The deep sea is a major sink for microplastic debris

Microplastic ingestion and its effects οn sea urchin Paracentrotus lividus: A field study in a coastal East Mediterranean environment

Microplastics (MPs) are recognized as an increasing threat to the marine environment, but little is known about their effects on benthic organisms, including sea urchins, when ingested. For this purpose, wild sea urchins (P. lividus) and seafloor sediment samples were investigated across three coastal areas of Zakynthos Island (Ionian Sea), each exposed to different anthropogenic pressures, revealing a consistent pattern in MP abundance, shape, and color. Biomarkers related to oxidative stress, neurotoxicity, and genotoxicity showed no significant effects of MP ingestion in the sea urchins, except for a positive correlation between GST activity and ingested MPs, suggesting a possible activation of their detoxification system in response to MP ingestion. While MP concentrations in sea urchins and sediments were within the low range reported in the global literature, it remains crucial to conduct further investigations in areas with MP pollution approaching predicted levels to fully comprehend the potential effects of MP pollution on marine organisms.

Hotspots of microplastic accumulation at the land-sea transition and their spatial heterogeneity: The Po River prodelta (Adriatic Sea)

Deltas are the locus of river-borne sediment accumulation, however, their role in sequestering plastic pollutants is still overlooked. By combining geomorphological, sedimentological, and geochemical analyses, which include time-lapse multibeam bathymetry, sediment provenance, and μFT-IR analyses, we investigate the fate of plastic particles after a river flood event providing an unprecedented documentation of the spatial distribution of sediment as well as of microplastics (MPs), including particles fibers, and phthalates (PAEs) abundances in the subaqueous delta. Overall sediments are characterized by an average of 139.7 ± 80 MPs/kg d.w., but display spatial heterogeneity of sediment and MPs accumulation: MPs are absent within the active sandy delta lobe, reflecting dilution by clastic sediment (ca. 1.3 Mm3) and sediment bypass. The highest MP concentration (625 MPs/kg d.w.) occurs in the distal reaches of the active lobe where flow energy dissipates. In addition to MPs, cellulosic fibers are relevant (of up to 3800 fibers/kg d.w.) in all the analyzed sediment samples, and dominate (94 %) with respect to synthetic polymers. Statistically significant differences in the relative concentration of fiber fragments ≤0.5 mm in size were highlighted between the active delta lobe and the migrating bedforms in the prodelta. Fibers were found to slightly follow a power law size distribution coherent with a one-dimensional fragmentation model and thus indicating the absence of a size dependent selection mechanism during burial. Multivariate statistical analysis suggests traveling distance and bottom-transport regime as the most relevant factors controlling particle distribution. Our findings suggest that subaqueous prodelta should be considered hot spots for the accumulation of MPs and associated pollutants, albeit the strong lateral heterogeneity in their abundances reflects changes in the relative influence of fluvial and marine processes.

Microplastics in marine-derived traditional Chinese medicine, potential threat to patients

Microplastics (MPs) contamination is widely found in marine organisms. Marine traditional Chinese medicines (MTCM) are derived from marine organisms, but there are no relevant reports on detecting MPs in MTCM. This study selected samples of MTCM from two representative pharmaceutical companies, Brand F and Brand Z, including mother-of-pearl, stone cassia, seaweed, pumice, oyster, kombu, calcined Concha Arcae, cuttlebone, and clam shell to detect and analyze the presence of MPs. The abundance, type, color, size, and composition of MPs were investigated. Varying degrees of MPs contamination was present in all MTCM. The abundance of MPs in different MTCM ranged from 0.07 to 9.53 items/g. Their type, color, and size are similar, mainly fiber, transparent and size <2 mm. The composition of MPs is primarily made of cotton, cellulose and rayon. This study contributes to the first record of MPs in MTCM. Our results show that microplastic pollution is common in MTCM, which may cause potential risk to patients consuming MTCM.

The co-presence of polystyrene nanoplastics and ofloxacin demonstrates combined effects on the structure, assembly, and metabolic activities of marine microbial community

Nanoplastic is increasing in environments and can address toxic effects on various organisms. Particle size, concentration, and surface functionalization most influence nanoplastic toxicity. Besides, nanoplastic can adsorb other contaminants (e.g., antibiotics) to aggravate its adverse effects. The combined effects of nanoplastics and antibiotics on planktonic/benthic microbial communities, however, are still largely unknown. In this study, the combined effects of polystyrene nanoplastic and ofloxacin on the structure, assembly, and metabolic activities of marine microbial communities were investigated based on amplicon sequencing data. The results mainly demonstrate that: (1) nanoplastic and ofloxacin have greater impacts on prokaryotic communities than eukaryotic ones; (2) niche breadths of planktonic prokaryotes and benthic eukaryotes were shrank with both high nanoplastic and ofloxacin concentrations; (3) increased ofloxacin mainly reduces nodes/edges of co-occurrence networks, while nanoplastic centralizes network modularity; (4) increased nanoplastic under high ofloxacin concentration induces more differential prokaryotic pathways in planktonic communities, while benthic communities are less influenced. The present work indicates that co-presence of nanoplastics and ofloxacin has synergistic combined effects on community structure shifts, niche breadth shrinking, network simplifying, and differential prokaryotic pathways inducing in marine microbial communities, suggesting nanoplastics and its combined impacts with other pollutions should be paid with more concerns.

Microplastic patterns in riverine waters and leaf litter: Leaf bag technique to investigate the microplastic accumulation trends in lotic ecosystems

Microplastics (MPs) are one of the major ecological concerns of the last years and despite the increasing interest and the rise of many studies regarding freshwater habitats, many aspects about distribution patterns, transport pathways and impacts of MPs in those systems need to be investigated. The present study characterizes the temporal trends of MP concentrations in waters of a riverine stretch of the northeastern Italy, subject to flow rate variations and investigates the MP accumulations patterns in the leaf litter, simulated in situ via leaf bag technique. MP concentrations in the water were significantly and negatively correlated to the flow rate regimes, with higher concentrations observed during low discharge periods. MPs accumulation in leaf bags agreed with trends observed in the water and the presence of wastewater discharge points positively affects the levels of MP contaminations within the leaf bags. These findings seem to suggest that the maintenance of a hydrological regime at relatively high levels in the investigated system could allow to maintain the self-purifying riverine processes and the disposal of microplastics like any other polluting substance. The use of leaf bag technique for the purpose to investigate MP accumulation trends on field provided useful information, is easy to modulate in terms of time periods and allow to record the evolution of the MP patterns also in relation to high flow rate episodes. Our results suggest that the method can be employed in new a perspective, to improve the knowledge about one of the major threats of the Anthropocene.

The bioaccessibility of adsorped heavy metals on biofilm-coated microplastics and their implication for the progression of neurodegenerative diseases

Microplastic (MP) tiny fragments (< 5 mm) of conventional and specialized industrial polymers are persistent and ubiquitous in both aquatic and terrestrial ecosystem. Breathing, ingestion, consumption of food stuffs, potable water, and skin are possible routes of MP exposure that pose potential human health risk. Various microorganisms including bacteria, cyanobacteria, and microalgae rapidly colonized on MP surfaces which initiate biofilm formation. It gradually changed the MP surface chemistry and polymer properties that attract environmental metals. Physicochemical and environmental parameters like polymer type, dissolved organic matter (DOM), pH, salinity, ion concentrations, and microbial community compositions regulate metal adsorption on MP biofilm surface. A set of highly conserved proteins tightly regulates metal uptake, subcellular distribution, storage, and transport to maintain cellular homeostasis. Exposure of metal-MP biofilm can disrupt that cellular homeostasis to induce toxicities. Imbalances in metal concentrations therefore led to neuronal network dysfunction, ROS, mitochondrial damage in diseases like Alzheimer's disease (AD), Parkinson's disease (PD), and Prion disorder. This review focuses on the biofilm development on MP surfaces, factors controlling the growth of MP biofilm which triggered metal accumulation to induce neurotoxicological consequences in human body and stategies to reestablish the homeostasis. Thus, the present study gives a new approach on the health risks of heavy metals associated with MP biofilm in which biofilms trigger metal accumulation and MPs serve as a vector for those accumulated metals causing metal dysbiosis in human body.

