Spatial distribution of microplastics around an inhabited coral island in the Maldives, Indian Ocean

Effect of alternative natural diet on microplastic ingestion, functional responses and trophic transfer in a tri-trophic coastal pelagic food web

The patchy distribution of microplastics (MP) and their size range similar to planktonic organisms, are likely to have major ecological consequences, through MP ingestion, food dilution, and transfer across trophic levels. Our study applied a community module using tritrophic food chain with zooplankton as prey, and a planktivorous seabass fry as predator. We conducted a series of feeding experiments and recorded the direct uptake of MP under six different concentrations ranging from 25 to 800 particles L-1. We also estimated the indirect transfer of MP via trophic link. The ingestion rates for Brachionus plicatilis, Mesocyclops isabellae, and Lates calcarifer, were 3.7 ± 0.3 MP ind-1 min-1, 1.69 ± 0.1 MP ind-1 min-1, and 3.51 ± 0.52 MP ind-1 h-1, respectively. In the presence of a natural diet, rotifers and copepods ingested significantly lower number, whereas, fish fry ingested a higher number of MP, suggesting further vulnerability to the consumers of MP-contaminated fish and potential biomagnification at higher trophic levels. Overall, the MP uptake rate increased with increasing concentration, and finally leveled off, indicating a type II functional response to MP concentration. The presence of natural diet led to a lower Km value. In the indirect transfer experiment, 74 % of B. plicatilis and 78 % of M. isabellae individuals were contaminated with MP, when offered as prey. Brachionid mastax and MP particles were observed in the gut of copepods. The fish fry gut content also recorded brachionid mastax, MP-contaminated copepods, and MP particles, showing direct evidence of trophic transfer pointing to a cascading effect on higher trophic levels including humans via piscivory.

Concentrations and carbonyl index of microplastic in surface seawater in southeastern coastal region off Japan, Northwestern Pacific

In this study, microplastic concentrations in the southeastern coastal regions of Japan were measured along the northward ocean current at seven stations from Okinawa to Tokai region. Concentrations ranged from 0.014 to 0.094 pieces/m3, except for a station near the Bungo Channel mouth, which had 0.723 pieces/m3. Polystyrene (PS) foam was most prevalent near the east side of Kyushu, suggesting origination from nearby coastal areas. Fragmentation levels were higher in the Tokai region. In addition, carbonyl index (CI) of polyethylene (PE) microplastics increased northward, indicating northward movement from southern regions. Standard PE microplastics showed chemical treatment does not significantly alter CI values. Further spectral analysis suggested potential oxidation of polypropylene (PP) and PS foam by chemical treatment. This study provides a comprehensive understanding of the abundance, distribution, and characteristics of microplastics in the southeastern coastal regions of Japan in the northwest Pacific, enhancing the understanding of environmental fate of microplastics.

Microplastic pollution status in the coral reef ecosystems on the Southern and Western coasts of Sri Lanka during the Southwest monsoon

We investigated the microplastics (MP) abundance, characteristics and pollution severity in the six coral reef ecosystems along the southern and western coasts of Sri Lanka during the southwest monsoon. The small blue-coloured fibres dominated within coral reefs and reef environments. The average coral, surface water and surface sediment MP concentration were 806.64 ± 93.72 particles kg-1ww, 23.42 ± 5.01 particles m-3, and 54.11 ± 8.04 particles kg-1dw, respectively. Coral MP concentration was significantly correlated with surface water (r = 0.65) and surface sediments (r = 0.59) indicating that the reef environment was the source of coral MP enrichment. Coral MP concentration was spatially different (p < 0.05) which may likely be due to the changes in winds, waves, coral biology and plastic sources. MP Pollution Load Index indicated that low MP contamination hazard. Since the presence of MP often deteriorates coral's health, further investigations are necessary to understand the MP's effects on the health of coral reef ecosystems.

Emerging pollutant in surface water bodies: a review on monitoring, analysis, mitigation measures and removal technologies of micro-plastics

Water bodies play a crucial role in supporting life, maintaining the environment, and preserving the ecology for the people of India. However, in recent decades, human activities have led to various alterations in aquatic environments, resulting in environmental degradation through pollution. The safety of utilizing surface water sources for drinking and other purposes has come under intense scrutiny due to rapid population growth and industrial expansion. Surface water pollution due to micro-plastics (MPs) (plastics < 5 mm in size) is one of the emerging pollutants in metropolitan cities of developing countries because of its utmost resilience and synthetic nature. Recent studies on the surface water bodies (river, pond, Lake etc.) portrait the correlation between the MPs level with different parameters of pollution such as specific conductivity, total phosphate, and biological oxygen demand. Fibers represent the predominant form of MPs discovered in surface water bodies, exhibiting fluctuations across seasons. Consequently, present study prioritizes understanding the adaptation, prevalence, attributes, fluctuations, and spatial dispersion of MPs in both sediment and surface water environments. Furthermore, the study aims to identify existing gaps in the current understanding and underscore opportunities for future investigation. From the present study, it has been reported that, the concentration of MPs in the range of 0.2-45.2 items/L at the Xisha Islands in the south China sea, whereas in India it was found in the range of 96 items/L in water samples and 259 items/kg in sediment samples. This would certainly assist the urban planners in achieving sustainable development goals to mitigate the increasing amount of emergent pollutant load.

Big brands impact small islands: Sources of plastic pollution in a remote and protected archipelago

Remote islands are disproportionately affected by plastic pollution, often originating from elsewhere, so it is important to understand its origins, to stop debris entering the ocean at their source. We investigated the origins of beached plastic drink bottles in the Chagos Archipelago, a large remote Marine Protected Area (MPA) in the Indian Ocean. We recorded the brands, countries of manufacture, types of drink, and ages of plastic bottles and their lids. The prevalent type of drink was water, with items mostly manufactured in Indonesia, China, and the Maldives. The main brands were Danone and the Coca-Cola Company. We deduced that 10 % of the items originated from ships passing the archipelago, including all the items manufactured in China. The identification of the brands creating plastic pollution in remote MPAs with high biodiversity supports extended producer responsibility, one of the proposed policy development areas of the Global Plastics Treaty.

