Contamination of plastic particles in environmental and biological systems raises concerns regarding their potential negative impacts. Human exposure to microplastics (MPs) and nanoplastics (NPs) is increasing; however, some potential adverse health effects might remain unclear, due to analytical challenges in detecting trace concentrations. To address this, we propose a workflow for NPs assessment in biological samples combining three complimentary methods, namely inductively coupled plasma mass spectrometry (ICP-MS), X-ray fluorescence imaging (XFI), and imaging mass cytometry (IMC) to detect palladium-doped NPs (Pd-NPs). This approach was used to quantify the temporal distribution and accumulation of Pd-NPs in mouse models under different experimental conditions, dosages, and time frames. Acute exposure showed a clear particle excretion from the gastrointestinal tract into feces, while subchronic exposure led to tissue accumulation. This workflow enhances our ability to analyze and study NP uptake and biodistribution mechanisms down to the nanoscale in complex biological samples.

When microplastics (MPs) enter water bodies, they undergo various transport processes, including sedimentation, which can be influenced by factors such as particle size, density, and interactions with other particles. Surface waters contain suspended natural particles (e.g., clay and silt), which may impact MP settling rates. Here, we investigated how the presence of suspended sediments (SS) influenced the deposition patterns and rates of MPs in turbid waters. We systematically analyzed the settling velocities of particles, including different MP sizes and SS concentrations, in a plexiglass column with a camera array. For each experimental variant, we collected data on thousands of individual MPs, strengthening the statistical analysis of the particles' velocities. Simultaneous measurements of the SS flow and MPs trajectories revealed that the SS induced complex flow patterns, with MPs spending more time in downwelling flow regions, thereby accelerating MPs sedimentation. This effect was more pronounced when SS were aggregated. Additionally, we found that smaller MP fragments were more affected by the fluctuations than spheres or larger fragments. Collectively, our results provide valuable data for future MP fate models and help to understand the sedimentation processes of MPs in natural waters, which is crucial for assessing their environmental transport and impact.

Plastics used in agriculture improve productivity and resource efficiency. As they fragment over time, microplastics are unintentionally released into soil, raising concerns regarding long-term implications for soil structure and fertility. Here we investigated microplastics transport and their impact on soil structure through a two-year field experiment. 45 re-packed soil columns were installed with three treatments: indium-doped polyethylene terephthalate fragments or fibers in the top 2 cm and a control with no microplastics. Soil pore structure was monitored with X-ray tomography, and microplastics vertical transport was assessed via the indium tracer. With time macropore volume, biopore fraction and critical pore diameter increased independent of microplastic addition. Microplastic transport was minimal, with only ~1% reaching below 8 cm soil depth in two years. This experimental design, simulating natural soil conditions, suggests that microplastics have a negligible influence on soil macropore architecture and its transport rate is limited in the short term.

The proportion of ice crystals in clouds can affect cloud albedo and lifetime, impacting the Earth's radiative budget. Ice nucleating particles (INPs) lower the energy barrier of ice nucleation and thus facilitate primary ice formation in the atmosphere. Atmospheric nanoplastics (NPs) have been detected in remote regions far from emission sources, suggesting that they can become airborne and undergo long-range transport in the atmosphere. During the atmospheric residence of NPs, they could catalyse primary ice crystal formation by acting as INPs. In this study, we present results from laboratory experiments in which model NPs composed of polystyrene and polyacrylonitrile were tested for their ice-nucleating ability using the horizontal ice nucleation chamber (HINC) as a function of ice-nucleation temperature and water saturation ratio. The results showed that NPs can be effective INPs under both cirrus and cold mixed-phase cloud conditions. The surface characteristics and wettability of the NPs were analysed via scanning electron images and dynamic vapour sorption measurements, which revealed the freezing mechanism as a combination of deposition nucleation and pore condensation and freezing. The results highlight the need to enumerate and characterise NPs in the atmosphere, given their potential to get scavenged by clouds via primary ice formation in clouds.

