Microplastics Treatment Research Articles

Occurrence Characterization and Contamination Risk Evaluation of Microplastics in Hefei’s Urban Wastewater Treatment Plant

As one of the primary nodes in the flow of micro-plastics (MPs) in the environment, it is critical to examine and assess the Sewage Treatment, occurrence, and removal of MPs in waste treatment plant (WWTP). This research explored the shape, size, and composition of MPs at various stages of the WWTP process in the south of the city of Hefei, China, in dry and rainy weather conditions, as well as the removal effectiveness of MPs in a three-stage process. The collected MPs were quantitatively and qualitatively examined using an Osmosis electron microscope and micro-FTIR. The pollution risk of MPs in WWTP was assessed using the EU classification, labelling and packaging (CLP) standard and the pollution load index (PLI). The findings revealed that the average abundance of fibrous MPs was greatest in WWTP sewage and sludge, 49.3% and 39.7% in dry weather, and 50.1% and 43.2% in rainy weather, respectively. The average distribution of MPs in the 0–500 μm range was highest in WWTP wastewater and sludge, 64.9% and 60.4% in dry weather and 67.9% and 69.0% in rainy weather, respectively. Finally, the overall removal rate was 87.7% and 83.5%. At the same time, it has been demonstrated that MPs with varied compositions are strongly tied to human activities, and environmental conditions (such as rainy weather) also influence their source. In both dry and wet weather, the amount of polymers and the risk score were linked to the pollution risk of MPs in WWTP. In wet weather, the MPS pollution index was more variable. The pollution indices of MPs in row water and tail water were 2.40 and 2.46, respectively, which were heavily contaminated, and 1.0 and 1.2, which were moderately polluted. MPs in dewatered sludge had severely polluted indexes of 3.5 and 3.4, respectively. As a result, there is still MPs efflux or buildup in sludge during and after the WWTP process, which presents an ecological contamination concern.

RNA sequencing provides insights into the effect of dietary ingestion of microplastics and cadmium in the sea cucumber Apostichopus japonicus

IntroductionMicroplastics (MPs) and cadmium (Cd) are persistent pollutants in aquatic environments. Sea cucumbers are susceptible to MPs and Cd due to their feeding behavior.MethodsThis study, based on Illumina sequencing, compared the transcriptomes of A. japonicus before and after Cd and/or MPs exposure. Additionally, we detected the changes of catalase (CAT), and superoxide dismutase (SOD) activity, glutathione (GSH), and malondialdehyde (MDA) content in sea cucumbers.Results and DiscussionHigh concentration of MPs caused the increase of SOD activity. High concentration combined treatment resulted in significant up regulation of these four indicators in A. japonicus and had the largest number of differential expression genes (DEGs) reaching 1,618 DEGs, consisting of 789 up regulated along with 829 down regulated DEGs. Transcriptome results showed that Cd induced up regulation of intestinal FAS associated death domain protein (FADD) expression, which may cause apoptosis and inflammation. The increase of intestinal putative heparan sulfate 2-O-sulfotransferase in cadmium treatment groups provided a mechanism for host defense. The imbalance of expression of the NOD-like receptor (NLR) family inflammatory bodies and caspase 6 in the microplastic treatment group also led to the inflammatory reaction in the intestine of sea cucumber. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis showed that in the process of fatty acid metabolism, MPs and Cd showed antagonistic effects, mainly in the inconsistent expression of Stearoyl CoA Ddesaturase (SCD1) protein. The significant changes of Toll interacting protein (TOLLIP) and E-selectin (SELE) in all Cd and MPs treatment groups may indicate the key immune response genes of sea cucumber to Cd exposure and MPs exposure. These genes were involved in the immune defense of sea cucumber exposed to different levels of Cd and MPs. This study provided insights into the mechanism of dietary MPs and Cd intake in an economically and ecologically important invertebrate species.

Transformation of microplastics by oxidative water and wastewater treatment processes: A critical review.

