Characteristics Of Microplastics Research Articles

Atmospheric Microplastics Emission Source Potentials and Deposition Patterns in Semi‐Arid Croplands of Northern China

AbstractFrequent wind erosion events in semi‐arid regions can lead to significant atmospheric microplastic (MP) emissions from croplands. We examine observed and predicted characteristics of atmospheric MPs over cropland in Northern China. Measurements showed that fibers were the predominant morphology, accounting for 69% of the 198 observed MPs. The observed atmospheric MP abundance varied widely, averaging 0.088 # m−3 in the absence of air masses passing through near‐surface croplands and increasing significantly to 0.26 # m−3 when such air masses were present. The predictions of deposition flux for atmospheric MPs over croplands indicated a spatial variation ranging from less than 0.5 g km−2 day−1 in the north to over 15 g km−2 day−1 in the south, corresponding to an average of approximately 13.3 g km−2 day−1. Our findings highlight the dual role of surface soil as both a potential source and sink of atmospheric MPs, underscoring the need for further research on the regional dynamics of wind‐driven MP emissions and their associated ecosystem health risks in semi‐arid croplands.

Differences in distribution and characteristics of microplastics in sediments of the south-eastern part of the Gulf of Trieste

IntroductionThe Gulf of Trieste is prone to the accumulation of various pollutants and microplastics due to its geomorphological and hydrological characteristics. However, the distribution and sources of microplastics in this semi-enclosed area are poorly studied. The aim of our study was to determine the distribution and chemical composition of MP particles in the sediments of the Gulf of Trieste.MethodsIn this study, we collected 24 surface sediment samples using a Van Veen grab. Microplastics were extracted by density separation using NaCl. The size, shape, and color of the extracted microplastics were determined using an optical microscope, and the composition of the polymers was determined by Fourier transform infrared spectroscopy.Results and discussionThe highest concentrations of up to 125 microplastic particles per 100 g dry sediment were found in coastal areas. Concentrations in the open sea were much lower, with an average of 3 particles per 100 g of sediment. Most of the microplastic was fibrous, made of polypropylene, 100–300 µm in size, and blue. This is the first study showing that microplastics are present in the sediments of the south-eastern part of the Gulf of Trieste. The findings suggest that microplastics exhibit a tendency to be retained within the sediment, leading to their accumulation primarily in a narrow coastal area rather than dispersing offshore. Our results will contribute to a better knowledge of the distribution and possible sources of plastics and microplastics in the Gulf of Trieste and even beyond in similar semi-enclosed marine areas.

Pollution characterization and multi-index ecological risk assessment of microplastics in urban rivers from a Chinese megacity

Currently, a comprehensive understanding of the pollution risks of microplastics (MPs) in urban river ecosystems is still lacking. This study investigated the spatial distribution and morphological characteristics of MPs in surface waters of major rivers in Shenzhen, a megacity in China, using laser direct infrared (LDIR) imaging. A promisingly comprehensive risk assessment method, MultiMP, was first proposed in this study, taking into account the multidimensional characteristics of MPs including abundance, size, shapes, and polymer types. The results showed that MPs were widespread and highly heterogeneous, and the abundance of MPs ranged from 38 to 18380 particles/L, with an average of 2305 particles/L. Morphologically, polyamide (PA) (average 53.7 %), 30–50 µm (73.8 %), and pellet (65.7 %) were the predominant MPs types. Driving factors analyses revealed geographical distance, salinity, water temperature, and total nitrogen had relatively higher impacts on the abundance and morphology of MPs. The MultiMP results indicated that most of the river sampling sites and five major basins in Shenzhen were at moderate to high-risk levels. Polymer type and abundance had a relatively high impact on the environmental risk of MPs in the region. These findings contribute to improving the insights and management of the MPs pollution risks in megacity water bodies.