Microplastics in remote coral reef environments of the Xisha Islands in the South China Sea: Source, accumulation and potential risk

Microplastics (MPs) are of great concern to coral health, particularly enhanced biotoxicity of small microplastics (< 100 µm) (SMPs). However, their fate and harm to remote coral reef ecosystems remain poorly elucidated. This work systematically investigated the distributions and features of MPs and SMPs in sediments from 13 islands/reefs of the Xisha Islands, the South China Sea for comprehensively deciphering their accumulation, sources and risk to coral reef ecosystems. The results show that both MPs (average, 682 items/kg) and SMPs (average, 375 items/kg) exhibit heterogeneous distributions, with accumulation within atolls and dispersion across fringing islands, which controlled by human activities and hydrodynamic conditions. Cluster analysis for the first time reveals a pronounced difference in their compositions between the southern and northern Xisha Islands and resultant distinct sources, i.e., MPs in the north part were leaked mainly from local domestic sewage and fishing waste, while in the south part were probably derived from industrial effluents from adjacent countries. Our ecological risk assessment suggests that the ecosystem within the Yongle Atoll is exposed to a high-risk of MPs pollution. The novel results and proposed framework facilitate to effectively manage and control MPs and accordingly preserve a fragile biosphere in remote coral reefs.

Selective enrichment of bacteria and antibiotic resistance genes in microplastic biofilms and their potential hazards in coral reef ecosystems

Microplastics become hotspots for bacteria to trigger a series of ecological effects, but few studies have focused on the potential impacts of microplastic biofilms in coral reef ecosystems. Here, we measured the bacterial communities and antibiotic resistance genes (ARGs) in the seawater and microplastic biofilms. Results showed that microbial biofilms were formed on the surface of microplastics. The alpha diversity of the bacterial community in the microplastic biofilms was lower than that in the seawater, and the bacterial communities were distinct between the two. Further analysis revealed that several bacteria in the microplastic biofilms carried ARGs, and the proportion of which was correlated to the concentration of antibiotics in the seawater. Specifically, Vibrio was positively correlated to sul1 in the microplastic biofilms under higher concentrations of sulfonamides. Pathway analysis reflected significant overrepresentation of human disease related pathways in the bacterial community of microplastic biofilms. These results suggest that the microplastic biofilms could selectively enrich bacteria from the reef environments, causing the development of ARGs under antibiotic driving. This may pose a serious threat to coral reef ecosystems and human health. Our study provides new insights into the ecological impacts of microplastic biofilms in coral reef ecosystems.

Seawater Accelerated the Aging of Polystyrene and Enhanced Its Toxic Effects on Caenorhabditis elegans

Microplastics (MPs) are emerging pollutants and pose a significant threat to marine ecosystems. Although previous studies have documented the mechanisms and toxic effects of aging MPs in various environments, the impact of the marine environment on MPs remains unclear. In the present study, the aging process of polystyrene (PS) in seawater was simulated and the changes in its physicochemical properties were investigated. Our results showed that the surface of the PS eroded in the seawater, which was accompanied by the release of aged MPs with a smaller size. In situ optical photothermal infrared microspectroscopy revealed that the mechanism of PS aging was related to the opening of the carbonyl group and breaking of the bond between carbon and benzene removal. To verify the toxic effects of aged PS, Caenorhabditis elegans was exposed to PS. Aged PS resulted in a greater reduction in locomotion, vitality, and reproduction than virgin PS. Mechanistically, aged PS led to oxidative stress, high glutathione s-transferase activity, and high total glutathione in worms. Together, our findings provided novel information regarding the accelerated aging of PS in seawater and the increased toxicity of aged PS, which could improve our understanding of MPs' ecotoxicity in the marine environment.

Microplastics in coral reef sediments underestimated? They may hide in biominerals

Microplastics (MPs) may be underestimated in coral reef sediments. Current pretreatments for determining MPs in the sediments are mainly density separation and organic matter removal, ignoring MPs that may be embedded or encrusted in biominerals. This could lead to discrepancies in assessing the potential risk of MPs contamination. To confirm whether MPs in coral reef sediments are underestimated, a two-step sequential digestion, including organic matter removal (H2O2 digestion) and biomineral removal (HCl digestion), was performed on sediments from the coral reef area of the South Penghu Marine National Park (SPMNP, Taiwan). The MPs abundance and characteristics of the two steps were analyzed separately. The results showed that the average MPs abundance after HCl digestion (78 ± 42 MPs/kg) was significantly higher than that of H2O2 digestion (38 ± 25 MPs/kg). The MPs diversity integrated index (MPDII) in coral reef sediments was low (MPDII = 0.35), and MPs were mainly small (<2.0 mm, 91.3 %), fibrous (93.5 %), colored (60.9 %), and rayon polymers (73.9 %). Correlation analysis showed that MPs in biominerals mainly dominated MPs in the sediments. These results confirm that current assessments of MPs contamination levels in biomineral-rich sediments may be underestimated and uncertain. In addition, the mineralization of organisms in SPMNP reef regions was affected by MPs from moderate to high levels, depending on the proportion of MPs in biominerals.

