First assessment of microplastic and artificial microfiber contamination in surface waters of the Amazon Continental Shelf

Microplastic pollution in the Amazon Basin: Current scenario, advances and perspectives

The presence of microplastics (MPs) has been reported in ecosystems in the most different regions of the world and rivers have been identified as one of the main means of transporting this debris to oceans. Recent research shows microplastic deposition and accumulation in the Amazon Basin and, despite being scarce, microplastic pollution is ubiquitous in the region. Of the 9 countries that make up the Amazon Basin, only Brazil, Guyana, Ecuador and Peru have published on the topic, with the main focus on biota (58 %). Several Amazon regions such as Northern Amazon in the Far North of Brazil still have no evidence of microplastic pollution with published data. MP abundance ranges from 5 to 74,500 MPs m-3 for waters, 0 to 8178 MPs kg-1 for sediment and 0.34 to 38.3 MPs individual-1 for biota, with nanoplastic scale (<100 μm) in the sediment. Blue and colorless are the predominant colors, mainly from secondary sources (fibers and fragments). The most commonly found polymers are polyamide, polyethyleneterephthalate and polypropylene. Microplastic abundance in aquatic systems is higher than that found in other rivers, such as the Guayas in Ecuador, the Magdalena, in Colombia and the Surabaya in Indonesia and are similar to regions with intense anthropogenic activity such as the Guanabara Bay - Brazil and the Yellow River in China. The precarious basic sanitation structure, urban planning, waste management, combined with the extensive network of navigable waters, are aggravating factors for the increase in plastic pollution in the region. It is necessary to increase research investment on the topic, considering MP quantification, impacts and the relationship with the hydrosedimentological dynamics of the Amazon Basin. The creation and enforcement of laws that minimize the accumulation of these materials is emerging, besides the development of the bioeconomy and sustainable proposals to minimize plastic pollution in the Amazon.

Contamination by microplastics and sorbed organic pollutants in the surface waters of the Tietê River, São Paulo-SP, Brazil

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.

A review of plastic debris in the South American Atlantic Ocean coast - Distribution, characteristics, policies and legal aspects

The presence of plastics in the oceans has already become a pervasive phenomenon. Marine pollution by plastics surpasses the status of an emerging threat to become a well-established environmental problem, boosting research on this topic. However, despite many studies on the main seas and oceans, it is necessary to compile information on the South American Atlantic Ocean Coast to identify the lack of research and expand knowledge on marine plastic pollution in this region. Accordingly, this paper conducted an in-depth review of monitoring methods, sampling, and identification of macroplastics and microplastics (MPs) in water, sediments, and biota, including information on legal requirements from different countries as well as non-governmental initiatives. Brazil was the country with the highest number of published papers, followed by Argentina. MPs accounted for 75 % of the papers selected, with blue microfibers being the most common morphology, whereas PE and PP were the most abundant polymers. Also, a lack of standardization in the methodologies used was identified; however, the sites with the highest concentrations of MPs were the Bahía Blanca Estuary (Argentina), Guanabara Bay (Brazil), and Todos os Santos Bay (Brazil), regardless of the method applied. Regarding legislation, Uruguay and Argentina have the most advanced policies in the region against marine plastic pollution due to their emphasis on the life cycle and the national ban on certain single-use plastics. Therefore, considering its content, this expert review can be useful to assist researchers dealing with plastic pollution along the South American Atlantic Ocean Coast.

First evidence of microplastics and their characterization in yellow-legged gull (Larus michahellis michahellis, Naumann, 1840) pellets collected from the Sfax salina, southeastern Tunisia

The aim of this work was to provide evidence on the presence of microplastics (MPs) in regurgitated Yellow-legged Gull pellets (n = 18) from Sfax salina (south-eastern Tunisia). This artificial area is subject to high anthropogenic pressure and hosts Yellow-legged Gulls, which are at the top of the trophic chain and can be used as sentinel species to monitor litter in the environment, including plastic pollution. The total number of MPs found in the samples was 309, 63.8 % fibres (4.95 ± 3.51 MPs/g) and 36.2 % fragments (2.87 ± 1.74 MPs/g). Micro-FTIR analysis evidenced that a large proportion of the fibres was attributed to artificial cellulose (40.7 %). Ethylene vinyl acetate (EVA) and polyethylene (PE) were found in the fragments.

