Accumulation Of Microplastics Research Articles

Trajectory, fate, and magnitude of continental microplastic loads to the inner shelf: A case study of the world's largest coastal shallow lagoon

The Patos Lagoon estuary is a highly significant ecosystem where freshwater from a vast and densely populated area continuously flows into the Atlantic Ocean by coastal plumes, exporting not only freshwater but also sediment, nutrients, plastics, and other contaminants. In this work, numerical modeling tools together with field data were used to assess for the first time the capacity of the coastal plume to export microplastics (MPs) to the inner shelf under different hydrodynamic conditions. Two field surveys were conducted during plume events to quantify MP concentrations and validate the model approach. A bottom-up approach was employed to estimate the potential MP export from the estuary's domain to the Atlantic Ocean. MP concentration in surface plume waters ranged from 0.20 items m−3 to 1.37 items m−3, confirmed by FTIR as synthetic polymers in a 90 %, being Polypropylene (PP) and Polyethylene (PE) the most abundant in a 73 %. The accumulation pattern was observed on the plume's frontal system, consistent with simulation results. The estimated average MP potential export rate attained 9.0 million items day−1 during moderate plume events and 47.5 million items day−1 during high discharge plume events. Strong discharge events, coupled with intense northeast winds, facilitated rapid southwestward export of MPs. Conversely, moderate to weak discharge events retained MPs closer to the estuary's mouth, enabling either longer trajectories or earlier deposition. Significant MP accumulation hotspots were identified in the gyre between the jetties and Cassino beach, as well as in the saline front within the plume boundaries. These accumulation zones may function as reservoirs for MP particles, potentially posing threats to local ecosystems. Understanding these dynamics is crucial for ongoing monitoring efforts to assess potential harmful interactions over time.

High performance flexible green triboelectric nanogenerator with polyethylene oxide/mica tribo-positive composite material

Innovating novel, green, biodegradable, and recyclable polymers are critical for the development of environmentally sustainable solutions, eliminating concerns of pollution and microplastic accumulation. Herin, this study presents remarkably enhanced tribo-positive polyethylene oxide (PEO) polarity, by incorporating for the first time, a clay inorganic filler, creating a novel biodegradable composite triboelectric material. The low-cost composite comprised a biodegradable polymeric PEO matrix, an abundant naturally sourced muscovite mica micro-platelet filler, and integrated simple material fabrication methods. A 4 cm2 PEO/Mica film was paired with polytetrafluoroethylene (PTFE), generating a peak-to-peak voltage, current density, and transferred charge density of respectfully, 296 V, 24.2 mA m−2, and 110.3 µC m−2. Reducing the film thickness to 40 µm dramatically enhanced the electrical output, resulting in a peak-to-peak voltage and instantaneous power density of respectfully, 424 V and 12.1 W m−2. The addition of mica greatly improved the dielectric permittivity, promoting the outstanding triboelectric performance. The composite material's long-term stability and flexibility demonstrated significant advantages for self-powering small electronic systems. Furthermore, PEOs facile water solubility allowed mica separation, recovery, recyclability, and integration within new PEO/Mica films, resulted in preserved triboelectric outputs. The PEO/Mica composite delivers exceptional sustainable, recyclable, and tribo-positive attributes, serving as an excellent energy harvesting solution.

Assessment of microplastics pollution level on clam farming and bathing beaches: a case study of Thanh Phu in Ben Tre, Vietnam

ABSTRACT This study focused on the investigation microplastics (MPs) with a size of ≤1.0 mm in sand samples from Thanh Phu beach, Ben Tre, Vietnam. MPs in sand from the clam beach (from 39.67 ± 6.67 to 92.00 ± 12.93 items kg−1 dried sand) were higher than those from the bathing beach (from 21.33 ± 8.76 to 51.67 ± 16.11 items kg−1 dried sand), indicating a direct contribution of MPs from coastal aquaculture. For the clam beach, MPs in surface samples (0–4 cm) were lower than in deep samples (4–6 cm). In contrast, MPs in surface samples (0–2 cm) from the bathing beach were higher than deep samples (2–5 cm). A combination of microscopy and Fourier-transform infrared spectroscopy methods confirmed that 62.5% of the representative MPs samples or 18.9% of the suspected MPs samples were plastics. Low-density polyethylene, polypropylene and polyethylene terephthalate were the largest in abundance. Further studies are needed to assess the environmental risk of MPs accumulation.