Fire and Oil Led to Complex Mixtures of PAHs on Burnt and Unburnt Plastic during the M/V X-Press Pearl Disaster

In May 2021, the M/V X-Press Pearl container ship burned for 2 weeks, leading to the largest maritime spill of resin pellets (nurdles). The disaster was exacerbated by the leakage of other cargo and the ship's underway fuel. This disaster affords the unique opportunity to study a time-stamped, geolocated release of plastic under real-world conditions. Field samples collected from beaches in Sri Lanka nearest to the ship comprised nurdles exposed to heat and combustion, burnt plastic pieces (pyroplastic), and oil-plastic agglomerates (petroplastic). An unresolved question is whether the 1600+ tons of spilled and recovered plastic should be considered hazardous waste. Due to the known formation and toxicity of combustion-derived polycyclic aromatic hydrocarbons (PAHs), we measured 20 parent and 21 alkylated PAHs associated with several types of spilled plastic. The maximum PAH content of the sampled pyroplastic had the greatest amount of PAHs recorded for marine plastic debris (199,000 ng/g). In contrast, the sampled unburnt white nurdles had two orders of magnitude less PAH content. The PAH composition varied between the types of spilled plastic and presented features typical of and conflicting with petrogenic and pyrogenic sources. Nevertheless, specific markers and compositional changes for burning plastics were identified, revealing that the fire was the main source of PAHs. Eight months after the spill, the PAH contents of sampled stray nurdles and pyroplastic were reduced by more than 50%. Due to their PAH content exceeding levels allowable for plastic consumer goods, classifying burnt plastic as hazardous waste may be warranted. Following a largely successful cleanup, we recommend that the Sri Lankans re-evaluate the identification, handling, and disposal of the plastic debris collected from beaches and the potential exposure of responders and the public to PAHs from handling it. The maritime disaster underscores pyroplastic as a type of plastic pollution that has yet to be fully explored, despite the pervasiveness of intentional and unintentional burning of plastic globally.

The Global Trend of Microplastic Research in Freshwater Ecosystems

The study of microplastics and their impact on aquatic ecosystems has received increasing attention in recent years. Drawing from an analysis of 814 papers related to microplastics published between 2013 and 2022 in the Web of Science Core Repository, this paper explores trends, focal points, and national collaborations in freshwater microplastics research, providing valuable insights for future studies. The findings reveal three distinct stages of microplastics: nascent development (2013-2015), slow rise (2016-2018), and rapid development (2019-2022). Over time, the focus of research has shifted from "surface", "effect", "microplastic pollution", and "tributary" to "toxicity", "species", "organism", "threat", "risk", and "ingestion". While international cooperation has become more prevalent, the extent of collaboration remains limited, mostly concentrated among English-speaking countries or English and Spanish/Portuguese-speaking countries. Future research directions should encompass the bi-directional relationship between microplastics and watershed ecosystems, incorporating chemical and toxicological approaches. Long-term monitoring efforts are crucial to assessing the sustained impacts of microplastics.

Role of organisms and their enzymes in the biodegradation of microplastics and nanoplastics: A review

Microplastic (MP) and Nanoplastic (NP) contamination have become a critical ecological concern due to their persistent presence in every aspect of the ecosystem and their potentially harmful effects. The current approaches to eradicate these wastes by burning up and dumping adversely impact the environment, while recycling has its own challenges. As a result, applying degradation techniques to eliminate these recalcitrant polymers has been a focus of scientific investigation in the recent past. Biological, photocatalytic, electrocatalytic, and, recently, nanotechnologies have been studied to degrade these polymers. Nevertheless, it is hard to degrade MPs and NPs in the environment, and these degradation techniques are comparatively inefficient and require further development. The recent research focuses on the potential use of microbes to degrade MPs and NPs as a sustainable solution. Therefore, considering the recent advancements in this important research field, this review highlights the utilization of organisms and enzymes for the biodegradation of the MPs and NPs with their probable degradation mechanisms. This review provides insight into various microbial entities and their enzymes for the biodegradation of MPs. In addition, owing to the lack of research on the biodegradation of NPs, the perspective of applying these processes to NPs degradation has also been looked at. Finally, a critical evaluation of the recent development and perspective for future research to improve the effective removal of MPs and NPs in the environment through biodegradation is also discussed.

Microplastics in sediments from the southern Gulf of Mexico: Abundance, distribution, composition, and adhered pollutants

Approximately 23 Mt of plastics reaches the ocean each year, fragmented into microplastics (MP). MPs are widely dispersed in the sea, becoming deposited in sediments. MPs are considered carriers of pollutants such as heavy metals and polycyclic aromatic hydrocarbons and, when ingested by biota, pose a high health risk. This study determined metals and PAHs in sedimentary microplastics from the southern Gulf of Mexico (GOM). One hundred twenty-four sediment samples were collected, covering an area of 26,220 km². The mean (±SD) of MPs in sediments was 16.46 ± 17.76 MPs/kg. The most abundant polymers were cellophane (CE), polyvinylidene fluoride (PVDF), polyethylene (PE), polyamides (PA), and nylon (NYL). A strong correlation (r: 0.83) was found between MP density and sediment depth. PA and PE were found near shorelines and PVDF near oil platforms. Aluminum, arsenic, and tin had the highest concentration (89.6 ± 94.6, 23.1 ± 70.3, and 19 ± 29.2 μg g^-1, respectively), and acenaphthylene was the PAH with the highest concentration (3.4 ± 12.6 μg g^-1). This study shows that MP with a higher density is found at greater depths, and this research is one of the first to cover a large area of the Gulf of Mexico.

Microplastic as an invisible threat to the coral reefs: Sources, toxicity mechanisms, policy intervention, and the way forward

Microplastic (MP) pollution waste is a global macro problem, and research on MP contamination has been done in marine, freshwater, and terrestrial ecosystems. Preventing MP pollution from hurting them is essential to maintaining coral reefs' ecological and economic benefits. However, the public and scientific communities must pay more attention to MP research on the coral reef regions' distribution, effects, mechanisms, and policy evaluations. Therefore, this review summarizes the global MP distribution and source within the coral reefs. Current knowledge extends the impacts of MP on coral reefs, existing policy, and further recommendations to mitigate MPs contamination on corals are critically analyzed. Furthermore, mechanisms of MP on coral and human health are also highlighted to pinpoint research gaps and potential future studies. Given the escalating plastic usage and the prevalence of coral bleaching globally, there is a pressing need to prioritize research efforts on marine MPs that concentrate on critical coral reef areas. Such investigations should encompass an extensive and crucial understanding of the distribution, destiny, and effects of the MPs on human and coral health and the potential hazards of those MPs from an ecological viewpoint.