Comprehensive risk assessment of microplastics in tidal channel sediments in amazonian mangroves (northern Brazil)

Pollution by microplastics (MPs) in mangroves is a growing concern, given its potential ecological and human health impacts. The characteristics of microplastic pollution and a risk assessment of MPs in the Amazon region's coastal sediments are still insufficient, and information about MP pollution in the benthic component of the mangrove ecosystem is lacking. We analyzed MP concentrations in the surface sediment of 9 stations in three tidal channels along the Ajuruteua Peninsula connected to the Caeté River estuary, aiming to assess the hazard level on the environment based on the Pollution Load Index (PLI). Raman and Fourier transform infrared spectroscopy determined the MP's chemical composition. The results showed that the abundance of sediment MPs ranged from 100 to 1200 items kg-1, with an average of 433 ± 261.6 items kg-1. The MPs were mainly composed of transparent and blue fragments and fibers, ranging in size from 100 to 5000 μm. Six types of polymers were identified, including alkyd varnish (AV), resin dispersion (RD), chlorinated polyethylene (CPE), polyethylene-polypropylene (PE-PP), low-density polyethylene (LDPE), and hostaperm blue (HB). Hydrodynamic processes within estuaries and tidal channels play a crucial role in explaining the concentrations found, as circulation determines the pattern of sediment deposition and the particles adhered to it. PLI risk assessment showed that all sampling sites were at hazard level I: a low level of contamination in the mangrove sediments. However, a more comprehensive and systematic monitoring campaign is needed to expand our knowledge about pollution and contamination by MPs in Amazon mangrove areas.

The retention of plastic particles by macrophytes in the Amazon River, Brazil

This study evaluated the presence of plastics and microplastics in macrophytes in an urbanized sector of the Amazon River. A total of 77 quadrats in 23 macrophyte banks were sampled during the dry (September 2020) and rainy (June 2021) season. Five species were identified: Paspalum repens, Pontederia rotundifolia, Pistia stratiotes, Salvinia auriculata and Limnobium laevigatum, with P. repens being dominant during the dry season (47.54%) and P. rotundifolia during the rainy season (78.96%). Most of the plastic particles accumulated in Paspalum repens (49.3%) and P. rotundifolia (32.4%), likely due to their morphological structure and volume. The dry season showed a higher accumulation of plastic particles than the rainy season. Microplastics were found in most samples, during both the dry (75.98%) and rainy seasons (74.03%). The upstream macrophyte banks retained more plastic particles compared to the downstream banks. A moderate positive correlation was observed between the presence of plastic particles and macrophyte biomass, and a weak positive correlation between the occurrence of microplastics and mesoplastics. White and blue fragments, ranging from 1 to 5 mm were the most common microplastics found in the macrophyte banks. Green fragments and green and blue fibers were identified as polypropylene, blue and red fragments as polyethylene, and white fragments as polystyrene. Therefore, the results of this study highlight the first evidence of the retention of plastic particles in macrophytes of the Amazon and highlight a significant risk due to the harmful effects that this type of plastic can cause to the fauna and flora of aquatic ecosystems.

Opportunistic sightings of manta rays on Brazil's Amazon Coast

Little is known about the ecology and distribution of mobulid rays along Brazil's extensive coastline. Here we report opportunistic sightings of manta rays (Mobula cf. birostris) in the Brazilian Amazon estuaries and the Great Amazon Reef System. These sightings consist of manta ray individuals stranded in tide pools, caught in artisanal fisheries, and footage obtained with a submersible. Future investigations on the spatial, temporal, and environmental drivers of manta rays' distribution on the northern Brazilian coast and the threats posed by fishing gear are warranted.

Analysing micro- and nanoplastics with cutting-edge infrared spectroscopy techniques: a critical review

The escalating prominence of micro- and nanoplastics (MNPs) as emerging anthropogenic pollutants has sparked widespread scientific and public interest. These minuscule particles pervade the global environment, permeating drinking water and food sources, prompting concerns regarding their environmental impacts and potential risks to human health. In recent years, the field of MNP research has witnessed the development and application of cutting-edge infrared (IR) spectroscopic instruments. This review focuses on the recent application of advanced IR spectroscopic techniques and relevant instrumentation to analyse MNPs. A comprehensive literature search was conducted, encompassing articles published within the past three years. The findings revealed that Fourier transform infrared (FTIR) spectroscopy stands as the most used technique, with focal plane array FTIR (FPA-FTIR) representing the cutting edge in FTIR spectroscopy. The second most popular technique is quantum cascade laser infrared (QCL-IR) spectroscopy, which has facilitated rapid analysis of plastic particles. Following closely is optical photothermal infrared (O-PTIR) spectroscopy, which can furnish submicron spatial resolution. Subsequently, there is atomic force microscopy-based infrared (AFM-IR) spectroscopy, which has made it feasible to analyse MNPs at the nanoscale level. The most advanced IR instruments identified in articles covered in this review were compared. Comparison metrics encompass substrates/filters, data quality, spatial resolution, data acquisition speed, data processing and cost. The limitations of these IR instruments were identified, and recommendations to address these limitations were proposed. The findings of this review offer valuable guidance to MNP researchers in selecting suitable instrumentation for their research experiments, thereby facilitating advancements in research aimed at enhancing our understanding of the environmental and human health risks associated with MNPs.