Occurrence of plastics and their characterization in wild caught fish species (Labeo rohita, Wallago attu and Mystus tengara) of River Ganga (India) compared to a commercially cultured species (L. rohita)

Ganga River in India is one of the top 10 polluted rivers in the world, yet there is no information on the occurrence of plastics in its wild caught fishes compared to commercially farmed fish species. In the present study, wild fish specimens belonging to nine species were caught along the River Ganga from two locations in Patna (Bihar). Organs (gastrointestinal tract, liver, gills and muscles) of fishes were analyzed for the presence of plastics. Plastics were identified using a stereomicroscope, and polymer types were characterized through FTIR analysis. Out of the nine wild fish species, only three (Labeo rohita, Wallago attu and Mystus tengara) showed presence of plastics in them. In contrast, organs of only one commercial fish species (L. rohita) were analyzed as this was the only fish species commercially farmed and available in local fish market of Gaya (Bihar, India). Specimens of this farmed fish species were procured from selected outlets having their supply from Fish Farm of the Department of Fisheries, Government of Bihar. The average number of plastic particles per fish in wild caught and commercial fishes was found to be 2.5 ± 1.6 and 5.2 ± 2.5, respectively. Further, wild-caught fishes indicated highest presence of microplastics (78.5%), followed by mesoplastics (16.5%) and macroplastics (5.1%). In commercial fishes, presence of microplastics was much higher (99.6%). Fragments (83.5%) represented the prominent microplastic type found in wild-caught fishes while fibers (95.1%) were the major type in commercial fishes. Colored plastic particles (white and blue) were abundant. The column feeder fishes were more plastic contaminated than the bottom feeder fishes. The predominant microplastic polymer type in the Gangetic and farmed fish(es) was polyethylene and poly(ethylene-co-propylene), respectively. This study, for the first time ever, reports plastic pollution in wild fishes of River Ganga (India) compared to farmed species.

Polyester microplastic fibers induce mitochondrial damage, apoptosis and oxidative stress in Daphnia carinata, accompanied by changes in apoptotic and ferroptosis pathway

With the widespread utilization of plastic products, microplastics (MPs) have merged as a newfound environmental contaminant in the United States, and the bulk of these MPs in the environment manifest as fibrous structures. Concerns have also been voiced regarding the potential hazards posed by microplastic fibers (MFs). However, research examining the toxicity of MFs, particularly in relation to planktonic organisms, remains severely limited. Meanwhile, polyester fiber materials find extensive applications across diverse industries. As a result, this investigation delved into the toxicology of polyester microplastic fibers (PET-MFs) with a focus on their impact on Daphnia carinata (D. carinata), a freshwater crustacean. Newly hatched D. carinata were subjected to varying concentrations of PET-MFs (0, 50, and 500 MFs/mL) to scrutinize the accumulation of PET-MFs within these organisms and their resultant toxicity. The outcomes revealed that D. carinata was capable of ingesting PET-MFs, leading to diminished rates of survival and reproduction. These effects were accompanied by mitochondrial impairment, heightened mitochondrial count, apoptosis, escalated generation of reactive oxygen species, augmented activity of antioxidant enzymes, and distinct patterns of gene expression. Interestingly, when comparing the group exposed to 50 MFs/mL with the one exposed to 500 MFs/mL, it was observed that the former triggered a more pronounced degree of mitochondrial damage, apoptosis, and oxidative stress. This phenomenon could be attributed to the fact that brief exposure to 500 MFs/mL resulted in greater mortality, eliminating individuals with lower adaptability. Those that survived managed to regulate elevated in vivo reactive oxygen species levels through an increase in glutathione S-transferase content, thereby establishing an adaptive mechanism. Low concentrations did not induce direct mortality, yet PET-MFs continued to inflict harm within the organism. RNA-seq analysis unveiled significant alterations in 279 and 55 genes in the 50 MFs/mL and 500 MFs/mL exposure groups, respectively. Functional enrichment analysis of the 50 MFs/mL group indicated involvement of the apoptosis pathway and ferroptosis pathway in the toxic effects exerted by PET-MFs on D. carinata. This study imparts valuable insights into the toxicological ramifications of PET-MFs on D. carinata, underscoring their potential risks within aquatic ecosystems.

Global research hotspots and trends on microplastics: a bibliometric analysis

In recent years, microplastics have become an integral part of the terrestrial and aquatic environments, which is one of the major concerns of communities around the world. Therefore, it is necessary to know the current status of studies and feasible potentials in the future. This study, conducted an in-depth bibliometric analysis of publications from 1990 to 2022 to present the influential countries, authors, institutes, papers, and journals on microplastics. Findings reveal that there has been a steady increase in microplastic publications and citations in recent years. And, the number of publications and citations has increased 19 and 35 times since 2015. Besides, we performed a comprehensive keyword analysis to show the significant keywords and clusters in this field. In particular, this study used the TF-IDF method as a text-mining analysis to extract the new keywords used in recent years (i.e., 2020-2022). New keywords can draw the attention of scholars to important issues and provide a basis for future research directions.

Degradation characteristics of polyethylene film by microorganisms from lake sediments

Polyethylene (PE) exists widely in many habitats as a persistent organic pollution and poses a major threat to the ecological environment. In this study, bacterial communities in freshwater lake sediments were exposed to culture media using PE films as the sole carbon source in aerobic and anaerobic microculture environments, and they were able to adhere and adapt to the PE films for a longer period of time. The results demonstrated that the pH value of the medium in the two cultural conditions was distinct, as were the rates of films weight loss and surface functional group alterations. We also concluded the certain bacterial genera from freshwater lake sediments who may be able to degrade PE films under either aerobic or anaerobic conditions. Simultaneously, the dominating bacterial communities between the medium and the film differed significantly under two cultural settings, as did the community composition, while metabolism was the primary function.

Cellulosic and microplastic fibers in the Antarctic fish Harpagifer antarcticus and Sub-Antarctic Harpagifer bispinis

Human settlements within the Antarctic continent have caused significant coastal pollution by littering plastic. The present study assessed the potential presence of microplastics in the gastrointestinal tract of the Antarctic fish Harpagifer antarcticus, endemic to the polar region, and in the sub-Antarctic fish Harpagifer bispinis. H. antarcticus. A total of 358 microfibers of multiple colors were found in 89 % of H. antarcticus and 73 % of H. bispinis gastrointestinal track. A Micro-FTIR analysis characterized a sub-group (n = 42) of microfibers. It revealed that most of the fibers were cellulose (69 %). Manmade fibers such as microplastics polyethylene terephtalate, acrylics, and semisynthetic/natural cellulosic fibers were present in the fish samples. All the microfibers extracted were textile fibers of blue, black, red, green, and violet color. Our results suggest that laundry greywater discharges of human settlements near coastal waters in Antarctica are a major source of these pollutants in the Antarctic fish.

The extent of microplastic pollution along the eastern coast of India: Focussing on marine waters, beach sand, and fish

In this study, for the first time, we evaluated microplastic contamination in water, beach sand, and fish samples collected from the seven most famous and crowded beaches of the eastern coast of India, which cover around 1200 km. The average number of microplastics found was 80 ± 33 microplastics/m3 and 4 ± 2 microplastics/kg dry weight with a numerical abundance of polyethylene and polystyrene for water and sand samples, respectively. The polymer hazard index score, which represents the severity of the microplastics scenario in the studied locations, depicts that this coastline falls under hazard levels IV and V (most hazardous) for water and sand samples, respectively. The study revealed that approximately 30 % of the commercially important fishes collected from the locations contained microplastics with polyethylene terephthalate and polypropylene being the most abundant types. Rastrelliger kanagurta and Sardinella gibbosa were identified as the most polluted species.

