Abundance, characteristics and variation of microplastics in different freshwater fish species from Bangladesh

Seasonal variation, spatial distribution and risk assessment of microplastics in surface waters of Periyar River, Kerala, India

Microplastics, an emerging contaminant, are widespread in oceans around the world, and rivers are the key conveyors of these pollutants into the oceans. There exists a dearth of available data pertaining to seasonal fluctuation, spatial distribution and risk assessment of microplastics in rivers extending from upper reaches to the lower reaches. The collection of such data is of utmost importance for the purpose of formulating beneficial management strategies for riverine microplastics. In order to bridge this research gap, an investigation was made in the Periyar River in Kerala, India, which is exposed to anthropogenic stress and is at risk of microplastic pollution. A total of eighteen sites (six sites each from downstream, midstream and upstream) along the 244 km of the river were investigated across three seasons in a year. The study revealed a discernible pattern in the spatial distribution of microplastic concentrations, wherein there was a rise in abundance from the upstream to midstream and then a sudden increase of abundance along the downstream regions towards the lower reaches. The highest mean microplastic abundance of 124.95 items/L was obtained during the monsoon season followed by post-monsoon season i.e. 123.21 items/L and pre-monsoon i.e. 120.50 items/L. The predominant forms of microplastics were found to be fibres, fragments and filaments. Most prevalent polymer types acquired were polyethylene (PE) and polypropylene (PP). Pollution hazard index (PHI) and pollution load index (PLI) were also evaluated to assess the water quality of this river. The findings of this study conclude that the Periyar River is polluted with microplastics throughout its course and offer significant insights into the detection of microplastic origins in river systems and lend support to the implementation of potential measures aimed at mitigating their impact.

Microplastic Contamination of Non-Mulched Agricultural Soils in Bangladesh: Detection, Characterization, Source Apportionment and Probabilistic Health Risk Assessment

Microplastic contamination in agricultural soil is an emerging problem worldwide as it contaminates the food chain. Therefore, this research investigated the distribution of microplastics (MPs) in agricultural soils without mulch at various depths (0-5, 5-10, and 10-15 cm) across different zones: rural, local market, industrial, coastal, and research areas. The detection of MP types and morphology was conducted using FTIR and fluorescence microscopy, respectively. Eight types of MPs were identified, including high-density polyethylene (HDPE), low-density polyethylene (LDPE), polypropylene (PP), polyethylene terephthalate (PET), polyvinyl chloride (PVC), polyvinyl fluoride (PVF), polyvinyl alcohol (PVA), and polytetrafluoroethylene (PTFE), with concentrations ranging from 0.6 ± 0.21 to 3.71 ± 2.36 MPs/g of soil. The study found no significant trends in MP concentration, with ranges of 0-2.1 ± 0.38, 0-2.87 ± 0.55, and 0-2.0 ± 0.34 MPs/g of soil at depths of 0-5 cm, 5-10 cm, and 10-15 cm, respectively. The highest MP quantity was recorded at 8.67 in coastal area, while the lowest was 6.44 in the local market area. Various MP shapes, e.g., fiber, film, pellet, fragment, and irregular, were observed across all layers. PCA suggested irrigation and organic manure as potential sources of MPs. The estimated concentrations of MPs possessed low non-carcinogenic and carcinogenic risks to the farming community of Bangladesh.

The silent threat of plastics along the coastal frontiers of Bangladesh: Are we concerned enough?

Globally plastic pollution is posing a significant threat to the health and integrity of coastal ecosystems. This study aimed to provide a comprehensive overview of plastic pollution in the coastal areas of Bangladesh by examining land-based macroplastic distribution, exploring microplastic (MP) contamination in the coastal aquatic ecosystem and enhancing our understanding of the potential risks associated with MP contamination. Citizen science based monitoring approach using the android application was applied to understand the land-based plastic pollution in the coastal area of Bangladesh. From December 2022 to December 2023, a total of about 3600 photographs of plastic items from 215 citizen scientists were received from the coastal area of Bangladesh covering 580 km long coast line. Polymer Hazard Index (PHI) and Pollution Load Index (PLI) were also calculated to understand the risk of plastic pollution in sediment, water, aquatic organism, dried fish and sea salt. A total of 43 land-based plastic items reported from the coastal area of Bangladesh. Among these plastic items single use items contributed 58.2 % while disposable plastic items contributed 41.8 %. A strong spatial variability in the distribution of these plastic items was observed. PHI and PLI values suggested hazard category-I for MP contamination in sediment, sea salt, water, commercial fishery resources and dry fish. This study highlighted that coastal land area, sea salt, dried fish, water, sediment and organisms are contaminated with plastics which might have the potential threats to human health. Findings from this study will serve as reference data and also baseline for future research to combat the plastic pollution.

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

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

Microplastics pollution in the Surma River, Bangladesh: A rising hazard to upstream water quality and aquatic life

The ecological health of freshwater rivers is deteriorating globally due to careless human activities, for instance, the emission of plastic garbage into the river. The current research was the first assessment of microplastics (MPs) pollution in water, sediment, and representative organisms (fish, crustacean, and bivalve) from the Surma River. Water, sediment, and organisms were sampled from six river sites (Site 1: Charkhai; Site 2: Golapganj; Site 3: Alampur; Site 4: Kazir Bazar; Site 5: Kanishail and Site 6: Lamakazi), and major water quality parameters were recorded during sampling. Thereafter, MPs in water, sediment, and organism samples were extracted, and then microscopically examined to categorize selected MPs types. The abundance of MPs, as well as size, and color distribution, were estimated. Polymer types were analyzed by ATR-FTIR, the color loss of MPs was recorded, the Pollution Load Index (PLI) was calculated, and the relationship between MPs and water quality parameters was analyzed. Sites 4 and 5 had comparatively poorer water quality than other sites. Microplastic fibers, fragments, and microbeads were consistently observed in water, sediment, and organisms. A substantial range of MPs in water, sediment, and organisms (37.33-686.67 items/L, 0.89-15.12 items/g, and 0.66-48.93 items/g, respectively) was recorded. There was a diverse color range, and MPs of <200 μm were prevalent in sampling areas. Six polymer types were identified by ATR-FTIR, namely Polyethylene (PE), Polyamide (PA), Polypropylene (PP), Cellulose acetate (CA), Polyethylene terephthalate (PET), and Polystyrene (PS), where PE (41%) was recognized as highly abundant. The highest PLI was documented in Site 4 followed by Site 5 both in water and sediment. Likewise, Sites 4 and 5 were substantially different from other study areas according to PCA. Overall, the pervasiveness of MPs was evident in the Surma River, which requires further attention and prompt actions.

What are the global patterns of microplastic ingestion by fish? A scientometric review

The billions of tons of plastic released into the environment mostly fragment into smaller particles that reach rivers and oceans, posing toxicity risks to aquatic organisms. As fish serve as excellent environmental indicator organisms, this study aims to comprehensively review and quantify published data regarding the abundance of microplastics (MPs) ingested by fish through scientometric analysis. Systematic analysis reveals that global aquatic ecosystems are contaminated by MPs, with the characteristics of these contaminants stemming from inadequate disposal management practices. The abundance of MPs was recorded in several fish species, notably Cyprinus carpio in natural environments and Danio rerio in controlled environments. According to the surveyed studies, laboratory experiments do not accurately represent the conditions found in natural environments. The results suggest that, in natural environments, the predominant colors of MPs are blue, black, and red. Fibers emerged as the most prevalent type, with polyethylene (PE) and polypropylene (PP) being the most frequently identified chemical compositions. On the other hand, laboratory studies showed that the spheres and fragments ingested were predominantly polystyrene (PS) green, followed by the colors blue and red. This discrepancy complicates drawing accurate conclusions regarding the actual effects of plastic particles on aquatic biota. Given the enduring presence of plastic in the environment, it is imperative to consider and implement environmental monitoring for effective, long-term management.