Standardized methods are essential for generating reliable and reproducible data to support risk assessment and decision-making related to soil contamination by environmental pollutants, including nanoplastics (NPs). This study evaluated the ability of the RHIZOtest method, a standardized soil-plant exposure system, in providing a high-throughput testing platform for investigating NP phytoavailability. As a proof of concept, tomato plants were exposed to artificial soil spiked with model NPs at concentrations of 400 and 4000 mg kg-1 dm. Palladium (Pd)-doped polystyrene particles (PS-P) (a Z-average diameter of 210 nm, a surface charge zeta potential of -45.20 ± 032 mV, a polydispersity index of 0.1, and a Pd doping ratio of 0.295% w/w Pd to PS-P) were used as surrogates for NPs. Pd content was measured as a proxy for quantifying PS-P uptake. After eight days of exposure, Pd was detected in both the roots and shoots of plants grown on both spiked soils, confirming PS-P uptake and translocation. On average, 5 ± 1% of the spiked PS-P were taken up by the plants across spiking levels. Root concentration factors varied slightly between the lower and higher levels (31 ± 2% and 24 ± 3%, respectively), while translocation factors remained similar (∼25%). Root biomass was significantly reduced compared to controls, suggesting possible concentration-dependent PS-P rhizotoxicity. Notably, the limited variability in concentration values measured in roots (±11%) and shoots (±23%), along with near-complete mass balance recovery (97-100%), demonstrated the reliability of the RHIZOtest in accurately and consistently quantifying NP uptake while accounting for rhizosphere processes.

Plastic pollution in marine environments poses ecological risks, in part because plastic debris can release hazardous substances, such as metal-based additives. While microplastics have received considerable attention as vectors of contaminants, less is known about larger macroplastics and their role in the spatial and temporal redistribution of substances. In this study, pristine, store-bought plastic items and macroplastics recovered from the North Pacific Subtropical Gyre (NPSG) were analysed using Fourier-Transform Infrared Spectroscopy (FTIR) to identify polymer types, and bulk acid digestion followed by Inductively Coupled Plasma Mass Spectrometry (ICP-MS) for total metal quantification. These techniques were complemented by high resolution elemental mapping by Laser Ablation Inductively Coupled Plasma Time-of-Flight Mass Spectrometry (LA-ICP-TOFMS). Detailed elemental maps revealed native metal distribution in pristine plastics, and evidence of both sorption and intrinsic metal depletion in weathered plastics. In particular, weathered plastics showed surface depletion of intrinsic metals, and enrichment of seawater-derived elements (e.g., Na, Mg, I). Linear regressions were used to quantify spatial distribution trends across cross sections, providing statistical support for directional gradients. Since pristine and weathered plastics were opportunistically collected, variability in product type, polymer chemistry, and weathering time limited direct comparisons. Instead, this study demonstrates the utility of LA-ICP-TOFMS for mapping elemental distribution in plastics, offering a novel analytical approach for investigating spatial metal distribution in plastics and laying the groundwork for future studies on weathering processes in marine environments.

Plastic pollution is found in polar sea ice with concentrations of microplastics (MPs, 1 mu m-5 mm) 2 to 4 orders of magnitude higher than in the underlying seawater. Such accumulation is often attributed to the scavenging of MPs by rising frazil ice crystals, but there is no direct evidence of such a process. Furthermore, nanoplastics (NPs, 1 nm-1 mu m) are suspected to be present, but their fate is unknown due to the lack of field measurements. Here micro- and nanoplastics' (MNPs) enrichment by frazil ice was quantified using model particles and an experimental setup which generated realistic frazil ice. Particle size had a significant impact on behavior: on one hand, high-density MPs concentrations were 2.97 +/- 1.13 times higher in the ice than in the underlying water, which is consistent with field observations. On the other hand, NPs were depleted to the same extent as sea salts, by a factor of 0.32 +/- 0.13. Like salts, NPs may be locally enriched in the brine channels and pockets of sea ice where microalgae thrive. Overall, this work shows that frazil ice plays an important role in the cycling of MNPs, as it can concentrate MPs in sea ice and concentrate NPs locally in brine channels and pockets.