The hyperbenthic environment: A forgotten habitat for plastic pollution

This study investigates the abundances and composition of microplastics (MP) among the shallow layers of a coastal Mediterranean Marine Protected Area (Cabrera MPA), seafloor sediments, hyperbenthic environment, and the water column. The mid waters samples were collected mid-way between the sea surface and the seafloor and hyperbenthic samples at the water layer adjacent to the seafloor. Sampling was carried out on patchiness seafloor of Posidonia oceanica meadows. The seafloor sediments showed a mean abundance of 378,769.20 ± 508,109.11 MPs/m3, three orders of magnitude higher than the hyperbenthic (209.17 ± 117.07 MPs/m3), and the mid waters layer (106.48 ± 107.17 MPs/m3). An increasing vertical gradient in MP abundances, mainly composed of fibers was observed. Fibers were made-up mainly of polystyrene (PS, 25 %), expanded polystyrene (EPS, 18 %) and cellulose acetate (CA, 16 %). The results stress the need to increase efforts to find solutions to mitigate fiber pollution in the marine environment.

First evidence of microplastic ingestion in the ocean giant sunfish (Mola mola)

Mola mola is the largest teleost inhabiting our ocean and the presence of microplastics (MP) in this flagship species was, before this study, never described. Thus, this investigation focused on analysing MP ingestion in 53 ocean giant sunfish in the Northeast Atlantic Ocean. A total of 116 MP were found in 79% of the specimens, with a median of 1 MP.ind-1, ranging from 0 to 11 MP.ind-1. Seasonal differences were observed, with more fibers registered in specimens caught in autumn. Among the different size classes observed, the smallest category (<300 μm) was the most frequent (43%). Blue (43%) was the most prevalent color, followed by green (29%) and black (10%). The majority of fragments were styrene acrylic copolymer (53%), while most fibers were rayon (78%). These findings emphasize that the ocean sunfish population crossing the southern waters of Portugal is exposed to microplastic pollution and highlight the need for effective management policies to address plastic pollution in marine ecosystems.

Using citizen science to understand floating plastic debris distribution and abundance: A case study from the North Cornish coast (United Kingdom)

Citizen science is now commonly employed to collect data on plastic pollution and is recognised as a valuable tool for furthering our understanding of the issue. Few studies, however, use citizen science to gather information on water-borne plastic debris. Here, citizen scientists adopted a globally standardised methodology to sample the sea-surface for small (1-5 mm) floating plastic debris off the Cornish coast (UK). Twenty-eight trawls were conducted along five routes, intersecting two Marine Protected Areas. Of the 509 putative plastic items, fragments were most common (64 %), then line (19 %), foam (7 %), film (6 %), and pellets (4 %). Fourier-transform infrared spectroscopy identified the most common polymer type as polyethylene (31 %), then nylon (12 %), polypropylene (8 %), polyamide (5 %) and polystyrene (3 %). This study provides the first globally comparative baseline of floating plastic debris for the region (mean: 8512 items km-2), whilst contributing to an international dataset aimed at understanding plastic abundance and distribution worldwide.

Occurrence and spatial distribution of microplastics in the intertidal sediments along the Oman Sea

Microplastics (MPs) have been found in marine systems more frequently. We aim to analyze the MPs abundances, distribution, and characteristics in the intertidal sediments along the Oman Sea. Samples were collected from 7 locations with three replicates. Density separation was used to extract MPs, which were then visually counted and categorized based on their size, shape, and color. MPs abundance ranged between 219.6 ± 38.3 particles.kg-1dw and 617.3 ± 99.9 particles.kg-1dw with a mean abundance of 315.4 ± 24.4 particles.kg-1 dw. Fragments and fibers were the dominant shapes. Red and blue colors were observed in 61.6 % of the collected MPs. In addition, 100-500 μm size range of MPs were more abundant. Micro-Raman spectroscopy analysis revealed polypropylene was the major polymer constituent. The present study revealed the widespread occurrence of MPs as anthropogenic pollutants throughout the Oman Sea and highlighted the urgent need for regulations and policies to reduce the entry of this material into marine environments.

Numerical simulation research of the transportation and distribution characteristics on sea surface of the microplastic released continuously for 12 years from China's coastal cities

Based on the Lagrangian random walk particle tracking method and the global ocean reanalysis data, this study simulated the drift-diffusion process in ocean of microplastic particles (density less than seawater) discharged by coastal cities in China for 12 consecutive years. The results reveal that most of the microplastics (80.33%) essentially end up ashore or in the marginal seas around China, a small portion of microplastics (18.22%) enter the Sea of Japan and the Northwest Pacific Ocean via the Tsushima Strait and the Osumi-Kaikyo with the Kuroshio Tide, a very small portion of microplastics (1.45%) enter into the waters of Southeast Asian countries along with the west boundary current of South China Sea. The concentration distribution characteristics have obvious seasonal variation in the high concentration areas (the marginal seas around China and Sea of Japan). The mainly destination area of microplastics released in different cities is different.

Contamination of microplastics in tropical coral reef ecosystems of Sri Lanka

Microplastics (MPs) in different marine compartments are a global concern. This study investigated the abundance, distribution, and characteristics of microplastics from ten coral reef ecosystems in Sri Lanka, a non-quantified threat for some context. Microplastics were isolated and quantified in terms of abundance, shape, size, color, and polymer type with average abundances 546.7 ± 170.3 items kg-1, 9.8 ± 7.6 items m-3, and 46.3 ± 29.7 items kg-1 in corals, water, and sediments respectively. The most dominant microplastic type was blue, LDPE fibres. Acropora exhibited the highest amount. The significant differences in average microplastic abundances among corals suggest that they are capable of enriching microplastics depending on species-specific characteristics. Similar microplastic characteristics in corals and reef environment indicate that corals may have enriched microplastics from surface water and surface sediments. Microplastics being ubiquitous in selected reefs highlights the importance of coral reefs as a long-term microplastic sink in the ocean, contributing to the missing plastic phenomena.

Is Zooplankton an Entry Point of Microplastics into the Marine Food Web?

Microplastics (MPs) overlap in size with phytoplankton and can be ingested by zooplankton, transferring them to higher trophic levels. Copepods are the most abundant metazoans among zooplankton and the main link between primary producers and higher trophic levels. Ingestion of MPs has been investigated in the laboratory, but we still know little about the ingestion of MPs by zooplankton in the natural environment. In this study, we determined the concentration and characteristics of MPs down to 10 μm in zooplankton samples, sorted calanoid copepods, and fecal pellets collected in the Kattegat/Skagerrak Sea (Denmark). We found a median concentration of 1.7 × 10-3 MPs ind-1 in the zooplankton samples, 2.9 × 10-3 MPs ind-1 in the sorted-copepods, and 3 × 10-3 MPs per fecal pellet. Most MPs in the zooplankton samples and fecal pellets were fragments smaller than 100 μm, whereas fibers dominated in the sorted copepods. Based on the collected data, we estimated a MP budget for the surface layer (0-18 m), where copepods contained only 3% of the MPs in the water, while 5% of the MPs were packed in fecal pellets. However, the number of MPs exported daily to the pycnocline via fecal pellets was estimated to be 1.4% of the total MPs in the surface layer. Our results indicate that zooplankton are an entry point of small MPs in the food web, but the number of MPs in zooplankton and their fecal pellets was low compared with the number of MPs found in the water column and the occurrence and/or ingestion of MPs reported for nekton. This suggests a low risk of MP transferring to higher trophic levels through zooplankton and a quantitatively low, but ecologically relevant, contribution of fecal pellets to the vertical exportation of MPs in the ocean.

