Spatial and seasonal distribution of microplastics in various environmental compartments around Sishili Bay of North Yellow Sea, China

Effects of microplastics on typical macrobenthos in sargassum ecosystems

Recently, microplastics (MPs) have attracted extensive attention to their wide distribution and potential toxicity in ecosystems. However, there was a lack of research focused on MPs in seaweed bed ecosystems. This study investigated the distribution and toxicity of MPs in macrobenthos in Sargassum ecosystem. According to the in-situ investigation results, the abundance of MPs in the sediment was 0.9-2.3 items/g, the indoor microcosmic experiment was constructed. After exposure to MPs (0, 2, and 20 items/g) for 30 days, the abundance of MPs in macrobenthos exhibits a concentration-dependent increase. However, there was no significant bioaccumulation of MPs at the trophic level. The indoor toxicity test revealed that MPs induced oxidative stress and altered intestinal microflora composition in macrobenthos, even at actual environmental concentrations (2 items/g). It may result in a perturbation of the organism's homeostatic equilibrium. High-concentration (20 items/g) MPs had a greater impact on alkaline phosphatase (AKP) in Mollusks. The increase in AKP activity could be indicative of an adaptive mechanism in some macrobenthos while the decline in AKP activity might signal a decrease in their survival. These results elucidated the fate of MPs in ecosystem and the ecological risks of MPs to large benthic animals on model environmental conditions.

Abundant small microplastics hidden in water columns of the Yellow Sea and East China Sea: Distribution, transportation and potential risk

Microplastics (MPs) pose significant concerns for marine ecological security due to their minuteness and ubiquity. However, comprehensive knowledge on their distribution and fate in seawater columns remains limited. This study investigated the abundances and characteristics of MPs across 3-6 water layers in the South Yellow Sea and East China Sea. Results indicate that high-abundance small MPs (< 100 µm) (average 6567 items/m3) were hidden beneath the sea-surface, predominantly fine-grained particles (< 20 µm) and high-density polymers (> 1.03 g/cm3). The total suspended MPs (5.0-834.2 µm) are estimated at 2.9-3.1 × 1017 particles, with most of them occurring in upper layers. In profiles, their distribution varied by physical properties with depth; fragment-shaped and high-density MPs increased in proportion at greater depths, contrasting with fibrous MPs. These MPs originated primarily from the Yangtze River and their winter transport was driven by the Yangtze River Dilution Water, East China Sea Coastal Current, and Yellow Sea Warm Current, resulting in their accumulation in coastal and estuarine regions. Consequently, the Yangtze River Estuary ecosystem faces substantial risks from MP pollution throughout the water column. This work unveils the prevalence of small MPs in coastal water columns and intricate interaction between their fate and hydrodynamic conditions.

Possible sink of missing ocean plastic: Accumulation patterns in reef-building corals in the Gulf of Thailand

Individual coral polyps contain three distinct components-the surface mucus layer, tissue, and skeleton; each component may exhibit varying extent of microplastic (MP) accumulation and serve as a short- or long-term repository for these pollutants. However, the literature on MP accumulation in wild corals, particularly with respect to the different components, is limited. In this study, we investigated the adhesion and accumulation of MPs in four coral species, including both large (Lobophyllia sp. and Platygyra sinensis) and small (Pocillopora cf. damicornis and Porites lutea) polyp corals collected from Si Chang Island in the upper Gulf of Thailand. The results revealed that MP accumulation varied significantly among the four coral species and their components. Specifically, P. cf. damicornis exhibited the highest degree of accumulation (2.28 ± 0.34 particles g-1 w.w.) [Tukey's honestly significant difference (HSD) test, p < 0.05], particularly in their skeleton (52.63 %) and with a notable presence of high-density MPs (Fisher's extract test, p < 0.05). The most common MP morphotype was fragment, accounting for 75.29 % of the total MPs found in the coral. Notably, the majority of MPs were black, white, or blue, accounting for 36.20 %, 15.52 %, and 11.49 % of the samples, respectively. The predominant size range of MP particles was 101-200 μm. Nylon, polyacetylene, and polyethylene terephthalate (PET) were the prevalent polymer types, accounting for 20.11 %, 14.37 %, and 9.77 % of the identified samples, respectively. In the large polyp corals, while MP shapes, colors, and sizes exhibited consistent patterns, remarkable differences were noted in the polymer types across the three components. The findings of this study improve the understanding of MP accumulation and its fate in coral reef ecosystems, underscoring the need for further investigation into MP-accumulation patterns in reef-building corals worldwide.

