Microplastics in coastal blue carbon ecosystems: A global Meta-analysis of its distribution, driving mechanisms, and potential risks

Retention of microplastics in Halophila decipiens seagrass meadows

Microplastic (MP) trapping and storage by seagrasses and sediments highlight their role as potential long-term reservoirs for plastic particles. This study evaluated the presence of MPs in Halophila decipiens meadows and its associated sediments in two localities, Pichilingue and Los Aripes, in the southwest Gulf of California. At each locality, 12 samples were collected along two 30-m transects: six from vegetated and six from unvegetated sites. At Pichilingue, 93 items were found on H. decipiens, with a maximum of 46 items on roots, with films and fibers being the main MP forms and black the most frequent color. For sediments, an average of 231 ± 145 items kg-1 DW was estimated; the vegetated site showed 406 ± 184 items kg-1 DW, with black films (1016 items) as the most abundant items, while the unvegetated site showed 56 ± 11 items kg-1 DW, with transparent fragments (25 items) as the dominant items. The main MP type was polyethylene (38 items). At Los Aripes, MPs were not found on any structure of H. decipiens; but in sediments, the average was 17 ± 7 items kg-1 DW, with 13 ± 3 items kg-1 DW in the vegetated site and black and blue fibers (seven items each) as the dominant items, and 21 ± 10 items kg-1 DW in the unvegetated site and blue fibers (16 items) as the dominant items. The main MP type was polyethylene terephthalate. This research provides insight into the capacity of sediments and H. decipiens structures (leaves, petioles, rhizomes, and roots) to retain MPs derived from local human activities and the effect of environmental factors.

DNA methylation regulates somatic stress memory and mediates plasticity during acclimation to repeated sulfide stress in Urechis unicinctus

Stress memory is an adaptive mechanism that enables organisms to develop resilience in response to environmental changes. Among them, somatic stress memory is an important means for organisms to cope with contemporary repeated stress, and is accompanied by transcription memory. Sulfide is a common environmental pollutant; however, some organisms have adapted to survive in sulfur-rich environments. Urechis unicinctus is a sulfur-tolerant organism that enhances sulfide stress tolerance by establishing a somatic sulfide stress memory mechanism. However, the molecular mechanisms that regulate sulfide stress memory remain unclear. To explore whether epigenetics, which plays a role in the response of organisms to environmental stress, is involved in regulating somatic sulfide stress memory, we performed a combined analysis of DNA methylation and transcriptome data. We found that elevated levels of DNA methylation under repetitive sulfide stress regulated gene expression and resulted in enhanced sulfide stress tolerance in U. unicinctus, a phenomenon verified using DNA methylase inhibitors. Transcriptional memory can be induced in genes related to oxidative stress, regulation of autophagy, and maintenance of protein homeostasis by altering the level of DNA methylation to facilitate sulfide stress acclimation. Our results provide new insights into adaptive mechanisms to cope with environmental fluctuations.

Microplastics in China's surface water systems: Distribution, driving forces and ecological risk

Comprehensively understanding the distribution, driving forces and ecological risk of microplastics (MPs) in China's surface water systems is crucial for future prevention and control of MPs pollution, particularly in the context of regional differences. Nevertheless, traditionally localized investigation and the limited MPs data availability hinder more comprehensive estimation of MPs pollution in surface water systems of China. This study presents a robust dataset, which consists of 14285 samples from 32 provincial districts, describing the MPs pollution characteristics using a data mining method combined with a machine learning model. The results show that the developed model has high accuracy in predicting the abundance, colors, shapes, and polymer types of MPs, with the coefficient of determination (R2) ranging from 0.825 to 0.978. MPs abundance varied greatly in China's surface water systems, ranging over 1-5 orders of magnitude due to the complex influence of anthropogenic activities and natural conditions. Human activities and natural conditions mutually impact the dynamics of MPs in China's surface water systems. Watersheds in almost all provinces of China are contaminated by high and extremely high ecological risk levels, highlighting the urgency for sustainable MPs management.

