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The contamination of surface waters by microplastics (MPs) is an emerging concern, due to their environmental impact and negative effects on biota. However, in recent years, although the occurrence of these pollutants has been widely reported in marine systems, studies on MPs in freshwater are still scarce in the literature, particularly in Southeastern Brazil. In this context, the current study aimed to provide unprecedented information on the abundance and spatial and temporal distribution of MPs in three sites located in the Atibaia river basin (Southeastern Brazil) - the main river, a tributary, and the discharge of effluent from a sewage treatment plant. Surface water was sampled in four sampling campaigns, two in wet season and two in dry season, between 2019 and 2020, at three sampling points. At each point, 200 L of water were collected with the aid of an aluminium bucket, followed by sieving in the field to isolate the particles between 100 μm and 5000 μm, using stainless steel sieves. Chemical identification of the polymer was performed by ATR-FTIR micro spectroscopy. The abundance of MPs in the water ranged from 188 to 533 items/m 3 . The water samples with the greatest MPs abundance corresponded to the sampling point that includes the receipt of domestic effluent treated by the local Sewage Treatment Station. The chemical identification of the polymers highlights polyester polyethylene terephthalate (PET), polyethylene (PE), polyvinyl chloride (PVC), and polypropylene (PP) as the most frequent, respectively. This study emphasizes the importance of discharged domestic effluents and rivers as MPs transport systems. Therefore, further studies should be carried out to identify the main sources and contribute to the gathering of information, aiming to mitigate the emission of this pollutant in aquatic systems., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (© 2024 The Authors.)

Microplastics (MPs) are particles between 1 μm and 5 mm in size, originating mainly from poor solid waste and effluent management, that can reach water bodies from various sources. In freshwater environments, the occurrence, distribution, and characterization of this new class of pollutants are still little explored, especially in Brazil. The aim of this study was to assess the occurrence of MPs, as well as the presence and concentration of polychlorinated biphenyls (PCBs) sorbed to these particles in the surface waters of the Tietê River - SP. Surface water samples were collected in duplicate during the dry and wet seasons. The identification and characterization of the MPs was carried out through visual inspection and the chemical identity of the particles was verified using Fourier transform infrared spectroscopy with attenuated total reflectance (FTIR-ATR). For the analysis of PCBs adsorbed to the MPs, the sample extracts were analyzed by gas chromatography coupled with mass spectrometry (GC-MS). The MPs were found in concentrations ranging from 6.67 to 1530 particles m -3 , with a predominance of the polymers polyethylene (PE, with 58.17 %) and polypropylene (PP, with 23.53 %). The main morphological categories identified were fragments (56.63 %), fibers (28.42 %), and transparent films (13.06 %). Higher abundances of PCBs were observed in the lower size range, between 0.106 and 0.35 mm. The total concentrations of PCBs in MPs ranged from 20.53 to 133.12 ng g -1 . The results obtained here are relevant for understanding the dynamics and level of contamination of MPs and organic pollutants sorbed to these particles in the Tietê River, as well as helping with mitigation measures for the restoration and preservation of this ecosystem., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (© 2024 The Authors.)

Microplastics are a class of contaminants that pose a threat to aquatic biota, as they are easily found in aquatic ecosystems and can be ingested by a wide variety of organisms, such as fish. The lambari rosa ( Astyanax altiparanae ) is a microphage fish, which feeds on microscopic beings and particles, making it potentially susceptible to ingesting MPs discarded in the environment. In addition, this fish is of great economic and food importance, as it is used for human consumption. This study aimed to evaluate the accumulation and possible toxicological effects caused to lambari rosa ( n = 450) by the ingestion of polyethylene (PE) and polyethylene terephthalate (PET) MPs, since the MPs of these polymers in the form of granules, fragments, and fibers are the most commonly reported in the aquatic environment. The parameters investigated here were the quantitative analysis of ingested MPs using microscopic and staining techniques, as well as the mortality rate, malformations/injuries, and impaired weight gain. At the end of the experiment, it was concluded that MPs from both polymers accumulated in the gastrointestinal tract of the lambari rosa, and that dietary exposure, especially to the PET polymer, was responsible for increasing the mortality rate in this species.

Microplastics (MPs) are contaminants of environmental concern that represent a threat to marine systems. Here we report data on the abundance and characteristics of MPs collected from surface waters of the urban Guanabara Bay. Samples were collected, by horizontal trawling of a plankton net on two occasions (summer of 2016). The MPs were obtained from samples by sieving and particles were manually sorted with microscope. Characterization of MPs was accomplished by gravimetry and digital image processing (for quantification and morphology categorization), and chemical composition identified by infrared spectroscopy and elemental analyses. Total MPs ranged from 1.40 to 21.3 particles/m 3 , which places Guanabara Bay amongst the most contaminated coastal systems worldwide by microplastics. Polyethylene and polypropylene polymers ≤1 mm were the most abundant particles. Therefore, the occurrence of MPs in Guanabara Bay is relevant to understand ecological hazards of exposition to marine biota and merits further investigation., (Copyright © 2018 Elsevier Ltd. All rights reserved.)