An equilibrium criterion for plastic debris fate in wave-driven transport

The nearshore zone turns out to be the area with the higher concentration of plastic debris and, for this reason, it is important to know the processes that affect the transport and the fate of this type of litter. This study focuses on investigating the dynamics of various plastic types under several hydrodynamic conditions primarily induced by waves. 2D tests were carried out at the Hydraulic Laboratory of the University of Messina reproducing the main phenomena that occurred during the wave propagation on a planar beach. More than 200 different conditions were tested changing the wave characteristics, the water depth, the plastic debris characteristics (density and shape), and the roughness of the fixed bottom. In general, it can be observed that the reduction in particle displacement occurs due to: i) a decrease in wave steepness; ii) an increase in depth; iii) an increase in particle size; iv) an increase in plastic density. However, the experimental investigation shows that some plastic characteristics and bed roughness, even when hydraulically smooth, can alter these results. The experimental data analysis identified a criterion for predicting the short-term fate of plastic debris under wave action. This criterion to determine equilibrium conditions, based on an empirical relationship, takes into account the wave characteristics, the bed roughness and slope, and the weight of the debris.

Integrated occurrence of contaminants of emerging concern, including microplastics, in urban and agricultural watersheds in the State of São Paulo, Brazil

Contaminants of emerging concern (CECs), including microplastics, have been the focus of many studies due to their environmental impact, affecting biota and human health. The diverse land uses and occupation of watersheds are important parameters driving the occurrence of these contaminants. CECs such as pesticides, drugs, hormones, and industrial-origin substances were analyzed in urban/industrial (Atibaia) and agricultural (Preto/Turvo) watersheds located in São Paulo state, Brazil. A total of 24 CECs were investigated, and, as a result, only 5 (caffeine, carbendazim, atrazine, ametrine and 2-hydroxytrazine) were responsible for 81.73 % of the statistical difference between watersheds contamination profile. The Atibaia watershed presented considerable concentrations of caffeine (ranging from 75 to 2025 ng L-1), while carbendazim (44 to 1144 ng L-1) and atrazine (3 to 266 ng L-1) presented highest levels in Preto/Turvo watershed. In all sampling points, the cumulative potential aquatic life risk assessed by the NORMAN database indicates some level of environmental concern associated to pesticides and caffeine (risk quotient >1). Microplastics had been analyzed in both watersheds, being the white/transparent fragments in size between 100 and 250 μm the most detected in this study. The estimated abundance in the Atibaia watershed ranged from 349 to 2898 items m-3 presenting some influence of pluviosity, while in Rio Preto/Turvo ranged from 169 to 6370 items m-3, being more abundant in the dam area without a clear influence of pluviosity. In both basins, polyethylene and polypropylene were the most detected polymers, probably due to the intense use of single-use plastics in urban areas. Possibly, due to the distinct physic-chemical properties of microplastics and organic CECs, no correlations were observed between their occurrence, which makes us conclude that they have different transport mechanism, behavior, and fate in the environment.

Spectral analysis of environmental microplastic polyethylene (PE) using average spectra

In this study, microplastic samples from surface seawater of Tokyo Bay were collected, polyethylene (PE) microplastics were used to calculate carbonyl index (CI), and average spectra of PE were analyzed and compared with a previous study applying agitation during chemical treatment. It was found that PE and polypropylene (PP) were the predominant polymer type in the samples. Among PE samples, fragments were the most commonly observed shape, with white being the dominant color. Deviations were found in the average spectra among different shapes and colors when compared to the standard PE spectrum. A comparison of the average spectra between the two datasets suggests that pronounced peaks related to oxidation are most likely resulted from agitation during the chemical treatment. Additionally, it was found a closer spectral resemblance between the sample spectra and the spectrum of standard sample of oxidized PE (PEOx) than with the standard PE spectrum, suggesting that using the oxidized PE as a reference spectrum might be more effective for identification. These findings highlight the complex factors affecting the spectral properties of microplastics and highlight the importance of understanding these variations to enhance the accuracy of microplastic identification workflows and understanding of environmental fate of microplastics.

Dynamics of microplastic abundance under tidal fluctuation in Musi estuary, Indonesia

Tidal dynamics contribute to fluctuations in microplastic abundance (MPs). This is the first study to characterize MPs under the influence of tidal fluctuations in the Musi River Estuary. MPs samples were collected during flood and ebb tides at 10 research stations representing the inner, middle and outer parts of the Musi River Estuary. MPs were extracted to identify the shape, color and size. MP abundances were 467.67 ± 127.84 particles/m3 during flood tide and 723.67 ± 112.05 particles/m3 during ebb tide. The concentration of MPs in the outer zone of the estuary (ocean) was detected to be higher than in the inner zone of the estuary (river). The MPs found were dominated by black color, film shape and size 101-250 μm. A greater abundance of MPs at ebb tide than at flood tide implies that the Musi Estuary's largest source of emissions is discharge from the river.

