Microplastic contamination in filter-feeding oyster Saccostrea cuccullata: Novel insights in a marine ecosystem

Microplastic (MP) pollution has become a pressing global concern. Oysters are well-known filter feeders who ingest food by filtering microscopic particles suspended in the surrounding water. Along with organic matter, filter-feeding also causes accidental ingestion of MP by oysters. Hence, the aim of the current investigation is to understand the MP contamination in filter-feeding oysters. A total of 500 specimens of oyster Saccostrea cuccullata collected from the intertidal zone of five sampling locations on the Gujarat coast, India. Specimens underwent analysis following established protocols. Each specimen was found to exhibit MP contamination, showing an abundance of 2.72 ± 1.98 MPs/g. A negative relationship was found between shell length and MP abundance. Predominantly, fibers were documented across all study sites. Black, blue, and red-colored MPs with 1-2 mm sizes were most dominant. MP polymer composition was identified as polyethylene terephthalate and polypropylene. Findings provide baseline information on levels of MPs contamination, which can be used to monitor future effects of MP pollution.

Occurrence and fate of pharmaceutical pollutants in wastewater: Insights on ecotoxicity, health risk, and state-of-the-art removal

Pharmaceutical active compound (PhAC) residues are considered an emerging micropollutant that enters the aquatic environment and causes harmful ecotoxicity. The significant sources of PhACs in the environment include the pharmaceutical industry, hospital streams, and agricultural wastes (animal husbandry). Recent investigations demonstrated that wastewater treatment plants (WWTPs) are an important source of PhACs discharging ecosystems. Several commonly reported that PhACs are detected in a range level from ng L-1 to μg L-1 concentration in WWTP effluents. These compounds can have acute and chronic adverse impacts on natural wildlife, including flora and fauna. The approaches for PhAC removals in WWTPs include bioremediation, adsorption (e.g., biochar, chitosan, and graphene), and advanced oxidation processes (AOPs). Overall, adsorption and AOPs can effectively remove PhACs from wastewater aided by oxidizing radicals. Heterogeneous photocatalysis has also proved to be a sustainable solution. Bioremediation approaches such as membrane bioreactors (MBRs), constructed wetlands (CWs), and microalgal-based systems were applied to minimize pharmaceutical pollution. Noteworthy, applying MBRs has illustrated high removal efficiencies of up to 99%, promising prospective future. However, WWTPs should be combined with advanced solutions, e.g., AOPs/photodegradation, microalgae-bacteria consortia, etc., to treat and minimize their accumulation. More effective and novel technologies (e.g., new generation bioremediation) for PhAC degradation must be investigated and specially designed for a low-cost and full-scale. Investigating green and eco-friendly PhACs with advantages, e.g., low persistence, no bioaccumulation, less or non-toxicity, and environmentally friendly, is also necessary.

Microplastic prevalence in epipelagic layer: Evidence from epipelagic inhabiting prawns of north-west Arabian Sea

The escalating global microplastic (MP) pollution severely threatens marine life due to insufficient waste management and widespread single-use plastic. This study focuses on assessing MP contamination in commercial prawns from Gujarat State, India. Ten prawn species collected at five main fishing harbors revealed 590 MP particles in their gastrointestinal tracts, averaging 6.08 ± 5.96 MPs/g and 1.15 ± 0.78 MPs/individual. Significant variations in contamination levels were observed between species and study sites. Pollution indices indicated very high contamination throughout the study sites. Threads were the predominant shape, with blue and black as prevalent colors. Size-wise, 1-2 mm MPs dominated. Polymer analysis identified polyethylene terephthalate, polyurethane, polystyrene, polypropylene, polyvinyl chloride, and acrylonitrile butadiene styrene. The findings provided crucial preliminary information for ecotoxicology and seafood safety investigations regarding MP contamination in commercially important prawns.

