Microplastic Fragments Research Articles

Advancing the Understanding of Microplastic Weathering: Insights from a Novel Polarized Light Scattering Approach.

Weathering is a significant process that alters the properties of microplastics (MPs) and consequently affects their environmental behaviors. In this study, we introduced a novel approach based on polarized light scattering technique, which offers advantages in terms of rapid, high-throughput, and submicron-sized detection. This technique was successfully applied to characterize the weathered MPs after a 180-day laboratory simulation of coastal environments. By employing polarization measurements, we obtained a 46-dimensional matrix data set for the weathered MP fragments and subsequently processed them using a backpropagation neural network. The successful extraction of effective polarization pulses confirmed the presence of MP fragments within the size range of 0.2-60 μm, yielding total accuracies for size classification ranging from 78.9 to 86.9%. Furthermore, this technique achieved an overall accuracy of 93.8% in classifying MPs with different weathering degrees and polymer types, revealing polarization parameters associated with size and morphological changes play a dominant role in characterizing the weathering process of MPs. Compared with conventional approaches, the novel polarized light scattering approach holds great promise for rapid, high-throughput, and accurate characterization of MPs with small sizes. The findings of this study provided new insights into how MPs change after long-term weathering in aquatic environments.

The Ability of Gastropods of Lake Baikal to the Feeding and Excretion of Microplastic Particles with Different Morphological Structures

Studies of the pollution of Lake Baikal with microplastic particles have been started quite recently. Almost all research is focused on the assessment of surface water pollution, while the impact of microplastics on Baikal organisms remains unexplored. We conducted a laboratory experiment involving three species of gastropod mollusks, the Palearctic Lymnaea stagnalis (L., 1758) and Radix auricularia (L., 1758), as well as the Baikal endemic Benedictia baicalensis (Gerstfeldt, 1859). Two types of microplastics were used in the experiment: fragments of polystyrene and polyester fibers, prepared independently in the laboratory. These plastic particles, along with the food mixture, were placed in aquariums with mollusks. In total, as a result of the experiment, 386 preparations with mollusk excrement were obtained, of which 144 preparations were for the Radix auricularia species, 176 for the Lymnaea stagnalis species, and 67 for the Benedictia baicalensis species, the experiment with the latter species was carried out only with microplastic fragments. All preparations were analyzed according to the degree of fluorescence. The data were statistically processed using Spearman’s rank correlation coefficient. The data obtained allowed us to conclude that gastropods of these species are able to absorb microplastic particles and remove them from the body. However, the rate of removal of microplastic particles from the body of a mollusk is species-specific, and also directly depends on the morphological structure of microplastic particles.

Effects of biological filtration by ascidians on microplastic composition in the water column

Plastic pollution, a widespread environmental challenge, significantly impacts marine ecosystems. The degradation of plastic under environmental conditions results in the generation of microplastic (MP; <5 mm) fragments, frequently ingested by marine life, including filter-feeders such as ascidians (Chordata, Ascidiacea). These organisms are integral to benthic-pelagic coupling, transporting MP from the water column through marine food web.Here, we explored the effect of filtration and digestion by the solitary ascidian Styela plicata on the composition of MP in the water column and on the sinking rates of faecal matter, focusing on differences between two distinct plastics, polystyrene (PS) and the biodegradable polylactic acid (PLA). The ascidians efficiently removed 2–5 μm particles within 2 h of filtration. Following digestion and secretion process, PS concentrations in water increased while PLA concentration remained stable. Some particles were egested into the water column repackaged inside faecal pellets, which significantly increased the pellets' drag force and sinking velocity. Raman spectral analysis of digested MP revealed distinct spectrum alterations due to coating by organic substances. These findings highlight the role of ascidians — and other filter-feeders— in modifying the structure of MP in their environment. Research into such modifications is crucial for understanding the MP cycle and its consequences in marine environments.