Microplastics (MPs) are contaminants of emerging concern that accumulate in various environments, where they pose threats to both the ecosystem and public health. Since MPs have been detected in drinking water resources and wastewater effluents, more efficient treatment is needed at wastewater treatment plants (WWTPs) and drinking water treatment plants (DWTPs). This review discusses the potential of biological, photochemical, Fenton (-like) systems, ozonation, and other oxidation processes in the treatment of MPs in terms of their indicators of oxidation such as mass loss and surface oxidation. The oxidation processes were further analyzed in terms of limitations and environmental implications. Most previous studies examining MPs degradation using conventional treatments-such as UV disinfection, ozonation, and chlorination-employed significantly higher doses than the common doses applied in DWTPs and WWTPs. Owing to such dose gaps, the oxidative transformation of MPs observed in many previous studies are not likely to occur under practical conditions. Some novel oxidation processes showed promising MPs treatment efficiencies, while many of them have not yet been applied on a larger scale due to high costs and the lack of extensive basic research. Health and environmental impacts related to the discharge of oxidized MPs in effluents should be considered carefully in different aspects: the role as vectors of external pollutants, release of organic compounds (including organic byproducts from oxidation) and fragmentation into smaller particles as MPs circulate in the ecosystem as well as the possibility of bioaccumulation. Future research should also focus on ways to incorporate developed oxidation processes in DWTPs and WWTPs to mitigate MPs contamination.

Microplastics reduce nitrogen uptake in peanut plants by damaging root cells and impairing soil nitrogen cycling.

Microplastic (MP) pollution severely impairs the sustainable development of modern agriculture. However, the mechanisms underlying the effects of MP contaminants on nutrient cycles in agroecosystems are poorly understood. In this study, we examined the impacts of two types of MPs, polypropylene (PP) and rubber crumb (RC), on nitrogen (N) transformation and N cycling in soil-peanut system. High concentrations of PP (1% w/w) and RC (1% w/w) inhibited vegetative growth and N uptake in peanut plants by damaging root cells and disturbing soil N cycling. These MPs damaged the plasma membranes of root cells and caused oxidative stress, as evidenced by the decreased number of xylem vessels, which in turn inhibited N uptake by roots. Integrated metagenomic and metabolomic analyses revealed that the differential soil metabolite levels in response to MP treatment affected the microbial community structure in the rhizosphere and the expression of key N cycling-related genes, resulting in altered N transformation and the decreased availability of N in rhizosphere soil. These findings provide the first evidence of the effects of MPs on N uptake in peanut plants and shed light on the importance of rational management of MPs for crop growth and yield in agroecosystems.

The Effects of Exposing Solea senegalensis to Microbeads with and Without Pesticides

Microplastics (MP) are contaminants able to cause adverse effects on organisms. MPs are capable to interact with other environmental contaminants, including pesticides, altering their toxicity. The objective of the study was to research the sublethal effects (enzymatic activity) of pesticides alone and in combination with MPs. Cholinesterase enzymes are used as biomarkers to determine and evaluate the effects produced in organisms after exposure to pollutants. This study showed the acetylcholinesterase (AChE) enzymatic activity in the tissue of Solea senegalensis exposed to two environmental pollutants, the insecticide chlorpyrifos (CPF) and antibacterial triclosan (TCS) with and without microplastics (MPs). Solea senegalensis was chosen because it is a species in high demand because of its high economic value in southern Europe, as well as the use of this species in ecotoxicology and its increasing use as sentinel species, which justify using it to assess biological effects of pollutants. Toxicity tests were performed in organisms exposed to concentrations of between 5 and 80 μg/L CPF and 0.1 and 0.4 mg/L TCS for 96 h. In addition, each test incorporated MPs that were added at different concentrations in order to evaluate their role as a possible enhancer of the effects caused by the previous pollutants. In the case of CPF, the head and muscle tissue cholinesterase activity was inhibited from a concentration of 5 μg/L both without and with MPs, and the AChE enzymatic activity for the treatment with MPs was approximately half the activity for the treatment without MPs in the tissues studied. Besides, TCS inhibited the cholinesterase activity at a concentration of 0.3 mg/L in the muscle of S. senegalensis. In contrast, no significant differences were observed in the TCS + MP treatment compared to the controls. These results showed the importance of studies in assessing the anticholinesterase effects of pesticides combined with microplastics due to the abundance of these contaminants in the marine environment and the role of cholinesterase activity (biomarker) in the neurotransmission of key physiological processes.