Incidence of microplastic contamination in fishes of the Ramsar Wetland, Loktak - The world's only floating lake from the Indian Himalayan region

Microplastics are ubiquitous, and their widespread prevalence in the ecosphere has generated concerns about their potential effects on terrestrial and aquatic organisms. However, studies pertaining to ecologically sensitive freshwater ecosystems, such as Ramsar wetlands, is scarce. Therefore, the study was conducted in Loktak, the world's only floating lake, and one of the largest wetland in the Indian Himalayan region. The wetland's degradation and pollution have resulted its inclusion in the Montreux Record, underscoring the need for studying this eco-sensitive freshwater system. This work investigated the (i) abundance, morphotype and size of microplastics in fish, and (ii) chemical composition of the microplastics consumed and accumulated in the fish of Loktak lake. Fish samples representing eight species were collected and analyzed for microplastics. Results revealed that ∼91% of the sampled fish ingested microplastics. Fragment was identified as the predominant morphotype (∼82%). Plastic polymers including polyamide (PA), polystyrene (PS), polycarbonate (PC) and carboxymethyl cellulose (CMC) were detected. The occurrence of heavy metals - chlorine (Cl), palladium (Pd), sodium (Na), zinc (Zn), lead (Pb) and copper (Cu) suggests their adhesion on the microplastics. The occurrence of microplastics in fish indicates pollution in the lake and poses a potential health risks to humans through consumption. Therefore, implementing comprehensive management approaches is imperative to mitigate this emerging pollution and uphold the ecological integrity of the Ramsar site. Substantial information on microplastics and their potential human exposure through fish consumption, particularly in the Indian Himalayan region, remains to be assessed, underscoring the need for extensive study.

Abundance and risk assessment of microplastics in water, sediment, and aquatic insects of the Nile River

Microplastics (MPs) are a serious threat in freshwater environments. The ecological risk and abundance level of MPs in abiotic and biotic compartments of the Nile River haven't been systematically reported. Thus, these issues were highlighted in the present study during different seasons of the sampling year. The results showed that MP concentrations in the river ranged from 2.24 ± 0.6 to 3.76 ± 1.1 particles/L, 298 ± 63 to 520 ± 80 particles/kg dry weight, and 0.081 ± 0.051 to 4.95 ± 2.6 particles/individual in surface water, sediment, and different species of aquatic insects, respectively. All the extracted MPs are colored blue, red, and black. Fiber-shaped polyesters (<500-1500 μm) were the most common MPs in all the river compartments. MPs' dominance was observed during the summer in comparison with that in the other seasons. Environmental risk indicators indicate the high ecological risk of MPs, which are widely distributed in the Nile River. In conclusion, MP consumption by aquatic insects may not only be related to levels of environmental contamination, since other variables, such as taxon size, weight, and particular feeding behavior, may also be significant. Additionally, the presence of MPs in insects (at lower trophic levels) creates the potential for predation-based inter-trophic level transmission. Thus, higher trophic-level investigations of various feeding groups should be carried out to identify any possible harm that MPs cause to various aquatic organisms.

Assessment of microplastic contamination in shrimps from the Bay of Bengal and associated human health risk

Microplastics (MPs) were analyzed in seven shrimp species Tiger shrimp (Penaeus monodon), Red tiger shrimp (Caridina cantonensis), Indian shrimp (Penaeus indicus), Red shrimp (Metapenaeus dobsoni), White shrimp (Penaeus merguiensis), Brown shrimp (Metapenaeus monoceros), and Roshna shrimp (Palaemon styliferus) collected from the Bay of Bengal. The abundance and characteristics of MPs were assessed in the gastrointestinal tract (GIT), which certainly translocated to the muscle of shrimp species. The highest MP abundance was found in C. cantonensis with 7.2 items/individual (25.3 items/g in the GIT and 6.3 items/g in muscle). The prominent types of MPs in shrimp samples were fibers (30 %) and fragments (29 %). The ingestion rate of MPs of black and transparent color was comparatively higher, with 64 % of the ingested MPs were < 100 μm. The primary polymer types detected based on Fourier Transform Infrared (FTIR) analysis were Low-Density Polyethylene (LDPE), High-Density Polyethylene (HDPE), Polymethyl Methacrylate (PMMA), Polyvinyl Chloride (PVC), Polypropylene (PP), and Ethylene Vinyl Acetate (EVA). Results from Scanning Electron Microscopy (SEM) showed rough surface textures and adhered particles on the MPs isolated from shrimps. The margin of exposure for females was 71.42, and for males, it was 80.64, indicating that women in Bangladesh are more likely to be exposed to MPs and face a higher risk than men. Sensitivity analysis revealed that MPs particle size was the most sensitive parameter. These findings provide a comprehensive understanding of MP ingestion, human exposure, and contamination in shrimps of Bangladesh, which can help future monitoring efforts.

Incidence of microplastic translocation in freshwater fish eggs

The issue of microplastic contamination in seafood is progressively recognised as a significant global issue. This study presents novel findings regarding the detection of microplastics within the eggs of commercially available fish intended for consumption by humans. Eggs of Ompok bimaculatus, Heteropneustes fossilis, Mystus vittatus and Anabas testudineus collected from the Periyar River, Kerala, India were subjected to analysis for the potential presence of microplastics. Out of the 91 fishes (containing eggs) examined, microplastics were observed in the eggs of 2 species, i.e., Ompok bimaculatus and Mystus vittatus. The polymers recorded were polyethylene and polypropylene. Fish eggs are commonly consumed by humans and are highly esteemed as a delectable food. Considering the widespread consumption of fish eggs as a delicacy among humans, there exists a potential route for human exposure to microplastics, which raises concerns regarding public health.

Microplastics in commercial marine fish species in the UK - A case study in the River Thames and the River Stour (East Anglia) estuaries

The aim of this study was to assess the abundance of microplastics in the gastro-intestinal tracts of three commercially important fish species in the UK, to determine whether catch location, feeding habits and fish size influence the amount of microplastics within fish. Fish were collected from two rivers in the UK: the River Thames and the River Stour (East Anglia). Fish were collected from two sites in the River Thames and one site in the River Stour. Species selected were European flounder (Platichthys flesus), whiting (Merlangius merlangus), and Atlantic herring (Clupea harengus), and were chosen to represent benthic and pelagic feeding habits. Across all locations, 41.5 % of fish had ingested at least one microplastic particle (37.5 % of European flounder, 52.2 % of whiting, and 28.6 % of Atlantic herring). The average number by species was 1.98 (±3.50) microplastics/fish in European flounder, 2.46 (±3.10) microplastics/fish in whiting and 1.47 (±3.17) microplastics/fish in herring. There were no significant differences in the number or mass of microplastics in fish based on river, site, species or habitat. However, the number and mass of microplastics within benthic fish (European flounder) in the River Stour were significantly higher than in benthic fish from the River Thames. By number of microplastics, larger and heavier fish were more highly contaminated. This study enhances our understanding of microplastics in commercially important fish but highlights that fish contamination is not easily predicted by feeding habits or catch location alone. Exposure and uptake is likely to vary with changing environmental conditions. Fish size tends to be a good predictor of contamination, with larger fish generally containing more microplastics. This is the first study to directly compare concentrations of microplastics in fish from different UK rivers and the first evidence of microplastics in the River Stour.

Microplastics as vectors of other contaminants: Analytical determination techniques and remediation methods

The ubiquitous and persistent presence of microplastics (MPs) in aquatic and terrestrial ecosystems has raised global concerns due to their detrimental effects on human health and the natural environment. These minuscule plastic fragments not only threaten biodiversity but also serve as vectors for contaminants, absorbing organic and inorganic pollutants, thereby causing a range of health and environmental issues. This review provides an overview of microplastics and their effects. This work highlights available analytical techniques for detecting and characterizing microplastics in different environmental matrices, assessing their advantages and limitations. Additionally, this review explores innovative remediation approaches, such as microbial degradation and other advanced methods, offering promising prospects for combatting microplastic accumulation in contaminated environments. The focus on environmentally-friendly technologies, such as the use of microorganisms and enzymes for microplastic degradation, underscores the importance of sustainable solutions in plastic pollution management. In conclusion, this article not only deepens our understanding of the microplastic issue and its impact but also advocates for the urgent need to develop and implement effective strategies to mitigate this critical environmental challenge. In this context, the crucial role of advanced technologies, like quantitative Nuclear Magnetic Resonance spectroscopy (qNMR), as promising tools for rapid and efficient microplastic detection, is emphasized. Furthermore, the potential of the enzyme PETase (polyethylene terephthalate esterase) in microplastic degradation is examined, aiming to address the growing plastic pollution, particularly in saline environments like oceanic ecosystems. These innovations offer hope for effectively addressing microplastic accumulation in contaminated environments and minimizing its adverse impacts.

