Microplastics, Volume 4, Issue 2 (June 2025) – 13 articles

The focus in microplastic research has shifted from marine ecosystems towards freshwater ecosystems. Still, most studies are based on small sample numbers, both spatially and temporally. Little is known about the spatiotemporal variability of microplastics (MPs) in large river systems such as the Rhine River, Germany. Within our study, we performed four cross-sectional sampling campaigns at two sites in the Rhine River, at Koblenz and Emmerich, involving depth-distributed sampling over a particle size range from 10 µm to 25 mm. For plastic particle analysis, we used both optical and thermoanalytical approaches to determine mass-based polymer concentrations. Our results show that MP variability within the water column is complex, but mostly follows the particles density: the ratio between superficial MPs concentration and mean concentration of the verticals was >1 for lighter polymers with a density below 1.04 g/cm³ and <1 for polymers with a density above 1.04 g/cm³ among all size classes with only a few exceptions, even though the Rouse theory would indicate a more homogeneous distribution for small particle sizes. Large sampling volumes are essential, particularly for larger MP particles, as the coefficient of variation rises with particle size. At our study sites, no significant lateral variation was apparent, while during a flood event, MP concentrations were significantly higher than during low and mean water stages. This study is the first to (i) gain insights into cross-sectional MPs distribution in the Rhine River and (ii) account for particle mass concentrations, and thus lays the foundation for potential future MPs flux monitoring. Full article

Riverbed sediments act as potential retention reservoirs or transport corridors for microplastic particles (MPs) from river water to groundwater. Vertical concentration profiles of MPs, together with river water and groundwater analysis, provide insight into their fate and transport behavior in freshwater systems. However, such data remain scarce. This study provides a depth-specific analysis of MPs ≥ 100 µm (abundance, type, and size) in gravelly riverbed sediments down to 200 cm, along with river water and groundwater analysis. Three sediment freeze cores were collected from the Alpine Rhine, a channelized mountain stream with high flow velocities and permanent losing stream conditions. The average MP abundance in the riverbed was 3.1 ± 2.3 MP/kg (100–929 µm); in the river, 92 ± 5 MP/m³ (112–822 µm); and in the groundwater, 111 ± 6 MP/m³ (112–676 µm). The dominant polymer types in the riverbed were polypropylene (PP), polyvinyl chloride (PVC), and polyethylene terephthalate (PET) (>70%), while polyamide (PA) dominated in the river water (56%) and the groundwater (76%). The comparable MP concentration, particle sizes, and polymer types between river water and groundwater, as well as the vertical MP concentration profiles, indicate that even large MPs up to 676 µm are transported from river water to groundwater without significant retention in the gravel sediment. Full article

Microplastic (MP) occurrence is a growing concern in environmental research, with significant attention focused on its presence in various ecosystems worldwide. While much research has centered on large lakes and water bodies, remote alpine lakes remain relatively unexplored in terms of microplastic occurrence. Studying microplastic occurrence in remote alpine lakes is important to understand the global spread of pollution, assess its impact on pristine ecosystems, and inform conservation efforts in these vulnerable environments. This study investigates microplastic presence in the sediment of Lake Cadagno, a remote alpine lake situated in the Piora Valley of southern central Switzerland. The lake has no effluents, and its meromictic nature means that the water on the bottom is not mixed with the water above, which can potentially lead to an enhanced accumulation of microplastics in the sediments that perpetuate in the lake system. Through sediment core sampling and analysis, we aim to identify the sources and deposition trends of microplastics in this pristine alpine environment. Our findings reveal the presence of microplastic within Lake Cadagno: in total, 186 MP particles were extracted from 756 cm³ of processed sediment (0.24 MP/cm³) with an average of 19.5 MP/sample (SD ± 11.8 MP/sample). Our results suggest that microplastics are predominantly attributable to localized sources associated with nearby human activities. The absence of synthetic fibers and the limited polymer types detected suggest a minimal contribution from atmospheric deposition, reinforcing the significance of local anthropogenic influences. Spatial clustering of microplastic particles near potential sources underscores the impact of surrounding land use activities on microplastic distribution. Overall, this study highlights the importance of addressing microplastic contamination even in remote and relatively unmodified ecosystems like Lake Cadagno, to elucidate the need for strict adherence to waste management and correct disposal actions to reduce the impacts of microplastic contamination. Full article