Environmental Microplastic Exposure Changes Gut Microbiota in Chickens

As novel environmental contaminants, MPs exist widely in the environment and accumulate in organisms, which has become a global ecological problem. MP perturbations of organismal physiology and behavior have been extensively recorded in aquatic animals, but the potential effects of MPs on poultry are not well characterized. Here, we explored the adverse effects of MP exposure on the growth performance and gut microbiota of chickens. Results showed that the growth performance of chickens decreased significantly during MP exposure. Additionally, Firmicutes, Bacteroidota, and Proteobacteria were found to be dominant in the gut microbiota of MP-exposed chickens, regardless of health status. Although the types of dominant bacteria did not change, the abundances of some bacteria and the structure of the gut microbiota changed significantly. Compared with the controls, the alpha diversity of gut microbiota in chickens exposed to MPs showed a significant decrease. The results of comparative analyses of bacteria between groups showed that the levels of 1 phyla (Proteobacteria) and 18 genera dramatically decreased, whereas the levels of 1 phyla (Cyanobacteria) and 12 genera dramatically increased, during MP exposure. In summary, this study provides evidence that exposure to MPs has a significant impact on the growth performance and gut microbial composition and structure of chickens, leading to a gut microbial imbalance. This may raise widespread public concern about the health threat caused by MP contamination, which is relevant to the maintenance of environmental quality and protection of poultry health.

Biofilm-induced effect on the buoyancy of plastic debris: An experimental study

Plastic floating on the ocean surface represents about 1 % of all plastic in the ocean, despite the buoyancy of most plastics. Biofouling can help to sink debris, which could explain this discrepancy. A set of laboratory experiments was conducted to investigate biofilm-induced effects on the buoyancy of different plastic debris. Ten materials of different densities (buoyant/non-buoyant), sizes (micro/meso/macro), and shapes (irregular/spherical/cylindrical/flat), including facemasks and cotton swabs, were evaluated. Biofilm was incubated in these materials from a few weeks to three months to investigate the effect of different growth levels on their buoyancy. Biofilm levels and rising/settling velocities were measured and compared at seven time-points. The results show a hindered buoyancy for solid materials, while hollow and open materials showed the opposite trend in early biofilm colonization stages. A relationship was established between biofilm-growth and equivalent sphere diameter that can be used to improve predictive modeling of plastic-debris transport.

Microplastics: a review of their impacts on different life forms and their removal methods

The pollution of microplastics (MPs) is a worldwide major concern, as they have become a major part of our food chain. MPs enter our ecosystem via different pathways, including anthropogenic activities and improper disposal of plastics. The aim of this article is to review the current scientific literature related to MPs and how they affect different life forms on earth. Briefly, MPs induced negative effects on humans are primarily linked with the oxidative stress and disruption in immunity. MPs not only affect the soil chemical and physical properties such as reduction in soil health and productivity but also impose harmful effects on soil microorganisms. Moreover, MP-induced plant growth reduction results from three complementary mechanisms: (i) reduction in root and shoot growth, (ii) reduction in photosynthesis accompanied by higher reactive oxygen species (ROS) production, and (iii) reduction in nutrient uptake via altered root growth. Given the negative effects of MPs on different life forms, it is important to remove or remediate them. We have discussed different MP removal methods including coagulation, membrane filtration technology, biochar, and biological degradation of MPs in soil and wastewater effluents. The use of ozone as ultrafiltration technique has also been shown as the most promising technique for MP removal. Finally, some future research recommendations are also put forward at the end to further enhance our understanding of the MPs induced negative effects on different life forms. The flowchart shows the interaction of MPs from water contaminated with MPs with different parts of the ecosystem and final interaction with human health.

A review of methods for modeling microplastic transport in the marine environments

Microplastic (MP) pollution is ubiquitous in the oceans and poses serious threats to the marine ecosystems. Nowadays numerical modeling has become one of the widely used tools for monitoring and predicting the transport and fate of MP in marine environments. Despite the growing body of research on numerical modeling of marine MP, the advantages and disadvantages of various modeling methods have not received systematic evaluation in published works. Important aspects such as parameterization schemes for MP behaviors, factors influencing MP transport, and proper configuration in beaching are essential for guiding researchers to choose proper methods in their work. For this purpose, we comprehensively reviewed the current knowledge on factors influencing MP transport, classified modeling approaches according to the governing equations, and summarized up-to-date parameterization schemes for MP behaviors. Critical factors such as vertical velocity, biofouling, degradation, fragmentation, beaching, and washing-off were reviewed in the frame of MP transport processes.

Spatial distribution and historical trend of microplastic pollution in sediments from enclosed bays of South Korea

Seafloor sediments are an important sink for microplastics (MPs), and the vertical profile of MP accumulation in a sediment core represents historical pollution trends. In this study, MP (20-5000 μm) pollution in surface sediments of urban, aquaculture, and environmental preservation sites in South Korea was evaluated, and the historical trend was investigated using age-dated core sediments from the urban and aquaculture sites. The abundance of MPs ranked in the order of urban, aquaculture, and environmental preservation sites. Polymer types were more diverse at the urban site compared to other sites, and expanded polystyrene was dominant in the aquaculture site. An increase in MP pollution and polymer types was observed from bottom to top of cores, and historical trends of MP pollution reflect local influences. Our results indicate that the characteristics of MPs are determined by human activities, and MP pollution should be addressed according to the characteristics of each site.

Tire wear particles in different water environments: occurrence, behavior, and biological effects-a review and perspectives

As an important source of microplastics, the water ecological risk of tire wear particles (TWPs) has attracted widespread attention worldwide. However, the occurrence and behavior of TWPs and their biological effects in water environments have not been clearly analyzed. For example, most contemporary studies have focused on the evaluation of the aquatic toxicity of TWPs leachate, and little attention has been paid to the behavior process and potential risks of its surface properties in water environments. In addition, most studies rely on preparing TWPs under laboratory conditions or purchasing commercial TWPs for studying their water environmental behavior or exposure. These obviously cannot meet the requirements of accurate assessment of water ecological risks of TWPs. As thus, in addition to describing the occurrence, distribution, and (aging) transformation of TWPs in different water environments, we further tried to explain the potential water environment behavior process and multiple pathways leading to potential adverse impacts of TWPs on aquatic organisms from the perspectives of particle self-toxicity and release toxicity, as well as synergistic effects of TWPs and other substances are also discussed. The existing data, such as studies on the self-characteristics of TWPs, environmental factors, and subjects, are insufficient to comprehensively evaluate the recent changes in essential water ecosystem services and multifunctions caused by TWPs, implying that the impact of TWPs on water environmental health needs to be further evaluated, and the corresponding countermeasures should be recommended. In this context, the current review provides an outlook on future research on TWPs in aquatic environments.

A Novel One Health Approach concerning Yeast Present in the Oral Microbiome of the Endangered Rio Skate (Rioraja agassizii) from Southeastern Brazil

The current climate change scenario caused by anthropogenic activities has resulted in novel environmental pressures, increasing the occurrence and severity of fungal infections in the marine environment. Research on fungi in several taxonomic groups is widespread although not the case for elasmobranchs (sharks and rays). In this context, the aim of the present study was to screen the oral fungal microbiota present in artisanally captured Rioraja agassizii, a batoid that, although endangered, is highly fished and consumed worldwide. Oropharyngeal samples were obtained by swabbing and the samples were investigated using morphological and phenotypic methods by streaking on Sabouraud Dextrose Agar (SDA) and subculturing onto CHROMagar Candida (BD Difco) and CHROMagar Candida Plus (CHROMagarTM), as well as molecular techniques by amplification of the ITS1-5.8S-ITS2 ribosomal DNA region and a MALDI-TOF MS assessment. The findings indicated the presence of Candida parapsilosis (seven isolates), Candida duobushaemulonii (one isolate) and Rhodotorula mucilaginosa (three isolates), several of these reported for the first time in Rioraja agassizii. In addition, a 100% agreement between the MALDI-TOF results and partial ITS region sequencing was noted, demonstrating that the MALDI-TOF MS is a rapid and effective alternative for yeast identification in Rioraja agassizii isolates and potentially in other elasmobranch species. These findings highlight the need for further research to determine the potential impact on elasmobranch health, ecology, and commercial fisheries. Furthermore, this research is paramount in a One Health framework and may be employed to predict elasmobranch responses to an evolving ocean, keep healthy populations in check, monitor species, and assess the public health consequences of consuming these species.

