Unraveling the Marine Microplastic Cycle: The First Simultaneous Data Set for Air, Sea Surface Microlayer, and Underlying Water

Quantification of micro- and nano-plastics in atmospheric fine particles by pyrolysis-gas chromatography-mass spectrometry with chromatographic peak reconstruction

The effects of micro- and nano-plastics (MNPs) on human health are of global concern because MNPs are ubiquitous, persistent, and potentially toxic, particularly when bound to atmospheric fine particles (PM2.5). Traditional quantitative analysis of MNPs by pyrolysis-gas chromatography-mass spectrometry (Py-GC/MS) is often inaccurate because of false positive signals caused by similar polymers and organic compounds. In this study, a reliable analytical strategy combining HNO3 digestion and chromatographic peak reconstruction was developed to improve the precision of pyrolysis-gas chromatography-mass spectrometry analysis of multiple MNPs bound to PM2.5. The optimized HNO3 digestion method using high-pressure oxidation conditions effectively removed organic matter within two hours, giving recovery rates of 64 %-110 % for eight target MNPs. The chromatographic peak reconstruction procedure minimized interferences caused by similar polymers and achieved high accuracy (101 % ± 10 %) for polyvinyl chloride, polyethylene terephthalate, and polystyrene, whose concentrations are often overestimated due to overlapping pyrolysis products. Quantification uncertainties for MNPs in real PM2.5 samples were up to 52 % lower using the new method than using previous methods. The method was validated using PM2.5 from urban Guangzhou. The total concentrations of the eight target MNPs in the PM2.5 samples were 100-990 ng/m3 (median 277 ng/m3) and the dominant MNPs were polyethylene, polyethylene terephthalate, and polyvinyl chloride, which contributed > 90 % of the MNPs. The new method allows the robust and accurate quantification of MNPs in atmospheric fine particles and will be useful in future studies on the environmental behaviors of MNPs and risks they pose.

Quantification of paint flakes and metal emissions during pro-active in-water hull cleaning

Pro-active in-water hull cleaning is a viable option for reducing greenhouse gas emissions and preventing the transportation of non-indigenous species. Conversely, pro-active in-water cleaning (IWC) might lead to the emission of antifouling paint particles and biocides, posing a risk to the marine environment. However, the analysis of these APPs is particularly challenging. We have therefore adapted a thermoanalytical approach using pyrolysis-gas chromatography/mass spectrometry to analyze the abrasion of APPs. In this approach, the mass of APPs is determined by analyzing the polymer backbone and external calibration. We investigated the particulate abrasion of antifouling coatings for one ship with a self-polishing coating, one with a foul-release coating and one with an abrasion-resistant coating, in order to evaluate the different abrasion behavior and the suitability of the respective coating types for pro-active IWC. In addition, the zinc and copper emissions were analyzed. The extrapolation of the abrasion for ships with 10,000 m2 of wetted surface shows that both the abrasion-resistant coating and the foul-release coating release only small quantities of APPs during IWC, with 1.2-2.1∗10-4 kg for the abrasion-resistant coating and 0.015 kg for the foul-release coating. The potential emissions for self-polishing coatings showed significantly higher abrasion with 1.9-4.3 kg. In addition, copper and zinc emissions showed the same distribution trends for the self-polishing coating samples and were between 2.2-9.5 and 1.1-3.2 mg/L, respectively, exceeding common water quality standards by far. These results demonstrate that caution is required when balancing the advantages and disadvantages of IWC, especially with regard to self-polishing coatings.

