High Concentrations Of Microplastics Research Articles

Response of soil biochemical properties and ecosystem function to microplastics pollution.

Microplastics (MPs)-induced changes in soil nutrient cycling and microbial activity may pose a potential risk to soil ecosystem. Although some studies have explored these topics, there is still a large space for exploration and a relative lack of research on the mechanism by which soil health and its functions are affected by these changes. Thus, this study investigated the effects of polyethylene (PE) MPs with two particle sizes (13μm and 130μm) at five concentrations (0%, 1%, 3%, 6% and 10%, w/w) on soil biochemical properties and ecosystem function. The findings revealed that the exposure to 13μm MPs significantly reduced soil respiration (Res) rate, β-glucosidase (Glu) and catalase (CAT) activity, which accompanied with enhanced urease activity and decreased soil pH, available phosphorus (AP), dissolved reactive phosphorus (DRP), dissolved organic carbon (DOC) and available potassium (AK) content in most cases. However, 130μm MPs exerted negligible influence on the DOC and DRP content, Glu and CAT activity. High concentrations of 130μm MPs significantly reduced soil pH, total dissolved nitrogen (TDN), AP and AK content, but significantly increased soil Res rate. Overall, soil ecosystem function was significantly reduced by the addition of MPs. The Res rate, soil AP and DRP content and Glu activity were the most important predictors of soil ecosystem function. We found that the risk posed by MPs to soil ecosystem function was dose-dependent and size-dependent. These findings underscore that MPs can alter soil functions related to soil nutrient cycling and provide further insights into MPs behavior in agroecosystems.

Oral exposure to high concentrations of polystyrene microplastics alters the intestinal environment and metabolic outcomes in mice

IntroductionOral exposure to microplastics (MPs) is a global health concern. In our previous study, MPs induced glucose intolerance and non-alcoholic fatty liver disease (NAFLD) under a high-fat diet-induced leaky gut syndrome (LGS). This study aims to evaluate the effects of high concentrations of MP on lipid metabolism under normal dietary conditions and to assess the changes in the intestinal tract resulting from MP exposure.MethodsC57BL6/J mice were fed a normal diet (ND) without polystyrene MPs (PS-MPs) or with PS-MPs (1000 µg/L or 5000 µg/L) for six weeks. Subsequently, intestinal permeability, gut microbiota, and metabolite levels in the serum, feces, and liver were determined.ResultsMice fed the ND showed no increase in intestinal permeability in either group. However, high MPs concentrations led to increased serum lipid levels and exacerbated fatty liver function. Oral exposure to MPs did not affect the number of innate lymphoid cells or short-chain fatty acids in the intestine. However, it increased the number of natural killer cells, altered the gut microbiota, induced inflammation, and modulated the expression of genes related to nutrient transport in the intestine. The severity of intestinal disturbance tended to worsen with dose.DiscussionDespite the absence of LGS, high concentrations of MPs induced dyslipidemia and NAFLD. Oral exposure to MPs triggered intestinal inflammation via natural killer cells, altered the gut microbiota, and modulated nutrient metabolism. Our study highlights the need for environmental measures to reduce oral MPs exposure in the future.

Electrochemically Coupled Anaerobic Membrane Bioreactor Facilitates Remediation of Microplastic-Containing Wastewater

Ubiquitous microplastics (MPs) severely affect the efficiency of anaerobic membrane bioreactors (AMBR) for wastewater treatment and energy recovery by inhibiting the metabolic activity of anaerobic microorganisms. The electrochemical system can not only accelerate waste metabolism but also improve microbial resistance by promoting interspecies electron transfer within the system, which has broad application potential in the remediation of MPs wastewater. This paper attempts to evaluate the effect of electrical stimulation on the efficiency of biological wastewater treatment processes containing MPs employing an electrochemical system coupled to an anaerobic membrane bioreactor (ECAMBR). The results showed that although MP exposure inhibited methanogenic performance, electrical stimulation effectively alleviated this inhibitory effect. Further analysis showed that microplastics increased cell damage and affected enzyme activity, but electrical stimulation could affect the stress response of microorganisms, leading to changes in their cell viability and enzyme activities. The 16S-rRNA sequencing indicated that the highest abundance of hydrolytic–acidogenic bacteria Firmicutes and Bacteroidota was found at the phylum level, whereas at the genus level, it was Christensenellaceae_R-7_group, and methanogens were dominated by Methylomonas, Methyloversatilis, and Methylobacter. Functional prediction analysis indicated that carbohydrate metabolism, amino acid metabolism, and energy metabolism were the dominant metabolic pathways and that electrical stimulation could enhance their activities. This study demonstrated the important role of electrochemical stimulation in the remediation of wastewater containing high concentrations of MPs.