New insights into estimation of bioavailable inorganic phosphorus in natural coastal seawater

Considering the impact of the high salinity and high turbidity of coastal seawater on phosphorus forms, a new method was proposed to determine bioavailable inorganic phosphorus (BIP). The phosphorus most relevant to eutrophication is BIP, and traditional analysis methods may underestimate the degree of eutrophication. In this study, a microelectrode of multigold (AuμE) was fabricated for direct voltammetric determination of BIP without filtration, and BIP environmental characteristics including distribution and correlation relationships with environmental factors in typical coastal seawater of Northern China were analyzed. The proposed AuμE showed a low detection limit of 0.03 μM. The surface and bottom BIP concentrations ranged from 1.00 to 2.13 and from 0.88 to 2.05 μM, respectively. BIP dominated the total P (TP) accounting for 48.5-67.5 % in the surface layer samples, and 32.6-92.7 % in the bottom layer samples, respectively. The concentrations of BIP were obviously higher than those of DIP, indicating that DIP may underestimate the probability of eutrophication occurring. And BIP was positively correlated with dissolved oxygen (DO) (P < 0.05). BIP may be a promising indicator of eutrophication potential in coastal areas with high salinity and high turbidity. The proposed reliable voltammetry method provides a new indicator for environmental assessment and represents a significant step in the comprehensive analysis of P species.

Trophic transfer and biomagnification of microplastics through food webs in coastal waters: A new perspective from a mass balance model

Since the 1950s, plastic pollution and its risk have been recognized as irreversible and nonnegligible problems as global plastic production has increased. In recent years, the transport and trophic transfer of microplastics (MPs) in biotic and abiotic environment have attracted extensive attention from researchers. In this study, based on the Ecotracer module from Ecopath with Ecosim (EwE) model, the marine ranching area of Haizhou Bay, Jiangsu Province, China, was taken as a case study by linking the environmental plastic inflow with MPs in organisms to simulate the variation of MPs in the marine food web for 20 years, as well as its potential trophic transfer and biomagnification. We found that the concentration of MPs in top consumers first increased when the concentration of MPs in the environment increased, while that in primary consumers first decreased when the concentration of MPs in the environment decreased. Moreover, high TL consumers had a stronger ability to accumulate MPs, and pelagic prey fishes was the opposite. From the perspective of the food web, all functional groups showed significant trophic magnification along with the trophic level and no biodilution. Generally, there is a direct relationship between the MPs in marine organisms and environmental inflow. If the pollutants flowing into the environment can be reduced, the MP pollution problem in coastal waters will be effectively alleviated. Our research can further provide a scientific basis for ecological risk assessment and management of MPs and biodiversity protection in marine ecosystems.

An identification of optimal waste disposal method for dumpsite remediation using the Fermatean fuzzy multi-criteria decision-making method

Improperly managed wastes that have been dumped in landfills over the years pose various challenges, but they also offer potential benefits. The feasibility of recycling such waste depends on the type of wastes, the condition of dumpsites, and the technology implemented for disposal. The selection of an alternative waste disposal method from the many available options for dumpsite remediation is a complex decision-making process among experts. The primary aim of this study is to assist in an extended multi-criteria decision-making (MCDM) method to reduce complexity in the proposed dumpsite remediation problem influenced by multiple criteria and to identify the optimal waste disposal method. Data uncertainties are managed with the proposed Fermatean fuzzy preference scale, and the importance of all socio-economic criteria is assessed using the full consistency method (FUCOM). The final ranking results of the weighted aggregated sum product assessment (WASPAS) method identify that the Waste-to-Energy (WtE) process could play a significant role in the disposal of land-filled unprocessed wastes, promoting sustainable waste management. Meanwhile, the methodology explores the idea that financial and logistical constraints may limit the feasibility of large-scale recycling efforts. This combination of environmental science and decision science addresses real-world challenges, helping municipal solid waste management authorities implement sustainable waste management practices.