Links between fecal microplastics and parameters related to metabolic dysfunction-associated steatotic liver disease (MASLD) in humans: An exploratory study

Microplastics (MPs) can persist in the environment and human body. Murine studies showed that exposure to MPs could cause metabolic dysregulation, contributing metabolic dysfunction-associated steatotic liver disease (MASLD) or steatohepatitis (MASH). However, research on the role of MPs in humans is limited. Thus, we aimed to assess links between human fecal MPs and liver histology, gene expression, immune cells and intestinal microbiota (IM). We included 6 lean healthy liver donors and 6 normal liver (obese) and 11 MASH patients. Overall, pre-BSx, we observed no significant differences in fecal MPs between groups. However, fecal MP fibers and total MPs positively correlated with portal and total macrophages and total killer T cells while total fecal MPs were positively correlated with natural killer cells. Additionally, 19 genes related to immune system and apoptosis correlated with fecal MPs at baseline. Fecal MP fibers correlated positively with fecal Bifidobacterium and negatively with Lachnospiraceae. Patients with MASH (n = 11) were re-assessed 12-months post-bariatric surgery (BSx) and we found that those with persistent disease (n = 4) had higher fecal MP fragments than those with normalized liver histology (n = 7). At 12-month post-BSx, MP fragments positively correlated with helper T cells and total MPs positively correlated with natural killer T cells and B cells. Our study is the first to look at 1) the role of MPs in MASH and its association with IM, immune cells and hepatic gene expression and 2) look at the role of MPs longitudinally in MASH persistence following BSx. Future research should further explore this relationship.

P21-06 Relative toxicity study of polystyrene, polypropylene, and polyethylene microplastic fragments in the respiratory system of mice

P21-06 Relative toxicity study of polystyrene, polypropylene, and polyethylene microplastic fragments in the respiratory system of mice

Microplastics characterization, abundance and distribution on the coast of Ordu province (Türkiye)

Plastics, one of the most common materials polluting our seas, are now a serious global problem. These plastics persist in our environment for a long time and gradually turn into much smaller particles that we call microplastics (MPs). In this study, the MPs profile of sand and seawater samples taken from 6 different stations from the coasts of Ordu Province was analysed in detail. As a result of MPs and μ FTIR spectroscopic analyses, the presence of MPs in sand and seawater samples was determined and their characterisation, abundance and distribution characteristics were revealed. In this study, 291.11 items kg-1 MPs was found in sediment samples and 0.263 items L-1 MPs in water samples. A total of 420 MP fragments were detected from seawater and sand samples on the coasts of Ordu Province and analysed for colour, shape, size and species. Fibre and film type MPs fragments were found the most and it was determined that these fragments were generally blue and transparent in colour. It was observed that MPs were commonly in the size range of 0-50µm (50.71%) and the detected MPs were not larger than 800 µm. Most of the MPs observed were polyethylene (56%), followed by polypropylene (19%), polystyrene (15%), polyvinyl acetate (7%) and polytylene tereftelate (3%). In conclusion, MPs pose serious threats to human health and the environment, and it is recommended that waste generation should be reduced, necessary precautions should be taken, monitoring studies should be carried out and necessary removal methods should be applied in order to reduce the risk caused by wastes released into the seas.

Tracing the Transport and Residence Times of Atmospheric Microplastics Using Natural Radionuclides.

While atmospheric microplastics are known to be transported over long distances, their residence times and transport processes lack clarity. This study utilized natural radionuclides 7Be, 210Pb, and 210Po to explore the transport of atmospheric microplastics in Tianjin, a coastal city in Northern China. Microplastic concentrations ranged from 0.03 to 0.13 particles m-3 over the course of a year. The proportion of microplastic fragments in winter was significantly higher than that in other seasons, with median microplastic sizes in autumn and winter being larger than those in spring and summer. The atmospheric microplastic surface was rough, exhibiting irregular pores and multiple depressions and cracks. Microplastics experienced vertical mixing with the upper atmosphere in April and August and were influenced by rainfall in July. The residence time of atmospheric particles ranged from 9.47 to 22.85 days throughout the year, with an average of 14.41 days. The peak residence time of atmospheric particulates in November may be correlated with increased 210Po levels from coal consumption. Their prolonged atmospheric presence and rough surface allow microplastics to act as carriers for various chemical pollutants, underscoring the complexity and potential risks associated with their presence in the atmosphere.