Impacts of marine debris on coral reef ecosystem: A review for conservation and ecological monitoring of the coral reef ecosystem

Coral reefs are the most spectacular underwater creation of nature. It enhances ecosystem functioning and marine biodiversity while also ensuring the livelihood of millions of coastal communities worldwide. Unfortunately, marine debris poses a serious threat to ecologically sensitive reef habitats and their associated organisms. Over the past decade, marine debris has been regarded as a major anthropogenic threat to marine ecosystems and gained scientific attention around the globe. However, the sources, types, abundance, distribution, and potential consequences of marine debris on reef ecosystems are hardly known. The goal of this review is to provide an overview of the current status of marine debris in various reef ecosystems across the world, with special emphasis on its sources, abundance, distribution, species impacted, major categories, potential impacts and management strategies. Furthermore, the adhesion mechanisms of microplastics to coral polyps, diseases caused by microplastics and are also highlighted.

Macro- and microplastics as complex threats to coral reef ecosystems

The impacts of macroplastics (macro-), microplastics (MPs, <5mm), and nanoplastics (NPs, <100 nm) on corals and their complex reef ecosystems are receiving increased attention and visibility. MPs represent a major, contemporary, sustainability challenge with known and unknown effects on the ocean, and coral reef ecosystems worldwide. However, the fate and transport processes of macro-, MPs, and NPs and their direct and indirect impacts on coral reef ecosystems remains poorly understood. In this study, we verify and briefly summarize MPs distribution and pollution patterns in coral reefs from various geographical regions and discuss potential risks. The main interaction mechanisms show that MPs may substantially affect coral feeding performance, proper skeletal formation, and overall nutrition and, thus, there is an urgent need to address this rapidly growing environmental problem. From a management perspective, macro-, MPs, and NPs should, ideally, all be included in environmental monitoring frameworks, as possible, to aid in identifying those geographical areas that are most heavily impacted and to support future prioritization of conservation efforts. The potential solutions to the macro-, MP, and NP pollution problem include raising public awareness of plastic pollution, developing robust, environmental, conservation efforts, promoting a circular economy, and propelling industry-supported technological innovations to reduce plastic use and consumption. Global actions to curb plastic inputs, and releases of macro-, MP, and NP particles, and their associated chemicals, to the environment are desperately needed to secure the overall health of coral reef ecosystems and their inhabitants. Global scale horizon scans, gap analyses, and other future actions are necessary to gain and increase momentum to properly address this massive environmental problem and are in good accordance with several relevant UN sustainable development goals to sustain planetary health.

A global snapshot of microplastic contamination in sediments and biota of marine protected areas

Microplastics (MPs) become ubiquitous contaminants in Marine Protected Areas (MPA) that have been planned as a conservation strategy. The present study provides a comprehensive overview of the occurrence, abundance, and distribution of MPs potentially affecting MPA worldwide. Data on MP occurrence and levels in sediment and biota samples were collected from recent peer-reviewed literature and screened using a GIS-based approach overlapping MP records with MPA boundaries. MPs were found in 186 MPAs, with levels ranging from 0 to 9187.5 items/kg in sediment and up to 17,461.9 items/kg in organisms. Peaked MPs concentrations occurred within multiple-use areas, and no-take MPAs were also affected. About half of MP levels found within MPA fell into the higher concentration quartiles, suggesting potential impacts on these areas. In general, benthic species were likely more affected than pelagic ones due to the higher concentrations of MP reported in the tissues of benthic species. Alarmingly, MPs were found in tissues of two threatened species on the IUCN Red List. The findings denote urgent concerns about the effectiveness of the global system of protected areas and their proposed conservation goals.

Assessment of microplastic bioconcentration, bioaccumulation and biomagnification in a simple coral reef food web

Plastics, and more specifically, microplastics (MPs, <5 mm) are considered a marine contaminant of emerging concern. To accurately assess the ecological risk of MPs, it is critical to first understand the relationship between MP contamination in organisms with that in their surrounding environment. The goal of this study was to examine the ecological risk of MPs in coral reef ecosystems by assessing the MP contamination found within a simple food web against contamination in the surrounding environment. Taxa representing three trophic levels (zooplankton, benthic crustaceans, and reef fish), as well as the distinct environmental matrices which they inhabit (i.e., mid-column water and sediment) were collected from two mid-shelf reefs in the central Great Barrier Reef, Australia. Microplastics were isolated using validated clarification techniques, visually characterised (i.e., shape, colour, size) by microscopy, chemically confirmed by Fourier transform infrared spectroscopy and recorded in all three trophic levels and all abiotic samples. MPs were found to bioconcentrate, with similar concentrations, polymer types, sizes, shapes, and colours at each trophic level compared to their surrounding environment. However, MP contamination varied across the three trophic levels, with no evidence of bioaccumulation. Further, MP concentrations did not increase up the food web, discounting MP biomagnification. Regardless, given the heterogeneity of MPs found in the marine environment, and the complexity of marine food webs, trophic transfer represents a prominent pathway of exposure from lower to higher trophic levels.