Exposure to microcrystallized cellulose affects the health of tadpoles and sheds light on the threat these materials pose to amphibians

The increasing use of cellulose-based materials (CBMs) has provided beneficial applications in different sectors. However, its release into environments may represent an ecological risk, therefore demanding that ecotoxicological studies be conducted to understand the risks (current and future) of CBM pollution. Thus, we evaluated the possible effects of microcrystalline cellulose (CMs) in Physalaemus cuvieri tadpoles. After seven days of exposure to CMs (at 58.29 and 100 mg/L), the animals were subjected to behavioral evaluation, and different biomarkers (biometric and biochemical) were evaluated. Although our data do not point to a neurotoxic effect of CMs (inferred by the absence of behavioral changes and changes in AChE and BChE activity), animals exposed to CMs showed differences in body condition. Furthermore, we noticed an increase in the frequency of erythrocyte nuclear abnormalities and DNA damage, which were correlated with the ingestion of CMs. We noticed that the antioxidant activity of tadpoles exposed to CMs (inferred by SOD, CAT, and DPPH radical scavenging activity) was insufficient to control the increase in ROS and MDA production. Furthermore, exposure to CMs induced a predominant Th2-specific immune response, marked by suppressed IFN-γ and increased IL-10 levels, with a consequent reduction in NO levels. Principal component analysis and IBRv-2 indicate, in general, a primarily more toxic response to animals exposed to the highest CM concentration. Therefore, our study evidence that CMs affect the health of P. cuvieri tadpoles and sheds light on the threat these materials pose to amphibians.

A mini-review on plasticrusts: occurrence, current trends, potential threats, and recommendations for coastal sustainability

Plasticrusts manifest as a coating on intertidal rocks due to environmental exposure. They refer to crushed plastic debris that blankets rocks found along intertidal shorelines. This study significantly contributes to a better understanding of the occurrence of these novel plastic formations, shedding light on their potential pathways of formation during the Anthropocene era. The research provides comprehensive insights into the composition, origins, challenges, and effective management strategies for removing coastal plastic litter. The findings of this investigation offer valuable evidence regarding the formation and impact of these recently discovered plastic items in coastal regions, prompting discussions about their formation processes and their effects on the marine ecosystem. Recognizing that these newly emerged plastic litter pose a considerable threat to the marine environment is crucial. With their emergence, we face an environmental challenge, especially concerning the health of coastal ecosystems. Plasticrusts, when degraded, can release microplastics (MPs) and nanoparticles (NPs) into the surrounding environment. These micro- and nano-sized plastic particles pose significant ecological risks as they persist in ecosystems, potentially harming wildlife and entering the food chain, causing widespread environmental contamination. Significantly, it outlines strategies to minimize the impact of this emerging plastic debris and its source.

A review of microplastic threat mitigation in Asian lentic environments

Microplastic (MP) pollution has evolved into a significant worldwide environmental concern due to its widespread sources, enduring presence, and adverse effects on lentic ecosystems and human well-being. The growing awareness of the hidden threat posed by MPs in lentic ecosystems has emphasized the need for more in-depth research. Unlike marine environments, there remain unanswered questions about MP hotspots, ecotoxic effects, transport mechanisms, and fragmentation in lentic ecosystems. The introduction of MPs represents a novel threat to long-term environmental health, posing unresolved challenges for sustainable management. While MP pollution in lentic ecosystems has garnered global attention due to its ecotoxicity, our understanding of MP hotspots in lakes from an Asian perspective remains limited. Hence, the aim of this review is to provide a comprehensive analysis of MP hotspots, morphological attributes, ecotoxic impacts, sustainable solutions, and future challenges across Asia. The review summarizes the methods employed in previous studies and the techniques for sampling and analyzing microplastics in lake water and sediment. Notably, most studies concerning lake microplastics tend to follow the order of China > India > Pakistan > Nepal > Turkey > Bangladesh. Additionally, this review critically addresses the analysis of microplastics in lake water and sediment, shedding light on the prevalent net-based sampling methods. Ultimately, this study emphasizes the existing research gaps and suggests new research directions, taking into account recent advancements in the study of microplastics in lentic environments. In conclusion, the review advocates for sustainable interventions to mitigate MP pollution in the future, highlighting the presence of MPs in Asian lakes, water, and sediment, and their potential ecotoxicological repercussions on both the environment and human health.

The path of microplastics through the rare biodiversity estuary region of the northern Bay of Bengal