Assessing the Microplastic Pandemic: Prevalence, Detection, and Human Health Impacts in Asian Aquatic Environments

Microplastics pose a major threat to the globe due to their increased pollution and concerning effects on biota and humans. Presently, every terrestrial and marine region is affected diversely by microplastic contamination. The most polluted locations are industrialized metropolitan areas and coastal regions with considerable human activity. In this study, we choose representative samples of freshwater, marine, and biota in water, as well as sediments with different levels of microplastic pollution and distinct geographical conditions. For individually chosen aquatic areas and matrices, we reviewed, assessed, and summarized the current microplastic pollution and various methods of microplastic pollution assessment. The highest concentration of microplastics in data collected in Asia was found to be 372 ± 14.3 item/L and 9630 ± 2947 item/kg in the water and sediments of the Mumbai, India, coast. This huge abundance might be generated by human activities near the coastal areas as well as due to migration and tourism. This could also be due to sewage discharge and untreated domestic wastewater that is being dumped into the environment. Consuming of microplastic particles can put humans at risk for cytotoxicity, hypersensitivity, an unwanted immune response, and acute responses such as haemolysis, autoimmune diseases, cancer, and neurological conditions. Focusing on pollution status and potential mitigation path for microplastics from freshwater to oceans, we compared the distribution and important characteristics of microplastics in different locations. This study leads researchers to emphasis the reduction of MP pollution in densely populated areas like Asia.

Polytetrafluoroethylene (PTFE) Microplastics Affect Angiogenesis and Central Nervous System (CNS) Development of Duck Embryo

Prolonged exposure to teratogens is known to cause neural tube defects (NTDs), a severe malformation of the central nervous system (CNS) that significantly contributes to global infant mortality. In recent years, exposure to nanoplastics (NPs) has been linked to faulty neural crest closure and altered neurulation by altering cellular adhesion molecules and accumulation of plastic particles in the neural tube leading to NTDs. However, research on the influence of various types of microplastics (MPs) on malformations of the CNS are still limited. In this study, we investigated whether MPs of polytetrafluoroethylene (PTFE)—a type of plastic commonly used as non-stick coatings of cooking utensils can affect angiogenesis and CNS development using ducks as model organisms. PTFE MPs were administered on Day 3 of duck embryo development at varying concentrations (0.01 mg/ml, 0.1 mg/ml, 1 mg/ml, and 5 mg/ml), and angiogenesis was evaluated using a chorioallantoic membrane (CAM) assay. Gross morphology and histology of the spinal column and brain were analyzed on Days 8 and 18, respectively. FTIR confirmed PTFE's structure, while SEM and DLS analyses showed particle sizes between 300 nm and 5 μm, classifying them as MPs. High concentrations (5 mg/ml) of PTFE MPs treated on duck embryos resulted in a 35% mortality rate and reduced vascular density, suggesting anti-angiogenic effects. Brain and spinal abnormalities, such as encephalomalacia and spinal cord discontinuities were observed in the PTFE-treated embryos. Based on these results, PTFE is an anti-angiogenic and teratogenic agent affecting the development of duck embryos.