Exposure to global change and microplastics elicits an immune response in an endangered coral

Global change is increasing seawater temperatures and decreasing oceanic pH, driving declines of coral reefs globally. Coral ecosystems are also impacted by local stressors, including microplastics, which are ubiquitous on reefs. While the independent effects of these global and local stressors are well-documented, their interactions remain less explored. Here, we examine the independent and combined effects of global change (ocean warming and acidification) and microplastics exposures on gene expression (GE) and microbial community composition in the endangered coral Acropora cervicornis. Nine genotypes were fragmented and maintained in one of four experimental treatments: 1) ambient conditions (ambient seawater, no microplastics; AMB); 2) microplastics treatment (ambient seawater, microplastics; MP); 3) global change conditions (warm and acidic conditions, no microplastics; OAW); and 4) multistressor treatment (warm and acidic conditions with microplastics; OAW+MP) for 22 days, after which corals were sampled for genome-wide GE profiling and ITS2 and 16S metabarcoding. Overall A. cervicornis GE responses to all treatments were subtle; however, corals in the multistressor treatment exhibited the strongest GE responses, and genes associated with innate immunity were overrepresented in this treatment. ITS2 analyses confirmed that all coral were associated with Symbiodinium ‘fitti’ and 16S analyses revealed similar microbiomes dominated by the bacterial associate Aquarickettsia, suggesting that these A. cervicornis fragments exhibited remarkably low variability in algal and bacterial community compositions. Future work should focus on functional differences across microbiomes, especially Aquarickettsia and viruses, in these responses. Overall, results suggest that when local stressors are coupled with global change, these interacting stressors present unique challenges to this endangered coral species.

Prevalence and implications of microplastics in potable water system: An update

Synthetic plastics, which are lightweight, durable, elastic, mouldable, cheap, and hydrophobic, were originally invented for human convenience. However, their non-biodegradability and continuous accumulation at an alarming rate as well as subsequent conversion into micro/nano plastic scale structures via mechanical and physio-chemical degradation pose significant threats to living beings, organisms, and the environment. Various minuscule forms of plastics detected in water, soil, and air are making their passage into living cells. High temperature and ambient humidity increase the degradation potential of plastic polymers photo-catalytically under sunlight or UV-B radiations. Microplastics (MPs) of polyethylene terephthalate, polyethylene, polystyrene, polypropylene, and polyvinyl chloride have been detected in bottled water. These microplastics are entering into the food chain cycle, causing serious harm to all living organisms. MPs entering into the food chain are usually inert in nature, possessing different sizes and shapes. Once they enter a cell or tissue, it causes mechanical damage, induces inflammation, disturbs metabolism, and even lead to necrosis. Various generation routes, types, impacts, identification, and treatment of microplastics entering the water bodies and getting associated with various pollutants are discussed in this review. It emphasizes potential detection techniques like pyrolysis, gas chromatography-mass spectrometry (GC-MS), micro-Raman spectroscopy, and fourier transform infrared spectroscopy (FT IR) spectroscopy for microplastics from water samples.

Impact of microplastics on lead-contaminated riverine sediments: Based on the enzyme activities, DOM fractions, and bacterial community structure

Microplastics (MPs) are able to interact with diverse contaminants in sediments. However, the impacts of MPs on sediment properties and bacterial community structure in heavy metal-contaminated sediments remain unclear. In this study, we investigated the adsorption of Pb(II) by sediment-MPs mixtures and the effects of different concentration MPs on sediment enzyme activities, DOM fractions, and Pb bioavailability in riverine sediments, and further explored the response of sediment microbial community to Pb in the presence of MPs. The results indicated that the addition of MPs significantly decreased the adsorption amount of Pb(II) by sediments, especially decreased by 12.6% at 10% MPs treatment. Besides, the changes in enzyme activities, DOM fractions exhibited dose-dependent effects of MPs. The higher level of MPs (5% and 10%) tends to transform Pb into more bioavailable fractions in sediments. Also, MPs amendment was observed to alter sediment bacterial community structures, and community differences were evident in the uncontaminated and lead-contaminated sediments. Therein, significant increase of Bacteroidota, Proteobacteria and decrease of Firmicutes abundance in Pb-contaminated sediment at the phylum level were observed. These findings are expected to provide comprehensive information for assessing the combined ecological risks of heavy metals and MPs in riverine sediments.

Stable Isotopic and Metagenomic Analyses Reveal Microbial-Mediated Effects of Microplastics on Sulfur Cycling in Coastal Sediments.