Sea ice accumulates contaminants and redistributes them laterally as the ice drifts and vertically as it melts. Contaminant incorporation into sea ice must be better understood to resolve contaminant cycling and exposure to polar organisms. Here we develop an experimental method that mimics the formation of young sea ice and enables the quantification of model contaminants separately in the ice matrix and brine. Several limitations inherent in field studies are overcome using this approach. Results show that dissolved contaminants (<1 nm) and dispersed colloidal contaminants (1 nm-1 μm) follow the same behavior as sea salts. When colloids aggregate they follow a similar transport pathway to high-density particulate contaminants (>1 μm). While high-density particles are depleted in sea ice and low-density particles are enriched relative to their initial concentration in seawater, both are engulfed and can travel in wide brine channels. These results can also help to predict the incorporation of natural species in sea ice.

Microplastic (MP) contamination of agricultural soils is a growing concern. Synthetic textiles shed MP fibres throughout their lifecycle, which can end up in agricultural soils through the application of urban by-products as soil amendment. MP fibres can affect soil structure and have potentially adverse effects on soil organisms in high concentrations. Polyesters, such as polyethylene terephthalate (PET), are highly resistant to biodegradation and thus very persistent in soils. Understanding the fate and transport behaviour of MP fibres in soils is therefore essential for estimating long-term exposure levels and the potential effects of MP fibres on soil health. Fibres are considered less mobile in soil porewater compared to other particle shapes, but earthworms potentially displace or ingest and excrete fibres, even those within the millimetre size range. Hence, MP fibres may be prone to biologically driven transport despite their relatively large length.We therefore investigated whether earthworm burrowing causes vertical transport of relatively large MP fibres in soil. We measured the redistribution of MP fibres in laboratory-based process-studies introducing anecic earthworms (Lumbricus terrestris) to soil columns (30 cm depth) spiked with PET MP fibres of 1.3±0.7 mm length. The MP fibres were spiked to an upper surface layer of soil and doped with a metal tracer to facilitate detection with inductively-coupled plasma mass-spectrometry after acid extraction. MP fibre transport was monitored over a total of 4 weeks in different depth segments of the soil columns. We further analyzed the size distribution of MP fibres for the different depths using a visual microscope. At the end of the experiment, MP fibres were detectable in all depth segments, highlighting the transport potential of MP fibres by larger earthworms, such as L. terrestris. We also observed that the depth-dependent decline for MP fibres was stronger in comparison to previous studies with smaller particles proposedly because these are ingested more easily. Accordingly, we expect a relative enrichment of smaller MP fibres in the deeper soil layers. We conclude that biologically driven transport may overall be influenced, but less dependent, on particle length than other transport processes such as advective transport in soil pores. In the field, MP fibres will be exposed to bioturbation processes for much longer times than in this current study, likely resulting in a successive downward transport of even larger fibres depending on the local soil conditions and earthworm activity.

Black soldier fly (Hermetia illucens L.) larvae (BSFL) are promising recycling agents of food waste nutrients. However, BSFL ingest micro- and nanoplastics (MNPs) present in food waste, consequently introducing them into the food chain when BSFL-derived products are used as feeds or fertilizers. Our short-term exposure study (180 min ingestion, 1080 min egestion) deepens the understanding of particle transport during bioconversion by BSFL by determining how the size of nanoplastics (NPs, 220 nm) and microplastics (MPs, 10-20 and 53-63 µm) and food waste moisture content (65 % vs. 75 %) affect particle uptake, progression, and egestion across the different morphofunctional digestive tract regions of BSFL. Results demonstrate distinct differences in gut retention time among MNPs. NPs were taken up and transported more rapidly than larger MPs. Indigestible MPs (10-20 µm) exhibited different residence times than soluble blue dye, suggesting distinct particle residence times or discrimination between food and plastics within the BSFL digestive tract. In the short-term experiment, particle egestion was slower than ingestion. Higher moisture content increased the retention time of food waste, suggesting the need for further investigation into whether this can be used to manipulate the clearance of MNPs. The study findings contribute to safer bioconversion processes during circular food waste management.