Microplastic pollution in Taihu Lake: Spatial distribution from the lake inlet to the lake centre and vertical stratification in the water column

The aim of this study was to analyse the distribution characteristics of microplastics in lakes, assess their potential impacts on ecosystems, and explore effective management and control strategies. Despite a wealth of research focused on lake water, the variations in microplastics with offshore distance and their vertical distribution within the water column are not well understood. Here, we investigated the freshwater continuum from the inlet of Taihu Lake to the centre, and vertically from the surface to the bottom water. The results revealed that the distribution of microplastics (<5 mm in size) exhibited a clear spatial gradient. The microplastic abundance at the lake entrance was 2.12 times greater than that at the centre, and on the lake surface, the microplastic abundance was 1.36–1.69 times higher than that estimated from the water column. Notably, the proportion of small-sized microplastics (<0.1 mm) in the bottom water was 1.72 times higher than that in the surface water. The main types of polymers identified were polyamide (PA) and polyvinyl chloride (PVC), and their main sources may be from clothes washing and industrial activities. The Monte Carlo simulation results indicated that the overall risk of microplastics in surface water was higher than that in the water column, and the contributions of PVC and polyurethane (PU) to the ecological risk were 90.10% and 9.57%, respectively. Therefore, PVC and PU should be the priority of microplastic pollution control. This study provides the first comprehensive evaluation of the spatial ecological risk of microplastics in Taihu Lake, which improves our understanding of the distribution and environmental risks of microplastics in lake systems.

Microplastic's Contamination in the Hemolymph and Organs (Gills and Hepatopancreas) of Perna viridis.

The issue of microplastics (MPs) has emerged as a significant concern globally, with discussions surrounding the potential environmental impact of these tiny plastic particles becoming increasingly prevalent. This study aimed to identify the concentration and characteristics of MPs in hemolymph and organs (gills and hepatopancreas) of green mussels (Perna viridis) that are frequently consumed by people in Pangkajene Kepulauan, South Sulawesi Province, Indonesia. Green mussels were collected from two different sampling sites for comparison. Screening was carried out on dispensed hemolymph and dissected organs to identify the characteristics of MPs. Surface seawater sampling was added as information on MP's characteristics from the mussel habitat. Visual observation of MP's characteristics using a stereomicroscope in laminar flow is to prevent contamination. The identification of MP's polymer type is using FTIR-ATR. The results showed that hemolymph, hepatopancreas, gills, and surface water were concentrated with MPs. Small (2-3.9cm) green mussels accumulated more MPs than medium (4-5.9cm) and large (> 6cm). MPs characteristics of fiber shape, transparent color, and size 0.1-0.5mm were dominant in all samples. A total of seven polymers of MPs were identified with polyethylene and polystyrene types most frequently found from all samples. Based on this study, green mussels are good for biomonitoring of MPs.

Assessment of microplastic exposure in nasal lavage fluid and the influence of face masks

Microplastics (MPs) can enter the human body through respiration and pose a hazard to human health. Wearing masks has become a routine behavior during the COVID-19 pandemic. The level of respirational exposure and the influence of wearing masks are currently unknown. We recruited 113 college students and divided them into natural exposure (NE), surgical mask (SM), and cotton mask (CM) groups. Nasal lavage fluid (NLF) was collected and MPs characteristics were analyzed using polarized light microscopy and laser direct infrared system. We found a relatively high abundance of MPs in NLF in the SM group (41.24 ± 1.73 particles/g). The particle size distribution and fibrous MP percentage significantly differed among the three groups. The main components in the NE, SM, and CM groups were polypropylene (58.70 %)，polycarbonate (PC, 49.49 %)，and PC (54.29 %). Components such as polyamide, polyethylene and polyethylene terephthalate were also detected. Wearing surgical masks increased the MP abundance in NLF (β = 0.36, P < 0.01). As the wear time increased, the abundance of MPs also rose (β = 0.28, P < 0.05). However, those who used bedding containing synthetic fibers had lower MP abundance in their NLF. This study highlights the use of NLF to evaluate MP exposure, which is associated with potential health risks.

Petrochemical industry as a source for microplastics; abundance and characteristics of pollution in soil, sewage, and bay