Microplastics are readily accumulated in coastal sediments, where active sulfur (S) cycling takes place. However, the effects of microplastics on S cycling in coastal sediments and their underlying mechanisms remain poorly understood. In this study, the transformation patterns of different S species in mangrove sediments amended with different microplastics and their associated microbial communities were investigated using stable isotopic analysis and metagenomic sequencing. Biodegradable poly(lactic acid) (PLA) microplastics treatment increased sulfate (SO42-) reduction to yield more acid-volatile S and elementary S, which were subsequently transformed to chromium-reducible S (CRS). The S isotope fractionation between SO42- and CRS in PLA treatment increased by 9.1‰ from days 0 to 20, which was greater than 6.8‰ in the control. In contrast, recalcitrant petroleum-based poly(ethylene terephthalate) (PET) and polyvinyl chloride (PVC) microplastics had less impact on the sulfate reduction, resulting in 7.6 and 7.7‰ of S isotope fractionation between SO42- and CRS from days 0 to 20, respectively. The pronounced S isotope fractionation in PLA treatment was associated with increased relative abundance of Desulfovibrio-related sulfate-reducing bacteria, which contributed a large proportion of the microbial genes responsible for dissimilatory sulfate reduction. Overall, these findings provide insights into the potential impacts of microplastics exposure on the biogeochemical S cycle in coastal sediments.

Soil properties, microbial diversity, and changes in the functionality of saline-alkali soil are driven by microplastics

With the intensification of microplastic (MP) pollution, the impact of MPs on soil ecosystems has garnered considerable attention. We investigated the effects of two commonly used MPs, polyethylene (PE) and polypropylene (PP), at different sizes and doses, on the properties and microbial communities in saline-alkali soil. We found that MP treatment significantly reduced the electrical conductivity but somewhat enhanced the enzyme activities and effective nutrient content of the soil. Microbial diversity is affected by the type, dose, size and interaction of MPs, with fungi being more sensitive than bacteria. Under high-dose PE treatment, the dominant bacteria and fungi enriched, and the diversity indexes declined significantly. Meanwhile, under high-dose PP treatment, several unique bacteria and fungi with low abundance were observed, which eventually increased the diversity indexes. Moreover, PE exerted a stronger effect on bacterial function than PP. High-dose PE treatment suppressed the nitrogen fixation potential of soil bacteria. However, high-dose PP treatment promoted that. In conclusion, our findings showed that PE exerts a stronger negative effect on saline-alkali soil ecosystems than PP. Our findings help bridge the knowledge gap in the impact of MPs on saline-alkaline soils and provide guidance for the rational use of agricultural plastics in saline-alkaline soils.

Physiological and transcriptome analysis of Mytilus coruscus in response to Prorocentrum lima and microplastics

Nowadays, diarrheic shellfish toxicity (DSP) toxin and microplastics (MPs) are commonly found in coastal waters worldwide. Due to their widespread use, their persistence and toxicity, they may induce adverse effects on Mytilus coruscus. However, the underlying toxic mechanisms of DSP and MPs on M. coruscus remain unclear. This study explored the physiological index and transcriptome change of the digestive gland of adult M. coruscus exposed for 3 days to polystyrene (PS) MPs (0.2 mg/L, 90-100 μm) and Prorocentrum lima alone or in combination. The results showed that the CAT activity and MDA content significantly increased, respiration rate and feeding rate significantly decreased. The combination of MPs and P. lima caused more structural damage to the rough surface endoplasmic reticulum and mitochondria in the digestive glands of M. coruscus. The transcriptome analysis showed that 485 and 220 genes were up- and down-regulated, respectively, after exposure to P. lima; 1,989 up-regulated DEGs and 1,098 down-regulated DEGs were identified after exposure to MP treatment, and 1,004 up-regulated DEGs and 664 down-regulated DEGs were identified after exposure to the combination of P. lima and MPs. The DEGs were mainly enriched in the lysosome, mRNA surveillance pathway, carbon metabolism, the mTOR signaling pathway, the complement and coagulation cascades, and the TNF signaling pathway. The MP, P. lima exposure mainly induced the expression of RNA-binding protein musashi, serine/arginine repetitive matrix protein 1, low affinity immunoglobulin epsilon Fc receptor, toll-like receptor 2, caspase 7, calmodulin, E3 ubiquitin-protein ligase, serine/threonine-protein kinase PRP4, glutathione S-transferase, and heat shock 70 kDa protein. MPs and P. lima poison mainly influence the expression of RNA transport, immune related gene, apoptosis, signal related gene, and antioxidant gene change. The combination of MPs and P. lima has a synergistic toxic effect. This study provides a new insights into its physiological and molecular responses of M. coruscus to MPs and P. lima toxic exposure.