Impacts of conventional and biodegradable microplastics in maize-soil ecosystems: Above and below ground

The increasing accumulation of microplastics (MPs) in agroecosystems has raised significant environmental and public health concerns, facilitating the application of biodegradable plastics. However, the comparative effects of conventional and biodegradable MPs in agroecosystem are still far from fully understood. Here we developed microcosm experiments to reveal the ecological effects of conventional (polyethylene [PE] and polypropylene [PP]) and biodegradable (polyadipate/butylene terephthalate [PBAT] and polycaprolactone [PCL]) MPs (0, 1%, 5%; w/w) in the maize-soil ecosystem. We found that PCL MPs reduced plant production by 73.6‐75.2%, while PE, PP and PBAT MPs elicited almost negligible change. The addition of PCL MPs decreased specific enzyme activities critical for soil nutrients cycling by 71.5‐95.3%. Biodegradable MPs tended to reduce bacterial α-diversity. The 1% treatments of PE and PBAT, and PCL enhanced bacterial networks complexity, whereas 5% of PE and PBAT, and PP had adverse effect. Moreover, biodegradable MPs appeared to reduce the α-diversity and networks complexity of fungal community. Overall, PCL reduced the ecosystem multifunctionality, mainly by inhibiting the microbial metabolic activity. This study offers evidence that biodegradable MPs can impair agroecosystem multifunctionality, and highlights the potential risks to replace the conventional plastics by biodegradable ones in agricultural practices.

Progress in Research on Microplastic Prevalence in Tropical Coastal Environments: A Case Study of the Johor and Singapore Straits

Microplastics are contaminants in marine ecosystems, posing great threats to biota and human health. In this work, we provide an overview of the progress made in understanding microplastic prevalence in tropical coastal environments, focusing on the Johor and the Singapore Straits as a case study. We examine the sources, distribution, transport, and ecological impact of microplastic pollution in this region through a systematic review. All papers relating to marine microplastics in Singapore’s sand and benthic sediments, seawater, and marine biota were used for analysis, from 2004 to 2023. In addition, we discuss the influence of envi-ronmental factors such as coastal morphology and anthropogenic activities on patterns of microplastic accumulation. We emphasize that microplastic pollution is more prevalent along the eutrophic Johor Strait compared to the Singapore Strait due to hydrological conditions. Rainfall is also a key factor that influences mi-croplastic abundance during the monsoon seasons. Furthermore, the bacterial and plankton assemblages of organisms on microplastic surfaces are diverse, with eutrophic waters enhancing the diversity of organisms on microplastic surfaces. Novel harmful cyanobacteria and bloom species of phytoplankton were also found on microplastic surfaces. By synthesizing existing research findings and highlighting regional characteristics, this paper contributes to ongoing efforts to mitigate microplastic pollution in tropical regions.

Comparison of rhodamine B adsorption and desorption on the aged non-degradable and degradable microplastics: Effects of charge-assisted hydrogen bond and underline mechanism

The accumulation of microplastics (MPs) in the environment and their role as carriers for ionic organic pollutants are increasingly attracting attention. This study evaluated the adsorption-desorption characteristics of the cationic organic pollutant on virgin and UV-aged non-degradable polystyrene (PS) as well as degradable poly(butylene succinate) (PBS) and poly(butylene adipate-co-terephthalate) (PBAT) MPs. The results showed that aging treatment made the surface of MPs rougher and more porous, causing the adsorption to shift from monolayer to multilayer adsorption. Aging increased the oxygen-containing groups on MPs, significantly enhancing the H bond (HB) donor capabilities of degradable aged PBS and PBAT, thereby improving adsorption by more than 10 times. This significant increase in adsorption is mainly due to the combined effects of strong HB (including ordinary HB (OHB) and charge-assisted HB (CAHB)), electrostatic interactions, and π-π interactions. Notably, the stronger HB enabled aged PBS and PBAT to achieve efficient and stable adsorption of rhodamine B over a wide pH range, with significant desorption hysteresis (HI > 1.80). This indicates that degradable aged MPs can act as carriers for long-distance pollutant transport. The significant total desorption of cationic pollutants from aged PBS and PBAT in simulated animal gastrointestinal fluids confirmed the greater environmental hazards of degradable aged MPs. This work is the first to demonstrate that degradable aged MPs, as unique HB donors, can primarily adsorb ionic organic pollutants through strong HB (CAHB and OHB), which helps assess the environmental fate of biodegradable microplastics and pollutants in aquatic systems.