Microplastics in the Amazon biome: State of the art and future priorities

Microplastics (MPs) have been identified as a major potential threat to the biota and human health. Despite the exponential increase in MP research worldwide, few studies have focused on the extensive Amazon biome. To assess research priorities, the present study reviewed and summarized the available scientific knowledge on MPs in the Amazon, in addition to analyzing population and waste-management data, to evaluate potential sources of MPs in the hydrographic system. Poor sanitation conditions are a main source of MPs for the vast hydrographic basin, and, consequently, for the adjacent ocean. Secondary MPs predominated, mostly fibers (96% of debris), composed of polyamide (32%). Mean MP concentrations ranged from 0.34 to 38.3 particles.individual-1 in biota, 5 to 476,000 particles.m-3 in water, and 492.5 to 1.30848 × 107 particles.m-3 in sediment, values in close comparison with those found in areas profoundly affected by anthropogenic pollution. MPs were widespread in a range of Amazonian environments and species, and negative effects are probably occurring at various ecological levels. However, limited research, methodological constraints, flaws and the lack of standardization, combined with the continental dimensions of the Amazon, hampers the collection of the fundamental knowledge needed to reliably evaluate the impacts and implement effective mitigation measures. There is an urgent need to expand scientific data available for the region, improving local research infrastructure, and training and deploying local researchers.

Microplastic in clams: An extensive spatial assessment in south Brazil

Microplastic pollution is becoming a continuously growing environmental concern, while bivalve mollusks are particularly vulnerable due to their sessile habits and feeding through water filtration processes. Microplastic incidence in soft tissues of the clam Amarilladesma mactroides was assessed along unconsolidated substrates distributed in extensive coastal regions of southern Brazil. Influence of urbanization levels, distance to rivers and local hydrodynamics on microplastic accumulation by the clam was tested. The average concentration of microplastics was high (3.09 ± 2.11 particles.g-1), considering 16 sampled sites. Particles were mainly composed by polyamide, polyethylene and polyethylene terephthalate, while were mainly smaller, fibrous and colorless. High urbanization and closer proximity to rivers insured higher contamination, which is a trend observed globally. No influence of coastal hydrodynamics was seen. Considering obtained findings, A. mactroides presents good potential to be used as a valuable tool to assess microplastic contamination in unconsolidated substrates of beach areas.

Microplastics as contaminants in the Brazilian environment: an updated review

Microplastics have long been present in marine and terrestrial environments and have emerged in recent decades as a global environmental concern. This pollutant has been detected with increasing frequency in Brazilian territory and herein primarily highlights current information and developments about the quantity, distribution, techniques of identification, origins, and sources of microplastics and related pollutants in the Brazilian environment. We evaluated 79 publications from 2018 to December 2022, and some aspects can be highlighted: 27% of studies were published in the Journal Marine Pollution Bulletin; 22% of all studies were conducted in São Paulo city; and 52% of all microplastics found were collected from biota followed by sediment samples. According to the findings given here, microplastics in Brazilian habitats, which can reach concentrations of 4367 to 25,794 items m-2 in sediments, are becoming a serious problem in the Anthropocene age, and some topics regarding the open questions in this area were pointed out in this review.

Microplastics and microfibers in the Guajará Bay, Amazon delta: Potential sources and variability

The role of Amazon on the transport and as a source of microplastics (MPs) to the ocean is uncertain. This study is an assessment on the distribution of MPs and microfibers (MFs) in a portion of the Amazon delta. Guajará bay is a potential source for surrounding waters, since a metropolis is located at the right margin. Surface water samples were collected during the dry and rainy season of 2014/2015 at six stations. MP and MF abundance ranged from 218 to 5529.98 (1565.01 ± 196.94) particles·m-3. Transparent, white and blue particles were frequent. Higher values were detected on the right, urbanized margin of the bay (p = 0.0124). Most of the particles were anthropogenic cellulose fibers (68.8 %). Polyethylene terephthalate (52.9 %) and polyamide (34.4 %) were the dominant polymers. Our results indicate higher MP and MF abundances near to the potential source, the urban nucleus, and related to local hydrodynamic characteristics.