Due to its harmful effects on ecosystems and human health, microplastic (MP) pollution has become a significant environmental problem on a global scale. Although MPs' pollution path and toxic effects on marine habitats have been examined worldwide, the studies are limited to the rare biodiversity estuary region of Hatiya Island from the northern Bay of Bengal. This study aimed to investigate the MP pollution path and its influencing factors in estuarine sediments and water in rare biodiversity Hatiya Island in the northern Bay of Bengal. Sixty water and sediment samples were collected from 10 sampling sites on the Island and analyzed for MPs. The abundance of MPs in sediment ranged from 67 to 143 pieces/kg, while the abundance in water ranged from 24.34 to 59 pieces/m3. The average concentrations of MPs in sediment and water were 110.90 ± 20.62 pieces/kg and 38.77 ± 10.09 pieces/m3, respectively. Most identified MPs from sediment samples were transparent (51%), while about 54.1% of the identified MPs from water samples were colored. The fragment was the most common form of MP in both compartments, with a value of 64.6% in sediment samples and 60.6% in water samples. In sediment and water samples, almost 74% and 80% of MP were <0.5 mm, respectively. Polypropylene (PP) was the most abundant polymer type, accounting for 51% of all identified polymers. The contamination factor, pollution load index, polymer risk score, and pollution risk score values indicated that the study area was moderately polluted with MPs. The spatial distribution patterns and hotspots of MPs echoed profound human pathways. Based on the results, sustainable management strategies and intervention measures were proposed to reduce the pollution level in the ecologically diverse area. This study provides important insights into evaluating estuary ecosystem susceptibility and mitigation policies against persistent MP issues.

Toxicity of carbon nanofibers in earthworms (Lumbricus terrestris) naturally infected with Monocystis sp

Although the ecotoxicity of carbon-based nanomaterials (CBNs) is known, the potential effect of carbon nanofibers (CNFs) on edaphic organisms has been insufficiently explored. Thus, we aimed at the ecotoxicity of CNFs (at 10 and 100 mg/kg) in Lumbricus terrestris earthworms naturally infected with Monocystis sp. After 28 days of exposure, treatments did not affect the survival rate. However, we observed a significant loss of body biomass, and Monocystis sp. infection in seminal vesicles was potentiated by exposure to CNFs. Earthworms exposed to CNFs showed a redox imbalance in the seminal vesicle, muscle, and intestine and an alteration in nitric oxide production in these organs. In muscles, we also noticed a significant reduction in AChE activity in earthworms exposed to CNFs. The histopathological analyses revealed the treatments' significant effect on the structures of the different evaluated tissues. Although we did not notice a concentration-response for several of the biomarkers, when taken together and after the application of Integrated Biomarker Response (IBR) and principal component analysis (PCA), we noticed that the response of earthworms to CNFs at 100 mg/kg showed a more significant deviation from the unexposed group. This was mainly determined by inhibiting antioxidant activity in the seminal vesicle, biochemical biomarkers assessed in muscle and intestine, and histomorphometric muscle biomarkers from earthworms exposed to CNFs at 100 mg/kg. Thus, we demonstrate that CNFs increase the parasite load of Monocystis sp. of adult L. terrestris earthworms and induce biochemical and histopathological changes, especially at 100 mg/kg. Our results point to the additional impact these nanomaterials can have on the health of earthworms, signaling the need for greater attention to their disposal and ecotoxicological effects on soil organisms.

Microplastics occurrence in commercial crab (Portunus segnis) from the western coast of India and pollution indices: First investigation and evidence

Microplastic (MP) pollution has increased drastically due to improper plastic waste management. The present study aimed to investigate the MPs contamination in the commercially important brachyuran crab Portunus segnis of Gujarat State, India. One hundred fifty crab specimens were collected from three principal fishing harbors in Gujarat. The collected specimens were analyzed for MP extraction using a previously documented protocol. The chemical composition of extracted MPs was assessed with ATR-FTIR. The average abundance of MPs contamination was recorded as 0.82 ± 0.58 MPs/g and 2.02 ± 1.48 MPs/individual. Findings of Contamination Factor (CF) revealed that study site Jakhau was identified as a low-contamination site, while Okha and Veraval were considered moderately contaminated. The H index has identified study sites Jakhau and Veraval as class IV risk categories, while study site Okha fell into the class V risk category. PRI value revealed the very high contamination of MPs in all the study sites. The guts were recorded as being more contaminated with MPs than the gills. The average abundance of MP contamination in males (0.77 ± 0.14 MPs/g in Jakhau, 1.19 ± 0.77 MPs/g in Okha, and 0.82 ± 0.43 MPs/g in Veraval) was recorded higher than in females (0.33 ± 0.11 MPs/g in Jakhau, 0.8 ± 0.49 MPs/g in Okha, and 0.75 ± 0.41 MPs/g in Veraval) in all the study sites. The average abundance of MP contamination varied significantly between males and females. Fibers were found dominantly in all study sites, followed by fragments, films, and foams. Black and blue-colored MPs with 1-2 mm sizes were found more abundantly. The chemical composition of the extracted MPs revealed polyethylene, nylon, polyurethane, and polystyrene as polymer compositions. Overall, the present study highlighted the MP contamination in commercially important crabs that can be used as a basis for further studies on ecotoxicology and seafood safety.