The interactions of environmental DNA (eDNA) with microplastics (MPs) in aquatic ecosystems are influenced by water chemistry and the surface properties of plastics, impacting the fate of genetic material. While MPs' fate and transport have been studied extensively, the adsorption of eDNA onto polymer surfaces and its persistence remain less understood. Here, we systematically studied eDNA adsorption onto poly(ethylene terephthalate) (PET), polyethylene (PE), and silica (Si) surfaces, where the latter material was used as a proxy for comparison to natural particles. Using quartz-crystal microbalance with dissipation monitoring (QCM-D), the impact of varying ionic conditions that mimic freshwater and seawater environments was analyzed for adsorption rate and extent. The role of cations, particularly divalent ions such as Ca2+, in promoting eDNA adsorption through cation bridging was particularly important. PET exhibited the highest adsorption rates, followed by those of PE and Si. Adsorption of eDNA in seawater led to thicker and more rigid adlayers compared with freshwater conditions. However, eDNA adlayers were susceptible to enzymatic degradation and replacement by DNase in both freshwater and seawater, suggesting limited protection from decay. Consequently, the longevity and potential for transfer of material over time and distance are brought into question. This study provides insights into the adsorption mechanisms and stability of eDNA on MPs, advancing our understanding of how MPs influence the transport and persistence of genetic material, including antibiotic-resistant genes, in aquatic environments.

Adsorption of biomacromolecules onto polymer surfaces, including microplastics (MPs), occurs in multiple environmental compartments, forming an ecocorona. Environmental DNA (eDNA), genetic material shed from organisms, can adsorb onto MPs which can potentially either (1) promote long-range transport of antibiotic resistant genes or (2) serve to gain insights into the transport pathways and origins of MPs by analyzing DNA sequences on MPs. However, little is known about the capacity of MPs to adsorb eDNA or the factors that influence sorption, such as polymer and water chemistries. Here we investigated the adsorption of extracellular linear DNA onto a variety of model MP fragments composed of three of the most environmentally prevalent polymers (polyethylene, polyethylene terephthalate, and polystyrene) in their pristine and photochemically weathered states. Batch adsorption experiments in a variety of water chemistries were complemented with nonlinear modeling to quantify the rate and extent of eDNA sorption. Ionic strength was shown to strongly impact DNA adsorption by reducing or inhibiting electrostatic repulsion. Polyethylene terephthalate exhibited the highest adsorption capacity when normalizing for MP specific surface area, likely due to the presence of ester groups. Kinetics experiments showed fast adsorption (majority adsorbed under 30 min) before eventually reaching equilibrium after 1-2 h. Overall, we demonstrated that DNA quickly binds to MPs, with pseudo-first- and -second-order models describing adsorption kinetics and the Freundlich model describing adsorption isotherms most accurately. These insights into DNA sorption onto MPs show that there is potential for MPs to act as vectors for genetic material of interest, especially considering that particle-bound DNA typically persists longer in the environment than dissolved DNA.

AbstractPredicting the response of aquatic species to environmental contaminants is challenging, in part because of the diverse biological traits within communities that influence their uptake and transfer of contaminants. Nanoplastics are a contaminant of growing concern, and previous research has documented their uptake and transfer in aquatic food webs. Employing an established method of nanoplastic tracking using metal-doped plastics, we studied the influence of biological traits on the uptake of nanoplastic from water and diet in freshwater predators through two exposure assays. We focused on backswimmers (Anisops wakefieldi) and damselfly larvae (Xanthocnemis zealandica) - two freshwater macroinvertebrates with contrasting physiological and morphological traits related to feeding and respiration strategies. Our findings reveal striking differences in nanoplastic transfer dynamics: damselfly larvae accumulated nanoplastics from water and diet and then efficiently eliminated 92% of nanoplastic after five days of depuration. In contrast, backswimmers did not accumulate nanoplastic from either source. Differences in nanoplastic transfer dynamics may be explained by the contrasting physiological and morphological traits of these organisms. Overall, our results highlight the importance and potential of considering biological traits in predicting transfer of nanoplastics through aquatic food webs.