Adsorption behavior of Methylene Blue and Rhodamine B on microplastics before and after ultraviolet irradiation

The accumulation of microplastics (MPs) and dyes has attracted extensive attention because of their environmental effects, which will be exacerbated especially after the aging of MPs. This study aimed at investigating the significance of Methylene Blue (MB) and Rhodamine B (RhB) adsorption behavior by PLA (polylactic acid) and PA66 (Polyamide 66) MPs after UV aging. After aging, there was an observed increase in the hydrophilicity, specific surface area, and oxygen content of MPs. The results indicate that aging enhances the adsorption capacity of both PLA and PA66. Furthermore, it is noteworthy that PLA undergoes more significant changes in its physicochemical properties compared to PA66 following aging. The adsorption process conformed the pseudo-second order (PSO) kinetic model and Langmuir isotherm well, and the adsorption capacity followed the sequence of aged-PLA > aged-PA66 > pristine-PA66 > pristine-PLA. Besides, the adsorption of dyes onto the MPs was studied across four variables (pH, salinity, surfactants, and dissolved organic matter). The aforementioned findings collectively demonstrate that the aged MPs still exhibit a higher adsorption capacity than the pristine MPs. In desorption experiments, the desorption efficiency of MB (PLA) was reduced from 35.29 % (P-PLA) to 32.76 % (A-PLA), and the similar trend was observed on other aged MPs. These findings suggest that aged MPs could have a more pronounced ability for dye transportation. These results would contribute to a deeper understanding of the adsorption and desorption behavior of dyes on MPs and their potential health risks.

Microplastics and Anthropogenic Particles in Recreationally Caught Freshwater Fish from an Urbanized Region of the North American Great Lakes.

Microplastics are a pervasive contaminant cycling through food webs-leading to concerns regarding exposure and risk to humans. We aimed to quantify and characterize anthropogenic particle contamination (including microplastics) in fish caught for human consumption from the Humber Bay region of Lake Ontario. We related quantities of anthropogenic particles to other factors (e.g., fish size) that may help in understanding accumulation of microplastics in fish. A total of 45 samples of six fish species collected from Humber Bay in Lake Ontario near Toronto, Ontario, Canada, were examined for anthropogenic particles in their gastrointestinal (GI) tracts and fillets. Using microscopy and spectroscopy, suspected anthropogenic particles were identified and characterized. We observed anthropogenic particles in the GI tracts and fillets of all species. Individual fish had a of anthropogenic particles, with a single fish containing up to 1,508 particles. GI tracts had particles/fish ( particles/gram), and fillets had particles/fish ( particles/gram). Based on a consumption rate of 2 servings/week, the average yearly human exposure through the consumption of these fish fillets would be particles. Our findings suggest that consumption of recreationally caught freshwater fish can be a pathway for human exposure to microplastics. The elevated number of particles observed in fish from Humber Bay highlights the need for large-scale geographic monitoring, especially near sources of microplastics. Currently, it is unclear what the effects of ingesting microplastics are for humans, but given that recreationally caught freshwater fish are one pathway for human exposure, these data can be incorporated into future human health risk assessment frameworks for microplastics. https://doi.org/10.1289/EHP13540.

Factors influencing microplastic abundances in the sediments of a seagrass-dominated tropical atoll

Seagrass meadows are one of the world's most diverse ecosystems offering habitats for an extensive array of species, as well as serving as protectors of coral reefs and vital carbon sinks. Furthermore, they modify hydrodynamics by diminishing water flow velocities and enhancing sediment deposition, indicating the potential for microplastic accumulation in their sediments. The build-up of microplastics could potentially have ecological impacts threatening to ecosystems, however little is known about microplastic abundance and controlling factors in seagrass sediments. Here we investigated microplastic characteristics and abundances within sediments underlying four seagrass meadow sites on the Turneffe Atoll, Belize. Sediment cores were collected and sub-sampled to include a range of replicate surface sediments (0–4 cm) and depth cores (sediment depths 0–2, 2–5, 5–10, 10–20 and 20–30 cm). These were analysed using 25 μm resolution μFTIR, with spectral maps processed using siMPle software. Microplastics were prevalent across the sites with an abundance range (limit of detection (LOD) blank-corrected) of < LOD to 17137 microplastics kg−1 dw found on the east side of the atoll. However, their abundances varied greatly between the replicate samples. Polyethylene and polypropylene were the most commonly detected polymers overall, although the dominant polymer type varied between sites. There were no differences in the abundance of microplastics between sites, nor could abundance distributions be explained by seagrass cover. However, abundances of microplastics were highest in sediments with lower proportions of fine grained particles (clay, <4 μm) suggesting that hydrodynamics override seagrass effects. Additionally, no patterns were seen between microplastic abundance and depth of sediment. This suggests that microplastic abundance and distribution in seagrass meadows may vary significantly depending on the specific geographical locations within those meadows, and that more complex hydrodynamic factors influence spatial variability at a localised scale.