Influence of soil microplastic contamination on maize (Zea mays) development and microbial dynamics

BackgroundMicroplastics are contaminants in soil ecosystems that alter biophysical processes, affect plant growth, ecosystems and humans in the long run. This study was conducted to investigate the influence of soil microplastic contamination on the growth, development, and microbial dynamics of maize (Zea mays).Composite soil samples were collected from the farm from 0 to 10 cm depth. Physicochemical properties were assessed before maize seed sowing. Three soil weight categories were treated with 30 g, 20 g and 10 g microplastics. Soil physicochemical properties and heavy metal content in maize plants were analyzed. Morphological parameters, microbial counts, and microorganism identification were conducted. FTIR analysis was carried out in selected plant parts.ResultsThe study revealed a pH range of 5.00–6.70, electrical conductivity of 70–158 µS/cm, organic carbon and organic matter, total nitrogen, average phosphorus content, clay and silt content. The concentrations of heavy metals in plant parts were within WHO standard limits of 425.5 and 500 mg/kg for iron and manganese, but above the limits of 40, 60, and 350 mg/kg for copper, zinc and magnesium. The plant had various leaf sizes and heights, with chlorosis and necrotic activity ranging from 0.33 to 2.67, and a range of 1.33 to 6.33, respectively. Soil samples showed a total bacterial count (TBC) of 2.00 × 103 cfu/g to 7.60 × 104 cfu/g and a total fungal count (TFC) of 4.00 × 103 cfu/g to 2.20 × 104 cfu/g. Pseudomonas aeruginosa, Bacillus subtilis, Escherichia coli, Staphylococcus epidermidis, Proteus mirabilis and Bacillus cereus had percentage occurrences of 44.31, 21.17, 9.12, and 3.26%, respectively. Penicillium notatum was the most prevalent, while Fusarium spp. was the least prevalent. The FTIR analysis of maize seeds from soil samples A, B, and C revealed various organic compounds, with opium powder and streptomycin sulphate being the most abundant. The study revealed that pot B had the highest microplastic concentration at 1 WAS, while pot C had the lowest at 0.10 mg/kg, indicating a differential soil microplastic accumulation.ConclusionMicroplastics impact soil health, plant growth, and nutrient cycling, necessitating sustainable agriculture. Long-term research is needed to understand ecological and physiological impacts and explore remediation techniques.

Comparative analysis of the microbial plastisphere at three sites along the Sarno river (Italy)

This study investigated microplastics (MP) and their associated microbial plastisphere in the Sarno river (Italy), its estuary and in the nearby coastal area in January 2020. Scanning Electron Microscopy (SEM), High Throughput Sequencing (HTS) and Fourier-Transformed Infrared Spectroscopy (FTIR) were used to characterize the collected MPs and their associated microbes. The three stations sampled differed substantially for MP concentrations and microbial communities, with the estuarine station showing very high MP concentrations (2048.6 MP m-3), highlighting the threat represented by the river for the coastal marine area and its ecosystem. The prokaryotic plastisphere showed differences between the three stations sampled, in terms of community composition, with only 75 Amplicon Sequence Variants (ASV) in common. The Comamonadaceae was the most abundant family in MP-attached and freshwater communities, and this lifestyle seems to be pivotal in the colonization of new habitats while flowing towards the sea. The results highlight the importance of the plastisphere in colonization of new habitats and support the need of correct management and risk mitigation efforts.

Decadal changes in microplastic accumulation in freshwater sediments: Evaluating influencing factors

Microplastics are small plastic particles with sizes ranging between 1 μm and 5 mm. Microplastics can originate from macro plastics and degrade to a smaller size or be produced directly by manufacturers. Few studies have examined microplastic contamination in freshwater sediment cores to estimate changes in microplastic contamination over time. We present the results of a study that examined sediment cores from four watersheds, Kiskiminetas River, Blacklick Creek, Raystown Lake, and Darby Creek, in Pennsylvania, USA to reveal the history of microplastic accumulation and factors that contribute to microplastic distribution. The abundance and morphology of microplastics varied over time and between these four locations. The highest microplastic abundance was found in Raystown Lake, ranging from 704 to 5397 particles kg−1 with fiber as the dominant microplastic type, while Darby Creek (0–3000 particles kg−1), Kiskiminetas River (0–448 particles kg−1), and Blacklick Creek (0–156 particles kg−1) had lower microplastic concentration. Moreover, Darby Creek had the most diverse microplastic morphology and a trend of decreasing concentration with depth. Although the Darby Creek watershed has the most developed area and highest population density, it did not have the highest microplastic concentration. Averaged over the four cores, microplastic abundance increased as global plastics production increased from the 1950s–2010s. Our findings provide insights into the fate and transport of microplastic contamination in freshwater environments, which is vital to establishing sustainable mitigation strategies.

