Effects of Polyester Microfibers on Microphytobenthos and Sediment-Dwelling Infauna

A global assessment of microplastic abundance and characteristics on marine turtle nesting beaches

Sandy coastal beaches are an important nesting habitat for marine turtles and a known sink for plastic pollution. Existing methodologies for monitoring the spatiotemporal patterns of abundance and composition of plastic are, however, disparate. We engaged a global network of marine turtle scientists to implement a large-scale sampling effort to assess microplastic abundance in beach sediments on marine turtle nesting beaches. Sand samples were collected from 209 sites spanning six oceans, microplastics (1-5 mm) were extracted through stacked sieves, visually identified, and a sub-sample verified via Fourier-transform infrared spectroscopy. Microplastics were detected in 45 % (n = 94) of beaches and within five ocean basins. Microplastic presence and abundance was found to vary markedly within and among ocean basins, with the highest proportion of contaminated beaches found in the Mediterranean (80 %). We present all data in an accessible, open access format to facilitate the extension of monitoring efforts and empower novel analytical approaches.

Benthic ecosystem function responses to plasticizer content in polyester and PVC

Plastics are ubiquitous contaminants in marine systems with a diverse set of chemical components. While eco-toxicological effects of plastic chemicals provide insights on how marine species respond to plastic exposure, there is lack in ecological understanding of such impacts. In a mesocosm experiment, we measured benthic fluxes to determine ecosystem function responses to polyester netting (low plasticizer concentration) and PVC netting (high plasticizer concentration). Gross primary production rates and ammonium efflux were higher in both plastic treatments compared to the control, but responses were stronger in the polyester treatment. In the PVC treatment we additionally observed a strong response in nitrate fluxes which suggests a disturbance of the benthic N cycle. Our results imply that the concentration of chemical additives in new plastics can be a driver for ecological responses and reduction of plastic emissions needs to remain at the forefront of environmental plastic pollution regulations.

Zooming in the plastisphere: the ecological interface for phytoplankton-plastic interactions in aquatic ecosystems

Phytoplankton is an essential resource in aquatic ecosystems, situated at the base of aquatic food webs. Plastic pollution can impact these organisms, potentially affecting the functioning of aquatic ecosystems. The interaction between plastics and phytoplankton is multifaceted: while microplastics can exert toxic effects on phytoplankton, plastics can also act as a substrate for colonisation. By reviewing the existing literature, this study aims to address pivotal questions concerning the intricate interplay among plastics and phytoplankton/phytobenthos and analyse impacts on fundamental ecosystem processes (e.g. primary production, nutrient cycling). This investigation spans both marine and freshwater ecosystems, examining diverse organisational levels from subcellular processes to entire ecosystems. The diverse chemical composition of plastics, along with their variable properties and role in forming the "plastisphere", underscores the complexity of their influences on aquatic environments. Morphological changes, alterations in metabolic processes, defence and stress responses, including homoaggregation and extracellular polysaccharide biosynthesis, represent adaptive strategies employed by phytoplankton to cope with plastic-induced stress. Plastics also serve as potential habitats for harmful algae and invasive species, thereby influencing biodiversity and environmental conditions. Processes affected by phytoplankton-plastic interaction can have cascading effects throughout the aquatic food web via altered bottom-up and top-down processes. This review emphasises that our understanding of how these multiple interactions compare in impact on natural processes is far from complete, and uncertainty persists regarding whether they drive significant alterations in ecological variables. A lack of comprehensive investigation poses a risk of overlooking fundamental aspects in addressing the environmental challenges associated with widespread plastic pollution.

Bioturbation effects and behavioral changes in buried bivalves after exposure to microplastics

Microplastic pollution has become an increasing concern. Vertical transport of microplastics is one of the major research questions concerning the distribution and fate of microplastics in the marine environment, and biologically mediated vertical transport is particularly significant. However, studies on the effects of different types of benthic organisms on the vertical distribution of microplastics in sediments are still scarce. The results of this study revealed that when exposed to environmentally relevant concentrations of fluorescent polystyrene microbeads (200 µm), Manila clams (Ruditapes philippinarum) exhibited prolonged acclimation period, yet subsequent burrowing behavior (burrowing rate and burrowing velocity) was unaffected. The condition index, clearance rate, and oxygen consumption rate of the clams similarly exhibited no stress response after 14 days of exposure. We determined that microplastics were rapidly transported to deeper layers (6-8 cm below the surface) in the sediment under bioturbation. This study elucidates the mechanisms of microplastic transport, showing that clam behaviors such as burrowing, movement, and ingestion contribute to this process. The results suggest that a biologically based management strategy may be a more environmentally friendly means of mitigating microplastic pollution in seawater.