Microplastic pollutants in sediments from a water supply reservoir: Spatial heterogeneity in abundance, characteristics and pollution evaluation

When assessing microplastics (MPs) in freshwater ecosystems, previous studies have primarily focused on natural rivers and lakes, with limited attention to urban water source areas. Sediments, recording the steady process of MPs accumulation during a long period of time, can act as an important sink for MPs. In this study, we investigated the distribution, characteristics and pollution evaluation of MP contaminants in sediments of a water supply reservoir of Hefei City (the Dafangying Reservoir). Meanwhile, the differences of MP concentrations in sediments in rural and urban areas were also compared. Our results detected five shapes, seven colors and six polymer types of MPs in sediments of the Dafangying Reservoir. Polystyrene, polyethylene and polypropylene were the most abundance types of MPs identified. The average MPs abundance of sediments in rural areas was 83.20 ± 32.99 n/100 g dry weight (d.w.), and 182.67 ± 72.21 n/100 g (d.w.) in urban areas. The total MP concentrations were significantly higher in sediments of urban sites than that in rural sites, which can be ascribed to more complex and diverse MP sources triggered by intensive anthropogenic activity in cities. Specifically, we also demonstrated significantly higher microbead abundance in urban sites, which may result from the widespread use of microbead in personal care products. Given the complexity and diversity of MPs in urban areas, we exhibited a relatively higher abundance of MPs in the Dafangying Reservoir than that in other rural larger reservoirs. According to the index of geoaccumulation, the sedimentary MPs were assessed as moderately polluted. Our study enriches valuable data on the distribution of MPs contaminants in water supply reservoir, and provides theoretical references for MPs control and management in reservoir ecosystems.

Microplastic pollution promotes soil respiration: A global-scale meta-analysis.

Microplastic (MP) pollution likely affects global soil carbon (C) dynamics, yet it remains uncertain how and to what extent MP influences soil respiration. Here, we report on a global meta-analysis to determine the effects of MP pollution on the soil microbiome and CO2 emission. We found that MP pollution significantly increased the contents of soil organic C (SOC) (21%) and dissolved organic C (DOC) (12%), the activity of fluorescein diacetate hydrolase (FDAse) (10%), and microbial biomass (17%), but led to a decrease in microbial diversity (3%). In particular, increases in soil C components and microbial biomass further promote CO2 emission (25%) from soil, but with a much higher effect of MPs on these emissions than on soil C components and microbial biomass. The effect could be attributed to the opposite effects of MPs on microbial biomass vs. diversity, as soil MP accumulation recruited some functionally important bacteria and provided additional C substrates for specific heterotrophic microorganisms, while inhibiting the growth of autotrophic taxa (e.g., Chloroflexi, Cyanobacteria). This study reveals that MP pollution can increase soil CO2 emission by causing shifts in the soil microbiome. These results underscore the potential importance of plastic pollution for terrestrial C fluxes, and thus climate feedbacks.

Influence of microplastic pollution on the toxicity of potamodromous fish grass carp (Ctenopharyngodon idellus) and its swimming capacity