Cellulose microcrystalline: A promising ecofriendly approach to control Culex quinquefasciatus larvae

The growing use of synthetic chemical compounds/substances in vector control of mosquitoes, associated with their adverse effects on the environment and non-target organisms, has demanded the development of eco-friendly alternatives. In this context, this study aimed to evaluate the larvicidal action of different cellulose microcrystalline (CMs) concentrations and investigate their toxicity mechanisms in Culex quinquefasciatus fourth instar larvae as a model species. Probit analysis revealed that the median lethal concentrations (LC50) for 24 h and 36 h exposure were 100 and 58.29 mg/L, respectively. We also showed that such concentrations induced a redox imbalance in the larvae, marked by an increase in the production of reactive oxygen species (ROS) and thiobarbituric acid reactive substances (TBARS), as well as a reduction in the activity of superoxide dismutase (SOD) and catalase (CAT). Furthermore, different alterations in the external morphology of the larvae were associated with the ingestion of CMs. On the other hand, exposure of adult zebrafish (Danio rerio) to LC5024h and LC5036h for seven days did not induce any behavioral changes or alterations mutagenic, genotoxic, biochemical, or in the production of cytokines IFN-γ and IL-10. Thus, taken together, our study demonstrates for the first time that the use of CMs can constitute a promising strategy in the control of C. quinquefasciatus larvae, combining insecticidal efficiency with an "eco-friendly" approach in the fight against an important mosquito vector of several human diseases.

Organic composts as A vehicle for the entry of microplastics into the environment: A comprehensive review

Plastic pollution is a widespread issue that poses a threat to agroecosystems. Recent data on microplastic (MP) pollution from compost and its application to soil have highlighted the potential impact of micropollutants that may be transferred from compost. Thus, we aim with this review to elucidate the distribution-occurrence, characterization, fate/transport, and potential risk of MPs from organic compost to gain comprehensive knowledge and mitigate the adverse impacts of compost application. The concentration of MPs in compost was up to thousands of items/kg. Among micropollutants, fibers, fragments, and films are the most common, with small MPs having a higher potential to absorb other pollutants and cause harm to organisms. Various synthetic polymers, including polyethylene (PE), polypropylene (PP), polyethylene terephthalate (PET), polystyrene (PS), polyvinyl chloride (PVC), polyester (PES), and acrylic polymers (AP), have been widely used of plastic items. MPs are emerging pollutants that can have diverse effects on soil ecosystems, as they can transfer potential pollutants from MPs to compost and then to the soil. Following the microbial degradation scheme, the transfer chain from plastics to compost to soil can be broken down into main stages, i.e., colonization - (bio)fragmentation - assimilation - and mineralization. Microorganisms and adding biochar play an essential role during composting, which can be an effective solution to enhance MP degradation. Findings have shown that stimulating free radical generation could promote the biodegradation efficacy of MPs and possibly remove their occurrence in compost, thereby reducing their contribution to ecosystem pollution. Furthermore, future recommendations were discussed to reduce ecosystem risks and health challenges.

Personal protective equipment-derived pollution during Covid-19 era: A critical review of ecotoxicology impacts, intervention strategies, and future challenges

During the COVID-19 pandemic, people used personal protective equipment (PPE) to lessen the spread of the virus. The release of microplastics (MPs) from discarded PPE is a new threat to the long-term health of the environment and poses challenges that are not yet clear. PPE-derived MPs have been found in multi-environmental compartments, e.g., water, sediments, air, and soil across the Bay of Bengal (BoB). As COVID-19 spreads, healthcare facilities use more plastic PPE, polluting aquatic ecosystems. Excessive PPE use releases MPs into the ecosystem, which aquatic organisms ingest, distressing the food chain and possibly causing ongoing health problems in humans. Thus, post-COVID-19 sustainability depends on proper intervention strategies for PPE waste, which have received scholarly interest. Although many studies have investigated PPE-induced MPs pollution in the BoB countries (e.g., India, Bangladesh, Sri Lanka, and Myanmar), the ecotoxicity impacts, intervention strategies, and future challenges of PPE-derived waste have largely gone unnoticed. Our study presents a critical literature review covering the ecotoxicity impacts, intervention strategies, and future challenges across the BoB countries (e.g., India (162,034.45 tons), Bangladesh (67,996 tons), Sri Lanka (35,707.95 tons), and Myanmar (22,593.5 tons). The ecotoxicity impacts of PPE-derived MPs on human health and other environmental compartments are critically addressed. The review's findings infer a gap in the 5R (Reduce, Reuse, Recycle, Redesign, and Restructure) Strategy's implementation in the BoB coastal regions, hindering the achievement of UN SDG-12. Despite widespread research advancements in the BoB, many questions about PPE-derived MPs pollution from the perspective of the COVID-19 era still need to be answered. In response to the post-COVID-19 environmental remediation concerns, this study highlights the present research gaps and suggests new research directions considering the current MPs' research advancements on COVID-related PPE waste. Finally, the review suggests a framework for proper intervention strategies for reducing and monitoring PPE-derived MPs pollution in the BoB countries.