Microplastics in commercial marine bivalves: Abundance, characterization and main effects of single and combined exposure

Microplastics (MPs) are persistent and ubiquitous pollutants in marine ecosystems, and they can be ingested and accumulated by marine organisms with economic value to humans, such as marine bivalves, which may pose a threat to the marine food chains and to human health. In this literature review, we summarized the recent findings on the abundance and main characteristics (shape, size, color, polymer) of MPs detected in valuable marine bivalve species. Furthermore, we surveyed the major impacts triggered by MP exposure, alone or in combination with other pollutants, in these organisms. Additionally, we discussed the methodologies, techniques and equipment commonly used by researchers for the determination of the abundance, characterization and effects of the MP particles in these organisms. We verified that MPs have been widely detected in multiple species of commercial marine bivalves, with a great variety of shapes, sizes, colors and polymer types. In general, the methodologies used by researchers to determine the MP abundance in marine bivalves need to be harmonized to facilitate the comparability between studies. So far, previous research showed that the main effects of MPs, either alone or combined with other pollutants, on commercial marine bivalves include the induction of immunological, physiological and behavioral responses, reproductive modifications, genotoxicity and neurotoxicity, which were surveyed by using a wide variety of techniques and analytical equipment. In the future, researchers should focus on less studied bivalve species and should use the most precise and innovative methodologies to assess the effects of MPs and other pollutants on marine bivalves.

Polyester fibres slowly degrade in marine sediments

Microplastics are everywhere, including marine sediment. In this study, we evaluated the degradation of polyester, rayon, and cotton sewing threads over nine months when buried in marine sediment in Waitematā Harbour, Auckland, New Zealand. Polyester tensile strength was tested pre- and post-burial to track changes over time. Fourier-transform infrared spectroscopy (FTIR) analysis enabled the examination of the change to the chemical structural integrity of the polyester molecules over time. After one month, rayon and cotton degraded and were invisible to the eye, while visible signs of polyester degradation were apparent after 6 months of burial. This was confirmed by both tensile strength testing and FTIR chemical analysis. While microplastic pollution remains a serious problem, these findings show that at least one type of common plastic does degrade when buried in marine sediments. This likely has implications for seafloor ecosystem functionality and provides hope for plastic circular economy infrastructure.

Estimation of bottom microplastic flux in the Indonesian seas

Marine debris, particularly microplastics, is an important environmental problem for Indonesia, impacting vast coastline and diverse marine ecosystems. However, little is known about the microplastics flux to the seafloor in the Indonesian Seas. This study employs HYCOM data and Lagrangian particle tracking model to analyze the distribution of microplastics flux to the seafloor from 68 rivers in Indonesia. Microplastics accumulation can be found in coastal waters near major islands, typically within 50-100 km of the coast. Accumulation regions within the Fisheries Management Area (FMA) in Indonesia are mostly located in Karimata Strait, Java Sea and South Java. This study highlights the importance of understanding sinking particles behavior for effective waste management strategies, as well as for mitigating environmental impacts in Indonesian waters.

Impacts of microplastic concentrations and sizes on the rheology properties of lake sediments

The information concerning the effects of microplastics (MPs) on lake sediment environment, particularly structural properties, is still scant. This study aimed to investigate the effect of MPs characteristics (including concentration and size) on the sediment rheological properties, which affected sediment resuspension. After 60-day experiments, it was found that (0.5-2 %) MP in sediments decreased sediment viscosity, yield stress, and flow point shear stress by 14.7-38.4 %, 3.9-24.1 % and 13.5-36.5 %. Besides, sediment (with 50 μm MP addition) yield stress and flow point shear stress also dropped by 1.1-14.1 % and 9.6-12.9 % compared to 100 and 200 μm MP addition. The instability in sediment structure could be attributed to MP-induced EPS production and cation exchange capacity (CEC) changes. Accordingly, the decreases in rheological properties induced by different sizes and concentrations MPs might facilitate the sediments resuspension with wind and wave disturbances. The study shed light on previously overlooked environmental issues caused by MPs characteristics from a new perspective, thereby enhancing our understanding about the environmental behavior of MPs in lake sediment ecosystems.

Rapid effects of plastic pollution on coastal sediment metabolism in nature

While extensive research has explored the effects of plastic pollution, ecosystem responses remain poorly quantified, especially in field experiments. In this study, we investigated the impact of polyester pollution, a prevalent plastic type, on coastal sediment ecosystem function. Strips of polyester netting were buried into intertidal sediments, and effects on sediment oxygen consumption and polyester additive concentrations were monitored over 72-days. Our results revealed a rapid reduction in the magnitude and variability of sediment oxygen consumption, a crucial ecosystem process, potentially attributed to the loss of the additive di(2-ethylhexyl) phthalate (DEHP) from the polyester material. DEHP concentrations declined by 89% within the first seven days of deployment. However, effects on SOC dissipated after 22 days, indicating a short-term impact and a quick recovery by the ecosystem. Our study provides critical insights into the immediate consequences of plastic pollution on ecosystem metabolism in coastal sediments, contributing to a nuanced understanding of the temporal variation of plastic pollution's multifaceted impacts. Additionally, our research sheds light on the urgent need for comprehensive mitigation strategies to preserve marine ecosystem functionality from plastic pollution impacts.