Pouring hot water through drip bags releases thousands of microplastics into coffee

Microplastics (MPs) released from food packaging have attracted widespread attention. In this study, drip bags made from polyethylene (PE), polypropylene (PP), polyester (PET), and rayon selected from eight brands were employed to investigate MPs releasing. Fourier-transform infrared microspectroscopy (μ-FTIR), optical microscope and scanning electron microscope (SEM) were used to study the effects of brewing time and temperature on the release of MPs. The results showed that a single plastic coffee bag steeped at 95 ℃ for 5 min could release more than 10,000 MPs particles into a cup of coffee. Irregular blocks, long strips, and size range of 10-500 μm MPs were easier to be released, implying that consuming 3-4 cups of coffee will lead to an intake of 50 thousand MPs particles daily. Rayon was the primary type of released MPs, accounting for over 80% of the total amount of the released MPs. Our results are hoped to provide evaluation standards of material selection for processing coffee bags.

Arctic Ocean sediments as important current and future sinks for marine microplastics missing in the global microplastic budget

To better understand unexpectedly low plastic loads at the ocean's surface compared with inputs, unidentified sinks must be located. Here, we present the microplastic (MP) budget for multi-compartments in the western Arctic Ocean (WAO) and demonstrate that Arctic sediments serve as important current and future sinks for MPs missing from the global budget. We identified an increase of 3% year^-1 in MP deposition from sediment core observations. Relatively elevated MP abundances were found in seawater and surface sediments around the summer sea ice retreat region, implying enhanced MP accumulation and deposition facilitated by the ice barrier. We estimate 15.7 ± 2.30 × 10¹⁶ N and 0.21 ± 0.14 MT as total MP loads in the WAO with 90% (by mass) buried in the post-1930 sediments, which exceeds the global average of the current marine MP load. The slower increase in plastic burial versus production implies a lag in plastic delivery to the Arctic, indicating more pollution in the future.

Abundance of microplastic in different coastal areas using Phragmatopoma caudata (Kroyer in Morch, 1863) (Polychaeta: Sabelariidae) as an indicator

Plastic debris has been reported in the marine environment since the '70s. These plastic materials are introduced into the marine environment in several sizes, one of them microplastics (MP), and they have drawn great interest and concern in the past decades. Consumption of MP can cause weight loss, feeding rate decrease, reproductive activity decrease, and several other negative effects. Ingestion of MPs has already been reported for some species of polychaetes but the use of these annelids in MP studies is still poorly reported. Costa et al. (2021) was the first study to investigate the capability of the reef-building polychaete Phragmatopoma caudata to incorporate microplastic in its colony's structures. This makes the colonies a reservoir of MP and thus they reflect the environment's quality regarding MP presence. Consequently, this specie becomes an important asset to MP pollution investigation in coastal areas. Therefore, this work aims to investigate the abundance of MPs on the coastline of Espírito Santo using P. caudata as an indicator of MP presence. For this, we collected samples of P. caudata colonies in 12 sampling sites along the Espírito Santo coast (three replicates at each site). These colony samples were processed to extract the MPs particles from the colony surface, its inner structure, and tissues from the individuals. These MPs were counted using a stereomicroscope and sorted according to their color and type (filament, fragment, and other). Statistical analysis was performed using GraphPad Prism 9.3.0. Significant values followed p < 0.05. We found MP particles in all 12 sampled beaches, configuring a pollution rate of 100 %. The number of filaments was notably greater than the number of fragments and others. The most impacted beaches were found inside the metropolitan region of the state. Finally, P. caudata is an efficient and trustable indicator of microplastic in coastal areas.

Risk assessments of microplastics accumulated in estuarine sediments at Cuddalore, Tamil Nadu, southeast coast of India

In this study, the abundance of microplastics (MPs) in the Uppanar and Gadilam estuaries in Cuddalore, on the southeast coast of India, is reported. In the estuarine sediments, MP abundance ranged from 36.3 ± 3.39 to 51.6 ± 2.05 particles/Kg dw. Different types of MP shapes, such as fibers (41.7-47.9%), films (21.2-27.2%), and fragments (18.3-25.5%) were observed in the size range of 100-1000 µm. Diverse colours of MPs were observed, among which red (30.1-34.5%) was predominantly noticed in the estuarine sediments. Six polymers were identified by µ-FTIR, among which LDPE (39%) and PP (35%) were dominant. MPs pollution in these estuaries is composed of domestic, industrial, and fishing wastes. Risk assessments show that the area falls under hazard categories I to III, indicating low to high risk. This study improves knowledge on MPs contamination in Uppanar and Gadilam estuaries and provides impetus for further research to identify the actual sources and impacts of MPs on aquatic systems along the east coast of India.

Extensive estuarine sedimentary storage of plastics from city to sea: Narragansett Bay, Rhode Island, USA

Plastics are an important new component of the global sedimentary system, and much concern exists about their transport, fate and impact. This study presents the first system-scale assessment of sedimentary storage of microplastic for an estuary, Narragansett Bay, RI (USA), and the measurements of shoreline and seabed sediments add to the growing body of literature demonstrating high coastal concentrations. Microplastic concentrations in sediments ranged from 396 to over 13,000 MP particles kg^-1 dry sediment (DW), comparable to other shoreline and seafloor sites located near urban centers. As previously reported for fine sediment and other pollutants, estuarine plastic storage is extensive in Narragansett Bay, especially within the upper urbanized reaches. Over 16 trillion pieces of plastic weighing near 1000 tonnes is calculated to be stored in surface sediments of the Bay based on a power-law fit. This work highlights that estuaries may serve as a significant filter for plastic pollution, and this trapping may have negative consequences for these valuable, productive ecosystems but offer potential for efficient removal.

Micro- and nanoplastic toxicity: A review on size, type, source, and test-organism implications

Polymeric wastes are among the current major environmental problems due to potential pollution and contamination. Within the spectrum of polymeric waste, microplastics (MPs) and nanoplastics (NPs) have gained ground in recent research since these particles can affect the local biota, inducing toxic effects on several organisms. Different outcomes have been reported depending on particle sizes, shape, types, and exposed organisms and conditions, among other variables. This review aimed to compile and discuss the current knowledge and possible literature gaps regarding the MPs and NPs generation and their toxicological effects as stressors, considering polymer type (as polyethylene, polypropylene, polyethylene terephthalate, polystyrene, polyvinyl chloride, or others), size (micro- or nano-scale), source (commercial, lab-synthesized, or environmental) and test organism group. In that sense, 615 publications were analyzed, among which 72 % discussed micro-sized plastics, while <28 % assayed the toxicity of NPs (<1 μm). For most polymers, MPs and NPs were commercially purchased and used without additional size reduction processes; except for polyethylene terephthalate studies that mostly used grinding and cutting methods to obtain MPs. Polystyrene (PS) was the main polymer studied, as both MPs and NPs. PS accounts for >90 % of NPs reports evaluated, reflecting a major literature gap if compared to its 35.3 % share on MPs studies. Among the main organisms, arthropods and fish combined accounted for nearly 40 % of toxicity testing. Overall, the different types of plastics showed a tendency to report toxic effects, except for the 'Survival/lethality' category, which might indicate that polymeric particles induce mostly sublethal toxic effects. Furthermore, despite differences in publication numbers, we observed greater toxicity reported for NPs than MPs with oxidative stress among the majorly investigated endpoints. This study allowed a hazard profile overview of micro/nanoplastics (MNPs) and the visualization of literature gaps, under a broad diversity of toxicological evidence.

