sugerindo que a presença de MP em ambientes marinhos pode favorecer o desenvolvimento de comunidade microbianas exóticas em detrimento das nativas, afetando negativamente as funções ecológicas e alterando os processos biogeoquímicos, além da capacidade de carregar organismos patógenos. O presente trabalho é dividido em três capítulos. O Capítulo 1 consiste em uma revisão bibliográfica, cujo objetivo é identificar as principais lacunas existentes na pesquisa relacionada aos MP em ambientes marinhos e estuarinos, e indicar possíveis direções para expandir tanto o conhecimento global quanto o regional acerca da formação de biofilmes em MP e da composição das comunidades microbianas associadas a essas partículas. O Capítulo 2 abrange um estudo descritivo sobre a distribuição quantitativa e qualitativa de MP na Baía de Ilha Grande, visando avaliar a poluição por microplásticos nessa região, que foi pouco investigada até o momento. O Capítulo 3 é uma abordagem experimental com o propósito de descrever as comunidades de microrganismos associadas à micropartículas de diferentes polímeros incubados na Baía de Guanabara, assim como examinar as alterações ocasionadas pela presença de biofilmes no comportamento hidrodinâmico dos MP, com vistas a sua futura aplicação em modelos hidrodinâmicos para a Baía de Ilha Grande e Baía de Guanabara.

The high level of dispersion of plastic waste in the marine environment has caused massive pollution in practically all ecosystems, which can cause the contamination of commercial salt reaching the human body when used in the preparation of salted meat (Beef Jerky). This exposure is dangerous as plastic contains toxic contaminants both adsorbed by the environment and incorporated in manufacturing. The present work aimed to investigate the presence of microplastics in beef jerky. Samples of three brands of meat were acquired in the city of Itacoatiara and Parintins, which were processed and the saline solution obtained was mixed with hydrogen peroxide for digestion of meat residues, then this solution was filtered through filter paper and the content retained it was analyzed. In Itacoatiara, there was a significant difference between the size of microplastic particles (H=7.3020; P=0.0260) and there was no significant difference in the amount of these particles (H= 4.7283; P=0.0940). In Parintins there was no significant difference between the size of the particles (H= 5.0493; P=0.0801), as well as in the abundance there was no difference between the marks (H= 1.4237; P=0.4907). Particles of different colors were found, with a predominance of blue (52% in Itacoatiara / 43% in Parintins), red (21% / 13%) and black (10% / 36%), as well as several types being the most prevalent the filaments (65% / 64%) of elongated shape. Considering all samples, regardless of brand, there was a significant difference between the size of microplastic particles (Z (U)=2.2719; P= 0.0231) with no significant difference in abundance (Z (U)=1.3245; P =0.1853). The prices of meats in Itacoatiara ranged from R$6.00 to R$13.00 reais, the brands with the lowest cost had a higher number of particles and the higher price had a lower number of microplastics. In Parintins there was no standard, the value of the meat was R$9.00 to R$10.00 reais, similar between all brands, and contamination varied regardless of price. The results of this study point to the evident contamination of some brands of salted meat by microplastic particles in both cities investigated, being an alert for human contamination by the consumption of meat with microplastic particles.

This thesis investigated the impact of polyethylene (PE) and biodegradable (BIO) microplastics derived from mulching films on growth-promoting bacteria (PGPB) and their influence on the growth of lettuce plants (Lactuca sativa L.). Plastic mulching in agriculture is a process by which the soil is covered with plastic films, with the advantages of better water retention and less erosion, but some synthetic mulches pose potential threats to environmental safety over time due to the release of microplastics. The work focused on five bacterial strains from the genera Bacillus, Enterobacter, Kosakonia, Rhizobium and Pseudomonas, and evaluated the tolerance of the strains to exposure to the two types of plastics and their possible involvement in relieving stress in plants growing in soil contaminated with plastic microparticles. The first part of this study contextualizes the use of plastic films as an agricultural methodology, its advantages and disadvantages. The second part was dedicated to investigating the effect of PE microplastics of different sizes on bacterial growth, revealing that smaller particles tend to cause more pronounced negative effects on most strains. However, one strain (Enterobacter sp. C11) demonstrated tolerance to PE microplastics and showed its potential as a bioinoculant to protect against oxidative damage caused by microplastic contamination in plants. The inoculated plants showed greater tolerance to PE microplastics, attenuating the phytotoxicity that would otherwise affect plant growth. The third part of the study was dedicated to determining the impact of biodegradable microplastics (BIO) on PGPBs and plants. Most of the bacterial strains showed growth inhibition in the presence of BIO microplastics. However, Kosakonia sp. O21 showed greater tolerance, suggesting its potential role as a bioinoculant in agricultural environments polluted with BIO materials. This research also highlights that BIO microplastics have damaging effects on plant biochemistry, largely through oxidative stress, impact on photosynthetic activity and growth disturbance, and bacterial inoculation is useful for mitigating toxic effects, especially at lower concentrations of microplastics. This thesis addresses the tripartite interactions between microplastics, soil bacteria and plants, arguing that bacterial inoculants have enormous potential in protecting crops against microplastic-induced stress. These results contribute to the development of sustainable agricultural practices, indicating strategies based on microorganisms to mitigate the risks of environmental contamination by microplastics.

