Microplastic pollution in water environment of typical nature reserves and scenery districts in southern China

How hydrodynamic conditions dominate the microplastic footprint in the largest freshwater lake in China

Understanding the migration and diffusion process of microplastics (MPs) in lakes is of great significance to the cumulative assessment of controlling land-based MP pollution. The MPs in the surface water of Poyang Lake were identified to be mainly composed of three representative particles (>91 %): polyethylene (PE) fiber, polypropylene (PP) fragment and PE film, and this study explored the migration process of different types of MPs in three flow regimes. The results show that MP particles migrate northward under the gravity flow and jacking flow. The average time required for MPs to reach the northern lakes in jacking flow was 21.29 % shorter than that in gravity flow. Instead, MPs undergo reverse movement driven by back flow. The difference in migration rates due to MPs physical properties can reach up to 36 % in the same flow regime. The average concentration of PE fiber in the lake area is 30.61 % and 68.68 % higher than both, PP fragment and PE film. In addition, the accumulation hotspots of MPs under three flow regimes were investigated, and MP monitoring in the corresponding areas based on the flow regime can effectively reduce the ecological risk. In terms of ecological risk, the PLI reached Level IV in hotspot areas, indicating severe ecological risk. If considering that the MP type of Poyang Lake is dominated by PE and PP, only the PSL of the Hukou area reaches level II. This study provides reference and warning for tracking the paths and risks of land-based MPs entering freshwater lakes.

The influencing mechanisms of different characteristics of polystyrene microplastics on Saccharomyces cerevisiae: functional group, particle size and dosage

ABSTRACTBased on the well-documented hazards of microplastics and the importance and typicality of Saccharomyces cerevisiae (S. cerevisiae) in the environment, in this study, the influencing mechanisms of functional group, particle size and dosage of polystyrene microplastics (PS MPs) on S. cerevisiae were studied systematically. The results showed that compared with the bigger particle size and lower concentration of carboxylated PS MPs, the smaller particle size and higher concentration of aminated PS MPs had the most serious inhibition of the growth of S. cerevisiae, and their cell morphology was more abnormal, the more PS MPs attached to the yeast cells. The results of orthogonal experiment showed that the inhibitory effects of PS MPs on S. cerevisiae followed the order: functional groups > concentrations > particle sizes. Through the analysis of the antioxidant properties of S. cerevisiae, it was found that the activities of superoxide dismutase and catalase were first stimulated and then inhibited, and the concentrations of superoxide dismutase enzymes in the environment with bigger particle size and lower concentration of PS MPs was higher than that in the environment with smaller particle size and higher concentrations of PS MPs. catalase enzyme showed an opposite trend in particle sizes and a similar trend in concentrations. The concentrations of malondialdehyde increased with the increase of PS MPs concentrations and the decrease of particle sizes, indicating that PS MPs could induce S. cerevisiae to produce a large amount of reactive oxygen species, resulting in severe oxidative damage to S. cerevisiae.

Microplastics in the Amur tiger's habitat: Occurrence, characteristics, and risk assessment

Microplastics (MPs) are emerging environmental pollutants that pose a significant threat to wildlife within forest ecosystems. However, the quantity and types of MPs in wildlife forest habitats remain unclear. This study is the first to assess the distribution of MPs in the Amur tiger habitat of northeast China. Our results showed that MPs were detected in soil, water, atmosphere, forage plants, and ungulate and top predator feces within the forest ecosystem, respectively. The average diameter of all detected MPs was 44.99 ± 34.80μm. The predominant polymers found in the samples were polyamide, polyvinyl chloride, and polyurethane. Certain sample types shared similar MP polymer type distributions, indicating potential links in their sources and transfer pathways. Consequently, these findings provide some new insights on the new pollution problem in Amur tiger forest habitats and prompt us to consider how to control and manage the MPs pollution sources in the tiger conservation.