Instant deep sea debris detection for maneuverable underwater machines to build sustainable ocean using deep neural network

Deep sea debris is any persistent man-made material that ends up in the deep sea. The scale and rapidly increasing amount of sea debris are endangering the health of the ocean. So, many marine communities are struggling for the objective of a clean, healthy, resilient, safe, and sustainably harvested ocean. That includes deep sea debris removal with maneuverable underwater machines. Previous studies have demonstrated that deep learning methods can successfully extract features from seabed images or videos, and are capable of identifying and detecting debris to facilitate debris collection. In this paper, the lightweight neural network (termed DSDebrisNet), which can leverage the detection speed and identification performance to achieve instant detection with high accuracy, is proposed to implement compound-scaled deep sea debris detection. In DSDebrisNet, a hybrid loss function considering the illumination and detection problem was also introduced to improve performance. In addition, the DSDebris dataset is constructed by extracting images and video frames from the JAMSTEC dataset and labeled using a graphical image annotation tool. The experiments are implemented on the deep sea debris dataset, and the results indicate that the proposed methodology can achieve promising detection accuracy in real-time. The in-depth study also provides significant evidence for the successful extension branch of artificial intelligence to the deep sea research domain.

Stressors of emerging concern in deep-sea environments: microplastics, pharmaceuticals, personal care products and deep-sea mining

Although most deep-sea areas are remote in comparison to coastal zones, a growing body of literature indicates that many sensitive ecosystems could be under increased stress from anthropogenic sources. Among the multiple potential stressors, microplastics (MPs), pharmaceuticals and personal care products (PPCPs/PCPs) and the imminent start of commercial deep-sea mining have received increased attention. Here we review recent literature on these emerging stressors in deep-sea environments and discuss cumulative effects with climate change associated variables. Importantly, MPs and PPCPs have been detected in deep-sea waters, organisms and sediments, in some locations in comparable levels to coastal areas. The Atlantic Ocean and the Mediterranean Sea are the most studied areas and where higher levels of MPs and PPCPs have been detected. The paucity of data for most other deep-sea ecosystems indicates that many more locations are likely to be contaminated by these emerging stressors, but the absence of studies hampers a better assessment of the potential risk. The main knowledge gaps in the field are identified and discussed, and future research priorities are highlighted to improve hazard and risk assessment.

The relationship between microplastics in eastern oysters (Crassostrea virginica) and surrounding environmental compartments in Long Island Sound

Microplastics (MP, <5 mm) are found in coastal waters across various environmental compartments (biota, water, marine snow, sediment). The eastern oyster (Crassostrea virginica) is a commercially important species that ingests MP; however, oysters are discriminant suspension feeders that do not consume all particles to which they are exposed. This study explored the relationship between MP in oysters on a recreational oyster bed and the surrounding environmental compartments in Long Island Sound (LIS; USA). The quantity and types of MP in oysters, water, marine snow, and sediment samples were determined. Precautions were taken to minimize and monitor MP contamination in the field and laboratory to improve the quality of data collected. Microplastics were isolated from samples via chemical digestion, and any suspected particles were identified using micro-Fourier transform infrared spectroscopy. A total of 86 MP were identified out of 885 suspected particles across environmental media. The highest MP count in an individual oyster was nine, indicating low concentrations of MP in oysters and the surrounding environment. Few polymers, except polyethylene terephthalate, were shared between oysters and the surrounding environmental compartments. Sediments contained the highest number of MP across all environmental compartments (42 total). These data aid in determining the types of MP (polymer composition, shape, size) to which oysters are exposed and identified those ingested. The low numbers of MP recorded, coupled with the lack of alignment of polymers between oysters and their surrounding environment, demonstrates further that oysters are a poor bioindicator species for MP pollution.

Attachment of potential cultivable primo-colonizing bacteria and its implications on the fate of low-density polyethylene (LDPE) plastics in the marine environment

Plastics released in the environment become suitable matrices for microbial attachment and colonization. Plastics-associated microbial communities interact with each other and are metabolically distinct from the surrounding environment. However, pioneer colonizing species and their interaction with the plastic during initial colonization are less described. Marine sediment bacteria from sites in Manila Bay were isolated via a double selective enrichment method using sterilized low-density polyethylene (LDPE) sheets as the sole carbon source. Ten isolates were identified to belong to the genera Halomonas, Bacillus, Alteromonas, Photobacterium, and Aliishimia based on 16S rRNA gene phylogeny, and majority of the taxa found exhibit a surface-associated lifestyle. Isolates were then tested for their ability to colonize polyethylene (PE) through co-incubation with LDPE sheets for 60 days. Growth of colonies in crevices, formation of cell-shaped pits, and increased roughness of the surface indicate physical deterioration. Fourier-transform infrared (FT-IR) spectroscopy revealed significant changes in the functional groups and bond indices on LDPE sheets separately co-incubated with the isolates, demonstrating that different species potentially target different substrates of the photo-oxidized polymer backbone. Understanding the activity of primo-colonizing bacteria on the plastic surface can provide insights on the possible mechanisms used to make plastic more bioavailable for other species, and their implications on the fate of plastics in the marine environment.

Nanoplastics pose a greater effect than microplastics in enhancing mercury toxicity to marine copepods

Due to human activities, high abundances of nano/microplastics (N/MPs) concurrent with metal pollution have become a serious problem in the global marine environment. Because of displaying a high surface-area-to-volume ratio, N/MPs can serve as the carriers of metals and thus increase their accumulation/toxicity in marine biota. As one of the most toxic metals, mercury (Hg) causes adverse effects on marine organisms but whether environmentally relevant N/MPs can play a vector role of this metal in marine biota, as well as their interaction, is poorly known. To evaluate the vector role of N/MPs in Hg toxicity, we first performed the adsorption kinetics and isotherms of N/MPs and Hg in seawater, as well as ingestion/egestion of N/MPs by marine copepod Tigriopus japonicus, and second, the copepod T. japonicus was exposed to polystyrene (PS) N/MPs (500-nm, 6-μm) and Hg in isolation, combined, and incubated forms at environmentally relevant concentrations for 48 h. Also, the physiological and defense performance including antioxidant response, detoxification/stress, energy metabolism, and development-related genes were assessed after exposure. The results indicated N/MPs significantly increased Hg accumulation and thus its toxicity effects in T. japonicus as exemplified by decreased transcription of genes related to development and energy metabolism and increased transcriptional levels of genes functioning in antioxidant and detoxification/stress defense. More importantly, NPs were superimposed onto MPs and produced the most vector effect in Hg toxicity to T. japonicus, especially in the incubated forms. Overall, this study highlighted the role of N/MPs as a potential risk factor for increasing the adverse effects of Hg pollution, and emphasized the adsorption forms of contaminants by N/MPs should doubly be considered in the continuing researches.

Review of microplastics in museum specimens: An under-utilized tool to better understand the Plasticene

This study summarises the status of microplastic research in marine and freshwater specimens in natural museum collections around the world. Abundances, distributions, and types of microplastics in the archived collections are discussed. Museum collections can fill knowledge gaps on evolution of microplastic pollution before and during the Plasticene era. The specimens in these studies, ranging from plankton to vertebrates, were collected and archived between 1900 and 2019, and are dominated by specimens from marine ecosystems. All the specimens included in this review were preserved by freezing or in ethanol/formaldehyde except for specimens in one study that were preserved via cryomilling. Microfibers were the most common microplastics in the reviewed studies. We recommend more microplastic studies over a wider taxonomic range of species and across a longer span of years utilizing archival specimen collections around the world in order to establish reference points and develop temporal trends for microplastic pollution of the environment.