Microplastics (MPs), as a ubiquitous environmental contaminant in marine and freshwater systems, produced a significant influence on the physiological characteristics of aquatic organisms, and inevitably posed unknown effects on their swimming capacity. Herein, we evaluated the MPs accumulation in potamodromous fish, Ctenopharyngodon idellus, and their potential effects on oxidative stress, neurotoxicity, gut microbial diversity, and swimming capability through a toxic-control experiment. Juvenile fish were exposed to 5 µm polystyrene-MPs (PS-MPs) for 6 days at concentrations of 0.1, 1, and 10 mg/L. Exposure to PS-MPs resulted in significant inhibition of acetylcholinesterase (AChE) in the brain of fish, with significant increases in superoxide dismutase (SOD) activity and malondialdehyde (MDA) levels at 1 and 10 mg/L exposures. Meanwhile, MPs altered grass carp gut microbiota and reduced the Shannon diversity index. In addition, MPs significantly increased induced swimming speed by observing the flow rate at which grass carp happened to produce a reverse current behavioral response. The 1 and 10 mg/L of MPs treatments can significantly reduce the critical swimming speed of grass carp, meaning that the completion of the life history of grass carp may be delayed. Furthermore, there were significant correlations between biomarkers and indicators of swimming capacity. Therefore, the present study suggests that MPs produced a negative effect on the physiological properties of fish, reducing the swimming capacity of migratory fish.

Assessment of microplastic occurrence in tidal flat biota of the Tsurumi River estuary (Tokyo Bay, Japan): Preliminary study and first evidence

As concerns grow over the detrimental impacts of microplastics (MPs) on aquatic ecosystems, understanding their dynamics in Japanese biota has become increasingly urgent. We identified and compared MPs (diameter 20–5000 µm) in 11 organisms (fish, invertebrates, and a macroalga) and in sediments in the Tsurumi River estuary, Japan. A total of 1260 MPs were detected across all samples. The most common polymer was polyethylene (n = 492), followed by polypropylene (136) and polyamide (120). The mass concentration of MPs entangled in macroalgae was approximately two orders of magnitude higher than in sediment by wet weight. While there seemed to be no indication of increased bioaccumulation of MPs via trophic transfer, the results suggest that MP accumulation in macroalgae might play an important role in adverse effects of MPs on tidal flat organisms. Due to additional technical challenges, we were unable to process many samples. Further work is needed to clarify the dynamics of MPs in this area.

Dampak Mikroplastik terhadap Ekosistem Pesisir: Sebuah Telaah Pustaka

Microplastics can cause physical, chemical, and biological damage to marine organisms. Small microplastic particles can become trapped in the tissues of organisms or be ingested by marine biota, causing physical injuries and even death. The findings of this study are expected to provide information to companies, governments, and the public regarding the impact of microplastics on coastal ecosystems, as well as recommendations for solutions that can be implemented to minimize the pollution impact. The study results indicate that microplastics can also absorb hazardous chemicals and pollutants, which can enter the bodies of marine organisms and cause toxicity. The accumulation of microplastics in the bodies of organisms can impact higher-level organisms in the food chain, including humans. In this regard, recommendations for strategies and public awareness are necessary to safeguard the environment and ensure a healthy life. The public should play an active role in controlling environmental impacts, reducing the use of single-use plastics, and implementing proper waste management systems. Additionally, governments need to create effective national policies for managing plastic waste, implementing the 4R hierarchy, and educating the public to increase awareness of the negative impacts of microplastics on coastal ecosystems. Lastly, continuous research and monitoring of microplastics in coastal ecosystems are necessary to develop more effective control strategies.

Performance of bioretention systems by umbrella plant (Cyperus alternifolius L.) and common reed (Phragmites australis) for removal of microplastics

Domestic wastewater is one of the main sources of microplastic (MP) contamination in aquatic environment; however, most wastewater treatment plants (WWTPs) have not been designed for the removal of MPs. In this study, the release rate of MPs in the treated water from a WWTP into the river was estimated to be approximately 105 × 103 pcs/capita/day. Thus, bioretention systems are designed as tertiary wastewater treatment systems to reduce the number of MPs in water resources. The objective of this study was to evaluate the performance of bioretention systems using the umbrella plant (Cyperus alternifolius L.) and common reed (Phragmites australis) for MP removal. After 17 weeks, MPs were found in the common reed bioretention system. The common reed root system and substrate influence the MP retention process to a greater extent through physical filtration, substrate ratio, plant roots, and biofilms on the roots. Additionally, the common reed root system played an important role in the removal of low-density MPs. The accumulation of MPs in roots and root hairs inevitably impacts plants. The results showed that the common reed at a 3:2:9 ratio (gravel: sand: soil) had the highest relative height growth rate (RHGR) (1.8 mm cm−1 week−1). These results show that the HSFs–3 at a ratio of 3:2:9 was able to reduce the number of MPs, with an average removal efficiency of 62.89 % and 95.45 % for sizes >1000 µm, 89.21 % for sizes 500–1000 µm, and 44.16 % for sizes <500 µm. The highest average microbeads removal efficiency was 95.24 %. Our results suggest that plant bioretention using Horizontal Subsurface Flow system is an effective treatment for removing MPs from wastewater.