Physiological and genetic responses of the benthic dinoflagellate Prorocentrum lima to polystyrene microplastics

Microplastics are well known as contaminants in marine environments. With the development of biofilms, most microplastics will eventually sink and deposit in benthic environment. However, little research has been done on benthic toxic dinoflagellates, and the effects of microplastics on benthic dinoflagellates are unknown. Prorocentrum lima is a cosmopolitan toxic benthic dinoflagellate, which can produce a range of polyether metabolites, such as diarrhetic shellfish poisoning (DSP) toxins. In order to explore the impact of microplastics on marine benthic dinoflagellates, in this paper, we studied the effects of polystyrene (PS) on the growth and toxin production of P. lima. The molecular response of P. lima to microplastic stress was analyzed by transcriptomics. We selected 100 nm, 10 μm and 100 μm PS, and set three concentrations of 1 mg L-1, 10 mg L-1 and 100 mg L-1. The results showed that PS exposure had limited effects on cell growth, but increased the OA and extracellular polysaccharide content at high concentrations. After exposure to PS MPs, genes associated with DSP toxins synthesis, carbohydrate synthesis and energy metabolism, such as glycolysis, TCA cycle and pyruvate metabolism, were significantly up-regulated. We speculated that after exposure to microplastics, P. lima may increase the synthesis of DSP toxins and extracellular polysaccharides, improve the level of energy metabolism and gene expression of ABC transporter, thereby protecting algal cells from damage. Our findings provide new insights into the effects of microplastics on toxic benthic dinoflagellates.

New insights into changes in phosphorus profile at sediment-water interface by microplastics: Role of benthic bioturbation

Microplastics (MPs) have attracted increasing attention due to their ubiquitous occurrence in freshwater sediments and the detrimental effects on benthic invertebrates. However, a clear understanding of their downstream impacts on ecosystem services is still lacking. This study examines the effects of bio-based polylactic acid (PLA), fuel-based polyethylene terephthalate (PET), and biofilm-covered PET (BPET) MPs on the bioturbator chironomid larvae (Tanypus chinensis), and the influence on phosphorus (P) profiles in microcosms. The changes in biochemical responses and metabolic pathways indicated that MPs disrupted energy synthesis by causing intestinal blockage and oxidative stress in T. chinensis, leading to energy depletion and impaired bioturbation activity. The impairment further resulted in enhanced sedimentary P immobilization. For larval treatments, the internal-P loadings were respectively 11.4%, 8.6%, and 9.0% higher in the PLA, PET, and BPET groups compared to the non-MP control. Furthermore, the influence of bioturbation on P profiles was MP-type dependent. Both BPET and PLA treatments displayed more obvious impacts on P profiles compared to PET due to the changes in MP bioavailability or sediment microenvironment. This study connects individual physiological responses to broader ecosystem services, showing that MPs alter P biogeochemical processes by disrupting the bioturbation activities of chironomid larvae.

Polyester microfiber impacts on coastal sediment organic matter consumption

As plastic pollution continues to accumulate at the seafloor, concerns around benthic ecosystem functionality heightens. This research demonstrates the systematic effects of polyester microfibers on seafloor organic matter consumption rates, an important benthic ecosystem function connected to multiple reactions and processes. We used a field-based assay to measure the loss of organic matter, both with and without polyester microfiber contamination. We identified sediment organic matter content, mud content, and mean grain size as the main drivers of organic matter consumption, however, polyester microfiber contamination decoupled ecosystem relationships and altered observed organic matter cycling dynamics. Organic matter consumption rates varied across horizontal and vertical spaces, highlighting that consumption and associated plastic effects are dependent on environmental heterogeneity at both small (within sites) and larger (between sites) scales. Our results emphasize the important role habitat heterogeneity plays in seafloor organic matter consumption and the associated effects of plastic pollution on ecosystem function.

Impacts of microplastic contamination on the rheology properties of sediments in a eutrophic shallow lake

Microplastic (MP) contamination is a growing global concern, with lake sediments serving as a significant sink for MP due to both anthropogenic and natural activities. Given the increasing evidence of MP accumulation in sediments, it was crucial to assess their influence on sediment erosion resistance, which directly affected sediment resuspension. To fill this gap, this study focused on the effect of MP on the sediments rheological properties. After 60-day experiments, it was found that MP addition into sediments reduced sediment viscosity, yield stress, and flow point shear stress. Meanwhile, MPs also significantly altered sediment properties and extracellular polymer composition. MP addition reduced extracellular polymeric substances production and cation exchange capacity, which then worked together and led to a weak sediment structure. Seemingly, MPs changed fluid sediment characteristics and caused stronger fluidity under less shear force. Consequently, the accumulation of MP might facilitate the resuspension of sediments under smaller wind and wave disturbances. This study provided novel insights into the direct impact of MPs on sediment physical properties using rheology, thereby enhancing our understanding of the environmental behavior of MPs in lake ecosystems.