Size Distribution of Micro-/Nanoplastic Particles and Their Chemical Speciation in the Atmosphere of Shanghai, China

The significance of microplastics in urban air has gained increasing recognition; however, a comprehensive understanding of their size distribution and composition remains limited. This study presents analyzed results of micro-/nanoplastics collected from Shanghai's winter atmosphere using thermal desorption/pyrolysis-gas chromatography-mass spectrometry. Six major plastic types were identified, with polyethylene (PE) accounting for 40.0% of the detected atmospheric plastics. Fine plastic particles (FPPs, ≤3.2 μm) constituted 59.2% of the total mass concentration of microplastics (MPs), while nanoplastics (NPs, ≤1.0 μm) accounted for 36.3%. As the aerodynamic particle size decreased, the proportion of plastics other than PE increased. This size-dependent compositional variation suggests that nanoplastics, due to their smaller size, can more easily penetrate sensitive biological regions. At the nanoscale, the accumulated mass in pulmonary regions exceeds that in the head airway. These findings underscore the critical need for detailed assessments of plastic characteristics in the atmosphere to better understand their environmental behavior and potential health impacts.

Relationships between sediment size distribution and microplastic abundance and characteristics along the strandline of a sandy embayment (Whitsand, Southwest England)

Beach sediments taken from 1 m2 areas of strandline across an embayment in southwest England (Whitsand) have been analysed for grain size distribution and elemental content. Large (1-5 mm) and small (< 1 mm) microplastics were isolated by sieving and flotation in NaBr solution, respectively, and characterised by size, shape, colour and polymeric makeup. Sediments displayed varying median diameters and degrees of sorting but distributions were always positively skewed. Concentrations of Fe, K, Mn and Ti were relatively invariant, but Ca concentrations exhibited heterogeneous distributions across the bay. Large microplastics were largely composed of polyolefin-based pre-production pellets, bio-beads and fragments whose numbers were correlated with each other. Positive and inverse relationships between beads and sediment skewness and sorting, respectively, suggests that deposition of this type of plastic is favoured where sediment is well-sorted and contains a high proportion of fine material. Small microplastics were dominated by fragments and fibres <200 μm in size composed of a broader array of polymers (including epoxy resin, polyetherimide and polyvinyl alcohol). Fibres exhibited an inverse relationship with bead and pellet abundance but there was no evidence of dependency on grain size distribution, and their presence is attributed to entrapment in interstitial spaces between sediment grains. Compositional differences between large (1-5 mm) and small (< 1 mm) microplastic fragments suggests they are derived from different sources, with the former coupled with pellet and bead deposition and the latter small enough to be retained in interstitial spaces with fibres. However, a positive relationship between mean (small) fragment size and median sediment diameter suggests that their retention is more constrained by interstitial space than fibres. The study provides evidence that microplastics of different size and shape behave differently but are, ultimately, related to or controlled by sediment size distribution in the coastal littoral zone.

What influences the distribution of microplastics in the marine environment? An interdisciplinary study reveals key factors driving microplastic in the North Sea

Microplastics (MP) are known to be ubiquitous. The pathways and fate of these contaminants in the marine environment are receiving increasing attention, but still knowledge gaps exist. In particular, the link between mass-based MP quantification and oceanographic parameters is often lacking. In this study, we aim to interconnect different parameters for the first time through in-situ measurements with an autonomous surface vehicle in the German Bight. It simultaneously sampled air, sea surface microlayer, and underlying water for analysis of MP and additionally, extracellular polymeric substances (only in water). These compounds, secreted by microorganisms, can interact with particulate matter, influencing their transport dynamics and aggregation behavior in the environment. During the entire sampling, a weather station and conductivity, temperature, and depth sensors were installed on the vehicle. Depth profiles were taken with an accompanying research vessel to learn more about the stratification and horizontal processes of MP in the marine environment. Additionally, an acoustic Doppler current profiler recorded water current velocities and flow direction. A relationship was found between wind direction and the presence of MP in the atmosphere. Furthermore, wind speeds may seem to increase heterogeneity in both the composition and concentration of MP in the water. A tentative correlation between extracellular polymeric substances and MP was documented. Investigating horizontal and vertical velocities of currents within the surface and the water column helped to explain the distribution of MP. Up- and downwelling processes corresponded to the accumulation of MP along density fronts and across depth profiles.