A case study on microplastics pollution characteristics in fouling organisms in typical aquaculture bay, China

Microplastics (MPs) and fouling organisms are prevalent in oceans worldwide. The study aims to investigate the pollution characteristics of MPs in fouling organisms. The study found significant inter-specific differences in the MPs abundance, while the length of MPs is consistent. The average number of MPs in N. exigua is 0.00 ± 0.00. There is a correlation between MPs abundance and weight in sessile group, while gastropods don't. Direct observation has demonstrated that the radulae of N. radula can envelop MPs. Fiber and blue are the predominant forms and colors of MPs found in fouling organisms. It is noteworthy that all film and fragment MPs observed were of a blue hue and had a size limitation of 500 μm. The characteristics of MPs between sessile organisms are more similar than those between gastropods. This study has improved our understanding of the pollution characteristics of MPs in fouling organisms, specifically gastropods.

Microplastic transport during desertification in drylands: Abundance and characterization of soil microplastics in the Amu Darya-Aral Sea basin, Central Asia

Desertification and microplastic pollution are major environmental issues that impact the function of the ecosystem and human well-being of drylands. Land desertification may influence soil microplastics' abundance, transport, and distribution, but their distribution in the dryland deserts of Central Asia's Amu Darya-Aral Sea basin is unknown. Here, we investigated the abundance and distribution of microplastics in dryland desert soils from the Amu Darya River to the Aral Sea basin in Central Asia at a spatial scale of 1000 km and soil depths ranging from 0 to 50 cm. Microplastics were found in soils from all sample locations, with abundances ranging from 182 to 17841 items kg-1 and a median of 3369. Twenty-four polymers were identified, with polyurethane (PU, 37.3%), silicone resin (SR, 17.0%), and chlorinated polyethylene (CPE, 9.8%) accounting for 64.1% of all polymer types. The abundance of microplastics was significantly higher in deep (20-50 cm) soils than in surface (0-5, 5-20 cm) soils. The main morphological characteristics of the observed microplastics were small size (20-50 μm) and irregular particles with no round edges (mean eccentricity 0.65). The abundance was significantly and positively related to soil EC and TP. According to the findings, desertification processes increase the abundance of microplastic particles in soils and promote migration to deeper soil layers. Human activities, mainly grazing, may be the region's primary cause of desertification and microplastic pollution. Our findings provide new information on the diffusion of microplastics in drylands during desertification; these findings are critical for understanding and promoting dryland plastic pollution prevention and control.

Vertical distribution of microplastics in a river water column using an innovative sampling method

Due to limitations of sampling methods, subsurface water is usually a less well-investigated compartment of the water column when scientists assess microplastic contamination. In this study, microplastic (MP) contamination was assessed in a freshwater river both in surface and subsurface using an innovative sampling method. Microplastic contamination in the lower part of the water column, i.e., near-bottom water and in sediments, was also studied. Three sampling campaigns were carried out during different weather conditions: stormy, rainy, and dry in order to observe their influence on the microplastics vertical distribution. No significant difference was observed between the abundance and types of MPs in surface and subsurface water. The proportion of polymer with theoretical density < 1 (polypropylene d = 0.9, polyethylene d = 0.91-0.95) and polystyrene (d = 0.1-1.06) in the surface and subsurface samples was 73.5%, and this proportion drops to 40.8% for the samples located in the near-bottom water and the sediments. Our results indicate that the MP concentration of the different compartments analyzed can be significantly influenced by rainfall during and prior to the sampling day. This study highlights that in shallow rivers, surface water sampling is representative of the water column MP contamination, but that sampling without taking environmental conditions into account may lead to erroneous estimation of MPs concentration and flux entering the marine environment.

Microplastics are overestimated due to poor quality control of reagents

Microplastics are widely distributed in the environment and pose potential ecological risks, increasing to be one of the most important environmental pollutants. However, when assessing the characteristics of microplastic contamination in environmental samples, inadequate quality control measures for the working solutions may introduce additional microplastic contamination and lead to an overestimation of microplastic abundance in the samples. In this study, we evaluated the microplastic contamination characteristics in commonly used flotation and digestion reagents to assess errors caused by microplastics in the reagents. The results showed that the abundance of microplastics in the reagents ranged from 0.8 to 43.4 items/g, with the abundance of microplastics in flotation reagents being lower than that in digestion reagents. The shapes of the detected microplastics included particles, fibers, and fragments, and their size and outline were generally small, with most being below 100 µm. The most common types of polymers detected were polyethylene and polypropylene. In order to improve the universality and readability of the results, the detected microplastic abundances were converted into the actual application concentration of the working fluid. It was found that the potential contamination of microplastics in untreated flotation solutions ranged from 1.5 to 30.8 items/mL, while in digestion solutions ranged from 0.1 to 2.3 items/mL. Our study emphasizes the need for quality control measures, such as suction filtration, when evaluating microplastics in environmental samples or conducting chemical and biological tests related to microplastics.