Evidence of microplastics in leachate of Randegan landfill, Mojokerto City, Indonesia, and its potential to pollute surface water

About 80-90 tons municipal solid waste (MSW) in Mojokerto City, Indonesia, is disposed of into Randegan landfill daily. The landfill was facilitated with a conventional leachate treatment plant (LTP). The plastic waste component in the MSW, which is 13.22 % weight, possibly contaminates leachate with microplastics (MPs). This research aims to determine the presence of MPs in leachate of the landfill, its characteristics, and the removal efficiency of the LTP. The potential of leachate as MP pollutant source to surface water was also discussed. Raw leachate samples were collected from the LTP inlet channel. Leachate samples were also taken from each LTP's sub-units. Leachate collection was performed two times using a 2.5 L glass bottle during March 2022. The MPs were treated using Wet Peroxide Oxidation method, and filtered using PTFE membrane. MP size and shape were determined using a dissecting microscope with 40-60 x magnifications. The polymer types in the samples were identified using Thermo Scientific™ Nicolet™ iS™ 10 FTIR Spectrometer. The average MP abundance in raw leachate was 9.00 ± 0.85 particles/L. MP shape in the raw leachate was dominated by fiber (64.44 %), followed by fragment (28.89 %), and film (6.67 %). The majority of the MPs were of black color (53.33 %). Abundance of 350 - <1000 μm sized MPs was the highest (64.44 %) in the raw leachate, followed by those of 100-350 μm (31.11 %), and 1000-5000 μm (4.45 %). MP removal efficiency of the LTP was 75.6 %, leaving <100 μm fiber shaped MP residuals of 2.20 ± 0.28 p/L in the effluent. Based on these results, effluent of the LTP is considered potential as MP contamination source to surface water.

In-situ and real-time nano/microplastic coatings and dynamics in water using nano-DIHM: A novel capability for the plastic life cycle research

A novel nano-digital inline holographic microscope (nano-DIHM) was used to advance in-situ and real-time nano/microplastic physicochemical research, such as particle coatings and dynamic processes in water. Nano-DIHM data provided evidence of distinct coating patterns on nano/microplastic particles by oleic acid, magnetite, and phytoplankton, representing organic, inorganic, and biological coatings widely present in the natural surroundings. A high-resolution scanning transmission electron microscopy confirmed nano-DIHM data, demonstrating its nano/microplastic research capabilities. The sedimentation of two plastic size categories was examined: (a) ∼10 to 700 µm, and (b) ∼ 1 to 5 mm. Particle size was the primary factor affecting the sedimentation for studied (a) microplastics and (b) pellets. Two types of silicone rubbers exhibited different sedimentation processes. We also demonstrated that inorganic ions in seawater and oleic acid organic coatings altered the sedimentation velocity of studied plastics by 9 - 13% and 5 - 9%, respectively. Semi-empirical probability functions were developed and incorporated into a numerical model (CaMPSim-3D) to simulate the transport of studied microplastics and pellets in the Saint John River estuary. Water dynamics was the driving force of plastic transport, yet the accumulation of plastics was selectively dependant on particle physicochemical properties such as size and density by ∼ 7%. The usage of nano-DIHM for targeted identification of nano/microplastic hotspots and aquatic plastic wastes remediation were discussed.

A new point to correlate the multi-dimensional assessment for the aging process of microfibers

Fiber, the most prevalent plastic type, can be weathered and eroded easily in the natural environment. Although a variety of techniques have been applied to characterize the aging characteristics of plastics, a comprehensive understanding was critically essential to correlate the multi-dimensional assessment of the weathering process of microfibers and their environmental behavior. Therefore, in this study, microfibers were prepared from the face masks and Pb²⁺ was selected as a typical metal pollutant. The weathering process was simulated by xenon aging and chemical aging, and then subjected to Pb²⁺adsorption to examine the effect of weathering processes. The changes in fiber property and structure were detected by using various characterization techniques, with the development of several aging indices to quantify the changes. The two-dimensional Fourier transform infrared correlation spectroscopy analysis (2D-FTIR-COS) and Raman mapping were also performed to understand the order of changes in the surface functional groups of the fiber. The results showed that both aging processes altered the surface morphology, physicochemical properties, and polypropylene chain conformations of the microfibers, with stronger effect after chemical aging. The aging process also enhanced the affinity of microfiber to Pb²⁺. Moreover, the changes and correlation of the aging indices were analyzed, showing that the maximum adsorption capacity (Q_max) was positively related to carbonyl index (CI), oxygen-to-carbon atom (O/C) ratio and intensity ratio of the Raman peaks (I_841/808), but negatively related to contact angle and the temperature at the maximum weight loss rate (T_m). The O/C ratio was more suitable to quantify the surface changes with lower aging degree while the CI value explained the chemical aging process better. Overall, this study discussed the weathering processes of microfibers based on a multi-dimensional investigation, and attempted to correlate the aging characteristics of the microfibers and their environmental behavior.

Comprehensive analysis of common polymers using hyphenated TGA-FTIR-GC/MS and Raman spectroscopy towards a database for micro- and nanoplastics identification, characterization, and quantitation

Environmental contamination by micro- and nanoplastics (MNPs) is well documented with potential for their increased accumulation globally. Growing public concern over environmental, ecological, and human exposure to MNPs has led to exponential increase in publications, news articles, and reports (Casillas et al., 2023). Significant knowledge gap exists in standardized analytical methods for the identification and quantification of MNPs from real world environmental samples. Here, we report comprehensive datasets utilizing thermogravimetric analyzer (TGA) coupled to a Fourier transformed infrared spectrometer (FTIR) and a gas chromatography/mass spectrometer (GC/MS) with corresponding Raman spectral data for the most common polymers documented to be present in the environment (35 plastics of 12 polymer types), to serve as a base line reference for the identification and quantitation of MNPs. Various parameters for TGA-FTIR-GC/MS data acquisition were optimized. Commercial consumer plastic product compositions were identified using this analytical database. Case studies to showcase the utility of the method for polymer mixtures analysis is included. This dataset would serve towards the development of a collaborative, global, comprehensive, and curated public database for the identification of various MNPs and mixtures.

Micro- and nanoplastics transfer from seawater to the atmosphere through aerosolization under controlled laboratory conditions

Sea spray has been suggested to enable the transfer of micro- and nanoplastics (MNPs) from the ocean to the atmosphere, but only a few studies support the role of sea spray aerosols (SSAs) as a source of airborne particles. We demonstrated that MNPs are aerosolized during wave action, via SSAs, under controlled laboratory conditions. We used a mini-Marine-Aerosol-Reference-Tank (miniMART), a device that mimics naturally occurring physical mechanisms producing SSAs, and assessed the aerosolization of fluorescent polystyrene beads (0.5-10 μm), in artificial seawater. The SSAs contained up to 18,809 particles/mL of aerosols for 0.5 μm beads, with an enrichment factor of 19-fold, and 1977 particles/mL of aerosols for 10 μm beads with a 2-fold enrichment factor. Our study demonstrates that the use of the miniMART is essential to assess MNPs aerosolization in a standardized way, supporting the hypothesis which states that MNPs in the surface of the ocean may be transferred to the atmosphere.

Seasonal distribution of microplastics in surface waters of the Northern Indian Ocean

Seven expeditions were carried out during pre-monsoon, monsoon and post monsoon in 2018-2019 for marine plastic collection in surface waters of Northern Indian Ocean. PE and PP (83 %) is the dominant type of polymer found in the surface waters. Colored particles account for 67 % of all particles, with fibre/line accounting for 86 %. The average (Mean ± SD) microplastics concentration in the Northern Indian Ocean during pre-monsoon is 15,200 ± 7999 no./km², Monsoon is 18,223 ± 14,725 no./km² and post monsoon is 72,381 ± 77,692 no./km². BoB during pre-monsoon and post monsoon the microplastic concentration remains same except in the northern BoB this change is caused due to weak winds. Microplastics concentration varied both spatially, temporal and heterogeneity in nature. These differences are caused by effect of wind and seasonal reversal of currents. Microplastics collected in the anticyclonic eddy are 129,000 no./km².