Photo-oxidation of Micro- and Nanoplastics: Physical, Chemical, and Biological Effects in Environments

Micro- and nanoplastics (MNPs) are attracting increasing attention due to their persistence and potential ecological risks. This review critically summarizes the effects of photo-oxidation on the physical, chemical, and biological behaviors of MNPs in aquatic and terrestrial environments. The core of this paper explores how photo-oxidation-induced surface property changes in MNPs affect their adsorption toward contaminants, the stability and mobility of MNPs in water and porous media, as well as the transport of pollutants such as organic pollutants (OPs) and heavy metals (HMs). It then reviews the photochemical processes of MNPs with coexisting constituents, highlighting critical factors affecting the photo-oxidation of MNPs, and the contribution of MNPs to the phototransformation of other contaminants. The distinct biological effects and mechanism of aged MNPs are pointed out, in terms of the toxicity to aquatic organisms, biofilm formation, planktonic microbial growth, and soil and sediment microbial community and function. Furthermore, the research gaps and perspectives are put forward, regarding the underlying interaction mechanisms of MNPs with coexisting natural constituents and pollutants under photo-oxidation conditions, the combined effects of photo-oxidation and natural constituents on the fate of MNPs, and the microbiological effect of photoaged MNPs, especially the biotransformation of pollutants.

Modelled broad-scale shifts on seafloor ecosystem functioning due to microplastic impacts on bioturbation

Bioturbating species play an essential role in regulating nutrient cycling in marine sediments, but their interaction with microplastics (MP) remains poorly understood. Here we investigated the linkage between MP and ecosystem functioning using experimental observations of luminophore distribution in the sediment to parametrize bioturbation coefficients (Db). this information as fed into a simplified transport-reaction model, allowing us to upscale our experimental results. We found that the composition of bioturbators modulated shifts in the ecosystem functioning under microplastic stress. Maldanid worms (Macroclymenella stewartensis), functionally deep burrowing and upward-conveyor belt feeders, became less active. The Db of M. stewartensis reduced by 25% with the addition of 0.002 g MP cm-2 at surface sediment, causing accumulation of organic matter in the oxic sediment zone and stimulating aerobic respiration by 18%. In contract, the tellinid bivalve Macomona liliana, functionally a surface -deposit feeder that excretes at depth, maintained particle mixing behaviour in MP-contaminated systems. This study provides a mechanistic insight into the impacts of MP and indicates that the functional role of bioturbating species should be involved in assessing the global impact of MP. The model allowed us to understand the broad-scale impact of MP on seafloor habitat.

On the horns of a dilemma: Evaluation of synthetic and natural textile microfibre effects on the physiology of the pacific oyster Crassostrea gigas

Fast fashion and our daily use of fibrous materials cause a massive release of microfibres (MF) into the oceans. Although MF pollution is commonly linked to plastics, the vast majority of collected MF are made from natural materials (e.g. cellulose). We investigated the effects of 96-h exposure to natural (wool, cotton, organic cotton) and synthetic (acrylic, nylon, polyester) textile MF and their associated chemical additives on the capacity of Pacific oysters Crassostrea gigas to ingest MF and the effects of MF and their leachates on key molecular and cellular endpoints. Digestive and glycolytic enzyme activities and immune and detoxification responses were determined at cellular (haemocyte viability, ROS production, ABC pump activity) and molecular (Ikb1, Ikb2, caspase 1 and EcSOD expression) levels, considering environmentally relevant (10 MF L^-1) and worst-case scenarios (10 000 MF L^-1). Ingestion of natural MF perturbed oyster digestive and immune functions, but synthetic MF had few effects, supposedly related with fibers weaving rather than the material itself. No concentration effects were found, suggesting that an environmental dose of MF is sufficient to trigger these responses. Leachate exposure had minimal effects on oyster physiology. These results suggest that the manufacture of the fibres and their characteristics could be the major factors of MF toxicity and stress the need to consider both natural and synthetic particles and their leachates to thoroughly evaluate the impact of anthropogenic debris. Environmental Implication. Microfibres (MF) are omnipresent in the world oceans with around 2 million tons released every year, resulting in their ingestion by a wide array of marine organisms. In the ocean, a domination of natural MF- representing more than 80% of collected fibres-over synthetic ones was observed. Despite MF pervasiveness, research on their impact on marine organisms, is still in its infancy. The current study aims to investigate the effects of environmental concentrations of both synthetic and natural textile MF and their associated leachates on a model filter feeder.

Impact of Fibrous Microplastic Pollution on Commercial Seafood and Consumer Health: A Review

The omnipresence of microfibers in marine environments has raised concerns about their availability to aquatic biota, including commercial fish species. Due to their tiny size and wide distribution, microfibers may be ingested by wild-captured pelagic or benthic fish and farmed species. Humans are exposed via seafood consumption. Despite the fact that research on the impact of microfibers on marine biota is increasing, knowledge on their role in food security and safety is limited. The present review aims to examine the current knowledge about microfiber contamination in commercially relevant fish species, their impact on the marine food chain, and their probable threat to consumer health. The available information suggests that among the marine biota, edible species are also contaminated, but there is an urgent need to standardize data collection methods to assess the extent of microfiber occurrence in seafood. In this context, natural microfibers should also be investigated. A multidisciplinary approach to the microfiber issue that recognizes the interrelationship and connection of environmental health with that of animals and humans should be used, leading to the application of strategies to reduce microfiber pollution through the control of the sources and the development of remediation technologies.