Why do microplastics aggravate cholestatic liver disease? The NLRP3-mediated intestinal barrier integrity damage matter

Microplastics (MPs) are becoming a significant environmental and public health concern because they are present in freshwater and marine environments and are ingested by living organisms. Cholestatic liver disease (CLD) is closely related to intestinal homeostasis, but there are no data investigating the effects of MPs on CLD. In this study, we used Mdr2-/- mice (a model of CLD) to investigate the effects of polystyrene microplastics (PS-MPs, 0.5 μm) on CLD and the underlying mechanisms. Our data revealed that, compared with Mdr2-/- mice, PS-MPs (200 μg/day)-challenged Mdr2-/- mice presented more severe collagen deposition, infiltration of inflammatory cells in liver sections and higher alkaline phosphatase (ALP)/γ-glutamyltransferase (γ-GGT) concentrations in the serum. Furthermore, the number of mucous cells in the colonic tissues of mice with CLD was strongly inhibited by PS-MPs, accompanied by the downregulation of intestinal barrier integrity proteins (ZO-1, Occludin and Claudin-1). Through correlation analysis to further verify the connection between ALP/γ-GGT levels and intestinal barrier integrity genes, as well as a significant positive correlation with IL-1β after PS-MPs exposure. Our results also revealed that PS-MPs exposure accelerated the NOD-like receptor protein 3 (NLRP3)-associated inflammatory response in the colon but did not affect NLRP3 expression in the livers of Mdr2-/- mice. Further study confirmed that the inhibition of NLRP3 by the MCC950 inhibitor abrogated the exacerbating effects of PS-MPs on hepatobiliary injury and intestinal barrier integrity damage. These findings provide the first evidence that NLRP3-mediated inflammation is an important participant in intestinal barrier integrity damage crosstalk that drives CLD under MPs exposure and identify NLRP3 as a potential therapeutic target.

The role of habitat preference and feeding strategy on exposure to microplastic pollution in freshwater fish species

Microplastic (MP) pollution has been observed in a variety of ecosystems, but there is a limited number of studies on reservoir ecosystems. The aim of this study was to determine the levels of MP contamination in sediment, water and commercially important fish species (Cyprinus carpio, Perca fluviatilis, Atherina boyeri and Sander lucioperca) collected from the Yamula Reservoir in Türkiye. Water samples were collectes at five stations. Four sediment samples were collected from the lake. As sediments from the lake represent a vital element of the lake ecosystem, they function as a historical archive that reflects alterations in land use and the characteristics of the lake over time. The average amounts of MPs observed in sediment and water samples were 0.12 MP/g and 0.58 MP/m3 respectively. The digestive systems of 30 individuals of each fish species were examined. The highest amount of MP was observed for C. carpio (6 ± 5.9 MP/individual), while the lowest amount of MP was observed for A. boyeri (1.8 ± 1.7 MP/individual). MP abundance in S. lucioperca and P. fluviatilis was 2 ± 2.8 and 4.6 ± 6.3 MP per individual. The most commonly observed polymer types were polypropylene (67%), polyvinyl alcohol (13%), polyethylene resin (13%) and high-density polyethylene (7%). The pollution load indexes determined for each fish species from the highest to the lowest were as follows: 1.83 (C. carpio) 1.6 (S. lucioperca) 1.05 (P. fluviatilis) and, 1 (A. boyeri). The findings of the study indicate that all sampling stations, including both sediment and water, are contaminated with MPs. Furthermore, the results demonstrate that all examined fish species ingest MPs. Additionally, the results indicate that fish inhabiting a wide range of habitats and consuming diverse diets are more susceptible to MP contamination.

Microplastics occurrence in commercial crab Scylla serrata from Kaveri River of Tamil Nadu: An emerging concern for community health

Microplastic (MPs) pollution has engulfed global aquatic systems, and the concerns about MPs translocation and bioaccumulation in fish, crabs, and other marine organisms are now an unpleasant truth. In the past few years, MPs pollution in freshwater systems, particularly rivers, and subsequently in freshwater organisms, especially in crabs, has caught the attention of researchers. Rivers provide livelihood to approximately 40% of the global population through food and potable water. Hence, assessment of emerging contaminants like MPs in waterways and the associated fauna is crucial. This study assessed MPs in crab S. serrata across the largest riverine system of south India, the Kaveri River. The MPs were characterized by optical microscopy, and field emission scanning electron microscopy-energy dispersive X-ray (FESEM-EDX) analysis for their number, shape, size, and color. Polymer composition was analyzed using attenuated total reflectance Fourier-transform infrared spectroscopy (ATR-FTIR) and Raman spectroscopy. Polypropylene (PP), polystyrene (PS), polyamide (PA), and polyvinyl chloride (PVC) were the dominant plastic polymers in the crab intestine. Additionally, the FE-SEM analysis revealed that the MPs have differential surface morphology with rough surfaces, porous structures, fissures, and severe damage. Most MPs comprised Na, Si, Mg, Cl, K, and Ca, according to EDX analyses. The findings might provide insight into the status of MPs in S. serrata at Kavery river that could help in formulating regulations for MPs reduction and contamination in rivers eventually to protect the environment and human health. PRACTITIONER POINTS: The first findings on the identity and properties of MPs in crabs from the Kaveri River at Mettur Dam. A simple and cost-effective approach for extracting microplastics from crab samples from Mettur Dam, Kaveri River, Salem District, Tamil Nadu, India. Microplastics were detected using optical microscopy, ATR-FTIR, and FE-SEM.