Microplastics are threatening materials directly produced by anthropogenic activities or resulting products of macroplastic degradation. Extended scientific research is being carried out on micro-/nanoplastics due to their relentless and increasing presence in the marine ecosystem with unpredicted ecological consequences. Thus, assessment of origin, life cycle, chemical nature, or composition of such polymer-based materials is essential and extremely valuable. The application of optical and electron (SEM/EDS) microscopy on the analysis and characterization of micro-/nanoplastics in aquatic environment is described in this chapter. It focuses on the benefits of using optical and electron imaging techniques for the detection and characterization of microplastics. Currently, these advanced imaging and analytical techniques have been essential in the categorization of such pollutants and other toxic substances that may be adsorbed at their surface. The emerging importance of SEM/EDS in the identification of microplastic-associated pollutants such as toxic metals is addressed. Suggestions for appropriate sample preparation and observation of these micromaterials under a microscope are briefly discussed. This chapter also highlights the importance of combining optical microscopy with spectroscopic techniques such as infrared and Raman scattering since it further enables precise chemical identification and analysis of microplastics. Ultimately, the collective use of SEM/EDS and optical microscopy associated with the spectroscopic analytical tools results in the most powerful strategy for accurate microplastic analysis.

Marine litter, defined as any solid, human-made material discarded in marine environments, originates from both land- and ocean-based sources. Plastics are the most persistent and prevalent component of marine litter, due to their durability, low cost, and widespread use across industries. Microplastics, which can either be intentionally manufactured or result from the breakdown of larger plastic items, are now pervasive contaminants, transported by ocean currents and present across all marine habitats. Marine litter poses significant ecological risks, impacting marine life through ingestion, entanglement, habitat destruction, and increased invasive species dispersal. Microplastics are particularly harmful due to their high bioavailability across trophic levels and their ability to adsorb and transport toxins that bioaccumulate in marine organisms, potentially leading to physiological harm, including endocrine disruption and organ toxicity and dammage. Marine mammals, as top predators and pollution indicators, serve as key sentinels for monitoring the impacts of marine plastic pollution on ecosystem health. Cetaceans are at increased risk in litter-aggregated oceanic zones. In Portuguese waters, with high cetacean diversity (28 species), marine litter poses risks through ingestion and entanglement, leading to harmful physiological effects, impaired migration, and even death. In this study, a particular group of floating litter categories (DDFC-Dangerous Debris for Cetaceans) that may pose the greatest threat to cetaceans was evaluated through a shipboard survey covering a 252,833 km² area off continental Portugal. Plastic was the dominant litter type (56.53%), followed by derelict fishing gear (10.14%), which poses particular risks to cetaceans. High accumulation of litter near the Gorringe Bank highlighted the important impact of discarded fishing gear, particularly on cetaceans that may feed in these highly productive areas. While DDFC hotspots and cetacean distributions mostly did not overlap, certain areas showed a moderate risk of interactions. Another survey of floating macrolitter in a coastal NATURA 2000 area (PTCON0063 Maceda-Praia da Vieira), Portugal, revealed high densities of litter (4.856 items/km²), primarily plastics, in comparison to offshore waters. A hotspot for floating macrolitter was identified between Porto and Aveiro, linked to the main urban centres and river discharge. Plastic packages and fishing items were the most common macrolitter items, indicating sources related to consumer waste and local fisheries. In the same coastal NATURA 2000 area, samples from a net tow survey revealed that microplastics were mainly represented by fibres (2018: 92.66%; 2019: 80.91%), likely originating from textile industries and wastewater treatment plants, which struggle to retain synthetic fibres. In the surveyed area, blue fibres were predominant (they were later found to be common in cetacean digestive tracts) as well as white and transparent microplastic fragments, which suggest in-situ breakdown of larger plastics. These results underscore the influence of local pollution sources. The analysis of marine litter ingestion in cetaceans stranded along the Portuguese coast (Delphinus delphis, Phocoena phocoena, and Stenella coeruleoalba) revealed a high microplastic ingestion among individuals (F.O.%=92.11%), with microfibers being the most common type (76.77%), reflecting their prevalence in the Portuguese coastal environment. Striped dolphins showed higher ingestion of plastic fragments (F.O.%=83.33%), likely due to their offshore habitats where litter accumulates. The shapes of ingested fragments suggest they originated from the breakdown of larger plastics. Findings support the "secondary ingestion" hypothesis, as the characteristics of microplastics described in fish (common prey for the evaluated cetacean species) matched those found in the analysed cetaceans. While the sample size was limited, higher microplastic ingestion in harbour porpoises may stem from their demersal feeding habits. Although immediate toxic effects were not evident, the potential of microplastics as pollutant vectors raises concerns, especially for at-risk populations like the Iberian harbour porpoise, warranting further research on pollutant bioaccumulation in cetaceans. Finally, the evaluation of macrolitter ingestion in deep-diving cetaceans revealed a high frequency of occurrence of ingested marine litter (45.61%). This ingestion resulted in significant lethal (30.77%) and sublethal (53.85%) effects, highlighting its role as a major contributor to mortality in species that forage on or near the seafloor, such as Cuvier’s beaked whales, sperm whales, and pygmy sperm whales along the Atlantic Iberian Coast. Lethal ingestion was specifically noted in these species, with reported rates of 41.67%, 40.00%, and 20.00%, respectively. The prevalence of litter ingestion is linked to their benthic feeding behaviour, as these species often consume cephalopods through suction and may inadvertently ingest marine litter. This study supports the proposal of sperm whales as a global indicator species for macrolitter in the deep ocean. Challenges in accurately assessing the impact of marine litter on deep diving cetaceans include the rarity of these species and the underreporting of strandings, emphasising the need of improved sampling methods through marine animal strandings networks to gather more comprehensive data on their macrolitter ingestion. Long-term studies with broader temporal and spatial scales are essential to understand the risk of marine litter to cetacean populations and the factors affecting their distribution. Continuous monitoring of stranded cetaceans is necessary to evaluate population-level impacts and standardized protocols for microplastic analysis (in water and in biota) should be established to enable accurate assessments and comparisons across different regions.