Bioaccumulation of microplastics in the edible tissues of fish collected from urban lakes of Bangladesh: a potential exposure to public health

Microplastic (MP) pollution is an emerging environmental problem, due to its universal dispersion. In the present study, we determined the MP pollution in water, sediment, and fish samples of three different urban lakes of Bangladesh to assess the bioaccumulation of MPs from the lake environment to fish's edible (flesh) and inedible tissue (gut), ecological risk and consequent human exposure to MPs by fish consumption. A total of forty-three fishes were collected from Jahangirnagar Co-Operative Housing Society (JCHS), Dhanmondi Lake (DL), and Saturia Thana Lake (MST). The average MP concentration in sediment and water of the lakes is 7588 ± 4353 MPs/kg dry weights; 142 ± 22 MPs/L, respectively. MPs were identified in the edible (2.8-20.2 MPs/g) and inedible (2.27-20.93 MPs/g) tissue of all fish species. The highest number of MPs was observed in the flesh of Labeo bata of the JCHS Lake and in the gut of Catla catla of DL. The most dominant shape of MPs was fiber and fragment, 0.1-0.4 mm was the dominant size range, and blue, purple, and transparent were the dominant colors. The presence of six polymer types was revealed by FT-IR analysis, which were polystyrene, polypropylene, nitrile, ethylene vinyl acetate, high-density polyethylene, and nylon. The concentration of MPs in fish is found to increase with the increment in body weight. The bioconcentration factor (BCF) analysis reveals that among all the fish species, Labeo bata and Oreochromis mossambicus accumulate the highest number of MPs from the lake environment. The pollution load index of MPs indicates that the sampling sites were within hazard levels III-IV. Estimated annual intake reveals that humans will be exposed to the highest number of MPs if they consume the flesh of Labeo bata of DL and JCHS Lake.

Impacts of microplastic on fisheries and seafood security - Global analysis and synthesis

This review paper collected, collated, analysed, interpreted, synthesised, and documented the research investigations conducted on microplastic (MPs) pollution impacts on seafood organisms (including fish, sharks, shrimps, lobsters, crabs, oysters, mussels, and seaweeds) during the last ten years (2012-2022) covering fifty-seven locations/countries in the world. MPs contaminated 926 seafood species comprising 895 finfish, 09 crustaceans, 20 molluscs and 02 seaweeds. Seafood from Asia was found to be most contaminated with MPs. High MP contamination/ingestion was revealed in several seafood organisms. The ingestion of MPs can reduce fish growth and fish fitness, leading to reduced yield/fish production. Fish and seafood play a significant role in supporting the economy, employment, food sources, and livelihoods of people across the globe, which can be threatened due to the contamination of seafood organisms with MPs. MPs have bioaccumulated in fish skin, gills, stomachs, liver, intestine, and muscles as well as dry fish and canned fish. Hence, the consumption of MP-contaminated fresh fish, whole fish, dried fish or canned fish poses risks as it may be a pathway of MP transfer to humans. MPs can increase the health risks to seafood fish consumers since there is a probability that high risks pollutants adsorbed on MPs (heavy metals, pesticides, and oil compounds) can transfer to humans via the food chain. Several of the chemicals (heavy metals, DDT, PAHs) adsorbed onto MPs are carcinogenic. MPs have also been detected in fish meals, therefore, farmed livestock such as aquaculture fish and chicken fed to fish meals can be exposed to MPs and ultimately to humans. Preventive and safety measures are suggested to reduce the exposure of MPs to humans. In addition, several policy strategies are recommended to reduce the impacts of plastic waste and plastic pollution on the environment, aquatic biota, wildlife, seafood and human health.

Microplastic contamination in water and sediments of Mahanadi River, India: An assessment of ecological risk along rural-urban area

Worldwide, environmental concerns about MPs pollution have increased. Microplastic contamination that pollutes the ocean is mostly caused by terrestrial transfer from close proximity locations. A study of MPs pollution near coastal locations becomes necessary to address the MPs transit, fate, and mitigation. In the current study MPs pollution in the surface water and sediment of the Mahanadi River estuary was assessed during Pre-MS and MS. The size, shape, and colour of the MPs were determined using a stereomicroscope, and the MPs polymer composition was identified by Attenuated Total Reflection-Fourier Transform Infrared (ATR-FTIR) spectroscopy. The mean concentration of MPs that were potentially discovered in water was 16.6 ± 5.2 and sediments 197.3 ± 5.4 during Pre-MS. In the MS observed mean abundance of MPs was 15.1 ± 5.4 in water and 164.6 ± 76.9 in sediments. The highest abundant size was smaller than 1 mm; the most prevalent shape were fibers followed by film and fragments; black and white was a prominent colour in water and sediments respectively. Polyesters (PEs), polyethylene (PE), polyvinyl chloride (PVC), polypropylene (PP), polyamide (PA), Polystyrene (PS), and Polycarbonates (PC) were found in the analysis of the chemical composition of MPs in water and sediments samples. The calculated PLI value shows pollution load at category I, with polymer hazard levels at categories III, IV, and V, indicating very high risk. The current research results show that river inflows and fishing-related actions are probably the main causes of MPs pollution.

Characterization of microplastics in digestive tract of commercial fish species from the Oman Sea

Microplastics (MPs) content of the digestive tract of two commercial fish from the northern shores of the Oman Sea were investigated. The MPs were characterized by optical microscopy, fluorescent microscopy, and SEM-EDX for their number, shape, size, and color. Polymer composition was analyzes using micro-Raman spectroscopy (RMS). MPs were recovered in all fish samples (100 %), with an average of 43.16 ± 8.23 items/individual in Otolithes ruber, and 29.9 ± 2.73 items/individual in Acanthopagrus latus. The predominant shape of MPs in both fishes was fiber (46 %) with black, transparent, and white colors. The majority of MPs were <1000 μm (75 %), and half of the MPs were smaller than 300 μm in size. Their synthetic nature was confirmed by Nile Red staining and determination of the elemental composition of selected items. Polypropylene (PP) and polyethylene (PE) were the dominant plastic polymers in the fish digestive tracts. This study reveals abundance distribution of MPs in digestive tract of commercial marine fish. High number of ingested MPs can alarm the accumulation of MPs in the northern of Oman Sea ecosystem with anthropogenic activities and raises issues in public health.

Transfer pattern of microplastics at an individual level: A case study of two typical Sciaenidae fish in coastal waters

Microplastics (MPs) are recognized as global pollutants. The occurrence and distribution of MP transfer at the species level have been reported, but few studies have focused on the individual level. In this study, two typical migratory demersal species (Collichthys lucidus and Larimichthys polyactis, family Sciaenidae) from the coastal waters of the Lvsi fishing ground were selected to analyze the distribution characteristics of MPs in their gastrointestinal tracts and to explore the potential biomagnification of MPs in different body lengths. The results showed that the main MP color found in both species was blue (>80 %), while the main MP shape was fiber (>90 %), and the main MP polymer type was polyethylene terephthalate (PET) (>70 %). Overall, the abundance of MPs in C. lucidus (3.24 ± 1.57 pieces/fish) was higher than that in L. polyactis (2.24 ± 0.56 pieces/fish). The abundance of MPs in C. lucidus with a body length >90 mm was significantly higher than that with a body length <90 mm, and no significant difference was found in L. polyactis. We believe that the shift in feeding habits during the life history of the two species is an important factor that affects the variation in MPs between body lengths. Additionally, there was a significant positive correlation between MPs and the length (weight) of C. lucidus but no correlation in L. polyactis. There was no significant correlation between trophic level and MPs in either species. This indicated that MP bioaccumulation only occurred in C. lucidus, and MP biomagnification did not occur in either species. We suggest that further research be conducted on MPs ingested by more species at an individual level regarding the biomagnification/bioaccumulation phenomenon. This will help further elucidate the characteristics of MP transfer in the food webs of ecosystems and provide theoretical support for understanding MP pollution in coastal waters.