Remote sensing research on plastics in marine and inland water: Development, opportunities and challenge

The accumulation of plastic waste from various sources into marine and inland water is considered a global problem due to its serious impacts on aquatic ecosystems and human health. In the past decade, remote sensing has played an important role in monitoring of plastic pollution in marine and inland water sources and has achieved a series of research results in this field. In this study, a comprehensive review was conducted on the development, opportunities, and challenges of datasets and methods in Marine and Inland Water Plastics Remote Sensing (MIWPRS) monitoring over the past decade, based on the Web of Science (WOS) core database. The results indicated that compared with traditional methods, remote sensing has attracted the attention of scholars due to its advantages. Since 2014, the number of related publications has been increasing year by year, especially in China and the United States, which have achieved tremendous development. The MIWPRS research focus mostly on the use of different satellite remote sensing data and related algorithms to obtain the distribution of plastics in marine and inland water. However, it faces the challenge of lacking subsequent systematic impact assessment models and key pollution prevention measures. In terms of data acquisition, there is a lack of continuous observation models due to the fluidity of marine and inland water. Therefore, MIWPRS has great development opportunities in developing specialized sensors and combining multi-source data with interdisciplinary knowledge such as artificial intelligence (AI) and GIS. It is necessary for us to improve the seasonal migration model of plastics in water and promote the development of MIWPRS towards broader and deeper fields.

Co-exposure of microplastics with heavy metals increases environmental pressure in the endangered and rare wildlife reserve: A case study of the zhalong wetland red-crowned crane nature reserve, northeast China

Microplastics (MPs) exposure to remote areas, including endangered and rare wildlife reserves, has attracted increasing concern. Compared with previous research mostly draws attention to the single exposure of MPs to the environment, greater emphasis should be placed on understanding the complex environmental behaviors of MPs. Therefore, the potential risks of MPs to ecosystems need to be explored in combination with their coexistence with other contaminants, but this is not well-understood. The presented study, taking Zhalong National Nature Reserve (Zhalong wetland), the largest habitat and breeding site for migratory Red-crowned cranes (Grus japonensis) in China, as an example, reveals the possibility of the co-exposure of MPs with various heavy metals. The average abundance of MPs in surface water and sediments in Zhalong Wetland is 738 particles/L and 7332 particles/kg, respectively, which is at a high level of MP pollution worldwide. The obtained results figure out that MPs are also widely found in Red-crowned cranes' feces and feathers. Notably, this study confirms that MP co-exposes to the wetland with Cr, Cd, and As via common sources, exposure routes, and the vector effect of MP. Importantly, we develop the methods of the environmental pressure for individual contaminants and achieve a comprehensive risk assessment of MPs co-exposure with other contaminants in the wetland ecosystem for the first time. It is found that co-exposure to heavy metal can increase the ecological risks of MPs. This is conducive to making a more standardized and reliable framework to estimate the environmental impacts of MP pollution and to formulate prevention and control policies.

Characterization of microplastic contamination and influencing factors in different environmental compartments of a coal mining subsidence area in northern Anhui, China

Environmental pollution caused by microplastics (MPs) has garnered significant global attention, however, research on MPs contamination of various environmental compartments within mining regions remains limited. The objective of this study was to investigate the occurrence and distribution of MPs in soil, surface water, and sediment, as well as the factors influencing the distribution of microplastics in the Panji Mining Area in Huainan City, Anhui Province, China. The findings indicate that MPs contamination in soil and surface water within the study area is substantial. The average abundance of MPs in soil, surface water, and sediment were 1860.8 n·kg-1, 11,323.7 n·m-3, and 384.0 n·kg-1, respectively. The dominant MPs were transparent, fibrous particles <0.1 mm, with polyethylene (PE) common in soil and polypropylene (PP) prevalent in surface water and sediment. A significant correlation was observed among MPs and environmental factors such as pH, total phosphorus (TP), and total organic carbon (TOC) (p < 0.05) showed a positive correlation in soil while in sediment, MPs abundance showed a positive correlation with pH and TOC (p < 0.05). Additionally, a positive correlation was observed of MPs abundance with pH, total nitrogen (TN), and nitrate nitrogen (NO₃--N) (p < 0.05) in surface water. This study provides insights into the characteristics, distribution, and environmental risks of MPs in mining areas, laying a foundation for the development of prevention and control strategies to mitigate MPs pollution in these regions.