Although the study of the effects of microplastics increased in the last years, terrestrial ecosystems remain less studied. In fact, the effects of microplastics in insects, the most abundant group of animals and major providers of key Ecosystem Services, are not well known despite the potential cascading negative effects on the ecosystems functioning in the habitats where they occur. In this paper, a revision on available studies on microplastics contamination is provided and potential consequences to major Ecosystem Services provided by insects are discussed, using the Common International Classification of Ecosystem Services (CICES) methodology. The revision underpinned probable and potential impacts for all tree CICES divisions, i.e.: Provision, Regulation and Maintenance and Cultural Services. The available studies seem to show that different groups react differently to microplastics contamination, which clearly indicates that the effects in Ecosystem Services provided by insects need a more empirical and targeted approach.

The growing plastic production and its continuous use is a significant problem. In addition, aquaculture practices have experienced a considerable growth and plastic is widely used in these activities, hence plasticizers must be considered due to their potential ecotoxicological impacts on species. Mussels placed inside an Integrated Multi-Trophic Aquaculture (IMTA) system and at two control locations were employed to quantify the ingestion of anthropogenic particles and associated chemical plasticizers, such as bisphenol A (BPA) jointly to bisphenol F (BPF) and bisphenol S (BPS), and phthalates represented by diethyl phthalate (DEP), dibutyl phthalate (DBP) and bis(2-ethylhexyl) phthalate (DEHP). In addition, some metabolism and oxidative stress related parameters were measured in mussels' whole soft tissue. Anthropogenic particle ingestion of mussels increased over time at the three locations and the following order of abundance of pollutants was observed: BPA> BPF> DEHP> DBP> BPS> DEP. Even though no differences according to location were found for pollutants' occurrence, time trends were evidenced for BPA and DEHP. On the other hand, a location effect was observed for biomarkers with highest values detected in mussels located at the vicinities of the aquaculture facility. In addition, a reduced detoxification activity was observed over time parallel to BPA decrease.

Microplastics became an unprecedented challenge and mapping their contamination all over the world is needed in order to establish baseline levels and identify the polymers in order to enhance adequate legislation and policy. The main objective of this study is to demonstrate the existence of microplastic pollution on three beaches on the coast of Granada (Spain), namely La Herradura, Motril Beach and La Rábita, characterizing the particles and the relationships in their distribution. This may contribute supporting the studies carried out at a national level in accordance with the Directive on Marine Strategy (2008/56/EC). The results showed a greater median concentration of particles/kg of dry sediment in La Herradura (45.0 ± 24.7) than in Motril (31.5 ± 21.5) and La Rábita (22.0 ± 23.2). These data revealed a higher contamination by microplastics in an enclosed bay-type beach (La Herradura) in comparison with open delta-type beaches. The predominant morphologies were microspheres and fragments, with maximum median concentrations of 38.0 ± 23.7 and 6.0 ± 0.7 particles/kg, respectively. The distribution and size of the particles is affected by the geomorphological and sedimentary characteristics of these beaches, which are different from any other in Spain and in the Mediterranean in general. The beaches of Granada showed more microplastic contamination than Greek or Slovenian beaches, but less than other Spanish beaches. In this area of the Mediterranean, the presence of microplastics can be affected by the wind, sea currents or methodological aspects such as the pore size of the filters used. All of these factors were analysed when comparing the beaches of Granada with other Mediterranean beaches. This study shows that there is contamination by microplastics on the beaches of Granada, which have been little explored until now due to the difficult geological and granulometric characteristics, and gives support to other national studies.