The bio–accumulation and –magnification of microplastics under predator–prey isotopic relationships

Recent studies on microplastics (MPs) in marine ecosystems have focused on their bioaccumulation and biomagnification within food chains, emphasizing their potential health risks to humans. However, these bio-effects of MPs in marine ecosystems remain a contentious issue. Employing the "consumer–dietary source" tracking function in stable isotope analysis can enhance our comprehension of how MPs magnify in organisms. In our research conducted in the coastal waters of Haizhou Bay, Jiangsu, China, we examined two commercially important fish species, Larimichthys polyactis and Collichthys lucidus, through stable isotope analysis to investigate the accumulation of MPs in their dietary sources. Results revealed fiber, blue, and PET as the primary shapes, colors, and polymers of MPs in the region. C. lucidus displayed a broader isotopic niche and a higher propensity for MP accumulation than L. polyactis. Biomagnification analysis indicated that dominant MP shapes, colors, and polymers were magnified in both fish species, with MPs smaller than 3 mm exhibiting substantial biomagnification. Factors such as feeding strategies and habitat preferences may influence MP ingestion by fish. We conclude that a high proportion of dietary sources in fish does not necessarily equate to a high concentration of MPs. Neglecting the proportion of dietary sources might lead to underestimating MP biomagnification. Therefore, a multidimensional approach to exploring the biomagnification of MPs is essential to accurately grasp this unique pollutant's impact.

Microplastics in freshwater food chains: Priority list based on identification of oxidative stress response characteristic

Exogenous exposure to high concentrations of microplastics (MPs) cause oxidative damage to freshwater food chains (FFCs). Thus, the patterns and mechanisms of oxidative stress responses (OSRs) induced by MPs in FFC organisms were investigated using theoretical simulation methods. Results showed an increasing (reduced) OSR was found in lower trophic levels (higher trophic levels). Besides, polycarbonate (polyvinyl chloride) causes the most (least) significant OSRs in FFC organisms, respectively. The impacts of MP additives were also analyzed using the full factorial experimental design, revealing flame retardants significantly influence oxidative stress variability. A constructive solution of "restriction-control-focus" is proposed for different types of MPs by the coefficient of variation-corrected CRITIC and the nested mean classification method. The mechanism analysis revealed a positive correlation between protein secondary structure orderliness and OSRs. Proteins in organisms that contain a high proportion of hydrophobic non-polar amino acids are more likely to bind to MP and enhance OSRs. This is the first study assessing the OSR patterns and ecological risks of MPs and their additives in FFCs with a proposed priority list, providing theoretical support for risk assessments and management strategies in freshwater environments.

Effects of microplastics concentration on plant root traits and biomass: Experiment and meta-analysis

The impact of microplastics (MPs) on plant growth, particularly root development, remains underexplored. To address this, a laboratory pot experiment and meta-analysis were conducted to assess how varying concentrations of MPs affect plant root growth. In pot experiments, the response of root traits to MPs differed by plant species. For F. arundinacea, a higher addition (1 % and 2 %) of polypropylene (PP) significantly increased the total length, surface area, volume, as well as fine root (<1 mm) surface area and volume. Partial least squares path modeling (PLS-PM) analysis showed that high concentrations of MPs affected plant root growth and plant root biomass by promoting fine root growth. Meta-analysis indicated that MPs increased shoot dry biomass by 32.7 % but reduced root dry biomass by 4.1 % and root length by 14.3 %. Higher concentrations (>0.5 %) of MPs significantly increased root length (35.2 %) and root dry biomass (6.3 %), whereas decreased shoot dry biomass (-8.6 %). Under the lower MPs concentration (<0.5 %), the root length and root dry biomass were decreased by 18.6 % and 11.1 %, respectively, and the shoot dry biomass was increased by 53.2 % compared with the treatment without MPs. The results emphasize the differences in performance between species for different MPs concentrations, implying that there may be future scope to select for species/varieties that are most resilient to the presence of MPs.