Petrochemical industries can potentially be sources of microplastics. This is the first report that studies the abundance and characteristics of microplastics in different parts of a petrochemical site, and process of changes in microplastics from the place of production to reaching open waters. Samples were taken from 10 points. In order to identify the microplastics, NaCl and ZnCl2 solutions were used for extraction and then H2O2 was used for cleaning and with using different filters, two groups of size were divided. Then, using a stereomicroscope and ATR-FTIR their abundance, color and shape and the type of polymers were determined. The number of microplastics in the soil samples varied from 1483 ± 475 items/Kgdws to 4620 ± 983 items/kgdws, the industrial WWTP sludge, the number of microplastics detected varied from 1233 ± 225 items/L to 1433 ± 372 items/L and in WWTP effluent was determined to be 276 ± 76 items/10 L. on average, 66.38 % and 33.62 % of the detected microplastic particles were in the size range of 0.45μ-20μ and 20μ-2mm, respectively. Also on average, 75.89 % and 24.11 % of the particles were in the density range of 1.2–2 g/cm3 and less than 1.2 g/cm3, respectively. On average, 68.33 %, 14.35 %, 10.55 %, and 6.77 % of the microplastics were in the form of fiber, film, pellet and other, respectively. On average, 29.84 %, 56.27 %, 1.02 %, 2.88 %, 0.97 %, and 8.99 % of the microplastics were black, white, red, blue, green and other respectively. 61 %, 23 %, 8 %, 4 % and 4 % of the investigated particles were classified as PES, PET, PE, PE and unknown, respectively. The results indicate that by moving away from the place of production of PES fibers, microplastics have undergone physical and chemical changes and their nature is changing. Results showed that the petrochemical industries can be potentially a microplastic source. It is a warning that if not taken into consideration will be a serious threat to environmental health.

Atmospheric microplastic input into wetlands: Spatiotemporal patterns, drivers, and unique ecological impacts

Wetlands are major microplastic sinks with a large atmospheric input. However, many details of such deposited atmospheric microplastics entering into wetlands remain unclear, including temporal patterns of input and ecological effects. We monitored the aerial microplastics during four seasons in eleven economically developed cities along the lower reaches of the Yangtze River Basin, China. The average microplastic deposition rate was 512.31 items m−2 d−1, equivalent to an annual contribution of 17.46 metric tons of plastic to the surveyed wetlands with a total area of 1652 km2. These microplastics were predominantly composed of polyamide and polyethylene terephthalate with 61.85 ± 92.29 µm sized pellets, and we obtained similar results for microplastics intercepted on moss in wetlands. Microplastic input varied between wet and dry periods, primarily influenced by wind, rainfall and ozone concentration. Civilian vehicle density and textile industry were the primary socioeconomic factors driving microplastic deposition. Further indoor microcosm experiments revealed that moss phyllosphere bacterial community structure and function were influenced by microplastic abundance and size, exemplifying the unique ecological risks of aerially deposited microplastics to wetlands. These results indicate that mosses and their phyllosphere microbiota could serve as bio-indicators of aerial microplastic characteristics and impacts.

Optimization of methylene blue dye degradation using heterogeneous Fenton-like reaction with Fe3O4 nanoparticles/PVDF macrospheres: A response surface methodology approach

Microplastics (MPs) are increasingly recognised for their significant impact on the environment and human health. Understanding MPs is crucial to grasp their widespread presence in various environmental areas. The unique properties of MPs, such as their small size, durability, and potential to adsorb and transport environmental pollutants, underscore the necessity of studying their characteristics. This study aims to investigate the physical and chemical characteristics of polypropylene microplastics (PPMPs) and address the dispersion stability issues associated with them. The PPMPs were characterised using scanning electron microscopy (SEM), revealing a surface structure marked by cracks, fractures, and a rough texture. The PPMPs were observed as irregularly shaped, white particles. Their size distribution spans from 14 to 96 µm, with a mean size of 50.00 µm. Fourier Transform Infrared Spectroscopy (FTIR) confirmed the presence of polypropylene functional groups, specifically identifying characteristic peaks at 2952-2846 cm-1 and 1456 -1376 cm-1, indicating C-H stretching and bending vibrations, respectively, with additional peaks suggesting degradation. The effect of different concentrations of sodium lauryl sulfate (SLS) on PPMPs dispersion indicated that 5% SLS led to superior dispersion of PPMPs, thereby addressing the stability issue. These findings provide comprehensive insights into the physical and chemical attributes of PPMPs and their dispersion stability, offering a foundation for informed environmental assessments and the development of effective mitigation strategies.