Coastal populations and river discharges as sources of microplastic pollution of the Ciénaga Grande de Santa Marta, Colombian Caribbean

The large-scale production of plastic began in the 1950s, leading to a significant global increase and has become one of the world's major problems since its disintegration generates small particles of microplastics (MPs), considered pollutants of emerging concern, which are commonly found in most ecosystems. In Colombia, research on microplastics (MPs) in coastal ecosystems is still in its early stages. This study seeks to advance understanding of MPs contamination in surface waters of the Ciénaga Grande de Santa Marta (CGSM), the most significant coastal lagoon in the Colombian Caribbean, which has been designated both a Biosphere Reserve and a Ramsar site of international importance. The study focuses on examining the relationship between MP pollution and two primary sources: coastal populations and discharges from tributary rivers into the lagoon system. Water samples were collected at 33 stations during the dry season (March 2021) and rainy season (May 2021), and MPs were identified and quantified by microscopy. The effect of the distance from river mouths (km) and populated zones (km) on the abundance of MPs was evaluated by applying a Generalized Additive Model (GAM) in R. The study revealed that the abundance of MPs was significantly influenced by proximity to pollution sources, with higher concentrations observed closer to river mouths and coastal settlements during both dry and rainy seasons. The seasonal composition of MP in the two studied zones reveals a consistent prevalence of filaments during the seasons, indicating the persistent influence of various sources of contamination. The findings show that inadequate waste management practices and the lack of proper infrastructure for waste disposal are key factors contributing to microplastic pollution in the area. The study provides critical insights for addressing deficiencies in waste management while promoting active community engagement to preserve the ecological and socioeconomic value of this vital lagoon complex. The CGSM is not only a key coastal ecosystem in Colombia but also supports diverse livelihoods and cultural heritage, emphasizing the importance of sustainable management.

N6-methyladenosine RNA methylation regulates microplastics-induced cell senescence in the rainbow trout liver

Microplastics are prevalent in aquatic ecosystems, impacting various forms of aquatic life, including fish. In this study, Rainbow trout (Oncorhynchus mykiss) were exposed to two concentrations of microplastics (0 and 500 μg/L) over a 14-day period, during which a comprehensive analysis was conducted to assess the liver accumulation of microplastics and their effects on oxidative stress, the liver response, and transcriptomics. Our findings indicated that microplastics significantly accumulated in the liver and activated the antioxidant system in fish by enhancing the activity of antioxidant enzymes. Histological lesions were also observed in the liver of the fish. Furthermore, microplastics induced alterations in the expression of hepatic N6-methyladenosine readers, specifically downregulating IGF2BP1 (encoding insulin like growth factor 2 mRNA binding protein 1) and upregulating YTHDF2 (encoding YTH N6-methyladenosine RNA binding protein F2), which in turn decreased mRNA stability and reduced the expression of C-myc and other regulatory factors involved in the cell cycle and proliferation. This sequence of events resulted in slowed cell proliferation, the induction of cell cycle arrest, and the promotion of cellular senescence. This study offers valuable insights into the toxicological mechanisms of microplastics and enhances our understanding of the threats that plastic pollution poses to freshwater organisms.

The combined effects of microplastics and their additives on mangrove system: From the sinks to the sources of carbon

Mangrove ecosystems, a type of blue carbon ecosystems (BCEs), are vital to the global carbon cycle. However, the combined effects of microplastics (MPs) and plastic additives on carbon sequestration (CS) in mangroves remain unclear. Here, we comprehensively review the sources, occurrence, and environmental behaviors of MPs and representative plastic additives in mangrove ecosystems, including flame retardants, such as polybrominated diphenyl ethers (PBDEs), and plasticizers, such as phthalate esters (PAEs). Mangrove ecosystems have a complex influence on the behaviors of MPs and additives. Under the action of natural and unnatural factors, these pollutants exhibit complex behaviors including migration, interception, deposition and transformation, that are closely linked to those of particulate carbon, particularly carbon sequestration processes. MPs and additives hinder the CS function of mangroves by harming the growth of flora and fauna, influencing microbial nitrogen and sulfur cycles, and enhancing the degradation of organic matter in the sediment. The increasing accumulation and widespread occurrence of MPs and additives will greatly influence the carbon cycle. Future work is encouraged on systematic investigation of new alternatives to plastics and additives, and research methods to uncover the impact mechanisms of MPs and additives on BCEs. The developments of management measures and engineering technologies are also required to enhance pollutant control and mangrove CS.

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.