Surface microplastics dynamics in the Persian Gulf and Arabian Sea using numerical modelling and CYGNSS satellite estimations

Microplastics have long-term negative effects on marine environment. One of the most significant threats of microplastics is their ability to absorb chemicals which enhances the transfer of pollutants. These pollutants eventually enter the tissues of living organisms e.g. through ingestion. To shed a light on the way these particles accumulate in the surface water of Persian Gulf and the Arabian Sea and the spatial and temporal distribution of their concentrations, a combination of field sampling, remote sensing techniques, and numerical modelling methods were used. Samples were collected using a Neuston net at 31 stations in 2018 and 2021. A hydrodynamic model was used to study the transport of these materials by tide, wind and density-driven currents, and microplastic pathways were mapped. Also, CYGNSS satellite data were used to estimate the particles concentration by measuring the roughness of the ocean surface. It was shown that the northeastern part of the Arabian Sea had the highest concentration of microplastics in winter. Oman's northern border and the Strait of Hormuz had relatively higher concentrations than other parts. This accumulation increases in winter and continues to rise until the end of summer. In autumn, the accumulation decreases, but it begins to increase again in the north of Oman during winter. During winter, the southern part of the Persian Gulf had high concentration, while from summer to autumn, the concentration in the northwest region had increased. In 2021, the average microplastic concentration in the Arabian Sea and the Gulf of Oman varied seasonally from 2.6x104 to 1.8x104 particle per km2. Meanwhile, the average concentration of pollutants in the Persian Gulf was almost invariable throughout the year, ranging from 2.8 x104 to 2.6 x104 particle per km2. Furthermore, the study reveals that these concentrations are influenced by various environmental factors. In the Persian Gulf, water density is the most significant factor controlling the surface concentration of microplastics, while in the Arabian Sea, the interaction of wind speed and sea surface currents is crucial.

Diving into the Depths: Uncovering Microplastics in Norwegian Coastal Sediment Cores.

High concentrations of microplastics (MPs) have been documented in the deep-sea surface sediments of the Arctic Ocean. However, studies investigating their high-resolution vertical distribution in sediments from the European waters to the Arctic remain limited. This study examines MPs in five sediment cores from the Norwegian Coastal Current (NCC), encompassing the water-sediment interface and sediment layers up to 19 cm depth. Advanced analytical methods for MP identification down to 11 μm in size were combined with radiometric dating and lithology observations. MPs were present across all sediment cores, including layers predating the introduction of plastics, with concentrations exhibiting significant variation (54-12,491 MP kg-1). The smallest size class (11 μm) predominated in most sediment layers (34-100%). A total of 18 different polymer types were identified across all sediment layers, with polymer diversity and depth correlations varying widely between stations. Our findings suggest that differences in seafloor topography and the impact of anthropogenic activities (e.g., fishing) lead to varying environmental conditions at the sampling sites, influencing the vertical distribution of MPs. This challenges the reliability of using environmental parameters to predict MP accumulation zones and questions the use of MPs in sediment cores as indicators of the Anthropocene.

Microplastics caused embryonic growth retardation and placental dysfunction in pregnant mice by activating GRP78/IRE1α/JNK axis induced apoptosis and endoplasmic reticulum stress

Microplastics (MPs), a brand-new class of worldwide environmental pollutant, have received a lot of attention. MPs are consumed by both humans and animals through water, food chain and other ways, which may cause potential health risks. However, the effects of MPs on embryonic development, especially placental function, and its related mechanisms still need to be further studied. We investigated the impact on fetal development and placental physiological function of pregnant mice by consecutive gavages of MPs at 0, 25, 50, 100 mg/kg body weight during gestational days (GDs 0–14). The results showed that continuous exposure to high concentrations of MP significantly reduced daily weight gain and impaired reproductive performance of pregnant mice. In addition, MPs could significantly induce oxidative stress and placental dysfunction in pregnant mice. On the other hand, MPs exposure significantly decreased placental barrier function and induced placental inflammation. Specifically, MPs treatment significantly reduced the expression of tight junction proteins in placentas, accompanied by inflammatory cell infiltration and increased mRNA levels of pro-inflammatory cytokines and chemokines in placentas. Finally, we found that MPs induced placental apoptosis and endoplasmic reticulum (ER) stress through the GRP78/IRE1α/JNK axis, leading to placental dysfunction and decreased reproductive performance in pregnant mice. We revealed for the first time that the effects of MPs on placental dysfunction in pregnant animals. Blocking the targets of MPs mediated ER stress will provide potential therapeutic ideas for the toxic effects of MPs on maternal pregnancy.