Insight into the physical and chemical attributes of polypropylene microplastics

Microplastics (MPs) are increasingly recognised for their significant impact on the environment and human health. Understanding MPs is crucial to grasp their widespread presence in various environmental areas. The unique properties of MPs, such as their small size, durability, and potential to adsorb and transport environmental pollutants, underscore the necessity of studying their characteristics. This study aims to investigate the physical and chemical characteristics of polypropylene microplastics (PPMPs) and address the dispersion stability issues associated with them. The PPMPs were characterised using scanning electron microscopy (SEM), revealing a surface structure marked by cracks, fractures, and a rough texture. The PPMPs were observed as irregularly shaped, white particles. Their size distribution spans from 14 to 96 µm, with a mean size of 50.00 µm. Fourier Transform Infrared Spectroscopy (FTIR) confirmed the presence of polypropylene functional groups, specifically identifying characteristic peaks at 2952-2846 cm-1 and 1456 -1376 cm-1, indicating C-H stretching and bending vibrations, respectively, with additional peaks suggesting degradation. The effect of different concentrations of sodium lauryl sulfate (SLS) on PPMPs dispersion indicated that 5% SLS led to superior dispersion of PPMPs, thereby addressing the stability issue. These findings provide comprehensive insights into the physical and chemical attributes of PPMPs and their dispersion stability, offering a foundation for informed environmental assessments and the development of effective mitigation strategies.

Characterization and ecological risks of microplastics in urban road runoff

Microplastics (MPs) deposited on urban roads are often flushed into water bodies via drainage systems without treatment, and MP concentrations in the initial road runoff may be particularly high. Yet, there is only a limited understanding of the characteristics, dynamics, and impacts of MPs in urban road runoff. In this study, stormwater and rainwater samples were collected from seven different locations in Hong Kong across 11 rainfall events between February 2021 and September 2022. Characteristics of MPs in the collected samples were analyzed in detail, along with the dynamics of MP concentration in rainfall events, possible influencing factors, and ecological risks. The results show that MP concentration in the initial road runoff is particularly high during a rainfall episode. Overall, the median MP abundance in the collected runoff samples (185 particles/L) was 4.6 times higher than that in rainwater (40 particles/L). The most common polymers identified were polyethylene, polypropylene, and polystyrene, with fragments being the dominant shape. Over 60 % of MP sizes were smaller than 300 μm in the runoff samples. Additionally, risk assessments based on the Polymer Risk Index (PRI) classified most road sites in pollution classes II to III (PRI = 13.3–138.0), indicating moderate to high ecological risks. It appears that MP abundance in the initial runoff was significantly influenced by seasonal changes. These findings highlight urban roads as a major source of MP pollution in stormwater runoff and emphasize the importance of addressing the initial runoff in pollution control.

Characteristics of soil microplastics and ecological risks in the Qilian Mountains region, Northeast Tibetan Plateau

Microplastics (MPs) pollution has become a vital global environmental issue. However, comprehensive understanding of the ecological risks of MPs in soils of Northeast Tibetan Plateau still requires further study. In this study, we used the Agilent 8700 Laser Direct Infrared (LDIR) spectroscopy to analyze the characteristics of 10–1000 μm MPs in soils of different vegetation types throughout the Qilian Mountains basin, and to comprehensively explore the ecological risks of MPs in various ecological environments. The results indicate that MPs abundance is highest in soil of shrub areas (26,369 ± 32,147 items kg−1-dry weight (dw)), followed by woodland (22,215 ± 22,544 items kg−1-dw), desert (17,769 ± 9,040 items kg−1-dw), grassland (16,462 ± 12,872 items kg−1-dw), and forest (15,662 ± 13,857 items kg−1-dw). MPs in soils of different vegetation types show similar physical and chemical characteristics, with the shape dominated by fragments (93%–96%), followed by fibers and a few beads, with dominant sizes of 10–30 μm (63%–76%), and polymers dominated by polyamide (PA) and polyethylene terephthalate (PET). Additionally, the environmental risks posed by the fundamental characteristics of MPs have been quantified through the Pollution Load Index (PLI), Pollution Hazard Index (PHI), and Potential Ecological Risk Index (PERI) models. According to the PLI assessment, the current levels of MPs in the environment have not yet imposed significant burdens on the ecosystem. However, the results of PHI and PERI indicate a higher risk of MPs pollution in the Qilian Mountains. This study offers vital information for MPs pollution in the whole Qilian Mountains regions and their potential environmental risks in remote areas’ soil.