Spatiotemporal variation in microplastics derived from polymer-coated fertilizer in an agricultural small river in Ishikawa Prefecture, Japan

Marine plastic pollution has highlighted the need to address the disposal of plastic materials used in agricultural fields and prevent their runoff. To assess the status of microplastics derived from polymer-coated fertilizers (microcapsules), we investigated their seasonal and daily variations in a small agricultural river in Ishikawa Prefecture, Japan, throughout the irrigation period of April to October 2021 and 2022. We also investigated the relationship between microcapsule concentration and water quality. The mean microcapsule concentration over the study period ranged from 0.0 to 783.2 mg/m³ (median 18.8 mg/m³) and was positively correlated with total litter weight, but it was not correlated with common water quality parameters such as total nitrogen or suspended solids. Concentrations of microcapsules in river water showed distinct seasonal variations, being particularly high in late April and late May (median 55.5 mg/m³ in 2021, 62.6 mg/m³ in 2022) and almost undetectable thereafter. The timing of the increase in concentration coincided with the timing of the outflow from paddy fields, suggesting that microcapsules that flowed out of the paddy fields would reach the sea relatively quickly. The results of a tracer experiment supported this conclusion. Intensive observations revealed that microcapsule concentrations varied widely over time, with differences reaching a maximum of 110-fold (range 7.3-783.2 mg/m³) over a 3-day period. Daytime concentrations were higher than those at night, reflecting the fact that microcapsules are discharged from paddies by daytime operations such as puddling and surface drainage. Microcapsule concentrations in the river were not correlated with river discharge, making estimating their loading a future research challenge.

Research and characterization of fibrous microplastics and natural microfibers in pelagic and benthic fish species of commercial interest

The ingestion of synthetic microfibers, the most prevalent type of microplastics in marine environments, and natural fibers was assessed in Engraulis engrasicolus and Mullus barbatus, two commercially important fish species in the Mediterranean Sea. Microfibers were isolated from the fish gastrointestinal tract using a 10% potassium hydroxide solution. For the microfiber characterization, the evaluation of specific morphological features using a light microscope, coupled with the Fourier-transform infrared (FTIR) analysis of a subsample of isolated particles, was applied. The preliminary results showed the occurrence of microfibers in 53 and 60% of European anchovy and Red mullet, respectively. A mean of 6.9 microfibers/individual was detected in anchovies, while on average Red mullet samples contained 9.2 microfibers/individual. The most common colors of fibers in both species were black, blue, and transparent. Visual characterization of fibers allowed the classification of 40% of the items as synthetic microfibers. FTIR spectroscopy confirmed the visual classification by fiber morphology. Microfibers were made of different typologies of polymers, represented by cellulose, cotton, and polyester. These findings confirm as the wide distribution of fibrous microplastics, and natural microfibers may impact both pelagic and deep-sea trophic webs. Despite the presence of microfibers in fish species poses a potential risk to human health, the literature is scarce regarding studies on the uptake by commercial marine fish mostly due to methodological issues. The visual characterization, corroborated by spectroscopic techniques, may be useful to differentiate synthetic and natural fibers, representing a fast and easy method to assess fibrous microplastic pollution in commercially important fish species.

Real-world impacts of microplastic pollution on seafloor ecosystem function

Emerging research shows that microplastic pollution could be impacting seafloor ecosystem function, but this has been primarily demonstrated without environmental and ecological context. This causes uncertainty in the real-world effects of microplastic pollution and leaves out essential information guiding policy and mitigation. In this study, we take a well-supported sampling design and statistical approach commonly employed in benthic ecology to evaluate real-world effects of microplastic pollution on coastal, benthic ecosystem function. We utilised environmental gradients in the Waitemata Harbour of Auckland, New Zealand to evaluate the importance of commonly assessed biological, chemical, and geological sediment variables and the characteristics of microplastic contaminants in driving essential ecosystem functions. Our results showed that models including microplastic terms were more accurate and explained more variability than those without microplastic terms, highlighting that microplastics impact real-world seafloor ecosystem function. Specifically, microplastic fibers significantly influenced oxygen flux (p < 0.03) and the diverse forms of microplastics (i.e., richness) significantly influenced ammonium flux (p < 0.02). Additionally, interactions between microplastic fiber concentrations and mollusc abundances significantly contributed to oxygen flux (p < 0.02). These results provide the first evaluation of in situ relationships between microplastics and ecosystem function. Even more importantly, this study suggests the value of environmental and ecological context for addressing microplastic impacts on benthic ecosystems and argues for further field examination.