Eastern oyster (Crassostrea virginica) shows physiological tolerance to polyester microfibers at environmental concentrations

Significant research has shown that microplastics are ubiquitous within the marine environment, organisms are interacting with microplastics regularly, and microplastics at high concentrations can have significant impacts on organismal physiology and health. However, the potential impacts of this pervasive pollutant on organismal physiology at environmentally relevant concentrations is less well studied. To this aim, we exposed eastern oysters, Crassostrea virginica to daily doses (45 d total exposure) of polyester microfibers (mean ± 1 SE: length = 662 ± 2 μm; width 16 ± 1 μm, n = 300 fibers, 1.38 g cm−3 density) at environmentally relevant concentrations (0, 2, and 95 fibers L−1) as well as a high exposure concentration (950 fibers L−1) to represent potential future microplastic increases. We quantified physiological responses in five key parameters: somatic growth, survival rate, clearance rate, plastic accumulation in somatic tissues, and cellular energy allocation (CEA). No significant responses were observed in any of these important physiological parameters, suggesting that polyester microfibers at current environmental concentrations appear to pose minimal threat to the physiological well-being of C. virginica within these study conditions. Substantial variation was observed in the number of fibers that accumulated per oyster ranging from 0 to 58 fibers per individual. This relatively broad range of fiber accumulation demonstrates individualistic interactions between oysters and microplastics, highlighting the need for sufficient sample sizes when investigating microplastic accumulation within somatic tissues in order to capture individual variance. Our study also highlights the importance of characterizing microplastic behavior (i.e., suspension time in water) in exposure studies to better understand actual exposure patterns and experimental outcomes. Results from our study demonstrate the critical importance of considering environmental relevance, in terms of exposure concentration, polymer type and particle sinking behavior, when conducting exposure studies and interpreting potential impacts of microplastics on organismal physiology. Our work provides novel information regarding the physiological responses of C. virginica when exposed to environmentally relevant microplastic pollution levels. Such information is beneficial for improving the design of future exposure studies to build upon and vital for understanding the current risk microplastics may pose to marine species and developing management strategies to deal with this emerging pollutant.

Centennial Records of Microplastics in Lake Cores in Huguangyan Maar Lake, China.

Microplastic records from lake cores can reconstruct the plastic pollution history. However, the associations between anthropogenic activities and microplastic accumulation are not well understood. Huguangyan Maar Lake (HML) is a deep-enclosed lake without inlets and outlets, where the sedimentary environment is ideal for preserving a stable and historical microplastic record. Microplastic (size: 10-500 μm) characteristics in the HML core were identified using the Laser Direct Infrared Imaging system. The earliest detectable microplastics appeared unit in 1955 (1.1 items g-1). The microplastic abundance ranged from n.d. to 615.2 items g-1 in 1955-2019 with an average of 134.9 items g-1. The abundance declined slightly during the 1970s and then increased rapidly after China's Reform and Opening Up in 1978. Sixteen polymer types were detectable, with polyethylene and polypropylene dominating, accounting for 23.5 and 23.3% of the total abundance, and the size at 10-100 μm accounted for 80%. Socioeconomic factors dominated the microplastic accumulation based on the random forest modeling, and the contributions of GDP per capita, plastic-related industry yield, and total crop yield were, respectively, 13.9, 35.1, and 9.3% between 1955-2019. The total crop yield contribution further increased by 1.7% after 1978. Coarse sediment particles increased with soil erosion exacerbated microplastics discharging into the sediment.

Effect of Low-density Polyethylene Microplastics on Natural Attenuation of Oxygenated Polycyclic Aromatic Hydrocarbons in Soil