Understanding the impacts of microplastics (MPs) on aqueous environments requires understanding their transport dynamics and how their presence affects other natural processes and cycles. In this context, one aspect to consider is how MPs interact with freshwater snow (FWS), a mixture of algae and natural particles. FWS is one of the primary drivers of the flux of organic matter from the water surface to the bottom sediment, where zooplankton, diurnal migration, fish faecal pellets settling and turbulent mixing can also play prominent roles. Understanding how MPs and FWS heteroaggregation affects their respective settling velocities is important to assess not only MPs fate and transport but also their ecological impacts by altering FWS deposition and thereby nutrient cycling. In this present study, we obtained a mechanistic understanding of the processes controlling MPs settling dynamics and heteroaggregation with FWS and the subsequent impacts on the settling rates of both MPs and ballasted FWS. Here we used a plexiglass column equipped with a stereoscopic camera system to track the settling velocities of (1) MPs of various compositions, densities and morphologies, (2) FWS flocs and (3) MP-FWS agglomerates. For each experimental set, thousands of particles were tracked over a series of image sequences. We found that agglomerates with high-density MPs settled at least twofold faster than FWS alone, implying a much smaller residence time in the water column, except for cases with MP fibres or low-density plastics. These findings will help to refine MP fate models and, while contingent on MPs number, may impact biogeochemical cycles by changing the flux of nutrients contained in FWS to the sediment.

To ensure the safe use of materials, one must assess the identity and quantity of exposure. Solid materials, such as plastics, metals, coatings and cements, degrade to some extent during their life cycle, and releases can occur during manufacturing, use and end-of-life. Releases (e.g., what is released, how does release happen, and how much material is released) depend on the composition and internal (nano)structures of the material as well as the applied stresses during the lifecycle. We consider, in some depth, releases from mechanical, weathering and thermal stresses and specifically address the use cases of fused-filament 3D printing, dermal contact, food contact and textile washing. Solid materials can release embedded nanomaterials, composite fragments, or micro- and nanoplastics, as well as volatile organics, ions and dissolved organics. The identity of the release is often a heterogenous mixture and requires adapted strategies for sampling and analysis, with suitable quality control measures. Control materials enhance robustness by enabling comparative testing, but reference materials are not always available as yet. The quantity of releases is typically described by time-dependent rates that are modulated by the nature and intensity of the applied stress, the chemical identity of the polymer or other solid matrix, and the chemical identity and compatibility of embedded engineered nanomaterials (ENMs) or other additives. Standardization of methods and the documentation of metadata, including all the above descriptors of the tested material, applied stresses, sampling and analytics, are identified as important needs to advance the field and to generate robust, comparable assessments. In this regard, there are strong methodological synergies between the study of all solid materials, including the study of micro- and nanoplastics. From an outlook perspective, we review the hazard of the released entities, and show how this informs risk assessment. We also address the transfer of methods to related issues such as tyre wear, advanced materials and advanced manufacturing, biodegradable polymers, and non-solid matrices. As the consideration of released entities will become more routine in industry via lifecycle assessment in Safe-and-Sustainable-by-Design practices, release assessments will require careful design of the study with quality controls, the use of agreed-on test materials and standardized methods where these exist and the adoption of clearly defined data reporting practices that enable data reuse, meta-analyses, and comparative studies.