International quantification of microplastics in indoor dust: prevalence, exposure and risk assessment

This international scale study measured the prevalence of indoor microplastics (MPs) in deposited dust in 108 homes from 29 countries over a 1-month period. Dust borne MPs shape, colour, and length were determined using microscopy and the composition measured using μFTIR. Human health exposure and risk was assessed along with residential factors associated with MPs via a participant questionnaire. Samples were categorised according to each country's gross national income (GNI). Synthetic polymers dominated in low income (LI) (39%) and high income (HI) (46%) while natural fibres were the most prevalent in medium income (MI) (43%) countries. Composition and statistical analysis showed that the main sources of MPs and dust were predominantly from indoor sources. Across all GNI countries, greater vacuuming frequency was associated with lower MPs loading. High income country samples returned higher proportions of polyamides and polyester fibres, whereas in LI countries polyurethane was the most prominent MPs fibre. Exposure modelling showed infants (0-2 years) were exposed to the highest MPs dose through inhalation (4.5 × 10^-5 ± 3 × 10^-5) and ingestion (3.24 × 10^-2 ± 3.14 × 10^-2) mg/kg-B_w/day. Health risk analysis of constituent monomers of polymers indicates cancer incidence was estimated at 4.1-8.7 per million persons across age groups. This study's analysis showed socio-economic factors and age were dominant variables in determining dose and associated health outcomes of MPs in household dust.

Distribution pattern and influencing factors for the microplastics in continental shelf, slope, and deep-sea surface sediments from the South China Sea

Marine microplastic pollution has become a major global concern in recent years and the fate of microplastics in the ocean is a hot issue of research. We investigated microplastic pollution in surface sediments in the northern South China Sea to explore its distribution characteristics and influencing factors across the continental shelf, continental slope, and deep-sea environments. It was found that the microplastic abundance of surface sediments was 130.56 ± 40.48 items/kg. The average abundance of microplastics in all three topographic areas gradually decreased with increasing distance offshore. However, the differences in microplastic diversity indices between the three areas were not significant and were higher than those in other seas of the world, indicating that the waters of the northern South China Sea are rich in microplastics from complex sources, with more pollution input channels. In the continental shelf, fibrous and low density microplastics accounted for the largest amount, with a low degree of microplastic aging, and were mostly transported by suspended-load. These microplastics were mainly influenced by human activities. In the deep sea, microplastics with higher density were the most abundant and the number of fibrous microplastics was fewer, while the average size was larger, mainly influenced by the bottom currents. These microplastics underwent long-term bedload transport. In the continental slope, the main factors affecting the distribution of microplastics were more complex. In addition to pollution by human activities, the slope also receives microplastic materials carried by bottom currents; therefore, the composition of microplastics in the slope combines those characteristics of microplastics in both the continental shelf and deep-sea areas. The findings of this study indicate that the South China Sea is affected by complex pollution sources under the dual effects of human activities and natural conditions; in particular, the pollution situation in the deep-sea area needs extensive attention.

Hidden problems in geological heritage sites: The microplastic issue on Saint Mary's Island, India, Southeast Arabian Sea

Microplastics (MPs) have become a dominant constituent of several oceanic islands. This study focuses on the occurrence and distribution of MPs present in the beach sediments of Saint Mary's Island (SMI), a geological heritage site located in the south-eastern part of the Arabian Sea. The average (standard deviation) abundance of MPs on this island was 97.18 (80.49) particles/kg. Attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy revealed that MPs are composed of high-density polyethylene (HDPE), low-density polyethylene (LDPE), polyethylene (PE), polypropylene (PP), polystyrene (PS), and polyamide (PA). Scanning Electron Microscopy (SEM) and Energy-Dispersive X-ray Spectroscopy (EDS) highlighted the presence of Cr, As, Pb, and Cd (harmful pollutants) on MP surfaces. The MPs in the SMI are largely contributed by the nearby fishing harbour, touristic beaches and estuaries. The results of this study, act as a starting point for continuous environmental monitoring in this unique region of the world.

Spatial distribution of microplastics in the tropical Indian Ocean based on laser direct infrared imaging and microwave-assisted matrix digestion

Suspended particulate matter was collected from subsurface (6 m) water along an E-W transect through the tropical Indian Ocean using a specialized inert (plastic free) fractionated filtration system. The samples were subjected to a new microwave-assisted "one-pot" matrix removal (efficiency: 94.3% ± 0.3% (1 SD, n = 3)) and microplastic extraction protocol (recovery: 95% ± 4%). The protocol enables a contamination-minimized digestion and requires only four filtration steps. In comparison, classical sample processing approaches involve up to eight filtration steps until the final analysis. Microplastics were identified and physically characterized by means of a novel quantum cascade laser-based imaging routine. LDIR imaging facilitates the analysis of up to 1000 particles/fibers (<300 μm) within approximately 1-2 h. In comparison to FTIR and Raman imaging, it can help to circumvent uncertainties, e. g. from subsampling strategies due to long analysis and post-processing times of large datasets. Over 97% of all particles were correctly identified by the automated routine - without spectral reassignments. Moreover, 100% agreement was obtained between ATR-FTIR and LDIR-based analysis regarding particles and fibers >300 μm. The mean microplastic concentration of the analyzed samples was 50 ± 30 particles/fibers m^-3 (1 SD, n = 21). Number concentrations ranged from 8 to 132 particles/fibers m^-3 (20-300 μm). The most abundant polymer clusters were acrylates/polyurethane/varnish (49%), polyethylene terephthalate (26%), polypropylene (8%), polyethylene (4%) and ethylene-vinyl acetate (4%). 96% of the microplastic particles had a diameter <100 μm. Though inter-study comparison is difficult, the investigated area exhibits a high contamination with particulate plastics compared to other open ocean regions. A distinct spatial trend was observed with an increasing share of the size class 20-50 μm from east to west.