An in-depth analysis of microbial response to exposure to high concentrations of microplastics in anaerobic wastewater fermentation

The impact of microplastics (MPs) in anaerobic wastewater treatment on microbial metabolism is significant. Anaerobic granular sludge (AS) and biofilm (BF) are two common ways, and their responses to microplastics will have a direct impact on their application potential. This study investigated the microbial reactions of AS and BF to three types of MPs: polyethylene (PE), polyvinyl chloride (PVC), and a mixture of both (MIX). Results exhibited that MPs reduced methane output by 44.65 %, 55.89 %, and 53.18 %, elevated short-chain fatty acid (SCFA) levels by 95.93 %, 124.49 %, and 110.78 %, and lowered chemical oxygen demand (COD) removal by 28.77 %, 36.78 %, and 33.99 % for PE-MP, PVC-MP, and MIX-MP, respectively, with PVC-MP showing the greatest inhibition. Meanwhile, microplastics also facilitated the relative production of reactive oxygen species (ROS, 40.29 %–96.99 %), lactate dehydrogenase (LDH, 20.01 %–75.02 %), and adenosine triphosphate (ATP, 26.64 %–43.80 %), while reducing cytochrome c (cyt c, 23.60 %–49.02 %) and extracellular polymeric substances (EPS, 17.44 %–26.58 %). AS and BF displayed distinct enzymatic activities under MPs exposure. Correspondingly, 16S-rRNA sequencing indicated that AS was mainly involved in acetate generation by Firmicutes, while BF performed polysaccharide degradation by Bacteroidota. Metatranscriptomic analysis showed AS to be rich in acetogens (Bacillus, Syntrophobacter) and methanogens (Methanothrix, Methanobacterium), while BF contained more fermentation bacteria (Mesotoga, Lentimicrobium) and electroactive microorganisms (Clostridium, Desulfuromonas) under MIX-MP. Moreover, BF exhibited higher glycolysis gene expression, whereas AS was more active in methane metabolism, primarily through the acetoclastic methanogenic pathway's direct acetate conversion. This study provides new insights into understanding the microbial response produced by microplastics during anaerobic wastewater digestion.

Microplastic fate in a chronosequence of biosolid‐amended agricultural soil in Southern Ontario, Canada

AbstractMunicipally sourced biosolids are commonly used as cost‐effective fertilizers, diverting material from landfills and contributing to the circular economy. However, biosolids contain high concentrations of microplastics (MPs), which are emerging contaminants of concern due to their ubiquity in the environment. Despite this, there is a lack of environmentally relevant field studies. In 2022, composite topsoil samples (0–15 cm depth) were collected from seven agricultural fields in Southern Ontario, Canada, representing a chronosequence of biosolid applications ranging from 1 to 9 years since amendment and a control (untreated) field. MP particles down to 20 μm in size were extracted by density separation, enumerated, characterized by stereomicroscope and polymers identified using attenuated total reflectance Fourier transform infrared (ATR‐FTIR) spectroscopy. Here, we report on the characteristics, abundance and polymer type of MP particles in the study area to assess their fate in biosolid‐amended soils. The average MP concentration among fields was 6.87 ± 1.47 MP g−1 (3.43 ± 0.74 mg MP kg−1). Additionally, the MP soil pool increased with repeated applications of biosolids. The dewatered biosolid plastic content of 8816 ± 1809 MP g−1 dry weight (11.6 ± 17.5 g MP kg−1 dry weight) was used to estimate a mean MP loading of 94.5 ± 10.9 kg ha−1 to each field per application, suggesting that 7% of the MP soil pool persisted over time. Quantifying the MP pool in biosolid‐amended agricultural soil will inform evidence‐based plastic policy changes in our global effort to understand and reduce plastic pollution.