Binding between Cu2+/Zn2+ and aged polyethylene and polyethylene terephthalate microplastics in swine wastewaters: Adsorption behavior, and mechanism insights

Microplastics (MPs) have aroused growing environmental concerns due to their biotoxicity and vital roles in accelerating the spread of toxic elements. Illuminating the interactions between MPs and heavy metals (HMs) is crucial for understanding the transport and fate of HM-loaded MPs in specific environmentally relevant scenarios. Herein, the adsorption of copper (Cu2+) and zinc (Zn2+) ions over polyethylene (PE) and polyethylene terephthalate (PET) particulates before and after heat persulfate oxidation (HPO) treatment was comprehensively evaluated in simulated and real swine wastewaters. The effects of intrinsic properties (i.e., degree of weathering, size, type) of MPs and environmental factors (i.e., pH, ionic strength, and co-occurring species) on adsorption were investigated thoroughly. It was observed that HPO treatment expedites the fragmentation of pristine MPs, and renders MPs with a variety of oxygen-rich functional groups, which are likely to act as new active sites for binding both HMs. The adsorption of both HMs is pH- and ionic strength-dependent at a pH of 4–6. Co-occurring species such as humic acid (HA) and tetracycline (TC) appear to enhance the affinity of both aged MPs for Cu2+ and Zn2+ ions via bridging complexation. However, co-occurring nutrient species (e.g., phosphate and ammonia) demonstrate different impacts on the adsorption, improving uptake of Cu2+ by precipitation while lowering affinity for Zn2+ owing to the formation of soluble zinc-ammonia complex. Spectroscopic analysis indicates that the dominant adsorption mechanism mainly involves electrostatic interactions and surface complexation. These findings provided fundamental insights into the interactions between aged MPs and HMs in swine wastewaters and might be extended to other nutrient-rich wastewaters.

The Extraction and Characterization of Microplastics of Biocompost and Water Samples Collected from the Different Semi-Urban Agronurseries

ABSTRACT Biocomposting at national and regional levels has recently been recognized as one of the feasible, nature-based solutions to prevent the accumulation and reuse of biodegradable waste in enhanced and effective mitigation measures for urban and semi-urban waste management. Recent research has mainly focused on organic compost contamination, as the negative effects of MP on soil systems have been extensively studied. According to current research, organic compost used as fertilizer on farmland contains many microplastics. In this context, microplastics (MPs) have been regarded as a global environmental problem and an emerging soil contaminant. The physico-chemical properties of water and compost samples were analyzed by APHA and AOAC methods. The extraction of microplastics was done using the density separation. In the current study, agricultural waste-based biocompost and water samples used for the production of biocompost were collected from four different agricultural nurseries in semi-urban areas of the Coimbatore city. The physicochemical properties (including heavy metal content) of the biocompost and water samples tested were on par/equal/lower than Indian standards. Interestingly, in the biocompost samples, 85% of the microplastic fragments and 15% of the fiber types were identified only in BC-B and BC-C, respectively, with different colors such as red, brown, blue, light yellow and transparency. However, no microplastics were found in the biocompost samples of BC-A and BC-D. Microplastic polymers such as polymethyl methacrylate (PMMA), polypropylene (PP), and ethylene vinyl acetate (EVA) were identified through ATR-FTIR analysis. The results suggest that semi-urban agricultural gardening may lead to the accumulation of microplastics in terrestrial environments, which may negatively impact soil and plant health. This study contributes to growing research into microplastic contamination in organic compost and its potential impact on agriculture and terrestrial ecosystems.

Tracing microplastic pollution in Mahi River estuary, Gulf of Khambhat, Gujarat, and their influence on functional traits of macrobenthos.