Size-selective microplastic uptake by freshwater organisms: Fish, mussel, and zooplankton

Microplastics, as an emergent pollutant, have garnered substantial attention within aquatic environments, yet a significant knowledge gap persists regarding the interplay of organism size and pollution impacts on microplastic uptake in freshwater ecosystems. The main aim of the current study is to assess the microplastic ingestion by aquatic organisms across diverse trophic levels. To achieve this objective, zooplankton, mussels (Anodonta anatina), and fish (Carassius gibelio) were collected from the highly polluted Susurluk River Basin in Türkiye. The size distribution encompassed 160.8 ± 56.9 μm for the prevailing zooplankton, 6.9 ± 2.2 cm for mussel, and 20.4 ± 3.1 cm for fish, respectively. While no microplastic ingestion was observed among zooplankton, the finding highlights the influence of body-size and pollution on microplastic ingestion. In contrast, A. anatina and C. gibelio contained 617 and 792 microplastic particles, respectively. Predominantly, fibers emerged as the most prevalent microplastic type across trophic levels (except zooplankton) followed by films. Notably, only fish exhibited fragments within their gastrointestinal tract. A substantial correlation emerged between microplastic abundance and mussel size and weight, but no such correlation manifested for fish. The study also revealed a positive link between microplastic count and turbidity (phosphate and high Chl a level), impacting mussel ingestion capacity due to the variability in the food availability and potential shifts in feeding preferences. Conversely, no distinct pattern emerged for fish concerning water quality parameters and ingested microplastics. Consequently, our study underscores diverse microplastic uptake patterns in freshwater ecosystems, with a predominant frequency of microplastics falling with the 0.3 mm-3.0 mm range, emphasizing the significance of size-selective uptake by organisms.

Distribution, characterization and contamination risk assessment of microplastics in the sediment from the world's top sediment-laden estuary

Microplastics (MPs) have gained a serious attention as an emerging contaminant throughout the world because of their persistence and possible risks to aquatic ecosystems and human well-being. However, knowledge on MPs contamination from sub-tropical coastal systems is limited, and no study has been conducted on the MPs contamination in sediment from one of the highest sediment-laden estuaries, Meghna River, in the world. This is the first study to examine the quantity, morpho-chemical characteristics and contamination risk level of MPs from this large scale river. MPs were extracted from the sediment samples of 10 stations along the banks of the estuary by density separation, and then characterized using a stereomicroscope and Fourier Transform Infrared (FTIR) spectroscopy. The incidence of MPs varied from 12.5 to 55 item/kg dry sediment with an average of 28.67 ± 10.80 item/kg. The majority (78.5%) of the MPs were under 0.5 mm in size, with fibers being the most (74.1%) prevalent MPs type. Polypropylene (PP) was found to be the predominant polymer (53.4%), followed by polyethylene (PE, 20%), polystyrene (PS, 13.3%), and polyvinyl chloride (PVC, 13.3%). The highest occurrence of PP indicted the MPs in the estuary might be originated from clothing and dying industries, fishing nets, food packages, and pulp industries. The sampling stations were contaminated with MPs as shown by the contamination factor (CF) values and pollutant load index (PLI), both of which were >1. This study exposed new insights on the status of MPs in the sediments of the Meghna River, laying the groundwork for future research. The findings will contribute to estimate the global share of MPs to the marine environment.

Microplastics in water from the confluence of tropical rivers: Overall review and a case study in Paraiba do Sul River basin

Rivers are known for carrying out a fundamental role in the transportation of human debris from continental areas to the marine environment and have been identified as hotspots for plastic pollution. We characterized microplastics (MPs) along confluence areas in the Paraíba do Sul River basin, the biggest river in southeastern Brazil. This water body crosses highly industrialized areas, with the highest population density, and the major water demand in South America. Considering the important ecological function of this extensive watershed and the implications of MP pollution, we evaluate the spatial variation of MP concentration in the confluence areas and upstream from the confluence. Samples were taken from the superficial layer of the water column in February and June 2022, using manta net with 300 μm mesh size. A total of 19 categories and 2870 plastic particles were determined. The confluences areas of rivers showed the highest concentration of MPs, highlighting the confluences of the Paraiba do Sul and Muriaé rivers (0.71 ± 0.25 MP/m3), followed by Paraíba do Sul and Dois Rios rivers (0.42 ± 0.23 MP/m3) and Paraíba do Sul and Pomba rivers (0.38 ± 0.14 MP/m3). Black fibers were the main category, followed by blue fibers and blue fragments. The MPs in the surface waters of Paraíba do Sul River is significantly influenced by the sampling points spatiality. This result corroborates other studies around the world and reinforces the argument that affluents are important sources for the introduction of MPs in larger rivers. Nevertheless, our results provide a better understanding of the different contributing factors and occurrence of MPs in river basins.

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.

Ecological traits do not predict the uptake of microplastics by fishes in a Neotropical River

Pollution by synthetic polymers is even more problematic to the environment when this material is fragmented into small portions, forming microplastics (MPs). We analyzed the contamination of ichthyofauna by MPs in an important river of the Atlantic Rainforest in regard to abundance, diversity of morphotypes, polymers, colors, and sizes of the synthetic particles in 20 species of fish. Fish were collected in November 2019 and in March 2020 in five sites along the Pomba River. Of the 101 fish analyzed, 49 (49%) presented MPs in at least one organ. Of the 20 species of fish collected 13 included individuals with at least one MP in their analyzed organs. The organs, trophic categories and feeding areas did not affect the general abundance of MPs types. Blue MPs were predominant, followed by the colors black, red, and white. MP fibers represented 91% of total MPs. Most MPs were between 2 and 3 mm in size. Polyethylene terephthalate (PET), polypropylene (PP), polyamide (PA), polyvinylidene chloride "Nylon" (PVDC), and high-density polyethylene (HDPE) were detected in the fishes. The exposure of the fish species to MPs was associated mainly with individual size and species-specific aspects, regardless of ecological traits. Considering that 55% of the fish species studied are consumed by humans, it is necessary to study the potential impact of MP ingestion on human health and to understand to what extent we may be consuming both plastic particles and contaminants that are adsorbed to MPs.

Microplastics contamination in fish feeds: Characterization and potential exposure risk assessment for cultivated fish of Bangladesh

Fish feed is becoming an increasingly vital source of nourishment for farmed fish, which are mainly coming from marine fish and agricultural sources. Anthropogenic particles, such as microplastics, are abundant in both marine fish and agricultural byproducts that are utilized to make fish feed. This study investigated whether fish feed could be a source of microplastic contamination, and revealed that a 20 weeks adult farmed tilapia fish might consume up to 268.45 ± 1.438 microplastic particles via fish feed where finisher type feeds were found to be mostly contributory in this number. The microplastics were initially observed with a stereomicroscope and FESEM-EDS. Polymeric composition of microplastics was determined to be polypropylene (PP), nylon-6 (NY-6), polyethylene terephthalate (PET), polystyrene (PS), polyvinyl alcohol (PVA), polyethylene (PE), high- and low-density polyethylene (HDPE, LDPE), ethylene vinyl acetate (EVA), polycarbonate (PC), poly vinyl acetate (PVAc), poly urethane (PU) and polyvinyl chloride (PVC) by FTIR. Results also revealed that the size of microplastic particles in all fish feed ranged from 14 μm to 4480 μm, with 550 ± 45.45 to 11,600 ± 56.1 microplastic particles/kg of fish feed. The FESEM-EDS data demonstrated to overlook the microplastic surface along with attachment of heavy metals onto that surface such as Pb, Ni, and Co in finisher type feed that could create additional health risks.

Occurrences, sources, fate and impacts of plastic on aquatic organisms and human health in global perspectives: What Bangladesh can do in future?

Bangladesh is not an exception to the growing global environmental problem of plastic pollution. Plastics have been deemed a blessing for today's world thanks to their inexpensive production costs, low weight, toughness, and flexibility, but poor biodegradability and massive misuse of plastics are to blame for widespread contamination of the environmental components. Plastic as well as microplastic pollution and its adverse consequences have attracted significant investigative attention all over the world. Plastic pollution is a rising concern in Bangladesh, but scientific studies, data, and related information are very scarce in numerous areas of the plastic pollution problem. The current study examined the effects of plastic and microplastic pollution on the environment and human health, and it examined Bangladesh's existing knowledge of plastic pollution in aquatic ecosystems in light of the rapidly expanding international research in this field. We also made an effort to investigate the current shortcomings in Bangladesh's assessment of plastic pollution. This study proposed several management approaches to the persistent plastic pollution problem by analyzing studies from industrialized and emerging countries. Finally, this work pushed investigators to investigate Bangladesh's plastic contamination thoroughly and develop guidelines and policies to address the issue.