Concentrations and risk assessment of metals and microplastics from antifouling paint particles in the coastal sediment of a marina in Simon's Town, South Africa

Maintenance of maritime vessels includes the removal of paint from hulls that are sources of metals, antifouling paint particles (APPs) and microplastics (MPs) that end up in the coastal environment. Simon's Town is a small urban town in False Bay, Cape Town, South Africa, where maritime activities take place (there is a naval harbour, marina and shipyard). The aim of this study was to measure metals, APPs and MPs in Simon's Town, to assess the impact of maritime activities and a storm water pipe in a sheltered marina. Sediment samples were collected from six sites during winter 2018. Sediment and extracted APPs were analysed for metal concentrations (Al, As, B, Ba, Cd, Co, Cr, Cu, Hg, Mo, Ni, Pb, Se, Sb, Sn, Sr, V and Zn) and MPs characterised based on type (shape and polymer), colour and size. Highest average metal concentrations in sediment for all sites were Fe (32228 ± SEM 4024), Al (12271 ± 1062) and Cu (1129 ± 407). Metals in paint particles were highest for Fe (80873 ± 19341), Cu (66762 ± 13082) and Zn (44910 ± 1400 µg/g). Metal and MP fragment concentrations were highest at the slipway of the shipyard, decreasing with increased distance from the slipway. MP filaments were highest close to the storm water outfall pipe. Our results suggest that shipyards are potential sources of metals and MP fragments (mainly APPs), with storm water pipes potential sources of MP filaments. Various indices applied to assess the potential impacts of metals and MPs suggest that these contaminants have the potential to adversely impact the intertidal ecosystem investigated.

Microplastics in intertidal water of South Australia and the mussel Mytilus spp.; the contrasting effect of population on concentration

Microplastics, plastic particles <5 mm in size, are of global concern as human-caused pollutants in marine and fresh waters, and yet little is known of their distribution, behaviour and ecological impact in the intertidal environment of South Australia. This study confirms for the first time, the presence of microplastic in the South Australian intertidal ecosystem by quantifying the abundance of particles in intertidal water and in the keystone species, the blue mussel, Mytilus spp., an important fisheries species, at ten and six locations respectively, along the South Australian coastline. For a remote region known for its pristine environment, microplastic concentration in intertidal water was found to be low to moderate (mean = 8.21 particles l^-1 ± 4.91) relative to global levels and microplastic abundance in mussels (mean = 3.58 ± 8.18 particles individual^-1) was within the range also reported globally. Microplastic particles were ubiquitous across sites and bioavailable by size in water (mean = 906.36 μm) and in mussel (mean = 983.29 μm) raising concerns for the health of South Australia's unique coastal ecosystems and for the human food chain. Furthermore, a positive correlation was found between human coastal population size and microplastic concentration in intertidal water, irrespective of influences from industry - tourism, fishing and shipping ports. FTIR analysis determined plastic type to include polyamide (PA), polyethylene (PE), polypropylene (PP), acrylic resin, polyethyleneterephthalate (PET) and cellulose, suggesting synthetic and semi-synthetic particles from single-use, short-life cycle products, fabrics, ropes and cordage. Our findings shed light on the urgent need to establish the local sources of microplastic pollution in order to assist the community, industry and government to reduce the impact of microplastic on the fragile marine systems within South Australian intertidal waters and on the organisms associated with the human food chain.

Occurrence, spatial distribution, and risk assessment of microplastics in surface water and sediments of Saint Martin Island in the Bay of Bengal

Microplastics (MPs) are emerging contaminants in aquatic and terrestrial ecosystems and have caused substantial concern worldwide. This study surveyed the presence of MPs in surface water and sediments across the coastal area of Saint Martin Island in the Bay of Bengal. MPs were collected following the standard protocol and identified as various types like expanded polystyrene, foam, filaments, fragments, lines, fibres, and paint flakes. Total MPs pollution in beach sediment was 317 particles/kg across 14 sampling sites, varied from 11 to 10589 particles/m² of dry sediment and 0.95 particles/m³, having ~2 to 19 particles/30 min trawl in coastal surface water samples. Most of the frequent MPs in beach sediments ranged from 1.0 to 2.0 mm, whereas the fragments were predominant in sediment and surface water samples. MPs distribution revealed that different shapes were dominant at different sites within the Island. The calculated pollution risk index due to the presence of MPs indicated that the sediment and surface water samples were under the low-risk category. However, polymeric risk assessment and contamination factors suggest that the coastline is significantly polluted, as high pollution load indices (PLI >1) were observed for sediments and coastal surface water samples. This work provides the detailed MPs data in the coastal environment of Saint Martin Island for the first time; hence it may be helpful to develop proper strategies to deal with environmental problems.

Microplastic pollution in the surface seawater in Zhongsha Atoll, South China Sea

The prevalence of microplastics in the marine environment has attracted extensive attention. So far, no information is known regarding the temporal and spatial variations of microplastics in Zhongsha Atoll. This study, for the first time, comprehensively investigated the occurrence and distribution of microplastics in the surface seawater in Zhongsha Atoll based on two ocean cruises. The abundances of microplastics measured in the surface seawater of Zhongsha Atoll were in the ranges of not detected (ND) to 67 items/m³, and ND to 160 items/m³ in 2019 and 2020, respectively. All microplastics detected in Zhongsha Atoll were fibers, most of which were transparent and less than 2 mm. Polyethylene terephthalate was the dominating composition of microplastics. These results suggested that sewage, surface runoff, atmospheric deposition by neighboring land, and fishing activities may be the primary pollution sources. This study provides critical information on microplastic pollution in Zhongsha Atoll for the first time, calling for more research in the management of marine plastic debris in the future.