Impact of polyethylene microplastics and copper nanoparticles: Responses of soil microbiological properties and strawberry growth

Microplastics (MPs) can act as vectors of contaminants such as fungicides and trace metals. Their presence in water or soil might affect fruits and vegetables, while interactions between MPs and copper (Cu) nanoparticles might pose greater risks to soil properties, plant development and yield. The objective of this study was to evaluate the effect of the presence of MPs and Cu nanoparticles on plant growth and yield of strawberry, as well as on soil microbiological properties. The experiment was carried out in pots in a greenhouse; the soil was contaminated with polyethylene MPs and Cu nanoparticles. The design was completely randomized with four treatments (control, MPs, Cu, and Cu + MPs). Six months after planting, significant changes were observed in terms of plant height, stem diameter and root surface area. When compared to the control treatment, the MPs treatment resulted in a 27 % decrease in plant height, lower stem diameter values in all the contaminant treatments, and decreases in root surface area by 20 %, 21 % and 17 % in the MPs, Cu, and Cu + MPs treatments, respectively. Regarding number of inflorescences, total number of fruits, fruit weight and total aerial biomass, the MPs, Cu, and Cu + MPs treatments were statistically lower than the control (p < 0.05). The soil dehydrogenase activity decreased by 30 % due to the combined application of MPs and Cu nanoparticles, but this was not observed when MPs or Cu nanoparticles were applied alone, evidencing possible effects on the biological activity of the soil. Significant differences were found in acid phosphatase and urease activities in the Cu treatments with respect to the control and MPs treatments except for soil respiration. It can be concluded that the presence of Cu nanoparticles combined with polyethylene MPs favored a greater Cu availability in the soil and root Cu accumulation of strawberry plants.

Distribution and toxicity of submicron plastic particles in mice

Although microplastics (MPs) have become a global issue, the biodistribution and toxicities of MPs were still unclear. In this study, c57BL/6 mice were treated with submicron-sized MPs labeled with Nile red fluorescence by oral gavage three times a week for four consecutive weeks. Flow cytometry and microscopy technique were used to examine the concentration and distribution of MPs in various tissues and biofluids. The oxidative stress and inflammation were assessed via liquid chromatography–mass spectrometry and enzyme-linked immunosorbent assay, respectively. Submicron-sized MP signals were found in the intestines, liver, spleen, kidney, lungs, blood, and urine of mice after MP exposure. Increased oxidative stress in mouse urine and elevated inflammatory cytokines in mouse kidney were also recorded. In conclusion, flow cytometry is a useful tool for examining the number concentrations of MPs. Increased oxidative stress and inflammation after MP treatment indicates that the toxicity of MP warrants further investigation.

Three typical microplastics affect the germination and growth of amaranth (Amaranthus mangostanus L.) seedlings

Microplastics (MPs) have been a global emerging contaminant and have aroused wide public concern. Currently, it is still unknown the phytotoxicity effect of MPs on amaranth (Amaranthus mangostanus L.). This study investigated the early responses of amaranth by exposing its seeds to suspensions of polystyrene (PS), polyethylene (PE), and polypropylene (PP) MPs. We observed the effects of MPs on seed germination and growth of amaranth, especially on the oxidative damage in amaranth roots. Impacts of MPs on the germination and growth of amaranth varied with the type, concentration, and particle size of MPs. PE MPs and PP MPs inhibited the shoot extension of amaranth, while the root length under PP MPs treatment was generally shorter than that under PS MPs and PE MPs. The accumulation of H2O2 in amaranth roots increased with the rising of MPs concentration. Compared with the control, a little number of dead cells were found in the roots of amaranth under high MPs treatment. It is noteworthy that only under 100 mg/L PP treatment, the amaranthus seedlings root cells were disorganized, due to the reactive oxygen species (ROS) damage in the roots. These findings provide essential information to assess the phytotoxicity of MPs in agricultural products, and provide insights into the underlying mechanisms of the observed phytotoxicity.