Record of microplastic deposition revealed by ornithogenic soil and sediment profiles from Ross Island, Antarctica

Microplastics (MPs) are a global concern as an emerging pollutant, and the investigation on MPs in Antarctic aids in informing their global pollution assessments. Therefore, there are urgent scientific concerns regarding the environmental behavior, origins, influencing factors, and potential hazards of MPs in Antarctica. This study presents the characteristics of MPs from one ornithogenic sediment profile (coded CC) and two ornithogenic soil profiles (coded MR1 and MR2) from ice-free areas on Ross Island, Antarctica. We explored the potential sources of MPs and the main influencing factors for deposition based on their distribution with depth in the profiles. Through laser-infrared imaging spectroscopy (LDIR), a total of 30 polymer types were identified in all samples, with polyethylene terephthalate (PET) and polyvinyl chloride (PVC) as the dominant types, accounting for more than 70% of the total. The abundance of MPs in the CC sediment profile ranged from 2.83 to 394.18 items/g, while in MR1 and MR2 soil profiles, the abundance ranged from 2.25 to 1690.11 and 8.24 to 168.27 items/g, respectively. The size of MPs was mainly concentrated in the range of 20-50 μm, and possible downward movement of certain polymer types was revealed. From the perspective of temporal variation, we suggest that MPs were heavily influenced by local human activities including scientific research, fishing, and tourism, balanced by protective regulations, while no solid evidence was obtained to support strong influence from biological transport through penguins. This research enhances our understanding on the environmental behavior of MPs in the terrestrial systems of remote polar regions.

Metabolic responses of the marine mussel Mytilus galloprovincialis after exposure to microplastics of different shapes and sizes

Microplastics (MP) are ubiquitous pollutants with diverse shapes, sizes, and characteristics that pose critical risks to marine organisms and the environment. In this study, we used the Mediterranean mussel Mytilus galloprovincialis as a marine benthic organism model to investigate the metabolic consequences of exposure to different polyethylene terephthalate MP sizes and shapes: round (27-32 μm), small fibers (200-400 μm), large fibers (3000 μm), small fragments (20 μm), medium fragments (45-75 μm), and large fragments (>150 μm). After exposure to high concentrations (100 mg L-1) of MP for 14 days, round and small fiber-type MP were highly accumulated in mussels. Metabolomic analysis revealed that exposure to round and small fiber-type MP induced significant changes in 150 metabolites. Partial least squares-discriminate analysis (PLS-DA) showed that the round and small fiber MP treatment groups displayed similar cluster patterns that differed from those of the control group. In addition, only 22 annotated metabolites related to histidine, valine, leucine, and isoleucine degradation/biosynthesis and vitamin B6 and aminoacyl-tRNA biosynthesis were significantly affected by round or small fiber-type MP. Among the histidine metabolites, round and small fiber-type MP upregulated the levels of L-histidine, L-glutamate, carnosine, imidazole-4-acetaldehyde, 4-imidazolone-5-propanoate, and methylimidazole acetaldehyde and downregulated methylimidazole acetic acid and N-formimino-L-glutamate. These results suggest novel insights into the potential pathways through which MP of specific sizes and shapes affect metabolic processes in mussels.

Microplastic pollution and ecological risk assessment of a pond ecosystem

Microplastic (MP) pollution has been observed in various ecosystems as a result of the rapid increase in plastic production over the past half-century. Nevertheless, the extent of MP pollution in different ecosystems, particularly in freshwater ecosystems, has not been well-studied, and there are limited investigations on this particular topic, specifically in Türkiye. Here, we quantify the occurrence and distribution of MPs in surface water samples collected from Topçu Pond (Türkiye) for the first time. Water samples were collected at five stations and filtered (30 L for each station) through stacked stainless steel sieves (5 mm, 328 µm, and 61 µm mesh size) with a diameter of 30 cm. The abundance, size, color, shape, and type of collected debris samples were analyzed after the wet peroxide oxidation process. MP particles were observed in all samples at an average abundance of 2.4 MPs/L. The most abundant MP size class and type were 0-999 µm and fiber respectively. On the other hand, prevalent colors were black and colorless in general. According to the Raman analysis results, the identified MP derivatives were polypropylene (40%), polyamide (30%), ethylene acrylic acid (20%), and polyvinylchloride (10%). Moreover, the pollution load index (PLI) index was used to determine the pollution status. PLI values were determined as 1.91 at station S1, 1.73 at station S2, 1.31 at station S3, 1 at station S4 and 1.24 at station S5. The PLI value determined for the overall pond was 1.4. The results of this research show that MP pollution is present in Topçu Pond and contributes to the expanding literature on MP pollution in pond ecosystems.