Most maritime habitats contain microplastic (MPs) contamination. The quality of the benthic ecosystem's habitat is declining as MPs accumulate in marine system. The contamination of MPs must therefore be investigated. We studied MPs pollution in the Mahi River, estuary, and macrobenthos. In the present study, the abundance of MPs fragments gradually decreased from the high tide zone to the low tide zone and muddy sediment has high MPsconcentrations due to sediment characteristics and particle size. The majority of sediment and biota MPs were fibrous and black. MPs in both silt and biota have identical chemical compositions (modified cellulose), shapes, and colors. A significant source of pollutants and MPs fluxing into the ocean is well within the river system. Perinereis aibuhitensis ingested the most MPs out of 11 species, whereas Amphipods did not show any presence of MPs. Our findings showed that functional characteristics are essential for macrobenthos MPs intake. MPs in macrobenthos are high due to biological functions such as feeding, ecological groups, feeding mechanisms, body size, and bioturbation. MPs in marine sediment and organisms aretracked down to the Mahi River exceeding 50km. The present work has investigated the idea that the macrobenthos that live in the sediment are ingesting the MPs that are building up there and this ingestion relies on the macrobenthos' functional characteristics.

Ecological assessment of microplastic contamination in surface water and commercially important edible fishes off Kadalundi estuary, Southwest coast of India.

This study focuses on the Kadalundi estuary, Kerala's first community reserve, investigating the prevalence and impacts of microplastics on both the estuarine environment and selected fish species. This study presents the initial evidence indicating the consumption of microplastic particles by 12 commercially important edible fish species inhabiting the Kadalundi estuary. Analysis revealed significant accumulations of microplastic fibers within the surface water. In examining 12 fish species from demersal and pelagic habitats, microplastics were found in both the gastrointestinal tracts and gills. In the digestive tracts, microplastic fragments constituted the highest proportion (46%), while in the gills, microplastic fibers were dominant (52.4%). This study observed a prevalence of blue microplastics over other colors in both water and fish samples. Notably, demersal species showed a higher incidence of ingested microplastics. Polymer analysis identified Polypropylene (PP), Nylon, Low-Density Polyethylene (LDPE), Polyethylene (PE), Polypropylene isotactic (iPP), PE 1 Octene copolymer, and Rayon in water samples, while fish samples predominantly contained LDPE, PP, PE, and Nylon. Risk assessment utilizing the Polymer Hazard Index (PHI) categorized certain polymers as posing minor to moderate risks. Pollution Load Index (PLI) computations indicated moderate to high levels of microplastic contamination across various sampling sites in the estuary. Principal Component Analysis (PCA) revealed a lack of correlation between fish size and microplastic ingestion, underscoring environmental factors' influence on microplastic intake. The study emphasizes the implications of microplastic pollution on the fragile ecosystem of the Kadalundi estuary, posing potential risks to biodiversity and human health.

Combined effects of polyethylene terephthalate and abamectin on enzymatic activity and histopathology response in juvenile zebrafish (Danio rerio).

One of the most pressing global environmental issues is the widespread abundance and distribution of microplastics (MPs). MPs can act as vectors for other contaminants in the environment making these small plastic particles hazardous for ecosystems. The presence of MPs in aquatic environments may pose threats to aquatic organisms that ingest them. This study examined effects of abamectin (ABM) and polyethylene terephthalate (PET) MP fragments on histopathological and enzymatic biomarkers in zebrafish (Danio rerio). Zebrafish were exposed for 96 h to pristine PET-MPs at concentrations of 5 mg/L and 10 mg/L, ABM alone at 0.006 mg/L, and the same concentration of ABM in the presence of PET-MPs in aquaria. Histopathological analysis revealed tissue content changes in liver and kidney in the presence of ABM individually and in combination with MPs. Results of enzymatic analysis showed that MPs increased the bioavailability and toxicity of pesticides due to inhibition of catalase (CAT) and acid phosphatase (ACP) enzymes. However, MPs did not affect the toxicity of ABM for glutathione s-transferase (GST) enzyme. Despite the inhibition of acetylcholinesterase (AChE) in MPs or ABM treatments, and some neurotoxicity, no change in activity of this enzyme and neurotoxicity was observed in the combined MPs and ABM treatments, although toxicity effects of MPs and ABM on zebrafish require more detailed studies.