Prevalence of microplastics in commonly consumed fish species of the river Old Brahmaputra, Bangladesh

Microplastics (MPs) are pervasive in aquatic environments, but inland waterbodies (rivers and floodplains) have received much less attention. The present study assesses the incidence of MPs in the gastrointestinal tracts of five commercially important edible fish species-two column feeders (n = 30) and three benthivores (n = 45) from upstream, midstream, and downstream of the Old Brahmaputra river in north-central Bangladesh. MPs were detected in 58.93% of fish, with the highest level in freshwater eel, Mastacembelus armatus (10.31 ± 0.75/fish). Fibers (49.03%) and pellets (28.02%) were the most frequent MPs. Nearly 72% MPs were smaller than 1 mm, and 50.97% were black. FTIR analysis showed 59% polyethelene (PE), followed by polyamide (40%) and unidentified (1%). MP ingestion was linked to fish size and weight, and a high incidence was recorded in the downstream river. Two omnivorous benthic fish ingest more MPs than others. The results corroborate the presence of MPs in the inland river and fish fauna and augment our understanding of heterogeneous MP uptake by fish.

Microplastic pollution in the gastrointestinal tract of giant river catfish Sperata seenghala (Sykes, 1839) from the Meghna River, Bangladesh

Freshwater rivers are considered the major route for microplastics (MPs), yet limited studies have been reported on MPs in freshwater river fish, especially in Bangladesh. This research reveals the intake of MPs by the giant river catfish Sperata seenghala, collected from the Meghna River, which is the only outlet of the Ganges-Brahmaputra River. Three locations, namely, Chandpur Sadar, Bhola Sadar, and Char Fasson, along the Meghna River, were selected in order to investigate the gastrointestinal tracts (GIT) of the fish. Ninety percent (n=27) of fish (n=30) were contaminated, with fragment-shaped MPs (65%) as the most abundant among the four types. A total of 179 MP particles were detected using micro-Fourier transformed infrared spectroscopy (μ-FTIR), with an average of 5.96 ± 1.32 MP particles per fish. Among the four size groups, the highest proportion of MPs (54%) occurred in the 45-100 μm group; the dominant color among the seven color groups was white (30%). The highest quantity of MPs was found in the relatively densely populated Chandpur Sadar region. Polypropylene-polyethylene copolymer (PP-PE, 23%) was proportionally dominant among the 15 types. No significant relationship was found between the total number of observed MPs and the GIT weight. This study will help us to understand MP pollution in S. seenghala that may transmit to the human body through the food chain.

Nowhere to go! Microplastic Abundances in Freshwater Fishes Living Near Wastewater Plants

Microplastic presence in aquatic environments is a major problem globally. This study quantified microplastic abundances in fish species across two systems in South Africa around wastewater treatment works. Fish (n=163) were examined for microplastic on gills and in gastrointestinal tracts. Microplastic levels were generally low during the cool-dry season (mean 11.0 - 34.0 particles per fish taxon), and high during the hot-wet season (mean 10.0 - 119.0 particles per fish taxon). The microplastic concentrations per fish were similar between these systems, with downstream of wastewater treatment plants having high microplastic abundances. Although benthopelagic feeders were dominant, pelagic feeders had high microplastic abundances (range 20-119 particles), followed by benthopelagic (range 10-110 particles) and demersal (22 particles) feeders. Multiple regression analysis revealed a significant positive relationship between fish standard length and total microplastic levels, which suggests fish consume more microplastics due to increased food demand as a result of growth.

Microplastics in freshwater wild and farmed fish species of Bangladesh

In today's world, microplastic contamination of aquatic systems is a subject of major concern. In this study, the incidence of microplastics in freshwater fish from both farmed and wild sources was evaluated. Wild catla (Gibelion catla), stinging catfish (Heteropneustes fossilis), rui (Labeo rohita), tengara catfish (Mystus tengara), and pabdah catfish (Ompok pabda) were collected from Padma River, Turag River, and Bhairab River. Farmed fishes of same species were collected from Mymensingh and Chandpur fish markets. A total of 68 (43.6%) microparticles out of 156 were identified as microplastics using ATR-FTIR. About 66.67% (20 out of 30) of farmed fish samples had microplastics in their digestive system, while 88.4% (23 of 26) of wild fish samples presented microplastics. There was a significant difference (p < 0.05) in average microplastic count between wild and farmed fish. Average microplastic count also showed a significant difference among five fish species (p < 0.01). A variety of polymers were observed, with polyethylene being the most abundant, followed by polyester, polypropylene, polyamide-6, and polyurethane. This study suggests that microplastic contamination is ubiquitous and contamination is common in all of the fish species investigated, independent of their origin (wild or farmed). However, wild fish population is at a greater risk of ingesting microplastics. This study, for the first time ever, reports plastic pollution in freshwater fishes of Bangladesh from wild and farmed sources.

Microplastics in surface water from a mighty subtropical estuary: First observations on occurrence, characterization, and contamination assessment

Estuarine contamination by Microplastics (MPs) is a mater of serious concern since these areas offer the society valuable ecosystem, economic, and recreational services such as breeding and feeding ground for fish, carbon fixation, nutrients recycling and port development. The Meghna estuary, located along the Bengal delta coast, provides livelihoods for thousands of peoples in Bangladesh, and served as breeding ground for national fish, Hilsha shad. Therefore, knowledge and understanding on any kind of pollution including MPs of this estuary is essential. In this study, the abundance, characteristics and contamination assessment of MPs from the surface water of a Meghna estuary were investigated for the first time. The results demonstrated that MPs were present in all samples and the abundance ranged from 33.33 to 316.67 item/m³ with a mean value of 128.89 ± 67.94 item/m³. Morphological analyses resulted in four types of MPs such as fibers (87%), fragments (6%), foam (4%), and films (3%) with the majority of these being colored (62%) and smaller (<0.5 mm) in size (88%). On the other hand, FTIR analysis for chemical characteristics confirmed five types of polymers, including polythene (PE), polystyrene (PS), polythene terephthalate (PET), polypropylene (PP), and polyvinyl chloride (PVC). The area was determined to be moderately to severely contaminated with MPs based on contamination factor (CF) values (6.18 ± 2.08 to 2.50 ± 1.0) and the pollutant load index (PLI) value (1.94 ± 0.33) as these values were > 3-6 for CF, and >1 for PLI. These results can be utilized to develop policy for the protection of this important environment.

Increase in temperature increases ingestion and toxicity of polyamide microplastics in Nile tilapia

Microplastics (MP) pollution and global warming are worldwide concerns, creating various physiological problems for aquatic organisms. This study was carried out to know the effects of different temperature (30, 33 and 36 °C) on ingestion of MP along with the physiological consequences in Nile tilapia (Oreochromis niloticus) exposed to virgin polyamide (PA) (10 mg/L water; 500 μm to 4 mm in size) for 15 days. A significant difference was found in PA ingestion of the fish treated with different temperature. Fish from 36 °C temperature groups ingested highest amount of PA (136 ± 24.40 item/fish) during the exposure period. The hemoglobin (Hb) and red blood cell (RBC) decreased significantly in the highest temperature (36 °C) without PA exposure. At the same time, Hb increased, but RBC significantly reduced in all the temperature conditions with PA exposure. The number of white blood cell (WBC) and glucose level increased significantly in the highest temperature (36 °C) without PA exposure. In contrast, WBC increased and glucose decreased significantly in all the temperature conditions with PA exposure. Frequencies of various nuclear and cellular abnormalities of erythrocytes increased significantly in the fish exposed to all temperature with PA exposure, though severity increased with temperature. Similarly, histological damage of gills (hyperplasia, epithelial necrosis, deformed pillar system, epithelial lifting, telangiectasia) and intestine (epithelium breakage, enterocyte vacuolization and shortening of villi) was found to be mild to severe by the accumulation of PA, increased severity with increase of temperature. This study confirms that global warming as a consequence of climate change might influence MP ingestion hampering physiological state of fish.

