A review of microplastic fibres: generation, transport, and vectors for metal(loid)s in terrestrial environments

Investigation of microplastics in advanced biological wastewater treatment plant effluent

In recent years, plastic pollution in the environment has also increased due to the increasing production and consumption of plastics worldwide. The presence of microplastics (MPs) in the environment from different sources is observed almost everywhere, especially in aquatic environments. A standard method for sampling, identification, and quantification of MPs in wastewater has not yet been established. In this study, it was aimed to determine the MPs and their characteristics in the effluent of an advanced biological domestic wastewater treatment plant. The seasonal changes of MPs in a year were revealed. Pre-treatments suitable for the studied wastewater were developed for visual determination of MPs. Fibers are the dominant type of MPs, with numbers ranging between 32.0 and 95.5 particle/L. MPs in five different polymer structures were determined by FTIR analysis. These are Polyethylene, Polypropylene, Polyester, Polyurethane and Polyethylene terephthalate. The results were evaluated according to QA/QC and determined to meet the standards.

Like noodles in a soup: Anthropogenic microfibers are being ingested by juvenile fish in nursery grounds of the Southwestern Atlantic Ocean

The balance between marine health and ecosystem sustainability confronts a pressing threat from anthropogenic pollution. Estuaries are particularly susceptible to contamination, notably by anthropogenic microfibers originated from daily human activities in land and in fishing practices. This study examines the impact of anthropogenic microfibers on the whitemouth croaker in an estuarine environment of the Southwestern Atlantic Ocean during cold and warm seasons. The presence of anthropogenic microfibers was revealed in 64 % of juvenile gastrointestinal tracts, and 94 % of water samples, and concentrations were influenced by factors such as temperature, bay zone, and fish body length. Blue and black anthropogenic microfibers, with a rather new physical aspect, were dominant. This study highlights the impact of microfibers in a heavily anthropized body of water, subject to federal and local regulations due to the presence of commercially significant fish species inhabiting this area.

Liquidlike, Low-Friction Polymer Brushes for Microfibre Release Prevention from Textiles

During synthetic textile washing, rubbing between fibres or against the washing machine, exacerbated by the elevated temperature, initiates the release of millions of microplastic fibres into the environment. A general tribological strategy is reported that practically eliminates the release of microplastic fibres from laundered apparel. The two-layer fabric finishes combine low-friction, liquidlike polymer brushes with "molecular primers", that is, molecules that durably bond the low-friction layers to the surface of the polyester or nylon fabrics. It is shown that when the coefficient of friction is below a threshold of 0.25, microplastic fibre release is substantially reduced, by up to 96%. The fabric finishes can be water-wicking or water-repellent, and their comfort properties are retained after coating, indicating a tunable and practical strategy toward a sustainable textile industry and plastic-free oceans and marine foodstuffs.

Microplastics in soils: Production, behavior process, impact on soil organisms, and related toxicity mechanisms

In recent years, microplastics (MPs) pollution has become a hot ecological issue of global concern and MP pollution in soil is becoming increasingly serious. Studies have shown that MPs have adverse effects on soil biology and ecological functions. Although MPs are evident in soils, identifying their source, abundance, and types is difficult because of the complexity and variability of soil components. In addition, the effects of MPs on soil physicochemical properties (PCP), including direct effects such as direct interaction with soil particles and indirect effects such as the impact on soil organisms, have not been reported in a differentiated manner. Furthermore, at present, the soil ecological effects of MPs are mostly based on biological toxicity reports of their exudate or size effects, whereas the impact of their surface-specific properties (such as environmentally persistent free radicals, surface functional groups, charge, and curvature) on soil ecological functions is not fully understood. Considering this, this paper reviews the latest research findings on the production and behavioral processes of MPs in soil, the effects on soil PCP, the impacts on different soil organisms, and the related toxic mechanisms. The above discussion will enhance further understanding of the behavioral characteristics and risks of MPs in soil ecosystems and provide some theoretical basis for further clarification of the molecular mechanisms of the effects of MPs on soil organisms.

The bioadhesion and effects of microplastics and natural particles on growth, cell viability, physiology, and elemental content of an aquatic macrophyte Elodea canadensis

Microplastics in the aquatic environment can interact with aquatic plants, but the consequences of these interactions are poorly understood. Therefore, the aim of this study was to investigate the effects of microplastics commonly found in the environment, namely polyethylene (PE) fragments, polyacrylonitrile (PAN) fibres, tire wear (TW) particles under a relevant environmental concentration (5000 particles/L) on the growth, cell viability, physiology, and elemental content of the aquatic macrophyte Elodea canadensis. The effects of microplastics were compared to those of natural wood particles. The results showed that all types of microplastics adhered to plant tissues, but the effect on leaves (leaf damage area) was greatest at PE > PAN > TW, while the effect of natural particles was comparable to that of the control. None of the microplastics studied affected plant growth, lipid, carbohydrate, or protein content. Electron transport system activity was significantly higher in plants exposed to PAN fibres and PE fragments, but also when exposed to natural particles, while chlorophyll a content was negatively affected only by PE fragments and TW particles. Elemental analysis of plant tissue showed that in some cases PAN fibres and TW particles caused increased metal content. The results of this study indicated that aquatic macrophytes may respond differently to exposure to microplastics than to natural particles, likely through the combined effects of mechanical damage and chemical stress.