Navigating a Microplastic Sea: How the Pacific Cupped Oyster (Magallana gigas) Respond to Microplastic Pollution in Lagoons.

Microplastic pollution poses an escalating concern, particularly in coastal lagoons rich in biodiversity. This study delved into the occurrence of microplastics (MPs) in Magallana gigas (formerly Crassostrea gigas) from the Orbetello and Varano coastal lagoons (Italy), also investigating the response of these filter-feeding organisms to various colors (P = pink; B = blue; W = white) of high-density polyethylene (HDPE) MP fragments. Oysters were exposed for 7 days under controlled conditions. Subsequently, the oysters underwent analysis for both MP presence and biochemical markers of oxidative stress. Diverse ingestion rates of HDPE were noted among oysters from the two lagoons, eliciting antioxidant responses and modifying baseline activity. The two-way ANOVA revealed the significant effects of treatment (control; HDPE_B; HDPE_P; HDPE_W), site, and the interaction between treatment and site on all biomarkers. Non-metric multidimensional scaling showed a divergent effect of HDPE color on biomarkers. Further investigation is warranted to elucidate the mechanisms underlying the influence of MP color, dose-dependent effects, and the long-term impacts of exposure. Comprehending these intricacies is imperative for devising effective strategies to mitigate plastic pollution and safeguard marine health.

Microplastic pollution characteristics and ecological risk assessment in the Wuding River Basin, China

Microplastics (MPs), as a new type of environmental pollutant, have attracted extensive attention in recent years. However, there has been relatively little research specifically focusing on MPs in the Yellow River Basin, China, particularly regarding MP migration patterns. Based on surface water and sediment samples from 19 sampling sites in the Wuding River (WDR), the abundances and characteristic distributions of MPs were analyzed, and the environmental factors affecting their distribution and potential ecological risks were evaluated. The results showed that the MP abundances in surface water and sediments of the WDR were significantly different (P < 0.05), with mean values of 2.98 ± 0.69 items/L and 419.47 ± 75.61 items/kg, respectively. In terms of MP characteristics, the most common size class was 0.1–0.5 mm in surface water. Polyethylene (PE, 32.50%) and polypropylene (PP, 27.50%) were the main polymer types of MPs in surface water. Although similar MP characteristics were observed in sediments, there were significantly more particles in the <0.1 mm particle size (P < 0.05), which was 15.0% higher than in surface water. Also, more high-density MP fragments were observed in sediment samples. The retention of MPs in sediments was influenced by the MP characteristics (density, shape, particle size) and sediment particle size. In contrast, the MP abundance in surface water was more closely related to the presence of other environmental pollutants, such as total phosphorus (WTP) and ammonia nitrogen (WAN). Temperature (T), agricultural land (AGR), and residential land (RES) only had significant effects on the distribution of MPs in surface water (P < 0.05). Potential ecological risk assessments revealed that MP pollution in sediments was more serious than in surface water, especially in the middle and lower reaches. The results of this study are important for understanding MP transport in a sandy river and for eliminating potential sources of MPs.

Sewage Derived Microplastic and Anthropogenic Fibre Retention by Integrated Constructed Wetlands

High loads of microplastics and anthropogenic fibres can be discharged from wastewater treatment plants (WWTPs) into surface water bodies. Integrated Constructed Wetlands (ICWs) are potentially well suited to provide a cost-effective mitigation solution at small WWTPs where conventional treatment is prohibitively expensive. This study aimed to assess the microplastic and anthropogenic fibre retention efficiency of two ICWs (Northrepps and Ingoldisthorpe) in Norfolk (UK) over a 12-month period (2022–2023). Analysing a total of 54 water and 23 sediment samples, the findings revealed that Northrepps ICW received on average 349,920 (± 763,776) anthropogenic fibres day−1, with a retention rate of 99.3%. No seasonal variation was observed in retention efficiency. Ingoldisthorpe ICW intermittently received anthropogenic fibres in low concentrations, with an average of 9504 (± 19,872) day−1 and a retention rate of 100%. Microplastics and anthropogenic fibres were prevalent in sediment samples of the first cell of Northrepps ICW, averaging 10,090 items kg−1 dry sediment, while none were found at concentrations above the limit of detection in the second or third cell. Of the 369 fibres analysed by ATR-FTIR, 55% were plastic (dominated by polyester). Of the 140 suspected microplastic fragments analysed by ATR-FTIR, 73% were confidently identified as plastic (mostly polystyrene, polyethylene, or polypropylene). This study demonstrates how ICWs can effectively retain sewage effluent derived microplastics and anthropogenic fibres. However, the accumulation of plastic waste in ICWs may complicate long term management and their cost-effectiveness.