The continuous accumulation of microplastics in agricultural soils may affect the natural attenuation of oxygen-containing polycyclic aromatic hydrocarbons (OPAHs). The effects of low-density polyethylene (LDPE) microplastics with the spiking proportion of 1 % and 0.01 % in soils on the natural attenuation of OPAHs were investigated via soil microcosm experiments. The relation between the response of bacterial communities and OPAHs dissipation was also explored. The initial content of OPAHs in the soil was 34.6 mg·kg-1. The dissipation of OPAHs in the soil on day 14 was inhibited by LDPE. The contents of OPAHs in LDPE groups were higher than that in the control by 0.9-1.6 mg·kg-1, and the inhibition degree increased with the proportion of LDPE. The contents of OPAHs were not significantly different among groups on day 28, indicating that the inhibitory effect of LDPE disappeared. LDPE did not change the composition of the dominant taxa in the OPAHs-contaminated soil community but influenced the relative abundances of some dominant taxa. LDPE increased the relative abundance of Proteobacteria and Actinobacteria at the phylum level and decreased that of Bacillus and increased those of Micromonospora, Sphingomonas, and Nitrospira (potential degrading bacteria of LDPE and endogenous substances) at the genus level, all four of which were the main genera dominating intergroup community differences. LDPE changed the α and β diversity of bacterial communities, but the extents were not significant. LDPE affected the function of the bacterial community, reducing the total abundance of PAHs-degrading genes and some degrading enzymes, inhibiting the growth of PAHs-degrading bacteria and thus interfering with the natural decay of OPAHs.

The accumulation of microplastics in fish freshwater in the Mun river, Thailand

Background: Microplastic pollution mainly occurs from terrestrial sources, but research on plastic contamination in aquatic environments is limited. Freshwater fish are widely consumed throughout Southeast Asia. Microplastic contamination is becoming an important issue that leads to human health risks from consumption. Objectives: The study aimed to determine the accumulation of microplastics ingested by fish in freshwater in the Mun River. Methods: Freshwater fishes in the Mun River caught by local fishermen and the most dominant species consumed in the Mun River include Paralaubuca typus, Phalacronotus bleekeri, and Morulius chrysophekaion. Twenty-four samples from each species were collected. Microplastics in these species were analysed for abundance, size, shape, color, and type of polymer. Results: The results showed that the average amounts of microplastic contamination in the gastrointestinal tracts (GIT) and gills of Morulius chrysophekadion were 17.70±8.20 pieces/fish, Phalacronotus bleekeri were 11.83±8.74 pieces/fish, and Paralaubuca typus were 10.25±7.56 pieces/fish, respectively. The average number of microplastics found in the urban area was 26.50±4.21 pieces/fish; in the agricultural area, it was 9.77±4.10 pieces/fish; in the confluence of the Mun and Chi River areas, it was 9.50±3.51 pieces/fish; and the natural area had 7.27±4.15 pieces/fish, respectively. The average size of microplastics found in fish was 878.29±904.41μm. The most common polymer type microplastic was polyethylene (PE) where the most common shape was Fiber-shaped, and the most common colour was blue. Conclusion: The study findings indicate a prevalent form of microplastic accumulation in three fish species especially among Morulius chrysophekaion. And findings show that every fish species in the urban area have the most contamination. As a result, fish GIT and gills should be removed before consumption to reduce exposure to microplastics instead of consuming them.

Ingestion of polyethylene terephthalate microplastic water contaminants by Xenopus laevis tadpoles negatively affects their resistance to ranavirus infection and antiviral immunity

Small plastic debris (0.1 μm–5 mm) or microplastics (MPs) have become major pollutants of aquatic ecosystems worldwide and studies suggest that MPs exposure can pose serious threats to human and wildlife health. However, to date the potential biological impacts of MPs accumulating in low amount in tissues during early life remains unclear. Here, for a more realistic assessment, we have used environmentally representative, mildly weathered, polyethylene terephthalate microplastics (PET MPs), cryomilled (1–100 μm) and fluorescently labelled. We leveraged the amphibian Xenopus laevis tadpoles as an animal model to define the biodistribution of PET MPs and determine whether exposure to PET MPs induce perturbations of antiviral immunity. Exposure to PET MPs for 1–14 days resulted in detectable PET MPs biodistribution in intestine, gills, liver, and kidney as determined by fluorescence microscopy on whole mount tissues. PET MPs accumulation rate in tissues was further evaluated via a novel in situ enzymatic digestion and subsequent filtration using silicon nanomembranes, which shows that PET MPs rapidly accumulate in tadpole intestine, liver and kidneys and persist over a week. Longer exposure (1 month) of tadpoles to relatively low concentration of PET MPs (25 μg/ml) significantly increased susceptibility to viral infection and altered innate antiviral immunity without inducing overt inflammation. This study provides evidence that exposure to MPs negatively impact immune defenses of aquatic vertebrates.