Exposure of Cyprinus carpio var. larvae to PVC microplastics reveals significant immunological alterations and irreversible histological organ damage

Microplastics have become pervasive in ambient aquatic ecosystems over the last decade and are currently a serious global scale concern. To evaluate the potential toxic effects of PVC (polyvinyl chloride) microplastics on the immune functions of freshwater fish, this study undertook a conducted chronic 60-day dietary exposure experiment with Cyprinus carpio var. larvae. We exposed the fish to four microplastic treatments of different concentrations (food rationed diets): no-plastic (control), 10%, 20% and 30%. At the end of the experimental period the impacts of microplastics on the histology, biochemistry, ROS (reactive oxygen species) levels and gene transcription of immune organs were investigated. The results revealed that PVC microplastics induced cytoplasmic vacuolation in the liver, damaged villi in the intestine, inflammatory cell infiltration, hemosiderosis and vacuolar degeneration in the spleen, glomeruli tuft shrinkage and aggregation of melanin macrophage cells in the kidney. Moreover, following PVC microplastics exposure, ROS levels in the liver and protein levels of pro-inflammatory cytokines including IL-6, IL-8, and TNFα in the liver and serum were increased. Furthermore, modifications in the activities of non-specific immunoenzyme ACP (Acid phosphatase), AKP (alkaline phosphatase), LZM (lysozyme), and expression levels of a range of immune-related genes were observed. Using various techniques at the histological, biochemical and molecular levels, our findings demonstrated the effects of PVC microplastics on changes and imbalances in the immune status of carp. The results of this study provide basic toxicological data toward elucidating and quantifying the impacts of microplastics immunotoxicity on aquatic organisms.

Distinguish the toxic differentiations between acute exposure of micro- and nano-plastics on bivalves: An integrated study based on transcriptomic sequencing

Plastic pollution represents one of the most severe marine environmental issues today. In the present study, mussel Mytilus coruscus, was selected as the model organism to probe the toxic effects of acute exposure to different sizes of plastic particles using integrated transcriptomic techniques and histological and biochemical analysis. Nanoplastics (NPs) were efficiently ingested by mussels, thereby inducing a severe inflammatory response. Although no distinct aggregation of microplastics (MPs) was observed, a slight inflammatory response has still occurred. Biochemical analysis revealed a significant up-regulation of biomarkers after exposure to plastic particles. Further, NPs caused more ROS production and higher T-AOC level than MPs. Transcriptomic sequencing was performed, and these differentially expressed genes after MNPs exposure were mostly enriched in pathways involved in stress and immune response. Notably, a contrast expression, substantial upregulation in MPs treatment and downregulation in NPs treatment of specific genes include in these pathways were revealed. Collectively, these results indicated that acute exposure to NPs is more toxic than MPs. Additionally, MPs exposure perhaps caused the impairment of olfactory function and neurotoxicity to mussels. These data provided some new clues for the elucidating of ecotoxicological mechanisms underlying plastic particles exposure.

Microplastics perturb colonic epithelial homeostasis associated with intestinal overproliferation, exacerbating the severity of colitis

A great amount of the population died due to living or working in an unhealthy environment, highlighting the critical role of environmental pollutants in inducing diseases. Microplastics are widespread environmental pollutants and have been found in various tissues of human beings, yet the risk of microplastics in the occurrence of disease, especially environmentally-related colitis, is unclear. This study focused on the effects of microplastics exposure on intestinal homeostasis and the initiation of colitis. We noticed that microplastics exposure had a limited impact on mice, as verified by no difference observed in bodyweight change, IL-1β and IL-6 levels in jejunum and liver. Nevertheless, in the colon, the IL-1β and IL-6 levels were slightly increased and the goblet cell number was decreased. Interestingly, we observed that crypt number and depth, the levels of intestinal stem cell markers, combined with the expression of proliferating cell nuclear antigen and proto-oncogene c-Myc were all significantly increased with microplastics treatment, indicating the overproliferation of colonic mucosa. The effect of microplastics on proliferation and differentiation of crypt was further demonstrated to be regulated by the overactivation of the Notch signaling pathway in intestinal organoids. Furthermore, microplastics exposure accelerated the development of colitis with severe bodyweight loss, diarrhea and bloody stools, macroscopic and pathological damage, and inflammation levels. Worsened liver pathological damage and inflammation in mice with colitis under microplastics exposure also were found. These results suggested that microplastics disrupted the balance between colonic epithelium self-renewal and differentiation, exacerbating the colitis, and might be an environmental-related disease risk factor.