Can Hediste diversicolor Speed Up the Breakdown of Cigarette Butts in Marine Sediments?

Cigarette butts (CBs) are non-biodegradable harmful residues of synthetic origin and are widespread in marine environments around the world. Although environmental factors are often primarily responsible for the fragmentation of microplastics in the marine environment, biotic factors have recently been shown to be equally important in plastic debris. This study evaluates the role of the Hediste diversicolor polychaete in the fragmentation of CBs in the marine environment. Polychaetes were exposed to three concentrations of CB (0 (as the control), 0.25, and 1 butt L−1) at two different temperatures (15 °C and 23 °C) for 28 days. At each temperature, aquaria without polychaetes were used to study the effect of the burrowing activity of the polychaete on CB fragmentation. Toxicants analysed from exposed sediments increased their concentration in a dose-dependent manner to the CB concentration at a temperature of 15 °C but not at 23 °C. CBs did not directly decrease Hediste survival, but prolonged elevated temperatures increased the polychaetes’ susceptibility. The negative effects of CBs on burial success and burrowing behaviour could not be offset by the reduced start time caused by elevated temperatures. Regardless of temperature, both the weight loss and physical fragmentation of CBs buried in polychaete-contaminated sediments were significantly higher than those without Hediste, with no differences between the two concentrations tested. FTIR-ATR analysis used to evaluate CB degradation in relation to cellulose acetate decomposition showed a greater degradation of this compound in treatments with Hediste than in those without polychaetes (~2.75 times), but these differences were not significant. This study is a promising initial step for future research, as any factor that facilitates the fragmentation of this prevalent and hazardous waste must be carefully studied to extract the maximum benefit to help to reduce CBs in the marine environment.

Trophic transfer, bioaccumulation and translocation of microplastics in an international listed wetland on the Montreux record

Microplastics (MPs) are concerning emerging pollutants. Here, MPs in four edible aquatic species of different trophic levels (between ∼2 and 4), including fish species Esox lucius (Esocidae: Esocinae); Cyprinus carpio (Cyprinidae: Cyprininae); and Luciobarbus caspius (Cyprinidae: Barbinae); and the swan mussel Anodonta cygnea (Unionidae), were assessed in the Anzali freshwater ecosystem. It is a listed wetland in the Montreux record. MPs were extracted from gastrointestinal tracts (GI), gills, muscles, and skin. All the studied fish and mussels (n = 33) had MPs. MP fibres, fragments and sheets were detected in every GI examined, however, fibres were the only type of MPs in skins, muscles and gills and were the most abundant MP. The MPs found in the fish and mussels were mainly made of nylon (35% of the total MPs), polypropylene-low density polyethylene (30%), and polycarbonate (25%). The average numbers of MPs found in every fish specimen, expressed per wet body mass, had a moderate negative correlation with the condition factor (K) (MP/g - K: Pearson correlation r = −0.413, p = 0.049), and there was no significant relation with the growth factor (b) (r = −0.376; p = 0.068). Importantly, Luciobarbus caspius (with trophic level 2.7–2.8) bioaccumulated MPs and presented a strong correlation between their MP contamination and age (r = 0.916 p < 0.05). Greater gill mass (or related factors) played an important role in the accumulation of MPs, and there was a strong correlation between these factors for Esox lucius and Cyprinus carpio (r = 0.876; r = 0.846; p < 0.05 respectively). The highest MP/g gills (1.91 ± 2.65) were in the filter feeder Anodonta cygnea inhabiting the benthic zone. Esox lucius (piscivorous, trophic level 4.1) was the most contaminated species overall (a total of 83 MPs in 8 individuals, with 0.92 MP/g fish), and their gills where MPs mainly accumulated. Cyprinus carpio was the most contaminated specimen (MPs in specimens), while the number of MPs per mass unit increased with the trophic level. Their feeding and ecological behavior in the aquatic habitat affected the level of accumulation. This work includes evidence of translocation of MPs within the aquatic organisms.