A holistic approach on the impact of microplastic discharge from WWTPs to the neighboring environment in Southeast Spain

The present study investigated the release of microplastics (MPs) from wastewater treatment plants (WWTPs) to the neighboring environment, including marine and coastal sediments, and fish. Here, we comprehensively investigated MP abundance in 34 samples of marine sediment, corresponding to 5,530.5 g of sediment (d.w.) collected at -8.0 m, -12.5 m, and -24.0 m, 69 samples of coastal sediment, accounting for 13,617.4 g (d.w.) from 17 different beaches from Mar Menor, and stomach and intestine of 17 fish samples of Sparus aurata, in the vicinity of Cartagena, a port city in Southeast Spain. The results showed that MPs were detected in all marine sediment samples, with an average abundance of 19.4 ± 2.4 items/kg (d.w.), in coastal sediments, with an average abundance of 52.5 ± 5.3 items/kg (d.w.), and fish samples, with an average of 8.2 ± 1.4 items per individual. The contribution of MPs from WWTPs to marine sediments is expected to be slow, as effluents were mostly dominated by fiber and film shapes, and by polymers less dense than seawater. There were no significant variations in the MP abundance of marine sediments after the atmospheric phenomenon named DANA, although a significant smaller MP size was reported, indicating a high mobility for tiny sizes. The same results were revealed for coastal sediment, although variations after DANA were statistically significant. Coastal sediment samples closer to WWTPs and agricultural fields with plastic mulching displayed higher MP concentrations, and an increase in the removal rate of MPs from WWTP effluents was negatively correlated with a decrease in MPs from fish collected. This study highlights the importance of sewage treatment plants in transporting MPs to the aquatic and terrestrial surrounding environment, which warrants further research on human health risks associated to MP pollution.

Simulation of seasonal transport of microplastics and influencing factors in the China Seas based on the ROMS model

Elucidating the mechanisms governing microplastic transport and spatial distribution in offshore waters is essential to microplastic control. However, current research on microplastic transport in the China Seas is largely restricted to small-scale investigations, which do not provide a comprehensive result. Therefore, in this study, we used the Regional Ocean Modeling System (ROMS) combined with the Lagrangian Transport (LTRANS v.2) model to investigate how microplastics are transported around the China Seas during different seasons and under climatological river discharge. Our findings showed that the microplastic pathways and spatial distributions exhibit marked seasonal variations controlled by circulation patterns in the China Seas, river discharge values, and the characteristics of the microplastic materials. Floating microplastics exhibited the longest transport distance in summer, when microplastics from the Pearl River could be transported up to 1375.8 km through the Tokara and Tsushima straits. The heavy pollution areas in summer were located in the South Yellow Sea and East China Sea, mainly resulting from the contribution of the Yangtze River (>66%). In autumn and winter, more than three-quarters of the microplastics beached off the south-central Chinese coast. In addition, simulating the vertical velocity of the water prolonged the time required for microplastics to reach the open ocean, thereby reducing the amount of microplastics entering the Pacific Ocean by 6% compared to the simulation without the vertical velocity of the water in summer. Microplastics with higher densities were generally transported shorter distances. The transmission distances of PET and PS were two orders of magnitude smaller than that of PE. This study enhances knowledge of the sources and fates of offshore microplastics and provides scientific support for offshore microplastic control.

Microplastic pollution in coastal areas of Colombia: Review

Microplastics are distributed in the environment and are considered emerging pollutants because they are not regulated by legislation. This article aims to know the current state of knowledge regarding microplastic pollution in coastal areas of Colombia. Therefore, a detailed search was carried out in databases such as Scopus, Google Scholar, and university repositories collecting scientific and academic information published between 2000 and March 2022. As a result of the review, the presence of microplastics in coastal areas of Colombia was identified, particularly in the water, sediments, and fish, thus evidencing the contamination in coastal ecosystems, where the Caribbean coast is the area with the highest amount of microplastics in sediments, especially Cartagena (249-1387 particles/m2) and Santa Marta (144-791 particles/m2). It was also found that of 302 species of fish, 7% contained microplastics in the Ciénaga Grande of Santa Marta. In the studies, on the other hand, it was observed that there is no standardized methodology; each researcher chooses a different approach according to the scientific literature. The studies showed that the most abundant microplastics were secondary microplastics, of which polypropylene and polyethylene are predominant due to their different applications in society. This review will serve as a baseline for future research on microplastics in coastal areas of Colombia and will identify the challenges and realities of the country in the face of these emerging pollutants.