Impact of face mask microplastics pollution on the aquatic environment and aquaculture organisms

Microplastic pollution in our environment, especially water bodies is an emerging threat to food security and human health. Inevitably, the outbreak of Covid-19 has necessitated the constant use of face masks made from polymers such as polypropylene, polyurethane, polyacrylonitrile, polystyrene, polycarbonate, polyethylene, or polyester which eventually will disintegrate into microplastic particles. They can be broken down into microplastics by the weathering action of UV radiation from the sun, heat, or ocean wave-current and precipitate in natural environments. The global adoption of face masks as a preventive measure to curb the spread of Covid-19 has made the safe management of wastes from it cumbersome. Microplastics gain access into aquaculture facilities through water sources and food including planktons. The negative impacts of microplastics on aquaculture cannot be overemphasized. The impacts includes low growth rates of animals, hindered reproductive functions, neurotoxicity, low feeding habit, oxidative stress, reduced metabolic rate, and increased mortality rate among aquatic organisms. With these, there is every tendency of microplastic pollution to negatively impact fish production through aquaculture if the menace is not curbed. It is therefore recommended that biodegradable materials rather than plastics to be considered in the production of face mask while recycle of already produced ones should be encouraged to reduce waste.

Review of research on migration, distribution, biological effects, and analytical methods of microfibers in the environment

Microplastics have been proven to be one of the critical environmental pollution issues. Moreover, microfibers, the most prominent form of microplastics in the environment, have likewise attracted the attention of various countries. With the increase in global population and industrialization, the production and use of fibers continue to increase yearly. As a result, a large number of microfibers are formed. If fiber products are not used or handled correctly, it will cause direct/indirect severe microfiber environmental pollution. Microfibers will be further broken into smaller fiber fragments when they enter the natural environment. Presently, researchers have conducted extensive research in the identification of microfibers, laying the foundation for further resourcefulness research. This work used bibliometric analysis to review the microfiber contamination researches systematically. First, the primary sources of microfibers and the influencing factors are analyzed. We aim to summarize the influence of the clothing fiber preparation and care processes on microfiber formation. Then, this work elaborated on the migration in/between water, atmosphere, and terrestrial environments. We also discussed the effects of microfiber on ecosystems. Finally, microfibers' current and foreseeable effective treatment, disposal, and resource utilization methods were explained. This paper will provide a structured reference for future microfiber research.

Products released from surgical face masks can provoke cytotoxicity in the marine diatom Phaeodactylum tricornutum

Surgical face masks are more present than ever as personal protective equipment due to the COVID-19 pandemic. In this work, we show that the contents of regular surgical masks: i) polypropylene microfibres and ii) some added metals such as: Al, Fe, Cu, Mn, Zn and Ba, may be toxic to some marine life. This work has got two objectives: i) to study the release rate of the products from face masks in marine water and ii) to assess the toxicity in Phaeodactylum tricornutum of these by-products. To achieve these two objectives, we performed release kinetic experiments by adding masks in different stages of fragmentation to marine water (i.e. whole face masks and fragments of them 1.52 ± 0.86 mm). Released microfibres were found after one month in shaking marine water; 0.33 ± 0.24 and 21.13 ± 13.19 fibres·mL^-1 were collected from the whole and fragmented face masks, respectively. Significant amounts of dissolved metals such as Mn, Zn and Ni, as well as functional groups only in the water containing the face mask fragments were detected. Water from both treatments was employed to study its toxicity on the marine diatom. Only the water from the face mask fragments showed a significant, dose-dependent, decrease in cell density in P. tricornutum; 53.09 % lower than in the controls. Although the water from the face mask fragments showed greater effects on the microalgae population than the water from the whole face mask, the latter treatment did show significant changes in the photosynthetic apparatus and intrinsic properties of the cells. These results indicate that during fragmentation and degradation face masks a significant chemical print can be observed in the marine environment.

Effects of microplastics on greenhouse gas emissions and microbial communities in sediment of freshwater systems

Microplastics can regulate greenhouse gas emissions from environmental systems and affect microbes in the environment. However, the effect of microplastics in freshwater sediment system is still not well studied. In this paper, polyethylene terephthalate (PET) particles with six different diameters of 5-2000 µm were added to freshwater sediment, PET exposing for 90 days was carried out and its effect on greenhouse gas emissions, nutrients cycle and microbial communities were studied. In the 5 µm experimental group, carbon dioxide (CO₂) emissions were significantly promoted in the 7-30 days and nitrogen monoxide (N₂O) emissions were significantly promoted in the 7 days after cultivation. Microplastics in the range of 300-800 µm significantly promoted CO₂ emissions after three days of culture. In addition, microplastics increased the total organic carbon (TOC) content in freshwater sediment and changed microbial diversity, especially increased the microorganisms capable of degrading complex organics such as Saprospiraceae. There was a positive correlation between N₂O emission and nitrate (NO₃^-) content in sediment after 3 days of culture, while greenhouse gas emission was mainly related to TOC content after 90 days of culture. These results showed that microplastics could affect the carbon and nitrogen cycling process of shallow lake ecosystem.