Coastal plastic pollution: A global perspective

Coastal ecosystems have ecological importance worldwide and require control and prevention measures to mitigate human pollution. The objective of this study was to perform a systematic review to provide a comprehensive overview of the global issue of coastal plastic pollution. 689 articles were eligible for qualitative synthesis and 31 were considered for quantitative analysis. There was an exponential increase in articles addressing coastal plastic pollution over the past 50 years. Studies were mainly carried out on beaches, and plastic bottles were the most found item, followed by cigarette butts. Polyethylene was the predominant plastic polymer, and white microplastic fragments stood out. China published most articles on the topic and Brazil had the highest number of sites sampled. Meta-analysis had significant effect sizes based on the reported data. These findings carry significant implications for environmental policies, waste management practices, and targeted awareness campaigns aimed at mitigating plastic pollution.

Do Added Microplastics, Native Soil Properties, and Prevailing Climatic Conditions Have Consequences for Carbon and Nitrogen Contents in Soil? A Global Data Synthesis of Pot and Greenhouse Studies.

Microplastics threaten soil ecosystems, strongly influencing carbon (C) and nitrogen (N) contents. Interactions between microplastic properties and climatic and edaphic factors are poorly understood. We conducted a meta-analysis to assess the interactive effects of microplastic properties (type, shape, size, and content), native soil properties (texture, pH, and dissolved organic carbon (DOC)) and climatic factors (precipitation and temperature) on C and N contents in soil. We found that low-density polyethylene reduced total nitrogen (TN) content, whereas biodegradable polylactic acid led to a decrease in soil organic carbon (SOC). Microplastic fragments especially depleted TN, reducing aggregate stability, increasing N-mineralization and leaching, and consequently increasing the soil C/N ratio. Microplastic size affected outcomes; those <200 μm reduced both TN and SOC contents. Mineralization-induced nutrient losses were greatest at microplastic contents between 1 and 2.5% of soil weight. Sandy soils suffered the highest microplastic contamination-induced nutrient depletion. Alkaline soils showed the greatest SOC depletion, suggesting high SOC degradability. In low-DOC soils, microplastic contamination caused 2-fold greater TN depletion than in soils with high DOC. Sites with high precipitation and temperature had greatest decrease in TN and SOC contents. In conclusion, there are complex interactions determining microplastic impacts on soil health. Microplastic contamination always risks soil C and N depletion, but the severity depends on microplastic characteristics, native soil properties, and climatic conditions, with potential exacerbation by greenhouse emission-induced climate change.

Experimental investigation of the fallout dynamics of microplastic fragments in wind tunnel: The BURNIA agenda

We present a methodology and the first tests to estimate the settling velocity of airborne microplastics based on wind tunnel experiments. A novel approach and original perspective are proposed, discussing in detail challenges and faced problems, both on the theoretical and experimental sides. Several experiments were performed, releasing fragments of different microplastic types, PET, PVC and LPDE. A statistical analysis was applied to the measurements and the values of the settling velocities were estimated to range between 0.1 and 0.2 ms−1, in agreement with most values found in the related literature. Based on the observed velocities, the applicability of the Stokes’ law, which is often used also for airborne microplastics, is then addressed, highlighting its potential limitations in the context of the microplastic dynamics in the atmosphere. We confirm that using the Stokes’ law may lead to a substantial overestimation of the settling velocity for the airborne microplastics. We also recommend to consider moving to the concept of ‘effective deposition velocity’, to account for the turbulent processes characterising the real atmosphere.