Inhibitory Effect of Combined Exposure to Copper Ions and Polystyrene Microplastics on the Growth of Skeletonema costatum

As two significant pollutants, the increased concentrations of copper ions and microplastics in coastal waters pose a substantial threat to the health of marine ecosystems. This study explored the individual and combined toxic effects of copper ions and microplastics on the marine diatom Skeletonema costatum. The results indicated that copper ions at a concentration of 0.05 mg/L exerted a negative impact on the growth of S. costatum; however, the influence of microplastics on algal cell growth was more complex: there was no significant inhibition of algal cell growth observed within the first 72 h of cultivation, but a pronounced negative effect on cell growth was noted between 72 and 96 h, with high concentrations (10.00 mg/L) of microplastics even causing a premature stagnation phase in algal cell growth. When both pollutants were present simultaneously, their impact on cell growth was similar to that of the microplastic pollution group, yet the growth condition was better than that of the copper ion pollution group. Through investigation of adsorption rates and toxicity mitigation rates, it was found that the adsorption of copper ions by microplastics was a significant reason for the improved growth condition of algal cells in the mixed pollution group compared to the copper ion pollution group. However, in the later stages of cultivation, the inhibitory effect of microspheres on algal cell growth counteracted their mitigating effect on copper ion toxicity. This study provides a reference for evaluating the impact of microplastics and heavy metals on coastal ecosystem health and for revealing the interactions between different pollutants.

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 accumulation and oxidative stress in sweet pepper (Capsicum annuum Linn.): Role of the size effect

Microplastics (MPs), which are widely dispersed in terrestrial environments, threaten crop growth and human food security. However, plant accumulation and phytotoxicity related to the size effects of MPs remain insufficiently explored. This study investigated the accumulation and toxicity of two sizes of MPs on Capsicum annuum Linn. (C. annuum) through fluorescence tracing and antioxidant defense system assessment. The results revealed that the size of MPs significantly impacts their accumulation characteristics in C. annuum roots, leading to variations in toxic mechanisms, including oxidative stress and damage. Smaller MPs and higher exposure concentrations result in more pronounced growth inhibition. C. annuum roots have a critical size threshold for the absorption of MPs of approximately 1.2 μm. MPs that enter the root tissue exhibit an aggregated form, with smaller-sized MPs displaying a greater degree of aggregation. MP exposure induces oxidative stress in root tissues, with high concentrations of smaller MPs causing lipid peroxidation. Analysis of the IBR values revealed that C. annuum roots utilize ascorbic acid (ASA) to prevent oxidative damage caused by larger MPs. Conversely, smaller MPs primarily induce superoxide dismutase (SOD) and glutathione (GSH). These results emphasize the significant impact of MP size on plant antioxidant defense response mechanisms, laying the foundation for further investigating the implications for human health.

Effect of different microplastics on the mobilization of soil inorganic phosphorus by exomycorrhizal fungi

&lt;p&gt;Microplastics (MPs) can affect the phosphorus (P) cycle in soil by changing soil properties and the function of microbial communities, but their impact on soil P availability remains unclear. To explore the effects of different types of MPs on the mobilization of soil inorganic P by exomycorrhizal fungi, Lactarius delicious (Ld) was used as the test strain, and polystyrene microspheres (PS), polypropylene (PP) and poly(lactic acid) (PLA) were used as test materials. The soil was used as the only P source for the media. The effect of different types of MPs on the mobilization of soil inorganic P by exomycorrhizal fungi was studied using liquid culture method. The results showed that exposure to MPs at low to medium concentrations (10 or 100 mg L-1) activated inorganic P in soil by stimulating the secretion of additional organic acids and hydrogen ions by ectomycorrhizal fungi, improving the available P in soil. The effect of mobilizing inorganic P was more significant in the treatment groups exposed to low and medium concentrations of biodegradable PLA. This may be related to the fact that PLA stimulated the ectomycorrhizal fungi to secrete more organic acids, and the release of a large amount of lactic acid after PLA was biodegraded. However, when the exposure concentration of MPs further increased, the growth of ectomycorrhizal fungal mycelium may be inhibited, the secretion of organic acids and hydrogen ions may be reduced, and the mobilization ability of soil inorganic P may be limited. In addition, it should be noted that high concentrations of non biodegradable MPs (PS and PP) had significant limiting effects on the mobilization of soil inorganic P by exomycorrhizal fungi. Therefore, our study results provide evidence that the presence of MPs may reduce the availability of soil P. Further research should focus on maintaining or improving P availability in plant-microbe systems in MP-polluted soil.&lt;/p&gt;