Characterization of microplastic pollution in the Pasur river of the Sundarbans ecosystem (Bangladesh) with emphasis on water, sediments, and fish

An emerging concern of today's world, due to their universal dispersion worldwide, is the environment's microplastic pollution. The Sundarbans, the world's largest mangrove, have unique and dynamic environmental settings with numerous pollution risk exposures, including microplastics (MPs). Thus, the present study has focused on the MP pollution in water, sediment, and fish samples of the Sundarbans of Bangladesh for the first time. Water and sediment samples were collected (n = 30/each) from sampling locations along the Pasur river (Bangladesh). Furthermore, nine species of fish samples were collected from a local fish market situated at the Mongla port. Results show that 100 % of the analyzed samples have evidence of MPs. On average, 2.66 × 10³ plastic particles/L and 1.57 × 10⁵ particles/kg were found in water and sediment samples, respectively. Furthermore, results show a higher number of MPs in the animals' gastrointestinal tract (GIT) (10.41 particles/g), concerning the average concentration recorded in the muscles (4.68 particles/g). O. pama and H. nehereus were the species that showed the highest MPs accumulation in the GIT. In the muscles, the highest MP levels were observed in T. ilisha and L. calcarifer. Most of the particles were smaller than 1 mm; black-colored particles dominated the pool. FT-IR analysis revealed the presence of seven polymer types where polyamide was abundant in water and sediment samples. SEM analysis showed morphological structures and adsorbed particles on the surface of plastic samples, and the spatial distribution of MPs indicates that the location with high human intervention has elevated levels of MPs. Therefore, our study demonstrates that Sundarbans mangrove forests are highly contaminated with MPs and that its fisheries can be a potential source of human exposure to these pollutants.

Exploring microplastic pollution in a Mediterranean river: The role of introduced species as bioindicators

Studies of plastic contamination in freshwater ecosystems and their biota remain scarce, despite the fact that the vast majority of plastic waste initially passes through lotic ecosystems. Biomonitoring provides valuable information regarding plastic pollution and microplastic threats to biota and human health. The aim of this study was to explore the potential use of a non-indigenous fish species as a bioindicator of microplastic pollution in an Eastern Mediterranean River. Our study area is located in a heavily modified and vastly impacted urban river which flows through the largest part of the Metropolitan area of Athens, Greece. We used an introduced chub species (Squalius vardarensis) to assess microplastic ingestion in the river. The results indicated moderate occurrence and abundance of microplastics in the fish gastrointestinal tracts; one-third of specimens (35%) contained microplastics, although the average number of microplastics per specimen was relatively low (1.7 ± 0.2). Overall, the abundance of microplastics in the water confirmed the moderate level of microplastics contamination in our study area. The major polymer types of microplastics identified by FT-IR analysis were: polyethylene (PE), polyvinyl alcohol (PVA) and polypropylene (PP); reflecting the fragmentation of larger litter from industrial packaging and/or household goods. Surface runoff of the urban environment, via motorways and major road networks, could be the contributing factor to the reported microplastics. Our results suggest that generalist's non-indigenous species such as chubs could be used as bioindicators of microplastics in inland waters. Introduced fishes can be a feasible, nondestructive, and cost-effective option for the assessment of microplastics in freshwater ecosystems, while freshwater chubs' high abundance and omnipresence in European rivers further serve this scope. However, it is worth noting that the suitability of any particular species as a bioindicator of microplastics may depend on a variety of factors, including their feeding behavior, habitat, and exposure to microplastics in their environment.

Abundance and characteristics of microplastics in major urban lakes of Dhaka, Bangladesh

Microplastics (MPs) are prevalent in nature due to the proliferation of plastic in the environment. However, the presence of microplastics in lakes is largely unknown in comparison to other aquatic bodies. This study was performed to evaluate the abundance and characteristics of MPs in water, sediment, and fish from three major urban lakes in Dhaka, Bangladesh, namely Dhanmondi, Gulshan, and Hatir Jheel lake. The highest concentrations of microplastics in surface water (36 items/L), sediment (67 items/kg), fish (17 items/individual), and the gastrointestinal tract (4.88 items/gm) were observed. Highest abundance of microplastic in an individual fish was observed in Oreochromis mossambicus from Dhanmondi Lake. The samples were visually examined using stereomicroscope and SEM, which revealed that films were the most prevalent kind of microplastics in both the water and the sediment samples, whereas pellets and foams predominated in the fish samples. Visual observation also revealed MPs dominated by <100 μm in size and transparent in color. According to the Fourier Transform Infrared (FTIR) analysis, the dominant polymers in the analyzed samples were high-density polyethylene, low-density polyethylene, ethylene vinyl acetate, polyvinyl chloride, polycarbonate, cellulose acetate, and polypropylene. MPs were relatively higher in the water and sediment samples of Gulshan Lake, and fish samples of Dhanmondi Lake. The results of this study indicate that microplastic contamination has occurred not only in the water and sediment but also in the inhabitant fishes of the lakes. However, it is discovered that the microplastic intake of fish was significantly related to body weight and length. The implication of the finding suggests that the presence of MPs in urban lakes has raised concerns about the potential human health impact.

Quantifying microplastics in fishes: The first case study contrasting the perspective of untrained and experienced researchers

Microplastic studies hold a low explored potential for citizen science and environmental education, but methodological issues challenge data produced by non-specialists. We compared microplastic abundance and diversity in the red tilapia Oreochromis niloticus recovered by untrained students with those recovered by researchers that have experience of three years studying the incorporation of this pollutant by aquatic organisms. Seven students dissected 80 specimens and performed digestion of digestive tract in hydrogen peroxide. The solution was filtered and inspected under a stereomicroscope by the students and by two expert researchers. A control treatment consisted of 80 samples handled only by experts. The students overestimated the abundance of fibers and fragments. Striking differences in abundance and richness of microplastics were verified between the fish dissected by students and by expert researchers. Therefore, citizen science projects involving the uptake of microplastics by fish should provide training until a satisfactory level of expertise is reached.

Microplastics pollution in the river Karnaphuli: a preliminary study on a tidal confluence river in the southeast coast of Bangladesh

Bangladesh is a deltaic country in Asia, and its riverine systems ultimately drain into the Bay of Bengal. Plastic is a severe environmental issue for coastal-marine ecosystems due to the indiscriminate usage and discarding of plastic items in the upstream river that eventually find their route into the Bay of Bengal. Microplastics (MPs) are widespread pollutants in almost all environmental compartments, including aquatic environments. This study aimed to quantify and understand the distribution of microplastics in surface water and sediments of the river Karnaphuli, a tidal confluence river adjacent to the Chattogram seaport city of Bangladesh, a highly inhabited and industrial area on the southeast coast of the Bay of Bengal. A manta trawl net (300-µm mesh size) was used to collect surface water samples, while an Ekman dredge was used to collect sediment samples. The concentrations of microplastics in the surface water of the river Karnaphuli during late monsoon, winter, and early summer were recorded to be 120,111.11, 152,222.22, and 164,444.44 items/km², respectively, while in sediments, those were recorded to be 103.83, 137.50, and 103.67 items/kg, respectively. A higher abundance of microplastics was observed in downstream surface water (228,888.88 items/km²) and sediments (164.17 items/kg). Smaller sizes (0.3 to 0.5 mm) of microplastics were predominant, fibers or threads were the frequent types, and black was the most common color in the river Karnaphuli. The Fourier transform infrared analysis revealed that polyethylene terephthalate (surface water: 22%, sediments: 19%), polyamide (surface water: 15%, sediments: 13%), polyethylene (surface water: 12%, sediments: 18%), polystyrene (surface water: 13%, sediments: 11%), and alkyd resin (surface water: 13%, sediments: 10%) were the most prevalent polymers in the river Karnaphuli. Moreover, there was a moderate positive correlation between MPs abundance in surface water and sediments. Therefore, improved long-term research (in different seasons with horizontal and vertical monitoring) is necessary in order to accurately determine the flux of microplastics from the river Karnaphuli to the Bay of Bengal.