The increasing exposure to nanoplastics (NPs) raises significant concerns for human health, primarily due to their potential bioaccumulative properties. While NPs have recently been detected in human blood, their interactions with specific immune cell subtypes and their impact on immune regulation remain unclear. In this proof-of-concept study, model palladium-doped polystyrene NPs (PS-Pd NPs) are utilized to enable single-cell mass cytometry (CyTOF) detection. The size-dependent impact of carboxylate polystyrene NPs (50-200 nm) is investigated across 15 primary immune cell subpopulations using CyTOF. By taking advantage of Pd-doping for detecting PS-Pd NPs, this work evaluates their impact on human immune-cells at the single-cell level following blood exposure. This work traces PS-Pd NPs in 37 primary immune-cell subpopulations from human blood, quantifying the palladium atom count per cell by CyTOF while simultaneously assessing the impact of PS-Pd NPs on cell viability, functionality, and uptake. These results demonstrate that NPs can interact with, interfere with, and translocate into several immune cell subpopulations after exposure. In vivo distribution experiments in mice further confirmed their accumulation in immune cells within the liver, blood, and spleen, particularly in monocytes, macrophages, and dendritic cells. These findings provide valuable insights into the impact of NPs on human health.

Anthropogenic contaminants can place significant stress on vegetation, especially when they are taken up into plants. Plastic pollution, including nanoplastics (NPs), could be detrimental to tree functioning, by causing, for example, oxidative stress or reducing photosynthesis. While a number of studies have explored the capacity of plants to take up NPs, few have simultaneously assessed the functional damage due to particulate matter uptake. To quantify NPs uptake by tree roots and to determine whether this resulted in subsequent physiological damage, we exposed the roots of two tree species with different water use strategies in hydroponic cultures to two concentrations (10 mg L-1 and 30 mg L-1) of model metal-doped polystyrene NPs. This approach allowed us to accurately quantify low concentrations of NPs in tissues using standard approaches for metal analysis. The two contrasting tree species included Norway spruce (Picea abies [L.] Karst), a water conservative tree, and wild service tree (Sorbus torminalis [L.] Crantz), an early successional tree with a rather water spending strategy. At both exposure concentrations and at each of the experimental time points (two and four weeks), NPs were highly associated and/or concentrated inside the tree roots. In both species, maximum concentrations were observed after 2 weeks in the roots of the high concentration (HC) treatment (spruce: 2512 +/- 304 mu g NPs per g DW (dry weight), wild service tree: 1190 +/- 823 mu g NPs per g DW). In the aboveground organs (stems and leaves or needles), concentrations were one to two orders of magnitude lower than in the roots. Despite relatively similar NPs concentrations in the tree aboveground organs across treatments, there were different temporal impacts on tree physiology of the given species. Photosynthetic efficiency was reduced faster (after 2 weeks of NPs exposure) and more intensively (by 28% in the HC treatment) in wild service trees compared to Norway spruce (ca. 10% reduction only after 4 weeks). Our study shows that both, evergreen coniferous as well as deciduous broadleaf tree species are negatively affected in their photosynthesis by NPs uptake and transport to aboveground organs. Given the likelihood of trees facing multiple, concurrent stressors from anthropogenic pollution and climate change, including the impact of NPs, it is crucial to consider the cumulative effects on vegetation in future. Anthropogenic contaminants can place significant stress on vegetation, especially when they are taken up into plants.

Microplastics (MPs) in natural waters are heterogeneously mixed with other natural particles including algal cells and suspended sediments. An easy-to-use and rapid method for directly measuring and distinguishing MPs from other naturally present colloids in the environment would expedite analytical workflows. Here, we established a database of MP scattering and fluorescence properties, either alone or in mixtures with natural particles, by stain-free flow cytometry. The resulting high-dimensional data were analyzed using machine learning approaches, either unsupervised (e.g., viSNE) or supervised (e.g., random forest algorithms). We assessed our approach in identifying and quantifying model MPs of diverse sizes, morphologies, and polymer compositions in various suspensions including phototrophic microorganisms, suspended biofilms, mineral particles, and sediment. We could precisely quantify MPs in microbial phototrophs and natural sediments with high organic carbon by both machine learning models (identification accuracies over 93%), although it was not possible to distinguish between different MP sizes or polymer compositions. By testing the resulting method in environmental samples through spiking MPs into freshwater samples, we further highlight the applicability of the method to be used as a rapid screening tool for MPs. Collectively, this workflow can be easily applied to a diverse set of samples to assess the presence of MPs in a time-efficient manner.