Pollution trends and ecological risks of heavy metal(loid)s in coastal zones of Bangladesh: A chemometric review

Heavy metal(loid)s inputs contribute to human and environmental stresses in the coastal zones of Bangladesh. Several studies have been conducted on metal(loid)s pollution in sediment, soil, and water in the coastal zones. However, they are sporadic, and no attempt has been made in coastal zones from the standpoint of chemometric review. The current work aims to provide a chemometric assessment of the pollution trend of metal(loid)s, namely arsenic (As), chromium (Cr), cadmium (Cd), lead (Pb), copper (Cu), zinc (Zn), and nickel (Ni) in sediments, soils, and water across the coastal zones from 2015 to 2022. The findings showed that 45.7, 15.2, and 39.1 % of studies on heavy metal(loid)s were concentrated in the eastern, central, and western zones of coastal Bangladesh. The obtained data were further modeled using chemometric approaches, such as the contamination factor, pollution load index, geoaccumulation index, degree of contamination, Nemerow's pollution index, and ecological risk index. The results revealed that metal(loid)s, primarily Cd, have severely polluted the sediments (contamination factor, CF = 5.20) and soils (CF = 9.35) of coastal regions. Water was moderately polluted (Nemerow's pollution index, P_N=5.22 ± 6.26) in the coastal area. The eastern zone was the most polluted compared to other zones, except for a few observations in the central zone. The overall ecological risks posed by metal(loid)s highlighted the significant ecological risk in sediments (ecological risk index, RI = 123.50) and soils (RI = 238.93) along the eastern coast. The coastal zone may have higher pollution levels due to the proximity of industrial effluent, residential sewage discharge, agricultural activities, sea transport, metallurgical industries, shipbreaking and recycling operations, and seaport activities, which are the major sources of metal(loid)s. This study will provide useful information to the relevant authorities and serve as the foundation for future management and policy decisions to reduce metal(loid) pollution in the coastal zones of southern Bangladesh.

Spatiotemporal trends and characteristics of microplastic contamination in a large river-dominated estuary

Microplastic (MP) pollution is a major global issue that poses serious threats to aquatic organisms. Although research on MP pollution has been extensive, the relationship between MPs and water quality parameters in estuarine water systems is unclear. This work studied the spatiotemporal distribution and characteristics of MPs in the Karnaphuli River estuary, Bangladesh. MP abundance was calculated by towing with a plankton net (300 μm mesh size) at three river gradients (up-, mid- and downstream) and the association between physicochemical parameters of water (temperature, pH, salinity, electrical conductivity, total dissolved solids, and dissolved oxygen) and MP distribution patterns was also investigated. Mean MP abundance in water was higher during the wet season (April) (4.33 ± 2.45 items per m³) compared to the dry season (September) (3.65 ± 2.54 items per m³). In descending order, the highest MP abundance was observed downstream (6.60 items per m³) > midstream (3.15 items per m³) > upstream (2.22 items per m³). pH during the wet season (April) and temperature during the dry season (September) were key physicochemical parameters that correlated with river MP abundance (r = -0.74 and 0.74 respectively). Indicating that if the Karnaphuli River water has low pH or high temperature, there is likely to be high MPs present in the water. Most MP particles were film-shaped, white in color, and 1-5 mm in size. Of the six polymers detected, polypropylene (PP), polystyrene (PS), polyethylene terephthalate (PET), and cellulose were predominant, comprising roughly 17-19% each. These results can be used to model MP transport in the freshwater ecosystem of the Karnaphuli River estuary in Bangladesh to help develop future mitigation strategies.