Microplastics (MPs), defined as plastic particles smaller than 5 mm, are an emerging global environmental and health concern due to their pervasive presence in aquatic ecosystems. This systematic review synthesizes data on the distribution, shapes, materials, and sizes of MPs in various water sources, including lakes, rivers, seas, tap water, and bottled water, between 2014 and 2024. Results reveal that river water constitutes the largest share of studies on MP pollution (30%), followed by lake water (24%), sea water (19%), bottled water (17%), and tap water (11%), reflecting their critical roles in MP transport and accumulation. Seasonal analysis indicates that MP concentrations peak in the wet season (38%), followed by the dry (32%) and transitional (30%) seasons. Spatially, China leads MP research globally (19%), followed by the USA (7.8%) and India (5.9%). MPs are predominantly composed of polyethylene (PE), polypropylene (PP), and polyethylene terephthalate (PET), with fibers and fragments being the most common shapes. Sub-millimeter MPs (<1 mm) dominate globally, with significant variations driven by anthropogenic activities, industrial discharge, and environmental factors such as rainfall and temperature. The study highlights critical gaps in understanding the long-term ecological and health impacts of MPs, emphasizing the need for standardized methodologies, improved waste management, and innovative mitigation strategies. This review underscores the urgency of addressing microplastic pollution through global collaboration and stricter regulatory measures. Full article

This review article aims to highlight the potential harm caused by microplastics (MPs) in different organs and systems and underscore the need for further investigation into their action mechanisms. MPs, such as polystyrene, polypropylene, and polyethylene, significantly impact human health, causing inflammation in the respiratory and gastrointestinal systems, compromising immune function, and increasing the risk of cardiovascular diseases and neurotoxicity. These effects are largely attributed to the role of MPs in disrupting hormonal regulation, which can lead to reproductive disorders and an elevated risk of cancer. These microscopic particles (less than 5 mm in size) are now ubiquitous in air, water, and food. However, much of the existing research on MPs focuses on their mechanisms of action and their association with health and disease, with limited emphasis on their direct impact on humans or long-term consequences. To effectively address plastic toxicity, it is crucial to understand the policy implications of MPs and their relevance to disease development. Recent research has highlighted the need for more stringent regulatory oversight of these materials to better understand and mitigate their impact on human health. Full article

Plastic pollution has become a critical environmental issue, with vast amounts of plastic waste accumulating in aquatic and terrestrial ecosystems. Plastic pollution poses significant risks to biodiversity by introducing toxic chemicals and disrupting biological functions. The drone fly, Eristalis tenax, is perhaps the most globally widespread hoverfly. This success is aided by its development as a rat-tailed maggot in a wide array of aquatic environments where it feeds on decaying organic matter. As an adult, E. tenax is a vital pollinator, visiting a wide range of crops and wild plants, and has been shown to vector pollen over hundreds of kilometres during seasonal migrations. Exposure to microplastics during larval stages has the potential to alter the provision of these ecosystem services and to provide a route for the long-distance vectoring of microplastics. To investigate this, we rear E. tenax in water contaminated with different concentrations of microplastic particles. We show that these plastics are retained in the gut from larval through to pupal to adult developmental stages. This contamination resulted in reductions of 33% and 60% in pupal and adult weight when exposed to the highest concentrations of microplastic particles but resulted in no detectable effects on mortality or developmental length. Our results demonstrate the potential for the vectoring of microplastics by this highly mobile species. However, the associated reductions in body size likely have profound consequences for movement capability in terms of foraging and migration and should be further investigated for their impact on ecosystem service provision. Full article