Recent advances in impacts of microplastics on nitrogen cycling in the environment: A review

Nitrogen cycling plays a decisive role in biogeochemistry, and largely depends on microbial driven nitrogen transformation. The environmental problems caused by microplastics are becoming more serious, and the analysis and control of its pollution in the environment have become a research hotspot in the field. The nitrogen transformation and nitrogen cycling in the environment are mainly driven by microorganisms in the environment, and the existence of microplastics can affect the microbial population, abundance and type, thus affecting the transformation of nitrogen. The effect of microplastics on microorganisms involved in nitrogen transformation is briefly described. This paper mainly reviews the research progress on the impacts of microplastics on nitrogen transformation and nitrogen cycling in water, soil, sediment and sewage sludge. Microplastic type, size and concentration can cause obvious difference in the impacts of microplastics on nitrogen transformation. Then, response and mechanism of microplastics to microorganism mediated nitrogen transformation and nitrogen cycling are introduced. Processes of nitrogen transformation are affected by interfering with microorganism diversity and structure, enzyme activities and related coding genes and oxygen flux. Additionally, additives released from microplastics can also affect the microbial activity. However, mechanisms of microplastics on environmental nitrogen transformation and nitrogen cycling are not fully understood due to the lack of relevant research. There are effective strategies to evaluate complex environmental systems, prolong action time, strengthen multi factor and multi-level research, and assist molecular biology and stable isotope technology. This review article can provide valuable insights into the impact of microplastics on microorganisms mediated nitrogen transformation processes and evaluate the impact on ecological and environmental health.

Microplastics: impacts on corals and other reef organisms

Plastic pollution in a growing problem globally. In addition to the continuous flow of plastic particles to the environment from direct sources, and through the natural wear and tear of items, the plastics that are already there have the potential to breakdown further and therefore provide an immense source of plastic particles. With the continued rise in levels of plastic production, and consequently increasing levels entering our marine environments it is imperative that we understand its impacts. There is evidence microplastic and nanoplastic (MNP) pose a serious threat to all the world's marine ecosystems and biota, across all taxa and trophic levels, having individual- to ecosystem-level impacts, although these impacts are not fully understood. Microplastics (MPs; 0.1–5 mm) have been consistently found associated with the biota, water and sediments of all coral reefs studied, but due to limitations in the current techniques, a knowledge gap exists for the level of nanoplastic (NP; <1 µm). This is of particular concern as it is this size fraction that is thought to pose the greatest risk due to their ability to translocate into different organs and across cell membranes. Furthermore, few studies have examined the interactions of MNP exposure and other anthropogenic stressors such as ocean acidification and rising temperature. To support the decision-making required to protect these ecosystems, an advancement in standardised methods for the assessment of both MP and NPs is essential. This knowledge, and that of predicted levels can then be used to determine potential impacts more accurately.

The distribution and ecological effects of microplastics in an estuarine ecosystem

Coastal sediments, where microplastics (MPs) accumulate, support benthic microalgae (BMA) that contribute to ecosystem functions such as primary production, nutrient recycling and sediment biostabilization. The potential interactions between MPs, BMA and associated properties and functions remain poorly understood. To examine these interactions, a survey of 22 intertidal sites was conducted. MP abundance, size and a suite of MP diversity indices (based on color and shape) were determined from surface sediments alongside biochemical and physical properties. MPs were detected at all sites and dominated by polypropylene (34%), polyester (18%) and polyethylene (11%). Fragment and fiber dominance (16-92% and 6-81% respectively) and color-shape category diversity varied significantly by site. Distance-based linear models demonstrated that estuary-wide, mean grain size and mud were the best predictors of MP abundance-diversity matrices, but variance explained was low (9%). Relationships were improved when the data was split into sandy and muddy habitats. In sandy habitats (<8% mud), physical properties of the bed (mean grain size, mud content and distance from the estuary mouth) were still selected as predictors of MP abundance-diversity (14% variance explained); but a number of bivariate relationships were detected with biochemical properties such as BMA associated pigments and organic matter. In muddy habitats (>8% mud), porewater ammonium was lower when fiber abundance and overall MP diversity were higher. The inclusion of porewater ammonium, organic matter content and pheophytins alongside physical properties explained a greater percentage of the variance in MP abundance-diversity for muddy habitats (21%). The results highlight the importance of examining plastic shapes and MP categories in addition to abundance and emphasize that functionally different habitats should be examined separately to increase our understanding of MP-biota-function relationships.

The input-output balance of microplastics derived from coated fertilizer in paddy fields and the timing of their discharge during the irrigation season

Polymer-based microcapsules derived from coated fertilizers are not recovered after use. Therefore, they are a source of microplastics to the agricultural lands and coastal areas of Japan. In this study, we investigated the input-output balance of microcapsules in three paddy fields and the timing of microcapsule discharge from the fields with the aim of developing effective techniques to reduce microcapsule discharge. Microcapsules were discharged from the paddy fields primarily during puddling, when the weir plate was overflowed, and when surface drainage was implemented. About 50% of the total discharge during the irrigation period occurred during puddling, which is a process for leveling paddy fields. Therefore, contamination of the surrounding environment by microcapsules from paddy fields can be effectively reduced by preventing the release of microplastics from paddy fields during puddling. We also showed that the total microcapsule discharge cannot be controlled solely by irrigation water management, such as by adjusting the height of the weir plate. We found that about 0.067-0.076% of the total number of microcapsules accumulated in the soil of the paddy fields was discharged during the irrigation season in 2020. Furthermore, 70% of the microcapsules discharged from one field in 2020 had resided in the soil for at least two years. The use as fertilizer coatings of biodegradable polymers that would degrade completely in the soil within a few years could therefore substantially reduce the amount of microplastics released into the ocean from agricultural fields, and their development is thus urgently needed.