ZIF-8 functionalized S-tapered fiber-optic sensor for polystyrene nanoplastics detection by electrostatic adsorption

Microplastic (MP) residues in marine have become an increasingly serious environmental pollution issue, and in recent years the detection of MPs in marine started to attract worldwide research interests. Optical-fiber-based environmental sensors have been extensively employed for their several merits such as high sensitivity, pressure resistance, compactness and ease of constructing communication networks. However, fiber-optic refractive index sensors are not specifically developed for distinguishing MPs from other inorganic particles suspended in water. In this paper, an metal-organic framework (MOF) ZIF-8 functionalized S-tapered fiber (STF) sensor is proposed for specific detection of polystyrene nanoplastics (PSNPs) in aqueous environment. ZIF-8 coordination nanoporous polymers with different film thickness were immobilized over the surface of the fabricated STF structure based on self-growth technique and yielding a large surface area over the sensor surface. High sensitivity detection can be achieved by converting the concentration perturbation of PSNPs into evanescent waves over the ZIF-8 functionalized STF surface through the strong electrostatic adsorption effect and π-π stacking, while the fabricated sensor is insensitive to gravels with silica as the primary component in water. It is found that the proposed detector with 18 film layers achieves a sensitivity up to 114.1353nm/%(w/v) for the PSNPs concentration range of 0.01 %(w/v) to 0.08 %(w/v).

Bioaccumulation of polycyclic aromatic hydrocarbons and their human health risks depend on the characteristics of microplastics in marine organisms of Sanggou Bay, China

Microplastics pose a threat to marine environments through their physical presence and as vectors of chemical pollutants. However, the impact of microplastics on the accumulation and human health risk of chemical pollutants in marine organisms remains largely unknown. In this study, we investigated the microplastics and polycyclic aromatic hydrocarbons (PAHs) pollution in marine organisms from Sanggou Bay and analyzed their correlations. Results showed that microplastic and PAHs concentration ranged from 1.23 ± 0.23 to 5.77 ± 1.10 items/g, from 6.98 ± 0.45 to 15.07 ± 1.25 μg/kg, respectively. The microplastic abundance, particularly of fibers, transparent and color plastic debris, correlates strongly with PAH contents, indicating that microplastics increase the bioaccumulation of PAHs and microplastics with these characteristics have a significant vector effect on PAHs. Although consuming seafood from Sanggou Bay induce no carcinogenic risk from PAHs, the presence of microplastics in organisms can significantly increases incremental lifetime cancer risk of PAHs. Thus, microplastics can serve as transport vectors for PAHs with implications for the potential health risks to human through consumption. This study provides new insight into the risks of microplastics in marine environments.

Navigating the nexus: climate dynamics and microplastics pollution in coastal ecosystems

Microplastics (MPs) pollution is an emerging environmental health concern, impacting soil, plants, animals, and humans through their entry into the food chain via bioaccumulation. Human activities such as improper solid waste dumping are significant sources that ultimately transport MPs into the water bodies of the coastal areas. Moreover, there is a complex interplay between the coastal climate dynamics, environmental factors, the burgeoning issue of MPs pollution and the complex web of coastal pollution. We embark on a comprehensive journey, synthesizing the latest research across multiple disciplines to provide a holistic understanding of how these inter-connected factors shape and reshape the coastal ecosystems. The comprehensive review also explores the impact of the current climatic patterns on coastal regions, the intricate pathways through which MPs can infiltrate marine environments, and the cascading effects of coastal pollution on ecosystems and human societies in terms of health and socio-economic impacts in coastal regions. The novelty of this review concludes the changes in climate patterns have crucial effects on coastal regions, proceeding MPs as more prevalent, deteriorating coastal ecosystems, and hastening the transfer of MPs. The continuous rising sea levels, ocean acidification, and strong storms result in habitat loss, decline in biodiversity, and economic repercussion. Feedback mechanisms intensify pollution effects, underlying the urgent demand for environmental conservation contribution. In addition, the complex interaction between human, industry, and biodiversity demanding cutting edge strategies, innovative approaches such as remote sensing with artificial intelligence for monitoring, biobased remediation techniques, global cooperation in governance, policies to lessen the negative socioeconomic and environmental effects of coastal pollution.

Adverse effects and potential mechanisms of polystyrene microplastics (PS-MPs) on the blood-testis barrier

Microplastics (MPs) are defined as plastic particles or fragments with a diameter of less than 5 mm. These particles have been identified as causing male reproductive toxicity, although the precise mechanism behind this association is yet to be fully understood. Recent research has found that exposure to polystyrene microplastics (PS-MPs) can disrupt spermatogenesis by impacting the integrity of the blood-testis barrier (BTB), a formidable barrier within mammalian blood tissues. The BTB safeguards germ cells from harmful substances and infiltration by immune cells. However, the disruption of the BTB leads to the entry of environmental pollutants and immune cells into the seminiferous tubules, resulting in adverse reproductive effects. Additionally, PS-MPs induce reproductive damage by generating oxidative stress, inflammation, autophagy, and alterations in the composition of intestinal flora. Despite these findings, the precise mechanism by which PS-MPs disrupt the BTB remains inconclusive, necessitating further investigation into the underlying processes. This review aims to enhance our understanding of the pernicious effects of PS-MP exposure on the BTB and explore potential mechanisms to offer novel perspectives on BTB damage caused by PS-MPs.