Microplastics (MPs) have been extensively studied in the marine environment, but reliable data on their sources and pathways in freshwater ecosystems, which are the main sources of such pollutants, are still limited. In this study, we investigated the spatiotemporal variations, characteristics, and sources of MPs in Nakivubo catchment, which drains waste and stormwater from Kampala city (Uganda) and empties it into Lake Victoria through the Nakivubo channel. Surface water samples (n = 117) were collected from thirteen sites in the Nakivubo catchment (S1 to S13) during the dry and wet seasons in 2022. The MPs were recovered by wet peroxide oxidation protocol, followed by salinity-based density separation, stereomicroscopy, and micro-attenuated total reflectance Fourier-transform infrared spectroscopy. All the samples had MPs, with mean concentrations ranging from 1568.6 ± 1473.8 particles/m³ during the dry season to 2140.4 ± 3670.1 particles/m³ in the wet season. Nakivubo catchment discharges an estimated 293.957 million particles/day into Lake Victoria. A Two-Way ANOVA revealed significant interactive effects of seasons and sampling sites on MPs abundance (p < 0.05). Spatially, the highest mean concentrations of MPs (5466.67 ± 6441.70 particles/m³) were in samples from site S3, which is characterized by poor solid waste and wastewater management practices. Filaments (79.7%) and fragments (17.9%) made of polyethylene (75.4%) and polyethylene/polypropylene co-polymer (16.0%) were the most common MPs. These are likely from single-use polyethylene and polypropylene packaging bags, water bottles, and filaments shed from textiles during washing. These results highlight the ubiquity of MPs in urban drainage systems feeding into Lake Victoria. To mitigate this pollution, urban authorities need to implement strict waste management policies to prevent plastic debris from entering drainage networks. Full article

Detecting microplastics (MPs) in marine organisms is vital for understanding the ecological impact of MP pollution. Free-living marine nematodes, key players in benthic ecosystems, are often employed as bioindicators because of their sensitivity to environmental changes and thus hold promise as bioindicators for MP pollution too. This study investigated the detection of MPs in nematodes using µ-Raman spectroscopy combined with a tailored digestion protocol, targeting MPs in size ranges between 1 and 15 µm. While this is the first documented attempt to detect MPs in field-collected nematodes, significant challenges were identified. Contamination, particularly from airborne MPs and plastic-based laboratory materials, posed a major obstacle. We found higher numbers of <5 µm particles of polypropylene (PP), polyethylene terephthalate (PET), polylactic acid (PLA), polymethyl methacrylate (PMMA), and polystyrene (PS) in a natural community of nematodes compared to blank controls, suggesting the potential ingestion of small-sized MPs by nematodes in the real world. However, small MPs exhibited greater contamination challenges, underscoring the need for improved contamination control measures, such as open-air filters and plastic-free workflows. Despite these challenges, this study highlights the potential of µ-Raman spectroscopy as a valuable tool for detecting small-sized MPs in field-collected marine invertebrates, provided contamination risks are minimized. The likelihood of nematodes encountering MPs in marine sediments is high, but whether this translates to significant ingestion remains uncertain pending on the analysis of more field samples and the application of efficient measures of contamination reduction. Full article

Microplastics have emerged as a global environmental concern due to their widespread presence and potential effects on ecosystems. Wastewater treatment plants (WWTPs) play a critical role in mitigating the release of microplastics into the environment. This study aimed to evaluate the abundance and distribution of microplastics in three municipal WWTPs exhibiting different sludge and water treatment technologies. Samples were collected at various stages of the treatment process, including influent, primary and biological sludge, treated water, thickened sludge and dehydrated sludge. Quantification analyses were performed and then coupled with operational data to assess pollution flow rates and the microplastic balance. An important removal rate (>97%) of microplastics along the water line was observed in all three WWTPs. The lower performance of 0.75 mm screening was observed regarding microplastic capture compared to conventional primary settling on the water line. No significant differences in the pollution flow rates between primary and biological sludge were detected. Whatever the thickening and dehydration technologies that were tested, the specific quantities of microplastics along the sludge treatment lines were steady, implying the comparable behaviour of microparticular pollution to total suspended solids. These results underscored the important role of the different concentration stages of sludge treatment lines in sequestrating microplastics within the sludge fraction. Full article

