Nowadays the proliferation of microplastics (MPs) in aquatic environments and impacts on the fate of organic contaminants (OCs) has drawn sustained worldwide attention. In this study, we investigated ...the effects of different types and aging degrees of MPs, specifically polystyrene (PSMPs), polyethylene terephthalate (PETMPs), and polylactic acid (PLAMPs), on the photo-transformation of LSTPs. Our results revealed that the facilitation of LSTP photoconversion by PSMPs exhibited a positive linear relationship with aging degree. On the other hand, the effects of PETMPs with different oxidation levels on LSTP photoconversion were weak, while the contribution of PLAMPs decreased as aging increased. Characterizations, quenching and probing experiments showed the aging mechanisms and the generation of reactive oxygen species (ROS) converged among various MPs. Specifically, theoretical calculations, TOC and GC-MS were conducted to verify that in the PLA0-mediated systems, it was the intermediates of PLA0 that prevailed in promoting the photoconversion of LSTP. The aged PLA own have a large propensity to consume ROS, which diminished their promotion of LSTP degradation. This differd from the reactions involving PSMPs and PETMPs, where the microplastic particles themselves were the main drivers of the photoconversion process rather than intermediates.
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•PSMPs and PETMPs enhanced the photoconversion of LSTP with elevated aging degree.•The effect of PLAMPs on LSTP photolysis decreased with increased aging degree.•ROS induced by PSMPs mainly attacked LSTP not PSMPs particles themselves.•PETMPs depleted ROS leading to insignificant facilitation of LSTP photoconversion.•Intermediates derived from PLAMPs promoted LSTP photolysis.
Microplastics (MP) are receiving increased attention as a harmful environmental pollutant, however information on the reproduction toxicity of MP in terrestrial animals, especially mammals, is ...limited. In this experiment, we investigated the impact of polystyrene microplastics (micro-PS) on the reproductive system of male mice. Healthy Balb/c mice were exposed to saline or to different doses of micro-PS for 6 weeks. The results showed that micro-PS exposure resulted in a significant decrease in the number and motility of sperm, and a significant increase in sperm deformity rate. We also detected a decrease in the activity of the sperm metabolism-related enzymes, succinate dehydrogenase (SDH) and lactate dehydrogenase (LDH), and a decrease in the serum testosterone content in the micro-PS exposure group. We found that micro-PS exposure caused oxidative stress and activated JNK and p38 MAPK. In addition, we found that when N-acetylcysteine (NAC) scavenges ROS, and when the p38 MAPK-specific inhibitor SB203580 inhibits p38MAPK, the micro-PS-induced sperm damage is alleviated and testosterone secretion improves. In conclusion, our findings suggest that micro-PS induces reproductive toxicity in mice through oxidative stress and activation of the p38 MAPK signaling pathways.
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•Micro-PS resulted in a significant decrease in the quantity and quality of sperm in mice.•Micro-PS exposure caused oxidative stress in testes.•Micro-PS exposure activated JNK and P38 MAPK.•Blocking oxidative stress or P38 MAPK can alleviate micro-PS-induced sperm damage.
Microplastics have become a contaminant of increasing concern in soils. Although biodegradable plastics were considered as alternatives of traditional plastics, some evidence showed that ...biodegradable plastics might produce more microplastics. Until now, the effect of biodegradable microplastics on soil functions and processes, as well as microbial communities is uncertain. Based on high throughput sequencing, enzymatic activity assay and dynamic analysis of soil carbon and nitrogen, we investigated the effects of biodegradable polylactic acid microplastics (PLA MPs) on soil microbiota and related ecological processes under conditions of high or low carbon content. The results showed that PLA MPs had no significant effect on the overall diversity and composition of bacterial communities or related ecosystem functions and processes. However, co-occurrence network analysis revealed that PLA MPs impacted the interactions between constituent species, which might have legacy effect on soil bacterial communities and functions. Our data also revealed that PLA MPs could trade off the priming effect of carbon source. Our results provided an integrated picture in understanding the effects of PLA MPs on soil microbes, properties and ecological functions, which will help to further understand the effects of MPs on terrestrial ecosystems.
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•2% PLA MPs did not impact soil nutrient pool and ecological functions.•A faster ammonia transformation rate was observed in PLA MPs amended soil.•The interaction among bacteria has been changed with the addition of PLA MPs.•Different effect of PLA MPs on soil under different carbon content was observed.