Micro- and mesoplastic pollution along the coast of Peru

Peru suffers from poor solid waste and coastal management, as well as evidenced plastic pollution in various forms. However, studies in Peru focusing on small plastic debris (i.e., meso- and microplastics) are still limited and inconclusive. Thus, the present study investigated the abundance, characteristics, seasonality, and distribution of small plastic debris along the coast of Peru. The abundance of small plastic debris is predominantly driven by specific locations, where a source of contamination is present, rather than presenting seasonal patterns. Meso- and microplastics were strongly correlated in both seasons (summer and winter), suggesting meso-plastic constantly breaking down as microplastic sources. Additionally, heavy metals (e.g., Cu, Pb) were found in low concentrations (mean concentrations < 0.4%) on the surface of some mesoplastics. Here, we provided a baseline on the multiple factors involving small plastic debris on the Peruvian coast and preliminarily identify associated contaminants.

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

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

Adsorptive behavior of micro(nano)plastics through biochar: Co-existence, consequences, and challenges in contaminated ecosystems

The abundance of micro(nano)plastics in natural ecosystems is a crucial global challenge, as these small-sized plastic particles originate from land-based and marine-based activities and are widely present in marine, freshwater, and terrestrial ecosystems. Micro(nano)plastics can significantly be reduced through various methods, such as biological, chemical, and physical techniques. Biochar is a low-cost adsorbent and is considered an efficient material and its application is ecologically effective carbon-negative for remediation of organic and inorganic pollutants. Therefore, this review critically discusses the fate and transport of micro(nano)plastics and their interactions with different biochar in aqueous and column porous media. This review outlines the implications of biochar with the co-existence of micro(nano)plastics in efforts to understand their coupled effects on soil physicochemical properties, microbial communities, and plant growth, along with the removal of heavy metals and other toxic contaminants. In batch experiments, biochar synthesized from various biomasses such as corn straw, hardwood, pine and spruce bark, corncob, and Prosopis juliflora had shown high level of removal efficiency (>90 %) for microplastic adsorption under varying environmental conditions viz., pH, temperature, ionic strength, particle size, and dose due to chemical bonding and electrostatic attractions. Increased temperature of the aqueous solutions encouraged higher adsorption, while higher pH and dissolved organic matter and nutrients may show decreased adsorption capacities for micro(nano)plastics using biochar. Compared to other available physical, chemical, and biological methods, biochar-amended sand filters in column experiments have been very efficient in removing micro(nano)plastics. In saturated column porous media, various microplastics could be inhibited using biochar due to decreased electrostatic repulsion, steric hindrance, and competitive sorption due to humic acid, ionic strength, and cations. Finally, this review provides in-depth insights on further investigations and recommendations for overall micro(nano)plastics removal using biochar-based materials.

Distribution, characteristics, and risk assessments analysis of microplastics in shore sediments and surface water of Moheshkhali channel of Bay of Bengal, Bangladesh

Microplastic pollution in various ecosystems has gained significant attention across the globe. Due to ubiquitous abundance, terrestrial and aquatic ecosystems at regional scales are polluted via uncontrolled anthropogenic actions. Therefore, this study investigates microplastic pollution and distribution in sediments and surface water of the Moheshkhali channel of Bangladesh, Bay of Bengal, along with their shape, size, color, and polymeric analysis. It has been observed that both sediments and surface water are significantly contaminated with microplastics at 14 sediments and 12 surface water sampling sites. 291 particles of microplastic were observed in two quadrants, separated 10-m away from each other, across 14 sediment sampling sites, with average concentrations registered in the range of 6.66 to 138.33 particles/m². At the same time, 163 particles were observed across 12 sampling sites in the surface water, ranging from 0 to ~0.1 particles/m³. Various shapes, like films, fragments, fiber/lines, foams, and pellets (resins), were observed extensively in the Moheshkhali channel. Besides, various risk assessments, like contamination factors, polymeric risk assessment, pollution risk index, and pollution load index, were analyzed for each sampling site across the channel. Pollution load index (PLI) of shore sediments and surface water were 2.51 and 1.67, respectively, indicating significant pollution in the Moheshkhali channel. This research investigation provides insight into anthropogenic activities and baseline microplastic pollution in the Moheshkhali channel of Bangladesh, which helps to prepare robust strategies for conservation and management to deal with such environmental issues.