The widespread presence of microplastics (MPs) is of growing concern for both the scientific community and the public. Contemporary research increasingly focuses on ecosystem transformation and global climate change. We conducted a literature review, consisting of 46 studies, to investigate the consequences of MPs’ influence on the carbon cycle in different soil types across various ecosystems. MPs can affect the cycling of carbon compounds and other biogenic elements by impacting the soil microbiome, enzyme activity, plant growth, litter decomposition, and more. The majority of authors report increased CO₂ and/or CH₄ emissions in soils containing MPs. However, some studies demonstrate the opposite or a neutral result, and the outcomes can differ even within a single study depending on the soil type and/or the type, form, and size of the MPs used. Further clarification and development of our understanding regarding the impact of MPs on the carbon cycle across different ecosystems remain crucial, taking into account the inclusion of as wide a variety of MPs as possible in future research. Full article

Cretan Graviera cheese is one of Greece’s most prized cheeses and holds a Protected Designation of Origin (PDO) status. For years, food packaging migration has been a key concern in food and health sciences, with plastics like low-density polyethylene (LDPE) and polypropylene (PP) widely used for cheese preservation and convenient handling during transport and storage. This study focused on Cretan Graviera cheese, examining two different levels of maturity: 4 and 8 months. The cheese samples were analyzed using two complementary vibrational spectroscopic techniques, FTIR-ATR and Raman spectroscopy, to assess the migration of LDPE and PP from plastic packaging to the cheese’s surface. The experimental period was set at 21 days, corresponding to the degradation time of the selected cheese, which becomes apparent after three weeks under refrigerated conditions at 7 °C. The results indicate that, with Raman and FTIR-ATR spectroscopy, LDPE and PP migration can occur from the plastic packaging to the surface of Graviera samples with different maturities. Microbial growth was observed sooner in the 4-month-old samples and 8-month-old samples. The migration of food packaging materials was confirmed using both Raman and FTIR spectroscopy, highlighting that Cretan Graviera cheese should be stored in appropriate packaging under refrigerated conditions at 7 °C. Full article

Nanoplastics and microplastics in agricultural systems have raised significant concerns due to their effects on plant health and potential risks to human consumption. This review examined these pollutants’ origins, behavior, and impacts in agricultural environments, emphasizing their primary contamination pathways, such as irrigation, plastic mulching, and sewage sludge application. It explored the transport, accumulation, and interactions of these particles in the soil, including their ability to adsorb other contaminants like pesticides and heavy metals. The effects on plant physiology and potential toxicity were highlighted, along with the implications for food quality and safety. Chronic exposure to these pollutants through the food chain posed notable health concerns for humans, emphasizing the urgency of addressing this issue. Research gaps, such as the toxicokinetics of nanoplastics and microplastics in plants and humans, were identified, underscoring the need for further investigation. The review also presented mitigation strategies, including improved waste management and the development of sustainable agricultural practices. Full article

Biscayne Bay in southeastern Florida, USA, has experienced dramatic ecological declines due to pollution. The Biscayne Bay and Southeastern Everglades Ecosystem Restoration will deliver water from a canal adjacent to coastal mangroves, intercepting pollutants before they are deposited into the estuary. Given their demonstrated capacity to filter nutrients and other contaminants from the water column, we hypothesized that mangrove wetlands also filter microplastics (“MPs”). Water and sediment samples were taken from 3 “zones”: the L-31E canal, a potential MP source; interior, dwarf mangroves; and coastal, tidal fringe mangroves. These three environments were replicated in coastal basins with and without canal culverts. MPs were expected to vary seasonally and be more abundant and larger in the dwarf zone and in low-bulk density sediments as particles settled into peat soils. In sediment, MPs were more abundant in the dry season (average 0.073 ± 0.102 (SD) MPs/g dw) before getting flushed by overland runoff resulting in greater concentrations in water during the wet season (average 0.179 ± 0.358 (SD) MPs/L). MPs were most abundant and larger in the low bulk density sediments of the dwarf zone, likely due to sheltering from fragmentation. Culvert presence had no effect, but MPs may increase as waterflows increase to planned volumes. Understanding MP dynamics enables managers to predict water quality impacts and leverage the potential ecosystem service of MP filtration by mangrove wetlands. Full article