Airborne microplastic concentrations and deposition across the Weser River catchment

Microplastic (MP) appears to be omnipresent in the atmosphere, raising concerns about dispersion across environmental compartments, ecological consequences and human health risks by inhalation. To date, data on the sources of atmospheric MP and deposition to river catchment areas are still sparse. We, therefore, took aerosol and total atmospheric deposition samples in the catchment area of the large German river Weser to estimate microplastic deposition fluxes (DFs) at six specific sites and airborne MP concentrations. Sampling in rural, suburban, and urban environments and wastewater treatment plants (WWTPs) was performed, aiming at a variation in airborne MP pollution and elucidating potential MP source areas. Aerosol samples were taken twice in April and October while monthly total deposition samples were collected over a period from March to October. Microplastics were detected in all analysed aerosol samples by Raman spectroscopy down to 4 μm, and in all 32 total deposition samples by μFT-IR down to 11 μm. Average MP number concentrations of 91 ± 47 m^-3 were found in aerosol samples. The measured total MP number DFs ranged between 10 and 367 N m^-2 day^-1 (99 ± 85 mean ± SD) corresponding to total deposition of 0.05 ± 0.1 kg ha^-1 per year and to an estimated 232 metric tons of plastic being deposited in the Weser River catchment annually. MP number DFs were higher in urban than rural sites. An effect of WWTPs on the MP abundance in air was not observed. Polypropylene, polyethylene, polyethylene terephthalate, polyvinyl chloride, polystyrene, and silicone fragments were found as the predominant polymer types in total deposition samples, while polyethylene particles dominated in aerosol samples. The results suggest that proximity to sources, especially to cities, increase the numbers of MP found in the atmosphere. It further indicates that atmospheric MP considerably contributes to the contamination of both aquatic and terrestrial habitats.

Sustainable Tourism Issues in European Countries during the Global Pandemic Crisis

Sustainable economic growth can be achieved through tourism by protecting the environment, maintaining natural resources, creating employment, improving cultural diversity, and recognizing cultural heritage values. The concept of tourism sustainability is gradually growing globally and becoming a dominant aspect in modern business, as companies need to meet stakeholders’ demands regarding environmental management. Sustainable tourism incorporates environmental, social, economic, and cultural issues into operations. The demand for green tourism, ethical consumption, protection of natural resources, and living close to nature is expected to increase. In particular, the latter gains more and more popularity due to the stress caused by the global pandemic and also because values have been re-evaluated at every level of society. In this paper, we explore sustainability in the tourism industry within the international context during the COVID-19 pandemic, with a specific focus on tourism in 35 European countries for the period between January 2020 and September 2021. We aimed to study the impact of tourism on sustainability based on the Eurostat database, using cluster analysis and descriptive statistics. The results indicate that tourism will recover slightly, even though the pandemic will continue, recording different effects in European countries. Furthermore, we highlight the relationship between income and tourism, the clusters on tourism being significantly different according to income. The results also identify potential recovery options to align this business area with global sustainable development goals, generate effective transformational change, and suggest how to create a viable growth process pushed by a glocal perspective.

Current status of microplastics pollution in the aquatic environment, interaction with other pollutants, and effects on aquatic organisms

Microplastics, as emerging pollutants, have received great attention in the past few decades due to its adverse effects on the environment. Microplastics are ubiquitous in the atmosphere, soil, and water bodies, and mostly reported in aqueous environment. This paper summarizes the abundance and types of microplastics in different aqueous environments and discusses the interactions of microplastics with other contaminants such as polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), antibiotics, and heavy metals. The toxicity of microplastics to aquatic organisms and microorganisms is addressed. Particularly, the combined toxic effects of microplastics and other pollutants are discussed, demonstrating either synergetic or antagonistic effects. Future prospectives should be focused on the characterization of different types and shapes of microplastics, the standardization of microplastic units, exploring the interaction and toxicity of microplastics with other pollutants, and the degradation of microplastics, for a better understanding of the ecological risks of microplastics.

Microplastics: impacts on corals and other reef organisms

Plastic pollution in a growing problem globally. In addition to the continuous flow of plastic particles to the environment from direct sources, and through the natural wear and tear of items, the plastics that are already there have the potential to breakdown further and therefore provide an immense source of plastic particles. With the continued rise in levels of plastic production, and consequently increasing levels entering our marine environments it is imperative that we understand its impacts. There is evidence microplastic and nanoplastic (MNP) pose a serious threat to all the world's marine ecosystems and biota, across all taxa and trophic levels, having individual- to ecosystem-level impacts, although these impacts are not fully understood. Microplastics (MPs; 0.1–5 mm) have been consistently found associated with the biota, water and sediments of all coral reefs studied, but due to limitations in the current techniques, a knowledge gap exists for the level of nanoplastic (NP; <1 µm). This is of particular concern as it is this size fraction that is thought to pose the greatest risk due to their ability to translocate into different organs and across cell membranes. Furthermore, few studies have examined the interactions of MNP exposure and other anthropogenic stressors such as ocean acidification and rising temperature. To support the decision-making required to protect these ecosystems, an advancement in standardised methods for the assessment of both MP and NPs is essential. This knowledge, and that of predicted levels can then be used to determine potential impacts more accurately.

Organic enrichment can increase the impact of microplastics on meiofaunal assemblages in tropical beach systems

The cumulative impact of microplastic and organic enrichment is still largely unknown. Here, we investigated the microplastic contamination, the organic enrichment and their effects on meiofaunal distribution and diversity in two islands of the Maldivian archipelago: one more pristine, and another strongly anthropized. Field studies were coupled with manipulative experiments in which microplastic polymers were added to sediments from the non-anthropized island (i.e., without organic enrichment) to assess the relative effect of microplastic pollution on meiofauna assemblages. Our results reveal that the impact of microplastic contamination on meiofaunal abundance and taxa richness was more significant in the anthropized island, which was also characterized by a significant organic enrichment. Meiofauna exposed experimentally to microplastic contamination showed: i) the increased abundance of opportunistic nematodes and copepods and ii) a shift in the trophic structure, increasing relevance in epistrate-feeder nematodes. Based on all these results, we argue that the coexistence of chronic organic enrichment and microplastics can significantly increase the ecological impacts on meiofaunal assemblages. Since microplastic pollution in the oceans is predicted to increase in the next decades, its negative effects on benthic biodiversity and functioning of tropical ecosystems are expected to worsen especially when coupled with human-induced eutrophication. Urgent actions and management plans are needed to avoid the cumulative impact of microplastic and organic enrichment.