Characteristics, drivers and ecological risk assessment of microplastics in the surface water of urban rivers in Guangdong-Hong Kong-Macao Greater Bay Area cities - A case study of Dongguan city

In the Guangdong-Hong Kong-Macao Greater Bay Area (GBA), microplastic pollution in urban rivers is a prominent problem due to the developed economy and high industrial intensity. Using the Xiaohai River, Hanxi River and Dongguan Canal in Dongguan City, an important node city in the GBA, as an example, microplastic characteristics, drivers and ecological risks in the surface water of three rivers were investigated. Results showed that the average abundance of rivers in the wet period (1646.22 ± 154.73 items/m3) was 4.7 times higher than that in the dry period (351.09 ± 34.2 items/m3). Microplastics were mainly in the form of fragments and fibers, with a size range of 30–500 μm, and appeared transparent with white color. The microplastic polymer types PE, PP, PET and PA accounted for more than 70%. There are large differences in the characteristics of microplastic pollution during different hydrological periods. Redundancy analysis showed that the distribution of plastics, chemical materials, packaging and printing industries along the rivers dominated the differences in microplastic abundance. The electronic information industry contributed most to the composition of microplastic polymer types. The polymer hazard index, pollution load index, and potential ecological risk index for rivers indicate a medium-high risk classification or higher. Therefore, the industrial layout along the urban rivers should be rationalized, the disposal of microplastics in wastewater should be increased, and the use of green plastic products should be promoted. This study provides support for the management of microplastic pollution in urban surface water in the GBA.

Microplastic-contamination in the flesh and gastrointestinal tract of nile tilapia (Oreochromis niloticus) reared in floating net cages at lake Ranu Grati, Pasuruan, East Java, Indonesia

In recent years, microplastics (MPs) have emerged as a prominent environmental problem in waters and environments, including lake waters. Microplastics in freshwater, such as those in floating net cages (FNC), can be consumed by Nile tilapia (Oreochromis niloticus), one of the commercially available cultivated fish in Indonesia. This study aims to determine the prevalence of microplastics and compare their characteristics in the surface water, flesh, and gastrointestinal tract (GIT) of Nile Tilapia (O. niloticus) at Lake Ranu Grati, Pasuruan, East Java, Indonesia. Visual characteristics of MPs were observed using a stereo microscope, and polymers were analysed by ATR-FTIR (Attenuated Total Reflection-Fourier Transform Infrared Spectroscopy). The abundance of MPs from water sample locations in Lake Ranu Grati reached 1116 MPs particles. In the water samples, the inner and outer sides of the FNC are dominated by the MPs with a size range of 251–500 µm and 1001-2000 µm in the milieu of Ranu Grati Lake. The most common MPs' types and colours are fibre and black, dominated by Polyethylene (PE). In 25 O. niloticus samples, 576 particles of MPs were found in the flesh and 724 particles in the gastrointestinal tract (GIT). This study found no significant variation in microplastic abundance between flesh and GIT samples (p>0.05; Mann-Whitney U test). Microplastics in Nile Tilapia flesh samples were dominated by blue fibres with a size range of 101–250 µm, and the polymer found was PA (polyamide). Meanwhile, in the GIT samples, microplastics were dominated by black fibre, with a size range of 251–500 µm, and the polymer found was PA (polyamide).

Occurrence, characteristics, and risk assessment of microplastics and polycyclic aromatic hydrocarbons associated with microplastics in surface water and sediments of the Konya Closed Basin, Turkey.

The presence of polycyclic hydrocarbons (PAHs) and microplastics (MPs) in aquatic environments affects the ecosystems and threatens human health. In this study, the abundance, composition, and morphological characteristics of MPs were determined for the first time in the inland freshwater resources of the Konya Closed Basin, Turkey. The abundance of MPs ranged from 1139 to 23,444 particles/m3 and 150 to 3510 particles/kg in the surface water and sediment, respectively. Fragments and fibers were the most abundant MP shapes in the surface waters (51%, 34%) and sediments (29%, 40%), followed by films, pellets, and foams. Transparent and white MPs were present at the highest percentage in surface waters (72%) and sediments (69%), followed by blue, grey, black, brown, and green. In addition, polyethylene, polypropylene, and cellophane were identified as the main polymers in surface waters (34%, 25%, 24%) and sediments (37%, 17%, 31%). In the Konya Closed Basin, 35% of the surface water samples and 54% of the sediment samples were exposed to very high contamination (CF ≥ 6). Surface waters (PLI: 2.51) and sediments (PLI: 1.67) in the basin were contaminated (PLI > 1) with MPs. The 16 PAHs sorbed on MPs in the surface water and sediment ranged from 394 to 24,754ng/g and from 37 to 18,323ng/g, respectively. Phenanthrene and fluoranthene were the most abundant PAHs sorbed on MPs in all surface waters and sediments. Two to three-ring PAH compounds sorbed on MPs were also dominantly detected in surface waters and sediments, accounting for 68% and 78% of the total 16 PAHs, respectively. The source of PAHs carried by MPs in the Konya Closed Basin was mainly of petrogenic origin. Incremental lifetime cancer risk (ILCR) results indicated that the maximum ILCR values were higher than the EPA acceptable level (10-6) for child (2.95 × 10-5) and adult (1.46 × 10-4), indicating a potential cancer risk.