Type-dependent effects of microplastics on tomato (Lycopersicon esculentum L.): Focus on root exudates and metabolic reprogramming

Much attention has been paid to the prevalence of microplastics (MPs) in terrestrial systems. MPs have been shown to affect the physio-biochemical properties of plants. Different MPs may have distinctive behaviors and diverse effects on plant growth. In the present study, the effects of polystyrene (PS), polyethylene (PE), and polypropylene (PP) MPs on physio-biochemical properties, root exudates, and metabolomics of tomato (Lycopersicon esculentum L.) under hydroponic conditions were investigated. Our results show that MPs exposure has adverse effects on tomato growth. MPs exposure had a significant type-dependent effect (p < 0.001) on photosynthetic gas parameters, chlorophyll content, and antioxidant enzyme activities. After exposure to MPs, the content of low molecular weight organic acids in tomato root exudates was significantly increased, which was considered as a strategy to alleviate the toxicity of MPs. In addition, MPs treatment significantly changed the metabolites of tomato root and leaf. Metabolic pathway analysis showed that MPs treatment had a great effect on amino acid metabolism. We also found that plants exposed to PS and PP MPs produced more significant metabolic reprogramming than those exposed to PE MPs. This study provides important implications for the mechanism studies on the toxic effect of various MPs on crops and their future risk assessment.

Deciphering the Fingerprint of Dissolved Organic Matter in the Soil Amended with Biodegradable and Conventional Microplastics Based on Optical and Molecular Signatures.

Biodegradable polymers are promoted as promising alternatives for conventional non-degradable plastics, but they may also negatively impact soil ecosystems. Here, we estimated the effects of biodegradable (polylactide (PLA) and polybutylene succinate (PBS)) and non-biodegradable (polyethylene (PE) and polystyrene (PS)) microplastics at a concentration of 1% (w/w) on dissolved organic matter (DOM) in two soil types, a black soil (BS) and a yellow soil (YS), by using fluorescence excitation-emission matrix spectroscopy and ultrahigh-resolution Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS). PBS significantly increased the contents of soil dissolved organic carbon (DOC) and the relative intensities of protein-like components. The turnover rates of soil DOM were statistically higher in PBS treatments (0.106 and 0.196, p < 0.001) than those in other microplastic groups. The FT-ICR-MS results indicated that more labile-active DOM molecules were preferentially obtained in biodegradable microplastic treatments, which may be attributed to the polymer degradation. The conventional microplastics showed no significant effects on the optical characteristics but changed the molecular compositions of the soil DOM. More labile DOM molecules were observed in BS samples treated with PE compared to the control, while the conventional microplastics decreased the DOM lability in YS soil. The distinct priming effects of plastic-leached DOM may trigger the DOM changes in different soils. This study provided important information for further understanding the impact of microplastics on soil carbon processes.

Multi stress system: Microplastics in freshwater and their effects on host microbiota

Microplastics are persistent and complex contaminants that have recently been found in freshwater systems, raising concerns about their presence in aquatic organisms. Plastics tend to be seen as an inert material; however, it is not well known if exposure to plastics for a prolonged time, in combination with organic chemicals, causes organism mortality. Ingestion of microplastics in combination with another pollutant may affect a host organism's fitness by altering the host microbiome. In this study, we investigated how microplastics interact with other pollutants in this multi-stress system, and whether they have a synergistic impact on the mortality of an aquatic organism and its microbiome. We used wild water boatmen Hemiptera (Corixidae) found at lake Erken located in east-central Sweden in a fully factorial two-way microcosm experiment designed with polystyrene microspheres and a commonly used detergent. The microplastic-detergent interaction is manifested as a significant increase in mortality compared to the other treatments at 48 h of exposure. The diversity of the microbial communities in the water was significantly affected by the combined treatment of microplastics and the detergent while the microbial communities in the host were affected by the treatments with microplastics and the detergent alone. Changes in relative abundance in Gammaproteobacteria (family Enterobacteriaceae), were observed in the perturbed treatments mostly associated with the presence of the detergent. This confirms that microplastics can interact with detergents having toxic effects on wild water boatmen. Furthermore, microplastics may impact wild organisms via changes in their microbial communities.