Microplastics in surface waters of tropical estuaries around a densely populated Brazilian bay

Brazil is the fourth largest producer of plastic waste in the world, but studies on pollution of rivers and estuaries by microplastics are still scarce. This study is located in the state of Bahia (Northeast region) in ten estuarine environments around Todos dos Santos Bay (TDB), the largest Brazilian bay, where more than 3 million Brazilians live. The aim of the study was the evaluation of the input of microplastics into the TSB by river. Microplastic abundance, size, morphology and water quality were determined during three sampling campaigns. All river samples were highly polluted with microplastics (mostly <150 μm), up to 33,000 items m^-3, exceeding values observed in most estuaries worldwide. The poor quality of the river water reflect the deficient treatment of domestic wastewater in the state of Bahia (49% are not treated), and in this study is shown a correlation with the abundance of microplastics, indicating their possible main source. Artisanal fishing can also contribute locally to this pollution. Morover, the results highlight the importance of sampling small microplastics (<100 μm) to avoid important underestimation of this pollution. Based on these data, the three major rivers would discharge 3.88 trillion items into the Bay each year, equivalent to 4.75 × 10⁵ m² of plastic. Further research in surface water systems is essential, given that the average wastewater treatment rates in the country and in the Northeast and North regions are only 43%, 32%, and 12%, respectively.

Microplastic pollution in sediments of tropical shallow lakes

Forty-eight tropical shallow lakes (depth ≤ 4 m) across a climatic gradient were assessed for microplastic (MPs; <5 mm) pollution based on MPs concentrations in archive samples from lake shore sediments. The MPs were classified by type (fragments or fibres), colour (yellow, black, red, green, blue, white, and transparent), size (0.55 to 4.93 mm), and polymer (polyester, polyethylene, chlorinated polyethylene, and polyamide). Sediments were predominantly medium sand, and all samples (144) contained MPs, consisting of 24 % fragments (6.3 ± 11.3 MPs·300 g^-1) and 76 % fibres (21.25 ± 12.7 MPs·300 g^-1). The lake climate (humid, transitional, or semi-arid), type of surrounding land use (urban, semi-arid, or rural), and distance from the shoreline (0, 5 or 10 m) did not explain the differences in MPs concentrations, partially refuting the initial hypothesis. The only significant difference was between the sample medians for the number of fragments based on the region (H = 7.586; p = 0.0481). The number of fragments in the lakes in the humid region was greater than that in the semi-arid region (p < 0.05). Poor sanitation, sewage effluents, and solid wastes reaching and accumulating in the lakes may be the primary and transversal conditioning factors for this small difference among diverse environments. Freshwater lakes are investigated in all continents, and the present study contributes to the first record of MPs in shallow lake sediments in eastern South America. The 48 shallow lakes assessed showed a relatively low concentration of MPs compared to other lake contaminants reported in the international literature. This information coincides with public policies issued, regarding the control and reduction of plastics and MPs in Brazil, and the study region.

Detection of Environmental Microfiber Pollutants through Vibrational Spectroscopic Techniques: Recent Advances of Environmental Monitoring and Future Prospects

A robust environmental monitoring system is highly essential for the instant detection of environmental microfiber pollutants for the sustainable management of the environment and human health. The extent of microfiber pollution is growing exponentially across the globe in both terrestrial and marine environments. An immediate and accurate environmental monitoring system is crucial to investigate the composition and distribution of these micropollutants. Fourier Transform Infrared Spectroscopy and Raman Spectroscopy are vibrational spectroscopic techniques that have the novel ability to detect microfibers within a minute concentration from diverse environmental samples. The major micropollutants which have been analyzed are polyethylene, polypropylene, nylon 6, polystyrene, and polyethylene terephthalate. After a detailed and critical study of the various aspects of spectroscopic analysis, the review is concluded with a comprehensive discussion of the significance of these robust methods and their application in future aspects for further preventing microfiber pollution in the marine environment. This study highlights the utilities and significance of vibrational spectroscopic detection techniques for the immediate and accurate identification of synthetic microfibers. This review also evaluated the implementation of spectroscopic methods as a precise tool for the characterization and monitoring of microfiber pollutants in the environment.