Pulmonary Flora-Derived Lipopolysaccharide Mediates Lung-Brain Axis through Activating Microglia Involved in Polystyrene Microplastic-Induced Cognitive Dysfunction

Microplastics (MPs) have been detected in the atmospheric and the human respiratory system, indicating that the respiratory tract is a significant exposure route for MPs. However, the effect of inhaled MPs on cognitive function has not been adequately studied. Here, a C57BL/6 J mouse model of inhalation exposure to polystyrene MPs (PS-MPs, 5 µm, 60 d) is established by intratracheal instillation. Interestingly, in vivo fluorescence imaging and transmission electron microscopy reveal that PS-MPs do not accumulate in the brain. However, behavioral experiments shows that cognitive function of mice is impaired, accompanied by histopathological damage of lung and brain tissue. Transcriptomic studies in hippocampal and lung tissue have demonstrated key neuroplasticity factors as well as cognitive deficits linked to lung injury, respectively. Mechanistically, the lung-brain axis plays a central role in PS-MPs-induced neurological damage, as demonstrated by pulmonary flora transplantation, lipopolysaccharide (LPS) intervention, and cell co-culture experiments. Together, inhalation of PS-MPs reduces cognitive function by altering the composition of pulmonary flora to produce more LPS and promoting M1 polarization of microglia, which provides new insights into the mechanism of nerve damage caused by inhaled MPs and also sheds new light on the prevention of neurotoxicity of environmental pollutants.

Exploring the Transport Path of Oceanic Microplastics in the Atmosphere

Microplastics (MP) have been recognized as an emerging atmospheric pollutant, yet uncertainties persist in their emissions and concentrations. With a bottom-up approach, we estimate 6-hourly MP fluxes at the ocean-atmosphere interface, using as an input the monthly ocean surface MP concentrations simulated by the global oceanic model (NEMO/PISCES-PLASTIC, Nucleus for European Modeling of the Ocean, Pelagic Interaction Scheme for Carbon and Ecosystem Studies), a size distribution estimate for the MP in the micrometer range, and a sea salt emission scheme. The atmospheric dispersion is then simulated with the Lagrangian model FLEXPART. We identify hotspot sources in the tropical regions and highlight the seasonal variability of emissions, atmospheric concentrations, and deposition fluxes both on land and ocean surfaces. Due to the variability of MP concentration during the year, the MP flux from the sea surface appears to follow a seasonality opposite to that of sea salt aerosol emissions. The comparison with existing observations of MP in the marine atmosphere suggests an underestimation of one to 2 orders of magnitude in our current knowledge of the MP in the oceans' surface. In addition, we show that the MP in the micrometer range is transported efficiently around the globe and can penetrate and linger in the stratosphere over time scales of months. The interaction of these particles with the chemistry and physics of the atmosphere is still mostly unknown and deserves to be further investigated.

Quantification and Characterization of Fine Plastic Particles as Considerable Components in Atmospheric Fine Particles

The negative effects of air pollution, especially fine particulate matter (PM2.5, particles with an aerodynamic diameter of ≤2.5 μm), on human health, climate, and ecosystems are causing significant concern. Nevertheless, little is known about the contributions of emerging pollutants such as plastic particles to PM2.5 due to the lack of continuous measurements and characterization methods for atmospheric plastic particles. Here, we investigated the levels of fine plastic particles (FPPs) in PM2.5 collected in urban Shanghai at a 2 h resolution by using a novel versatile aerosol concentration enrichment system that concentrates ambient aerosols up to 10-fold. The FPPs were analyzed offline using the combination of spectroscopic and microscopic techniques that distinguished FPPs from other carbon-containing particles. The average FPP concentrations of 5.6 μg/m3 were observed, and the ratio of FPPs to PM2.5 was 13.2% in this study. The FPP sources were closely related to anthropogenic activities, which pose a potential threat to ecosystems and human health. Given the dramatic increase in plastic production over the past 70 years, this study calls for better quantification and control of FPP pollution in the atmosphere.