Microplastics in different fish and shellfish species in the mangrove estuary of Bangladesh and evaluation of human exposure

The water bodies in Bangladesh thrive from plastic pollution. Estuaries are pools of environmental contaminants, and the world's largest mangrove forest, Sundarbans' estuary, is no exception. Thus, for the first time, we investigate MPs abundance in the muscle and gastrointestinal tract (GIT) of twenty estuarine species of fish and shellfish of the Sundarbans, as well as the human health risk. MPs abundance was evident in all the samples ranging from 5.37 ± 1.07 to 54.30 ± 16.53 MP items/g wet body weight (dw) in muscle samples and 7.33 ± 1.89 to 205.61 ± 136.88 MP items/g (dw) in GIT samples. The estimated health risk from MPs is substantial, where the average human intake will be 85,710.08 items of MPs per year per capita for the population of Bangladesh. The dominant polymer types observed using ATR-FTIR are PP and PE (17.5 %), PA (17.5 %) in the muscle tissues, and PP and PE (11.11 %), and EVA (11.11 %) in the GITs. Bottom-feeding species, such as demersal and benthic species, are more contaminated. However, the level of MPs in the species shows a negative correlation with the length and weight of the species. This study reveals that MP pollution is widespread and concerning in Bangladesh's Sundarban mangrove estuarine zone.

Microplastics toxicity, detection, and removal from water/wastewater

The world has witnessed massive and preeminent microplastics (MPs) pollution in water bodies due to the inevitable continuous production of plastics for various advantageous chemical and mechanical features. Plastic pollution, particularly contamination by MPs (plastic particles having a diameter lesser than 5 mm), has been a rising environmental concern in recent years due to the inappropriate disposal of plastic trash. This study presents the recent advancements in different technologies for MPs removal in order to gain proper insight into their strengths and weaknesses, thereby orchestrating the preparation for innovation in the field. The production, origin, and global complexity of MPs were discussed. This study also reveals MPs' mode of transportation, its feedstock polymers, toxicities, detection techniques, and the conventional removal strategies of MPs from contaminated systems. Modification of conventional methods vis-à-vis new materials/techniques and other emerging technologies, such as magnetic extraction and sol-gel technique with detailed mechanistic information for the removal of MPs are presented in this study. Conclusively, some future research outlooks for advancing the MPs removal technologies/materials for practical realization are highlighted.

Abundance, characteristics, and risk assessment of microplastics in indigenous freshwater fishes of India

Microplastic (MP) pollution has pressing concerns regarding environmental health and the availability of safe food for humans. Information on the occurrence of MP in freshwater biota in the Indian scenario is currently lacking. The present study examined MP contamination in edible and non-edible tissues of widely consumed freshwater fishes. All the fish species (n = 35/species) analyzed had microplastic contamination with the highest MP abundance of 7.86 ± 2.0 items/individual in Channa punctatus followed by Labeo rohita (4.17 ± 0.6 items/individual) and Labeo bata (3.03 ± 0.4 items/individual); whereas MP abundance in small indigenous fishes (SIF) such as Salmostoma bacaila and Puntius amphibius accounts for 0.83 ± 0.13 and 0.77 ± 0.2 items/individual respectively. The principal component analysis results showed a 77.434% variance from two components identified for MP distribution. Fibre type MP was the most dominant type besides fragments and pellets that opined the type of MP required for ecotoxicity assessment, the need of the hour. Raman spectroscopy analysis confirms high-density and low-density polyethylene-type polymers. Evidence of MP in edible tissue indicates the translocation phenomenon resulting in human exposure through the consumption of biota contaminated with MP. Risk assessment revealed a low risk of MP based on its abundance while polymer type indicates a high risk for the fish species investigated. A thorough investigation of the level of adsorbed organic contaminants in the MP is warranted to address the interactive effects on biota. To the best of our knowledge, this is the first detailed report on MP contamination and its risk assessment in Indian freshwater fishes.

Assessment of microplastics pollution in aquatic species (fish, crab, and snail), water, and sediment from the Buriganga River, Bangladesh: An ecological risk appraisals

Current work focus on microplastic (MPs) occurrence in the water, sediment, and aquatic species (fish, crab, and snail) of the Buriganga River, Bangladesh, with an ecological risk assessment perspective. It also includes the distribution of MPs in different river ecosystem segments and the presence of heavy metal (loid)s (HMs) in water, sediments, and MPs surface. The MPs were inspected by stereomicroscope to identify the shapes, color, and size, and Fourier transform infrared (FTIR) spectroscopy was used to characterize polymer types. The samples concentration of four HMs viz., As, Cd, Cr, and Pb were determined by atomic absorption spectrometry (AAS). The possible MPs content in water, sediment, fish, crab, and snail were varied from 0.250 to 0.117 MPs/mL, 3.5-8.17 MPs/g, 0.65-3.82 MPs/g, 3.75-4.28 MPs/g, and 0.84-1.12 MPs/g, respectively. Fibers and fragments were the most dominant shape, less than 0.5 mm was dominant in size, and blue was the dominant color. In the evaluation of the chemical composition of MPs in water, sediment, fish, snail, and crab samples, Polyethylene terephthalate (PETE), Ethylene-vinyl acetate (EVA), High-density polyethylene (HDPE), Acrylonitrile butadiene styrene (ABS), Cellulose acetate (CA), and Nylon were identified. Regarding HMs load, the river demonstrated a highly polluted environment following the abundance pattern Cr > Pb > As>Cd. SEM-EDAX of MPs was conducted to investigate the surface MP's surface and elemental composition. It reveals that the MPs surface has characteristic flakes, cracks, and adhering particles along with Si, K, Au, C, and O on the surface studied MPs. There is no significant relationship found among the ecosystem segments. However, Ompok bimaculatus species show a negative relationship of MPs distribution with water and sediment. Moreover, according to the ecological risk of MPs pollution in the Buriganga River, it was in category-I, indicating considerable pollution load due to the presence of MPs.

The different ways microplastics from the water column and sediment accumulate in fish in Haizhou Bay

Global microplastic (MP) pollution is a serious environmental problem that has been found in various ecosystems, especially marine ecosystems. In this study, the water (surface, middle and bottom water), sediment and fish (pelagic, demersal and benthic fish) in the artificial reef area and adjacent waters in Haizhou Bay were collected, and the mechanism of MP transmission among the three media was analyzed. The results showed that >96 % of the plastics in the region were MPs. The shape of MPs was mainly fibrous (water (73.3 %), sediment (56 %), fish (95.3 %)), color was mainly blue (water (49.3 %), sediment (47 %), fish (72.3 %)), and the material was mainly PET (water (39.6 %), sediment (33 %), fish (86.6 %)). We found that, except for the natural deposition of MPs, MPs could be ingested by pelagic fish and transmitted through vertical movement in the water, while there was an interaction between MPs in benthic fishes and the middle-bottom waters. In addition, as relevant variables, body length and body weight were more likely to explain the number of MPs ingested by fishes than were δ13C and δ15N. Therefore, based on the linear relationship between δ15N and body length, we concluded that there was a weak trophic magnification effect of MPs ingested by fish in this region. This study provides unique information for further exploring the factors influencing the spatial distribution of MPs and the transmission mechanism of MPs in fish.

Freshwater Fish Siberian Dace Ingest Microplastics in the Remote Yenisei Tributary

This study analyzed microplastics in the gastrointestinal tract of Siberian dace (Leuciscus leuciscus subsp. baicalensis (Dybowski, 1874)) in the remote Yenisei tributary of the Nizhnyaya (Lower) Tunguska River (Siberia, Russia). µRaman analysis showed that 60% of the fish from two different sites had ingested plastic microparticles (on average, 1.55 ± 1.95 items per individual). The most common type of microplastic were fibers, and the most abundant size category was 300 to 1000 µm. In the studied population, no significant differences in the MP content between the two sites or between males and females were found (p > 0.05). The tendency for higher MP ingestion by Siberian dace at earlier ages (2+ and 3+) compared to later (4+ and 5+) was observed, which may be connected to the features of the fish biology and ecology.

The ecological impact of plastic pollution in a changing climate

Assessing three interlinked issues, plastic pollution, climate change and biodiversity loss separately can overlook potential interactions that may lead to positive or negative impacts on global ecosystem processes. Recent studies suggest that threatened species and ecosystems are vulnerable to both plastic pollution and climate change stressors. Here we consider the connectivity and state of knowledge between these three environmental issues with a focus on the Global South. Nine out of top ten Long-Term Climate Risk Index (CRI) (2000-2019) ranked countries are located within the Global South, yet research is focused in the Global North. A literature search for the top ten Long-Term Climate Risk Index (CRI) (2000-2019) ranked countries matched a total of 2416 (3.3% of global publications) search results on climate change, with 56 (4% of the global publications) on plastic pollution, and seven (7.7% of the global publications) on both climate change and plastic pollution. There is a strong correlation between the Global South and high biodiversity hotspots, high food insecurity and low environmental performance. Using Bangladesh as a case study, we show the erosion rates and sea level rise scenarios that will increase ocean-bound plastic pollution and impact high biodiversity areas. Poverty alleviation and promoting renewable energy and green practices can significantly reduce the stress on the environment. We recommend that these connected planetary threats can be best addressed through a holistic and collaborative approach to research, a focus on the Global South, and an ambitious policy agenda.