Plastic waste is continuously introduced not only into marine, but also freshwater environments, where it fragments into microplastics. Organisms may be affected by the particles themselves due to ...ingestion and indirectly via incorporated additives such as plasticizers, since these substances have the ability to leach out of the polymer matrix. Although it has been indicated that the likelihood of additives leaching out into the gut lumen of organisms exposed to microplastics is low, studies distinguishing between the effects of the synthetic polymer itself and incorporated additives of the same polymer are scarce. Since this is obligatory for risk assessment, we analyzed the chronic effects of flexible polyvinylchloride (PVC), a widely used polymer, containing the plasticizer diisononylphthalate (DiNP) on morphology and life history of the freshwater crustacean Daphnia magna and compared these effects with the effects of rigid PVC, lacking DiNP, as well as a glass bead control. After up to 31 days of exposure, rigid PVC and glass beads did not affect body length and relative tail spine length of D. magna, whereas flexible PVC led to an increased body length and a reduced number of offspring. None of the treatments increased the mortality significantly. We were able to show that 2.67μg/L DiNP leached out of the flexible PVC into the surrounding medium using GC-MS. Yet, we were not able to measure leachate inside the gut lumen of D. magna. The effects emerged towards the end of the experiment, due to the time dependent process of leaching. Therefore, the results highlight the relevance of long-term chronic exposure experiments, especially as leaching of additives takes time. Further, our study shows the importance to distinguish between microplastics containing leachable additives and the raw polymer in ecotoxicological testing.
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•Flexible polyvinylchloride particles, containing diisononylphthalate affected Daphnia.•Flexible polyvinylchloride particles affected life history and morphology.•Rigid polyvinylchloride particles without diisononylphthalate did not affect Daphnia.•We measured a leached diisononylphthalate concentration of 2.67 μg/L medium.•Importance of long term exposition, as effects were visible at the end of the test.
Our study shows the importance to differentiate between microplastics containing additives and the raw polymer, thus exact composition of plastics used in toxicological testing is vital for risk assessment.
Microplastic (MP) appears to be omnipresent in the atmosphere, raising concerns about dispersion across environmental compartments, ecological consequences and human health risks by inhalation. To ...date, data on the sources of atmospheric MP and deposition to river catchment areas are still sparse. We, therefore, took aerosol and total atmospheric deposition samples in the catchment area of the large German river Weser to estimate microplastic deposition fluxes (DFs) at six specific sites and airborne MP concentrations. Sampling in rural, suburban, and urban environments and wastewater treatment plants (WWTPs) was performed, aiming at a variation in airborne MP pollution and elucidating potential MP source areas. Aerosol samples were taken twice in April and October while monthly total deposition samples were collected over a period from March to October. Microplastics were detected in all analysed aerosol samples by Raman spectroscopy down to 4 μm, and in all 32 total deposition samples by μFT-IR down to 11 μm. Average MP number concentrations of 91 ± 47 m−3 were found in aerosol samples. The measured total MP number DFs ranged between 10 and 367 N m−2 day−1 (99 ± 85 mean ± SD) corresponding to total deposition of 0.05 ± 0.1 kg ha−1 per year and to an estimated 232 metric tons of plastic being deposited in the Weser River catchment annually. MP number DFs were higher in urban than rural sites. An effect of WWTPs on the MP abundance in air was not observed. Polypropylene, polyethylene, polyethylene terephthalate, polyvinyl chloride, polystyrene, and silicone fragments were found as the predominant polymer types in total deposition samples, while polyethylene particles dominated in aerosol samples. The results suggest that proximity to sources, especially to cities, increase the numbers of MP found in the atmosphere. It further indicates that atmospheric MP considerably contributes to the contamination of both aquatic and terrestrial habitats.
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•Average airborne MP concentration of 91 ± 47 particles per m3 (>4 μm)•Average total MP deposition rate of 99 ± 85 particles per m2 per day (>11 μm)•Atmospheric deposition must be considered as a diffuse MP source.•Proximity to sources, especially to cities, increase MP numbers in the atmosphere.•PP and PE fragments predominate in air in Central and Northwest Germany.
Microplastics (MPs) as emerging contaminants have attracted attention worldwide, but little is known on their interactions with metallic contaminants in soil-plant systems. Here, we investigated the ...interactions between MPs, i.e., polyethylene (PE) and polylactic acid (PLA), and cadmium (Cd) on plant performance and arbuscular mycorrhizal fungal community in an agricultural soil. PE showed no noticeable phytotoxicity, while 10% PLA decreased maize biomass and chlorophyll content in leaves. A significant interaction on root biomass occurred between PE and Cd, but not between PLA and Cd. Both PE and PLA caused increase in soil pH and DTPA-extractable Cd concentrations, but no alterations in Cd accumulation in plant tissues. Different numbers of endemic and total OTUs were observed in various treatments. The relative abundance of arbuscular mycorrhizal fungi (AMF) genera highly varied with MPs and Cd. MPs altered AMF community structure and diversity, depending on their type and dose. Coexisting Cd produced slight but significant interactions with MPs on the dominant AMF genera. Overall, plant growth and AMF community varied with MPs type and dose, Cd, and their interactions, and the high dose of PLA produced stronger phytotoxicity. In conclusion, coexisting MPs and Cd can jointly drive shifts in plant performance and root symbiosis, thereby posing additional risks for agroecosystems and soil biodiversity.
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•Interactions of MPs and Cd on plant growth and AMF community were first studied.•PE showed no phytotoxicity, but PLA at the high dose produced severe phytotoxicity.•PLA caused higher Cd bioavailability than PE, but no alterations in plant Cd content.•MPs and Cd produced various impacts on AMF community structure and diversity.•Interactions of MPs and Cd could drive shifts in plant performance and root symbiosis.