Microplastic Pollution in the Gastrointestinal Tract and Gills of Some Teleost and Sturgeon Fish from the Caspian Sea, Northern Iran

The increasing microplastic pollution in the marine environment has raised global concern. The main risk of microplastics in aquatic ecosystem is their bioaccumulation in aquatic organisms. A few studies have reported microplastic pollution in the digestive system of Caspian Sea fish species, but there is no research on sturgeon species, nor on fish gills. We investigated the occurrence of microplastics in the gastrointestinal tract (GIT) and gills of 62 specimens belonging to four species including three teleosts (Cyprinus carpio, Rutilus kutum, and Chelon aurata) and one sturgeon (Acipenser persicus, a valuable endangered species) from the Caspian Sea between January and March 2022. Fish tissues were removed, exposed for 24 h to 10% KOH, and then dried on filter paper. Particles were observed under a stereomicroscope and analyzed by Raman microspectrometry, scanning electron microscopy, and energy-dispersive spectroscopy. A total of 91 microplastics were detected in the GIT (average of 1.46 ± 1.17 items/individual) and 63 microplastics in the gills (average of 1.01 ± 0.62 items/individual). A significant correlation was not found between the number of microplastics found in both tissues and fish body length, body weight, GIT weight, and gill weight (p > 0.05), except between microplastics isolated from gills and gill weight in C. carpio (rs  = 0.707, p = 0.022). The abundance of microplastics in fish followed the order of A. persicus > C. aurata > R. kutum > C. carpio. The microplastics were in the size range of 45 to 5000 µm, with particles of 300 to 1000 µm being the most prevalent; 74.68% of the particles were shaped like fibers, 30.53% were red, and 70.6% were composed of nylon polymer. Environ Toxicol Chem 2023;42:2453-2465. © 2023 SETAC.

Microplastics in the soil environment: Focusing on the sources, its transformation and change in morphology

Microplastics (MPs) are small plastic pieces less than 5 mm in size. Previous studies have focused on the sources, transports, and fates of MPs in marine or sediment environments. However, limited attention has been given to the role of land as the primary source of MPs, and how plastic polymers are transformed into MPs through biological or abiotic effects during the transport process remains unclear. Here, we focus on the exploration of the main sources of MPs in the soil, highlighting that MP generation is not solely a byproduct of plastic production but can also result from the impact of biological and abiotic factors during the process of MPs transport. This review presents a new perspective on understanding the degradation of MPs in soil, considering soil as a distinct fluid and suggesting that the main transformation and change mediated by abiotic factors occur on the soil surface, while the main biodegradation occurs in the soil interior. This viewpoint is suggested because the role of some abiotic factors becomes less obvious in the soil interior, and MPs, whose surface is expected to colonize microorganisms, are gradually considered a carbon source independent of photosynthesis and net primary production. This review emphasizes the need to understand basic MPs information in soil for a rational evaluation of its environmental toxicity. Such understanding enables better control of MPs pollution in affected areas and prevents contamination in unaffected regions. Finally, knowledge gaps and future research directions necessary for advancements in this field are provided.

Microplastic pollution in sediments of urban rainwater drainage system

The sink of microplastics (MPs) in sediments of urban rainwater drainage system (RDS) is of great concern, because the MPs deposited can be resuspended by flow disturbance. Previous research has confirmed the significant accumulation of MPs in sediments of urban RDS, but it remains poorly elucidated, such as pollution sources and influencing factors. In this study, we investigated the MPs in sediments from RDS of a university campus. MPs were detected from all sediment samples, showing the ubiquity of microplastic pollution. Among 11 samples MPs' abundance ranged from 80 to 2610 particles/kg (dry weight), with highly spatial variability, depending on land type and environmental management practice within the catchment. Sites from office & teaching area had the averaged abundance of 335.00 ± 196.85 particles/kg, while 270.00 ± 89.09 particles/kg for staff residential area, and 795.00 ± 1050.65 particles/kg for student living area, indicating that the sediments of RDS from student living area had the highest abundance of MPs. However, independent sample t-test analysis suggests there is no statistically significant difference between land types, because of effective environmental management practices in the catchment. The surfaces of MPs were much rough, which implies that the fragmentation of larger plastic particles resulted in the production of MPs. Although the MPs of <1000 μm were the most, 1000-2000 μm MPs also accounted for a significant proportion in this study, showing a slight difference from the previous study in which MPs over 1 mm were quite low. Polypropylene (PP) and polyester (PET) found to be dominant with 49.75 ± 18.69 % and 49.75 ± 18.69 % of the total number, respectively. As to shapes, the proportion of fiber and fragment MPs exceeded 80 %. The color of MPs diversified greatly, and the MPs with bright colors occupied over 80 %. Fabric fibers, food packaging and courier packaging materials were figured out to be the considerable contributors of MPs.