Micro-CT reconstruction reveals the colony pattern regulations of four dominant reef-building corals

Colonies are the basic geometric building blocks of coral reefs. However, the forming regulations of both colonies and reefs are still not understood adequately. Therefore, in this study, we reconstructed 25 samples using high-resolution micro-computed tomography to investigate coral growth patterns and parameters. Our skeleton and canal reconstructions revealed the characteristics of different coral species, and we further visualized the growth axes and growth rings to understand the coral growth directions. We drew a skeleton grayscale map and calculated the coral skeleton void ratios to ascertain the skeletal diversity, devising a method to quantify coral growth. On the basis of the three-dimensional (3D) reconstructions and growth parameters, we investigated the growth strategies of different coral species. This research increases the breadth of knowledge on how reef-building corals grow their colonies, providing information on reef-forming regulations. The data in this paper contain a large amount of coral growth information, which can be used in further research on reef-forming patterns under different conditions. The method used in this study can also be applied to animals with porous skeletons.

Synthetic textile and microfiber pollution: a review on mitigation strategies

Microfiber pollution is one of the recent threats to sustainability. Due to the increased use of synthetic textiles, microplastic fiber release to the environment has increased exponentially. This review aims to analyze the existing literature to identify the potential preventive measures to control microfiber pollution. The review consolidates the findings under the textile properties and laundry product category. The review results show that the use of finer count yarns with filaments and compact structures reduces microfiber shedding. Similarly, mechanical finishes like shearing and raising increase the microfiber release as they damage the fabric structure. A significant increment is noted in microfiber reduction percentage after the chemical (coating) finishing process. In the case of commercial products, the available external laundry filters are reported as more efficient than the in-drum devices in the market. An analysis of the existing regulatory norms showed that very few countries had developed their laws, and no global regulation and standards were found to test microfiber pollution. In the case of laundry filters, though they filter microfiber effectively, they do not prevent it, so it can be a control measure and not a solution for the issue. Out of the review results, it is identified that controlling the textile parameter is the only effective strategy to prevent the microfiber shedding from the synthetic textile. A proper production method and parameter will yield a textile that sheds lesser or no microfiber. However, no detailed research works are found in correlating these parameters together and indicate the potential scope for future research.

A comprehensive review on assessment of plastic debris in aquatic environment and its prevalence in fishes and other aquatic animals in India

The presence of meso, macro, and microplastics (MPs) in aquatic environments has raised concerns due to their potential risks to aquatic as well as human life. Though plastics are considered to be inert in nature, MPs with toxic additives and accumulated contaminants have harmful ecological effects. Reports of absorption of MPs by internal tissues and toxicity in vital organs such as lung cells, liver, and brain cells have proved its serious health hazards. The study of plastic debris in the aquatic environment deserves special attention due to its ecotoxicological impact. This review presents a detailed account of the assessment of plastic debris in marine as well as freshwater environments. The formation of MPs and their sources, sampling, isolation, identification and characterization methods adopted, and the prevalence of MPs in aquatic life are discussed. To the best of our knowledge, the present article is a first-ever comprehensive review covering the entire of India. Our review finds that, so far, very few studies have been carried out, and there is a paucity of information, especially on the prevalence of plastic debris in the freshwater environment, fish, and other aquatic animals in India. While major studies have been done at various coastal locations in the southern part of India and a few studies in the rest of India, south-eastern states remain neglected. Toxicological studies on various life forms, including humans, are lacking. The present review also fills the gap in our knowledge of the various locations studied across India and can guide future research.

Management of plastic waste: A bibliometric mapping and analysis

This work aims to provide the first holistic and deep bibliometric mapping and analysis of the management of plastic waste. Data from the last five years were obtained from a Scopus database search. Relevant information on scientific production, contributions by country and institutions, sources, reference authors, and topic trends were obtained, being analysed using the VOSviewer and Bibliometrix R-package software programs. The results clearly have shown a significant increase in the number of publications over the years, depicting the great influence of the People's Republic of China, since the most relevant authors, publications, and institutes are Chinese. Regarding the topic trends, there is a massive concern about plastic pollution, especially related to plastic in water bodies (mainly microplastics), and the socio-environmental problems which plastic may cause/aggravate, with recycling and the circular economy emerging as possible solutions.

Microplastics in the coral reefs and their potential impacts on corals: A mini-review

Plastic debris exists worldwide and research on microplastic pollution has gradually spread from the oceans to freshwater and terrestrial systems. Coral reefs not only serve as one of the most charismatic and biodiverse ecosystems on our planet, but also maintain the human harvesting of natural resources and livelihoods of hundreds of millions of people. However, the abundance and distribution characteristics of microplastics in coral reef systems receive little scientific attention. Meanwhile, the impacts of microplastics and nanoplastics on coral health and its potential mechanisms remain further studied. Herein, this review first summarized the current status of microplastics pollution in global coral reefs, especially included (i) abundance and distribution characteristics of microplastics in different media (e.g., seawater, sediment, corals), and (ii) possible sources of microplastics in reef regions. Furthermore, the main interaction mechanisms between microplastics and corals are highlighted. Following this, the direct or indirect impacts of microplastics on coral species are discussed. With the rapid increase of plastic consumption and background of pervasive global coral bleaching, research on marine microplastics must focus on the critical coral reef regions and include a comprehensive knowledge about the distribution, fate, and potential risks from an ecosystem perspective.