Unveiling microplastics pollution in a subtropical rural recreational lake: A novel insight

While global attention has been primarily focused on the occurrence and persistence of microplastics (MP) in urban lakes, relatively little attention has been paid to the problem of MP pollution in rural recreational lakes. This pioneering study aims to shed light on MP size, composition, abundance, spatial distribution, and contributing factors in a rural recreational lake, 'Nikli Lake' in Kishoreganj, Bangladesh. Using density separation, MPs were extracted from 30 water and 30 sediment samples taken from ten different locations in the lake. Subsequent characterization was carried out using a combination of techniques, including a stereomicroscope, Fourier transform infrared spectroscopy (FTIR) and field emission scanning electron microscopy (FE-SEM). The results showed a significant prevalence of MPs in all samples, with an average amount of 109.667 ± 10.892 pieces/kg3 (dw) in the sediment and 98.167 ± 12.849 pieces/m3 in the water. Small MPs (<0.5 mm), fragments and transparent colored particles formed the majority, accounting for 80.2%, 64.5% and 55.3% in water and 78.9%, 66.4% and 64.3% in sediment, respectively. In line with global trends, polypropylene (PP) (53%) and polyethylene (PE) (43%) emerged as the predominant polymers within the MPs. MP contents in water and sediment showed positive correlations with outflow, while they correlated negatively with inflow and lake depth (p > 0.05). Local activities such as the discharge of domestic sewage, fishing waste and agricultural runoff significantly influence the distribution of polypropylene. Assessment of pollution factor, pollution risk index and pollution load index values at the sampling sites confirmed the presence of MPs, with values above 1. This study is a baseline database that provides a comprehensive understanding of MP pollution in the freshwater ecosystem of Bangladesh, particularly in a rural recreational lake. A crucial next step is to explore ecotoxicological mechanisms, legislative measures and future research challenges triggered by MP pollution.

Effects of Microplastics on the Transport of Soil Dissolved Organic Matter in the Loess Plateau of China

Microplastics (MPs) pollution and dissolved organic matter (DOM) affect soil quality and functions. However, the effect of MPs on DOM and underlying mechanisms have not been clarified, which poses a challenge to maintaining soil health. Under environmentally relevant conditions, we evaluated the major role of polypropylene particles at four micron-level sizes (20, 200, and 500 μm and mixed) in regulating changes in soil DOM content. We found that an increase in soil aeration by medium and high-intensity (>0.5%) MPs may reduce NH4+ leaching by accelerating soil nitrification. However, MPs have a positive effect on soil nutrient retention through the adsorption of PO43- (13.30-34.46%) and NH4+ (9.03-19.65%) and their leached dissolved organic carbon (MP-leached dissolved organic carbon, MP-DOC), thereby maintaining the dynamic balance of soil nutrients. The regulating ion (Ca2+) is also an important competitor in the MP-DOM adsorption system, and changes in its intensity are dynamically involved in the adsorption process. These findings can help predict the response of soil processes, especially nutrient cycling, to persistent anthropogenic stressors, improve risk management policies on MPs, and facilitate the protection of soil health and function, especially in future agricultural contexts.

The impact of microplastics on bivalve mollusks: A bibliometric and scientific review

Bivalves are important members of the ecosystem and their populations are declining globally, making them a concern for their role in ecosystem services and the fishing industry. Bivalves are excellent bioindicators of MPs pollution due to their widespread distribution, filtering capabilities, and close association with human health. Microplastics (MPs) have direct and indirect impacts on bivalves, affecting their physiology, habitat structure, food sources, and persistence of organic pollutants. This review provides an extensive overview of the impact of MPs on bivalves, covering various aspects such as their economic significance, ecological roles, and importance in biomonitoring environmental quality. The article presents the current state of knowledge on the sources and pathways of MPs in aquatic environments and their effects on bivalves. The mechanisms underlying the effects of MPs on bivalves, including ingestion, filtration activity, feeding inhibition, accumulation, bioaccumulation, and reproduction, are also discussed. Additionally, a bibliometric analysis of research on MPs in bivalves is presented, highlighting the number of papers, geographical distribution, and keyword clusters relating to MPs. Finally, the review emphasizes the importance of ongoing research and the development of mitigation strategies to reduce the negative effects of MPs pollution on bivalves and their habitats in oceans and coastal waters.