Insight into effect of polyethylene microplastic on nitrogen removal in moving bed biofilm reactor: Focusing on microbial community and species interactions

Microplastics (MPs) pollution has emerged as a global concern, and wastewater treatment plants (WWTPs) are one of the potential sources of MPs in the environment. However, the effect of polyethylene MPs (PE) on nitrogen (N) removal in moving bed biofilm reactor (MBBR) remains unclear. We hypothesized that PE would affect N removal in MBBR by influencing its microbial community. In this study, we investigated the impacts of different PE concentrations (100, 500, and 1000 μg/L) on N removal, enzyme activities, and microbial community in MBBR. Folin-phenol and anthrone colorimetric methods, oxidative stress and enzyme activity tests, and high-throughput sequencing combined with bioinformation analysis were used to decipher the potential mechanisms. The results demonstrated that 1000 μg/L PE had the greatest effect on NH4+-N and TN removal, with a decrease of 33.5 % and 35.2 %, and nitrifying and denitrifying enzyme activities were restrained by 29.5-39.6 % and 24.6-47.4 %. Polysaccharide and protein contents were enhanced by PE, except for 1000 μg/L PE, which decreased protein content by 65.4 mg/g VSS. The positive links of species interactions under 1000 μg/L PE exposure was 52.07 %, higher than under 500 μg/L (51.05 %) and 100 μg/L PE (50.35 %). Relative abundance of some metabolism pathways like carbohydrate metabolism and energy metabolism were restrained by 0.07-0.11 % and 0.27-0.4 %. Moreover, the total abundance of nitrification and denitrification genes both decreased under PE exposure. Overall, PE reduced N removal by affecting microbial community structure and species interactions, inhibiting some key metabolic pathways, and suppressing key enzyme activity and functional gene abundance. This paper provides new insights into assessing the risk of MPs to WWTPs, contributing to ensuring the health of aquatic ecosystems.

Research on the Migration and Adsorption Mechanism Applied to Microplastics in Porous Media: A Review

In recent years, microplastics (MPs) have emerged as a significant environmental pollutant, garnering substantial attention for their migration and transformation behaviors in natural environments. MPs frequently infiltrate natural porous media such as soil, sediment, and rock through various pathways, posing potential threats to ecological systems and human health. Consequently, the migration and adsorption mechanisms applied to MPs in porous media have been extensively studied. This paper aims to elucidate the migration mechanisms of MPs in porous media and their influencing factors through a systematic review. The review encompasses the characteristics of MPs, the physical properties of porous media, and hydrodynamic factors. Additionally, the paper further clarifies the adsorption mechanisms of MPs in porous media to provide theoretical support for understanding their environmental behavior and fate. Furthermore, the current mainstream detection techniques for MPs are reviewed, with an analysis of the advantages, disadvantages, and applications of each technique. Finally, the paper identifies the limitations and shortcomings of current research and envisions future research directions.

Assessing the current state of plastic pollution research in Antarctica: Knowledge gaps and recommendations

Antarctica stands as one of the most isolated and pristine regions on our planet. Regardless, recent studies have evidenced the presence of plastic pollution in Antarctic environments and biota. While these findings are alarming and put into perspective the reach of plastic pollution, it is necessary to assess the current knowledge of plastic pollution in Antarctica. In the present review, an updated literature review of plastic pollution in multiple Antarctic environmental compartments and biota was conducted. Studies were cataloged based on environmental compartments (e.g., sediments, seawater, soil, atmosphere) and biota from different ecological niches. A detailed analysis of the main findings, as well as the flaws and shortcomings across studies, was conducted. In general terms, several studies have shown a lack of adequate sampling and analytical procedures for plastic research (particularly in the case of microplastics) and standard procedures; thus, compromising the reliability of the data reported and comparability across studies. Aiming to guide future studies and highlight research needs, a list of knowledge gaps and recommendations were provided based on the analysis and discussion of the literature and following standardized procedures.