Macro and microplastic intake in seafood variates by the marine organism's feeding behaviour: Is it a concern to human health?

Seafood is considered one of the healthiest sources of food intake for humans, mainly because of its high protein content. However, oceans are among the most polluted environments, and microplastics have been widely reported to be ingested, absorbed or bioaccumulated by marine organisms. The different feeding behaviour may contribute to infer the amounts of microplastic particles accidently intake by marine organisms. We investigated the putative levels of microplastics in different edible species of fish, molluscs, and crustaceans. Plastic fragments larger than 200 μm were detected in the digestive tract of 277 out of 390 specimens (71.5 ± 22.2%) of the 26 different species analysed. There was no evidence of microplastic translocation or bioaccumulation in the muscle tissue of fish, molluscs, and crustaceans. Organisms with carnivorous feeding habits had the highest prevalence of plastic ingestion (79 ± 9.4%), followed by planktivorous species (74 ± 15.5%), and detritivorous species (38 ± 36.9%), suggesting a transfer through the food chain. Moreover, we found evidence that species with less selective feeding habits may be the most affected by the ingestion of large microplastic particles. Our results provide further evidence to the ubiquitous presence of microplastics in marine organisms representing a direct threat to marine wildlife, and to human health with potential consequences for future generations according to the One Health initiatives approach.

Microplastic burden in invasive signal crayfish (Pacifastacus leniusculus) increases along a stream urbanization gradient

Microplastics are a globally pervasive pollutant with the potential to directly impact species and accumulate in ecosystems. However, there remains a relative paucity of research addressing their accumulation in freshwater ecosystems and a near absence of work in crayfish, despite their high ecological and economic importance. This study investigated the presence of microplastics in the invasive signal crayfish Pacifastacus leniusculus along a stream urbanization gradient. The results demonstrate a ubiquitous presence of microplastics in crayfish digestive tracts at all sites and provide the first evidence of microplastic accumulation in tail tissue. Evidence of a positive linear trend was demonstrated between microplastic concentration in crayfish and upstream urban area size in generalized linear models. Evidence for a positive effect of the upstream urban area and a negative effect of crayfish length on microplastic concentrations in crayfish was demonstrated in multiple generalized linear regression models. Our results extend the current understanding of microplastics presence in freshwater ecosystems and demonstrate their presence in crayfish in the wild for the first time.

Exploring the presence and distribution of microplastics in subterranean estuaries from southwest India

Rivers, surface runoff, and the wind all transport microplastics (MPs) to the ocean. There is a knowledge gap concerning the distribution of microplastics in transitional subterranean estuaries. Here, we report the presence of microplastics in the pore water, groundwater, and sea water from four locations in southwest India. Pore water, groundwater, and seawater had mean MP abundances (± standard deviations) of 0.75 (±0.66), 0.15 (±0.1), and 0.11 (±0.07) MPs/l, respectively. Fibres were the dominant category of MPs found. Fourier-transformed infrared spectroscopy revealed the presence of polymers like polyester, low-density polyethylene, and polystyrene. Possible sources of microplastic are fishing activities, tourism, and coastal residents. The microplastics-derived risk assessment scores indicate severe risk to the ecosystems. Fibrous microplastics in pore water indicate that these linear particles can migrate vertically through sandy sediments, reaching subterranean estuaries. We believe submarine groundwater discharge can act as a possible pathway for microplastics to enter the oceans.

The degradation of single-use plastics and commercially viable bioplastics in the environment: A review

Plastics have become an integral part of human life. Single-use plastics (SUPs) are disposable plastics designed to be used once then promptly discarded or recycled. This SUPs range from packaging and takeaway containers to disposable razors and hotel toiletries. Synthetic plastics, which are made of non-renewable petroleum and natural gas resources, require decades to perpetually disintegrate in nature thus contribute to plastic pollution worldwide, especially in marine environments. In response to these problems, bioplastics or bio-based and biodegradable polymers from renewable sources has been considered as an alternative. Understanding the mechanisms behind the degradation of conventional SUPs and biodegradability of their greener counterpart, bioplastics, is crucial for appropriate material selection in the future. This review aims to provide insights into the degradation or disintegration of conventional single-use plastics and the biodegradability of the different types of greener-counterparts, bioplastics, their mechanisms, and conditions. This review highlights on the biodegradation in the environments including composting systems. Here, the various types of alternative biodegradable polymers, such as bacterially biosynthesised bioplastics, natural fibre-reinforced plastics, starch-, cellulose-, lignin-, and soy-based polymers were explored. Review of past literature revealed that although bioplastics are relatively eco-friendly, their natural compositions and properties are inconsistent. Furthermore, the global plastic market for biodegradable plastics remains relatively small and require further research and commercialization efforts, especially considering the urgency of plastic and microplastic pollution as currently critical global issue. Biodegradable plastics have potential to replace conventional plastics as they show biodegradation ability under real environments, and thus intensive research on the various biodegradable plastics is needed to inform stakeholders and policy makers on the appropriate response to the gradually emerging biodegradable plastics.

Microfiber Emissions from Functionalized Textiles: Potential Threat for Human Health and Environmental Risks

The growing worldwide population is directly responsible for the increased production and consumption of textile products. One of the key reasons for the generation of microfibers is the use of textiles and garment materials, which is expected to increase. The textile industry is responsible for the invisible pollution that is created by textile microfibers, which have been detected in marine sediments and organisms. The present review paper demonstrates that the microfibers discharged from functionalized textiles exhibit non-biodegradable characteristics and that a considerable proportion of them possess toxic properties. This is primarily attributed to the impact of textiles' material functionalization on their biodegradability. The potential for these microfibers, which are released from textiles that contain a variety of dyes, toxic chemicals, and nanomaterials, to pose a variety of health risks to both humans and other living organisms is discussed in this paper. In addition, this paper covers a wide variety of preventative and minimizing measures for reduction, which are discussed in terms of several phases ranging from sustainable production through the consumer, end of life, domestic washing, and wastewater treatment phases.

New insights into the migration, distribution and accumulation of micro-plastic in marine environment: A critical mechanism review

Microplastics (MPs) are widely distributed in the marine environment, posing a significant threat to marine biota. The contribution of anthropogenic and terrestrial sources to the aquatic ecosystem has led to an increase in MPs findings, and their abundance in aquatic biota has been reported to be of concern. MPs are formed mainly via photo degradation of macroplastics (large plastic debris), and their release into the environment is a result of the degradation of additives. Eco-toxicological risks are increasing for marine organisms, due to the ingestion of MPs, which cause damage to gastrointestinal (GI) tracts and stomach. Plastics with a size <5 mm are considered MPs, and they are commonly identified by Raman spectroscopy, Fourier transfer infrared (FTIR) spectroscopy, and Laser direct infrared (LDIR). The size, density and additives are the main factors influencing the abundance and bioavailability of MPs. The most abundant type of MPs found in fishes are fiber, polystyrenes, and fragments. These microscale pellets cause physiological stress and growth deformities by targeting the GI tracts of fishes and other biota. Approximately 80% MPs come from terrestrial sources, either primary, generated during different products such as skin care products, tires production and the use of MPs as carrier for pharmaceutical products, or secondary plastics, disposed of near coastal areas and water bodies. The issue of MPs and their potential effects on the marine ecosystem require proper attention. Therefore, this study conducted an extensive literature review on assessing MPs levels in fishes, sediments, seawater, their sources, and effects on marine biota (especially on fishes), chemo-physical behavior and the techniques used for their identification.