Distribution and co-occurrence of microplastics and co-existing pollutants in bottom water and sediment of the East China Sea

Microplastics (MPs) contamination in marine environment has been an emerging issue worldwide, notably due to the potential ecological risks of MPs with co-existing environmental contaminants and released toxic plastic additives. To verify the co-occurrence characteristics of MPs and co-existing pollutants in the benthic boundary layer (BBL), the distribution characteristics of MPs, and selected heavy metals (HMs) and halogenated flame retardants (Polybrominated diphenyl ethers, PBDEs, and Dechlorane Plus) in the bottom water and sediment were comprehensively investigated in the East China Sea (ECS). The sampling sites were selected along the coast of ECS, where might be significantly affected by terrigenous inputs and anthropogenic sources. MPs were abundant in the bottom water (62.8–480.2 items/L) and sediment (80.1–1346.7 items/kg d.w.) with polyester, polyethylene, and polypropylene being as the most abundant types and characterized as fiber/line, particle size 200–500 μm, and transparent/white. The abundance and characteristics of MPs demonstrated strong correlations within the bottom water and sediment, which might be due to the frequent exchange of materials. In addition, the abundance of MPs was significantly positively correlated with HMs (Cd, Cr, Pb) in the bottom water and PBDEs in sediment, respectively. According to the scanning electron microscopy/energy dispersive X-ray spectrometry analysis, MPs might act as carriers to transport and co-sediment the co-existing pollutants in water, and physically adsorb or chemically bind with pollutants in sediment. These results could help to elucidate the sources, migration, and fate, and verify the occurrence and potential risks of MPs and their co-existing pollutants in BBL, thus realize the management and control of MPs contamination in marine.

Microplastic pollution in tropical coral reef ecosystems from the coastal South China Sea and their impacts on corals in situ

Coral reefs possess extremely high ecological value in tropical and subtropical waters worldwide. Microplastics as emerging and pervasive pollutants pose a great threat to the health of coral ecosystems. However, in situ studies on microplastics pollution and its impacts in coral ecosystems globally are limited. The occurrence characteristics of microplastics in the environment mediums and reef-dwelling organisms were investigated in coral reef areas from the southern Hainan Island, and the impacts of microplastics on corals in situ were evaluated in this study. Average microplastics abundance was 9.48 items L-1 in seawater, 190.00 items kg-1 in sediment, 0.36 items g-1 in coral, 1.50 items g-1 in shellfish, 0.48 items g-1 in fish gill, and 1.71 items g-1 in fish gastrointestinal tract. The prevalent microplastics in the above samples were characterized as being less than 1000 µm in size, fibrous, and transparent, with predominant polymer types as polyethylene terephthalate, polypropylene, polyethylene, and rayon. The microplastic enrichment capacity of different corals varied (Pocillopora >Acropora >Sinularia). Notably, microplastics were more abundant on the surface of corals compared to their interiors, with distinct characteristics observed, including larger-sized (>500 µm) and fiber-shaped polyethylene terephthalate microplastics on the surface and smaller-sized (20–200 µm) fragmented polyethylene microplastics within coral interiors. Furthermore, the investigation showed species-specific impacts of microplastics on corals in situ, including photosynthetic activity of photosymbionts and antioxidant and immune activities of corals. Furthermore, the ecological risks of microplastics were minor across most environmental media in the studied areas, with exceptions in the bottom seawater and surface sediment of YLW, which exhibited extreme and medium risk levels, respectively. Coral risk levels were generally medium, except for dangerous levels in DDH and high levels in LHT. The potential sources of microplastics in the marginal reefs of southern Hainan Island were primarily tourism, residential, and fishing activities.