Microplastic (MP) debris is considered as a potentially hazardous material. It is omnipresent in our environment, and evidence that MP is also abundant in the atmosphere is increasing. Consequently, ...the inhalation of these particles is a significant exposure route to humans. Concerns about potential effects of airborne MP on human health are rising. However, currently, there are not enough studies on the putative toxicity of airborne MP to adequately assess its impact on human health. Therefore, we examined potential drivers of airborne MP toxicity. Physicochemical properties like size, shape, ζ-potential, adsorbed molecules and pathogens, and the MP’s bio-persistence have been proposed as possible drivers of MP toxicity. Since their role in MP toxicity is largely unknown, we reviewed the literature on toxicologically well-studied non-plastic airborne microparticles (asbestos, silica, soot, wood, cotton, hay). We aimed to link the observed health effects and toxicology of these microparticles to the abovementioned properties. By comparing this information with studies on the effects of airborne MP, we analyzed possible mechanisms of airborne MP toxicity. Thus, we provide a basis for a mechanistic understanding of airborne MP toxicity. This may enable the assessment of risks associated with airborne MP pollution, facilitating effective policymaking and product design.
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•Airborne microplastic (MP) is a potential hazard for human health.•Size, shape, and surface charge are proposed as possible drivers for MP toxicity.•Comparisons with other dusts allow identification of putative toxicity mechanisms.•Mechanistic knowledge of airborne MP toxicity is crucial for hazard evaluation.
Rivers are viewed as major pathways of microplastic transport from terrestrial areas to marine ecosystems. However, there is paucity of knowledge on the dispersal pattern and transport of ...microplastics in river sediments. In this study, a three dimensional hydrodynamic and particle transport modelling framework was created to investigate the dispersal and transport processes of microplastic particles commonly present in the environment, namely, polyethylene (PE), polypropylene (PP), polyamide (PA), and polyethylene terephthalate (PET) in river sediments. The study outcomes confirmed that sedimental microplastics with lower density would have higher mobility. PE and PP are likely to be transported for a relatively longer distance, while PA and PET would likely accumulate close to source points. High water flow would transport more microplastics from source points, and high flow velocity in bottom water layer are suggested to facilitate the transport of sedimental microplastics. Considering the limited dispersal and transport, the study outcomes indicated that river sediments would act as a sink for microplastic pollutants instead of being a transport pathway. The patchiness associated with the hotspots of different plastic types is expected to provide valuable information for microplastic source tracking.
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•Microplastics with lower density have high mobility in sediments.•Dense microplastics prone to accumulate close to source points in river sediments.•High bottom water velocity result in longer transport of sedimental microplastics.•Limited transport of benthic microplastics makes river sediments function as a sink.•Patchiness in microplastics hotspots provide valuable data for source tracking.
Capsule: Modelling of transport processes of microplastics to understand their dispersal and fate in aquatic environments.
The increasing prevalence of microplastics in the environment has become a concern for various ecosystems, including wetland ecosystems. Here, we investigated the effects of three popular ...microplastic types: polyethylene, polylactic acid, and tire particles at 5 °C and 25 °C on the sediment microbiome and metabolome at the 3% (w/w) level. Results indicated that temperature greatly influenced catalase and neutral phosphatase activities, whereas the type of microplastic had a more significant impact on urease and dehydrogenase activities. The addition of microplastic, especially tire particles, increased microbial diversity and significantly altered the microbial community structure and metabolic profile, leading to the formation of different clusters of microbial communities depending on the temperature. Nonetheless, the effect of temperature on the metabolite composition was less significant. Functional prediction showed that the abundance of functional genes related to metabolism and biogeochemical cycling increased with increasing temperature, especially the tire particles treatment group affected the nitrogen cycling by inhibiting ureolysis and nitrogen fixation. These observations emphasize the need to consider microplastic type and ambient temperature to fully understand the ecological impact of microplastics on microbial ecosystems.
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•Evaluated the effects of polyethylene, polylactic acid, and tire particles (microplastics - MPs) on sediment.•MPs, especially tire particles, increased microbial diversity at higher temperatures.•Temperature influenced microbial diversity dynamics and had less of an effect on metabolites.•Comparatively, tire particle treatments had unique microbial communities and different metabolites.
Degraded plastic debris has been found in nearly all waters within and nearby urban developments as well as in the open oceans. Natural removal of suspended microplastics (MPs) by deposition is often ...limited by their excess buoyancy relative to water, but this can change with the attachment of biological matter. The extent to which the attached biological ballast affects MP dynamics is still not well characterised. Here, we experimentally demonstrate using a novel OMCEC (Optical Measurement of CEll colonisation) system that the biological fraction of MP aggregates has substantial control over their size, shape and, most importantly, their settling velocity. Polyurethane MP aggregates made of 80% biological ballast had an average size almost twice of those containing 5% biological ballast, and sank about two times slower. Based on our experiments, we introduce a settling velocity equation that accounts for different biological content as well as the irregular fractal structure of MP aggregates. This equation can capture the settling velocity of both virgin MPs and microbial-associated MP aggregates in our experiment with 7% error and can be used as a preliminary tool to estimate the vertical transport of MP aggregates made of different polymers and types of microbial ballast.
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