Pervasiveness and characteristics of microplastics in surface water and sediment of the Buriganga River, Bangladesh

Microplastics (MPs) are an emerging environmental problem due to their all-around existence and extraordinary stability. A significant number of studies are found in recent literature on the occurrence, distribution, transport, and fate of the MPs in several environmental compartments. In this study, we have investigated the occurrence and characteristics of MPs in the surface water and sediment of the Buriganga river, located beside the mega-city of Dhaka in Bangladesh. In the Buriganga river, the concentration of MPs in the surface water was found from 4.33 ± 0.58 to 43.67 ± 0.58 items L^-1, and in the sediment, MPs varied from 17.33 ± 1.53 to 133.67 ± 5.51 items kg^-1 of dry sediment. Fragment-type MPs were predominant in the surface water and sediment, which was 72.7% and 85.5% respectively. The most abundant polymer type polypropylene (PP) was found -to be 46% in the surface water and 61% in the sediment sample. The next major category, polyethylene (PE) was found to be 26% and 21%, respectively. Polystyrene (PS), polyvinyl chloride (PVC), polyethylene terephthalate (PET), and polyamide (PA) were other commonly detected polymer types. The MPs were found to be contaminated by Pb, Cd, Cr, Zn, Cu, and Sn from Energy dispersive-X-ray fluorescence (ED-XRF) analysis. Tannery-induced Cr was detected in the highest concentrations in the MPs, which were 20.67 ± 1.66 mg kg^-1 (in surface water) and 14.2 ± 1.25 mg kg^-1 (in sediment). The pollution load index (PLI) of the MPs contamination in different sampling sites along the Buriganga river was found in the risk level category of I and II. The anthropogenic influence of the city area was reflected in the PLI values, which had an increasing trend from the upstream sampling points (1.00 ± 1.00, 1.00 ± 1.00) to the downstream sites (10.09 ± 1.00, 7.71 ± 3.60).

Trophic transfer of microplastics in the aquatic ecosystem of Sundarbans mangrove forest, Bangladesh

Globally microplastics (MPs) contaminations have been widely reported across the large number of organisms in the marine ecosystem. Consequently, trophic transfer of MPs inferred to occur across the organisms of marine food webs. However, scientific evidence on trophic transfer of MPs across the marine organisms is very limited. Therefore, this study aimed to understand the transfer of MPs across the trophic levels in the marine ecosystem. We sampled individuals of different species of primary consumers, secondary consumers, tertiary consumers and quaternary consumers from the aquatic ecosystem of Sundarbans mangrove forest from June 2021 to December 2021. This study found that marine organisms in the aquatic ecosystem of Sundarbans mangrove forest are contaminated with MPs. The abundance of MPs in collected samples varied between 0.56 ± 0.25 items/individual and 6.06 ± 1.20 items/individual. Maximum MPs was recorded as 5.5 ± 1.21 items/individual in predators followed by 5.1 ± 0.85, 4.5 ± 0.39, 1.2 ± 0.26, 1.1 ± 0.28 and 1.01 ± 0.25 in filter feeders, browsers, deposit feeders, selective planktivores and variable feeders, respectively. Maximum MPs abundance was encountered in quaternary consumers (4.17 items/individual) followed by tertiary consumers (3.17 items/individual), secondary consumers (2.74 items/individual) and primary consumers (0.56 items/individual). We found that MPs abundance increases with the increase of trophic levels (R² = 0.64, p < 0.001) which indicates that transfer of MPs across different trophic levels and also showed the evidence of biomagnification of MPs in successive trophic levels. Our study is the first report of trophic transfer of MPs in sub-tropical mangrove ecosystem and will serve as a guideline to understand the MPs pollution in the coastal ecosystem of Bangladesh.

Surface water, sediment, and biota: The first multi-compartment analysis of microplastics in the Karnafully river, Bangladesh

The Karnafullly River, which flows through Chattogram and falls into the Bay of Bengal, Bangladesh, is vulnerable to microplastic contamination. In this study, we looked at microplastics in the Karnafully River's surface water (5 sites), sediment (9 sites), and biota (4 species). Microplastic concentrations ranged from 0.57 ± 0.07 to 6.63 ± 0.52 items/L in surface water, 143.33 ± 3.33 to 1240 ± 5.77 items/kg dry weight in sediment, and 5.93 ± 0.62 to 13.17 ± 0.76 items/species in biota. A significant difference (P < 0.05) was found in the concentration of MPs in the Karnafully River's sediment, biota, and surface water. High percentage of fiber-shaped and small-sized MPs (<1 mm) were detected throughout the samples. Water and sediment MPs were often transparent/white and blue, whereas biota MPs were mostly black and red, indicating a color preference during biological uptake. The Bay of Bengal received 61.3 × 10⁹ microplastic items per day. The feeding zone of biota influenced the level of microplastics, with a trend of pelagic > demersal > benthic > benthopelagic. Polyethylene and polyethylene terephthalate were the most abundant polymer. Using the average fish intake rate in Bangladesh, we computed a possible consumption of 4015-7665 items of MPs/person/year.

Assessment, characterization, and quantification of microplastics from river sediments

Microplastic (MP), as a pollutant, is currently posing a biological hazard to the aquatic environment. The study aims to isolate, quantify, and characterize the MP pollutants in sediment samples from 14 study sites at Kaveri River, Killa Chinthamani, Tiruchirappalli, South India. With Sediment-MP Isolation (SMI) unit, density separation was done with a hydrogen peroxide solution. Four forms of MPs namely, fragments, films, foams, and fibers with orange, white, green, and saffron red were observed. The plenitude and distribution of four forms of MPs and natural substrates were geometrically independent, with large amounts of microfragments within the research region accounting for 79.72% variation by Principal Component Analysis. FT-IR analyses of MPs showed the presence of polyamide, polyethylene, polyethylene glycol, polyethylene terephthalate, polypropylene, and polystyrene. Additionally, the scanning electron microscopic analysis revealed that the MPs have differential surface morphology with rough surfaces, porous structures, fissures, and severe damage. Most MPs comprised Si, Mg, Cu, and Al, according to energy dispersive X-ray analyses. The combined SMI, instrumental analyses and evaluation (heat map) of MPs in river sediments help assess contamination levels and types of MPs. The findings might provide an insight into the status of MPs in Kavery River sediments that could help in formulating regulations for MPs reduction and contamination in rivers eventually to protect the environment.

Distribution, biological effects and biofilms of microplastics in freshwater systems - A review

The rapidly rising output and mass use of plastics have made plastics pollution a major environmental problem. Since plastics are persistent in the environment, understanding the migration transformation characteristics of plastics is critical. Given the ever-increasing concern about the environmental risks posed by microplastics, their prevalence, fate, abundance and impact have been intensively studied. Most of these investigations focused on the marine environment, but research on freshwater microplastics is less extensive. This article aims to briefly summarize the research progress of freshwater microplastics, identify existing gaps and draw novel conclusions, so as to provide useful information for the research of freshwater microplastics. Using the statistics and analysis of freshwater microplastics studies in 2016-2021, this review systematically discusses microplastics in globally freshwater systems. The biological effects of microplastics on freshwater organisms were discussed as well. Some potential ecological effects of microplastic biofilms were shown, such as climate change and material circulation. More importantly, we present some unique conclusions. For example, the detection of freshwater microplastics is mainly concentrated in natural freshwater systems, while few are concentrated in artificial freshwater systems. In addition, polystyrene is the main mode for testing the biological effects of freshwater microplastics, and polyethene and polypropylene which are the most common in freshwater environments, have not been taken seriously. We also pointed out that studies on advanced freshwater plants in the topic of biological effects of microplastics still need strengthen.