Impact of Fenton aging on the incipient motion of microplastic particles in open-channel flow

Upon entering the environment, Microplastics (MPs) experience aging processes that modify their properties and integrity. Previous methods for predicting the incipient motion of MPs have been validated using pristine plastics, which do not account for the effects of aging. This can lead to uncertainties in both quantification and characterization. This study investigates the effect of aging on the incipient motion of MPs with different bed roughness (smooth and rough beds) and MP properties (e.g., grain sizes and densities) in an open-channel flow. Five types of MPs were subjected to four different degrees of aging using the Fenton reagent, and their incipient velocities were tested on beds with two distinct roughness. The results suggest that the incipient velocity of MPs increases linearly with aging. However, this increase is not uniform across different particles and bed roughness. Upon comparing various commonly employed sediment incipient velocity equations, experimental results are in agreement with Ruijin Zhang's equation as the most precise. The parameters in Ruijin Zhang's equation are modified to enhance its applicability for predicting the incipient velocity of aged MPs. This study provides novel insights into the incipient motion of aged MPs in an open-channel flow, highlighting the intricate interaction between aged MP characteristics and bed roughness.

Distribution characteristics of microplastics in the surface mixed layer of the western Indian Ocean

The abundance, characteristics, and distribution of microplastics in almost all aquatic environments have been well documented. However, the distribution of microplastics in open oceans, especially in the western Indian Ocean, is rarely studied. Hence, for the first time, we determined the meridional distribution characteristics of microplastics in the surface mixed layer of the western Indian Ocean during the boreal summer monsoon in 2017. We used the multiple opening and closing nets and environmental sampling system to collect microplastics from 11 stations between 5°N and 16°S along 67°E in the western Indian Ocean; the surveyed stations with similar temperature and salinity profiles were clustered into four groups. Microplastics were detected at all sampling stations. The mean abundance of microplastics in the study area was 0.23 ± 0.04 particles/m3, and black-colored polyester fibers 1.0–5.0 mm in size were the most abundant type of microplastics among the samples collected. However, the mean abundance of microplastics differed among the clustered groups due to the influence of different ocean currents associated with each group, indicating meridional heterogeneity in the distribution of microplastics in the surface mixed layer of the western Indian Ocean. These findings provide reliable information for a better understanding of the characteristics of microplastics in the surface waters of the western Indian Ocean.

Non targeted and targeted LC-MS/MS insights into the composition and concentration of atmospheric microplastics and additives: Impacts and regional changes of sandstorms in Shanghai and Hohhot, China

Increasing dust storms impact ecosystems and human health by resuspending dust and microplastics. Plastic pollution is a major global concern. This study examines the molecular composition and concentration of atmospheric microplastics and additives in Hohhot and Shanghai, China during dust and non-dust days using non-target and target LC-MS/MS analysis with Multiple Reaction Monitoring (MRM) methodology and a self-established plastic monomers database. In Hohhot, 98 microplastics and additives types were identified on dust days (41 unique) and 70 on non-dust days (10 unique), mainly PEG, HTPE, PET, PPG, and Nylon. The types fluctuate ranging from 35 to 65 due to dusty conditions. In Shanghai, 50 types were identified (no unique), with 25 to 30 types consistently present. Hohhot's microplastics concentration during dust days peaked at 3531.59 ng/m3, about three times higher than non-dust days (1669.17 ng/m3) and significantly higher than Shanghai's maximum of 589.85 ng/m3. Overall, microplastic monomers in both cities were mostly compounds with low unsaturation, indicating potential for long-term atmospheric persistence. Highly reactive monomers like HTPE, PEG, thrive on dust days in Hohhot due to insufficient light and strong winds. These conditions reduce photochemical reactivity, accelerate microplastic aging through collisions, and resuspend more microplastics from the soil, resulting in a wider variety of microplastics with different m/z and carbon contents during sandstorms. On non-dust days, microplastics have more concentrated m/z values, indicating that substances with similar chemical properties disperse more under normal conditions. These findings highlight the significant impact of dust storms on microplastics characteristics. SynopsisThis study indicates that dust storms and regional differences can have significant impacts on the diversity and abundance of atmospheric microplastics.