Abundance and characterization of personal protective equipment (PPE) polluting Kish Island, Persian Gulf

Plastic pollution is one of the major environmental threats the world is facing nowadays, which was exacerbated during the COVID-19 pandemic. In particular, multiple reports of single-use plastics driven by the pandemic, namely personal protective equipment (PPE) (e.g., face masks and gloves), contaminating coastal areas have been published. However, most studies focused solely on counting and visually characterizing this type of litter. In the present study, we complement conventional reports by characterizing this type of litter through chemical-analytical techniques. Standardized sampling procedures were carried out in Kish Island, The Persian Gulf, resulting in an average density of 2.34 × 10-4 PPE/m2. Fourier transformed infrared spectroscopy confirmed the polymeric composition of weathered face masks and showed the occurrence of additional absorption bands associated with the photooxidation of the polymer backbone. On the other hand, the three layers of typical surgical face masks showed different non-woven structures, as well as signs of physical degradation (ruptures, cracks, rough surfaces), possibly leading to the release of microplastics. Furthermore, elemental mapping through energy-dispersive X-ray spectroscopy showed that the middle layer of the masks allocated more elements of external origin (e.g., Na, Cl, Ca, Mg) than the outer and inner layers. This is likely to the overall higher surface area of the middle layer. Furthermore, our evidence indicates that improperly disposed PPE is already having an impact on a number of organisms in the study area.

Baseline marine litter abundance and distribution on Saint Martin Island, Bay of Bengal, Bangladesh

Baseline marine litter abundance and distribution on Saint Martin Island, Bay of Bengal, were assessed. Seventy-two transects (100-150 m) along 12 km of coastline were surveyed for litter items every two weeks for two months. The most abundant items were polythene bags, food wrappers, plastic bottles/caps, straws, styrofoam, plastic cups, plastic fragments, fishing nets, clothes, and rubber buoys. Tourism, local markets, hotels, domestic waste, and fishing activities were primary sources of marine litter. According to the mean clean coast index (CCI), all transects were clean, of which 11.3 % and 14.1 % of sandy beaches and rocky shores with sandy beaches were reported dirty, respectively. Northern Saint Martin Island comprised sandy beaches (2.8 %) and was extremely dirty. In addition, plastic abundance index (PAI) analysis showed that 24 % of sites, out of 72 sites, were under "very high abundance", 33 % were "high abundance", 33 % showed "moderate abundance", and 4 % were classified as "low abundance". Establishing baseline results of marine litter abundance and distribution on Saint Martin Island may help improve island conservation and mitigation strategies (e.g., improved waste management, beach cleaning activities to raise public awareness, local government litter reduction policies, and increase local pro-environmental behavioral change).

A comprehensive review of heavy metal pollution in the coastal areas of Bangladesh: abundance, bioaccumulation, health implications, and challenges

The coastal zone of Bangladesh, with a population density of 1278 people per square kilometer, is under serious threat due to heavy metal pollution. To date, many studies have been conducted on the heavy metal contamination in soils, water, aquatic animals, and plants in the coastal zone of Bangladesh; however, the available information is dispersed. In this study, previous findings on the contamination levels, distributions, risks, and sources of heavy metals in sediments and organisms were summarized for the first time to present the overall status of heavy metal pollution along coastal regions. Earlier research found that the concentrations of various heavy metals (HMs), particularly Co, Cd, Pb, Cu, Cr, Mn, Fe, and Ni in water, sediment, and fish in most coastal locations, were above their permissible limits. High concentrations of HMs were observed in sediments and water, like Cr of 55 mg/kg and 86.93 mg/l in the ship-breaking areas and Karnaphuli River, respectively, in coastal regions of Bangladesh. Heavy metals severely contaminated the Karnaphuli River estuary and ship-breaking area on the Sitakundu coast, where sediments were the ultimate sink of high concentrations of metals. Sedentary or bottom-dwelling organisms like gastropods and shrimp had higher levels of heavy metals than other organisms. As a result, the modified PRISMA review method was used to look at the critical research gap about heavy metal pollution in Bangladesh's coastal areas by analyzing the current research trends and bottlenecks.