Effect of microplastics on organic matter decomposition in paddy soil amended with crop residues and labile C: A three-source-partitioning study

Microplastics (MPs) are a widespread pollutant in terrestrial ecosystems. However, knowledge on how MPs impact soil organic matter (SOM) decomposition and the priming effect (PE) in rice paddy soil remains limited. By employing a three-source-partitioning approach, we investigated the interactive impact of MP dosage (none, low [0.01% w/w] or high [1% w/w]), labile C (¹⁴C-labeled glucose), and ¹³C-labeled rice straw addition on SOM decomposition and PE. Compared to soil without C addition (i.e., control), total SOM-derived CO₂ in low-MP soil declined by 13.2% and 7.1% after straw and glucose addition, respectively. Under combined glucose and rice straw addition, glucose-induced PE was up to 10 times stronger in the presence of low-MPs compared to that in high-MPs. However, glucose induced negative PE on rice straw decomposition in the presence of MPs. SOM decomposition was much higher under low MP dosage than under high MP dosage. However, MPs had a negligible effect on the mineralization of exogenous C substrate (glucose or straw). This study provides a novel and valuable insight on how MPs affect SOM turnover and C sequestration in paddy soil, highlighting the significance of interactions between environmental pollutants and biogeochemical processes that affect CO₂ fluxes.

Benthic species as mud patrol - modelled effects of bioturbators and biofilms on large-scale estuarine mud and morphology

Sediment-stabilizing and -destabilizing organisms, i.e. microphytobenthos (biofilms) and macrozoobenthos (bioturbators), affect the erodibility of muddy sediments, potentially altering large-scale estuarine morphology. Using a novel eco-morphodynamic model of an idealized estuary, we investigate eco-engineering effects of microphytobenthos and two macrozoobenthic bioturbators. Local mud erodibility is based on species pattern predicted through hydrodynamics, soil mud content, competition and grazing. Mud resuspension and export is enhanced under bioturbation and prevented under biostabilization through respective exposure and protection of the supra- and intertidal. Bioturbation decreases mud thickness and bed elevations, which increases net mud fluxes. Microphytobenthos reduces erosion, leading to a local mud increase of intertidal sediments. In multi-species scenarios, an effective mud-prone bioturbator strongly alters morphology, exceeding that of a more abundant sand-prone moderate species, showing that morphological change depends on species traits as opposed to abundance. Altering their habitat, the effective mud-prone bioturbator facilitates expansion of the sand-prone moderate bioturbator. Grazing and species competition favor species distributions of dominant bioturbators. Consequently, eco-engineering affects habitat conditions while species interactions determine species dominance. Our results show that eco-engineering species determine the mud content of the estuary, which suggests large effects on the morphology of estuaries with aggravating habitat degradation.

A call to evaluate Plastic's impacts on marine benthic ecosystem interaction networks

Plastic pollution continues to seep into natural and pristine habitats. Emerging laboratory-based research has evoked concern regarding plastic's impact on ecosystem structure and function, the essence of the ecosystem services that supports our life, wellbeing, and economy. These impacts have yet to be observed in nature where complex ecosystem interaction networks are enveloped in environmental physical and chemical dynamics. Specifically, there is concern that environmental impacts of plastics reach beyond toxicity and into ecosystem processes such as primary production, respiration, carbon and nutrient cycling, filtration, bioturbation, and bioirrigation. Plastics are popularly regarded as recalcitrant carbon molecules, although they have not been fully assessed as such. We hypothesize that plastics can take on similar roles as natural recalcitrant carbon (i.e., lignin and humic substances) in carbon cycling and associated biogeochemistry. In this paper, we review the current knowledge of the impacts of plastic pollution on marine, benthic ecosystem function. We argue for research advancement through (1) employing field experiments, (2) evaluating ecological network disturbances by plastic, and (3) assessing the role of plastics (i.e., a carbon-based molecule) in carbon cycling at local and global scales.

The impacts of polyethylene terephthalate microplastics (mPETs) on ecosystem functionality in marine sediment

The effects of microplastics (MPs) on the ecological functioning in marine sediments is largely unknown. However, coastal marine sediments and their resident communities play critical roles in the transformation of organic matter and the cycling of nutrients that influence both local and global processes. To investigate how microplastics influence ecosystem functions associated with sediment biogeochemistry, large bivalves and microphytobenthos, we conducted a 31-day laboratory experiment. The experiment tested the role of micro-polyethylene terephthalate (mPETs) at five concentrations (0%, 1%, 3%, 6%, and 8% based on wet weight of top 1 cm sediment). Canonical principle of coordinate analysis (CAP) was applied to assess change on the ecosystem functionality with increasing concentrations of mPETs. Our results highlight that stress effects on ecosystem function are the product of the interaction between Macomona liliana, microphytobenthos and mPETs.