First record of plastiglomerates, pyroplastics, and plasticrusts in South America

Beaches in the Anthropocene carry the heavy burden of human-derived pollution, like that induced by plastic litter. For decades, plastic debris has been classified based on its source or physical size. In recent years, studies described and documented new forms of plastic formations, including plastiglomerates, plasticrusts, and pyroplastics. However, reports of these newly described formations are substantially lacking. Therefore, in the present study, we reported the first evidence of plasticrusts (plastic encrusting rock surfaces), plastiglomerates (organic/inorganic composite materials in a plastic matrix), and pyroplastics (burned and weathered plastics) in Peru. The plastic pollutants were recovered from the field through marine litter surveys on four beaches where illegal litter burning and campfires take place. All the suspected plastic formations were analyzed and confirmed using Fourier transformed infrared (FTIR) spectroscopy, and one of each type was analyzed by X-Ray fluorescence (EDX) spectrometry. Plastiglomerates consisted of a high-density polyethylene (HDPE) or polypropylene (PP) matrix with rock and sand inclusions. Pyroplastics were found in various stages of weathering and consisted of various polymers, including HDPE, PP, polyethylene terephthalate (PET), and polyamide (PA). Interestingly, our field observations suggest a new plasticrust formation pathway based on plastic burning and filling of rock crevices with molten plastic. The latter was identified as either PP or HDPE. Elements typically found in the sand and seawater (e.g., Na, Cl, Ca, Si, Fe) were identified on the surface of the plastic formations, as well as others that could potentially be associated with the leaching of additives (e.g., Ti, Br). Although the present study contributed to the knowledge concerning the occurrence of the new types of plastic formations, as well as possible formation pathways, there are still many questions to answer. Hence, we encourage future studies to focus on the toxicity that new plastic formations may induce in contrast with conventional plastics, the release of secondary contaminants (e.g., microplastics, additives), and their degradation in the environment. Lastly, standardized sampling and data treatment protocols are required.

Seasonal behavior and accumulation of some toxic metals in commercial fishes from Kirtankhola tidal river of Bangladesh - A health risk taxation

Contamination of fish with heavy metals (Heavy metals) is one of the most severe environmental and human health issues. However, the contamination levels in tropical fishes from Bangladesh are still unknown. To this end, the evaluated concentrations of arsenic (As), chromium (Cr), cadmium (Cd), and lead (Pb) in 12 different commercially important fish species (Tenualosa ilisha, Gudusia chapra, Otolithoides pama, Setipinna phasa, Glossogobius giuris, Pseudeutropius atherinoides, Polynemus paradiseus, Sillaginopsis panijus, Corica soborna, Amblypharyngodon mola, Trichogaster fasciata, and Wallago attu) were collected from the Kirtankhola River assess human health risk for the consumers, both in the summer and winter seasons. Toxic metals surpassed the acceptable international limits in P. atherinoides, P. paradiseus, S. panijus, C. soborna, and W. attu. The target hazard quotient (THQ) revealed that non-carcinogenic health effects (HI < 1) for children and adults, and the carcinogenic risk (CR) indicated safety. Results show that children are more susceptible to carcinogenic and non-carcinogenic hazards from higher As. The multivariate analysis justified that heavy metals were from anthropogenic actions. The lessening of toxic metals might need strict rules and regulations as metal enrichment would continue to increase in this tidal river from both the anthropogenic and natural sources.

Personal protective equipment (PPE) pollution in the Caspian Sea, the largest enclosed inland water body in the world

The COVID-19 pandemic led to a still ongoing international health and sanity crisis. In the current scenario, the actions taken by the national authorities and the public prioritized measures to control the transmission of the virus, such as social distancing, and face mask-wearing. Unfortunately, due to the debilitated waste management systems and incorrect disposal of single-use face masks and other types of personal protective equipment (PPE), the occurrence of these types of items has led to the exacerbation of marine plastic pollution. Although various studies have focused on surveying marine coasts for PPE pollution, studies on inland water are largely lacking. In order to fill this knowledge gap, the present study assessed PPE pollution in the Iranian coast of the Caspian Sea, the largest enclosed inland water body in the world by following standard monitoring procedures. The results concerning the density (1.02 × 10^-4 PPE/m²) composition (face masks represented 95.3% of all PPE) of PPE are comparable to previous studies in marine waters. However, a notable decrease in the occurrence of PPE was observed, probably to behavioral and seasonality reasons. The possible consequences of PPE pollution were discussed, although much more research is needed regarding the ecotoxicological aspects of secondary PPE contaminants, such as microplastics and chemical additives. It is expected that face mask mandates will be eventually halted, and PPE will stop being emitted to the environment. However, based on the lessons learned from the COVID-19 scenario, several recommendations for coastal solid waste management are provided. These are proposed to serve during and after the pandemic.

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

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

Are we underestimating floating microplastic pollution? A quantitative analysis of two sampling methodologies

Microplastics (MPs) are widespread in the water column of several aquatic ecosystems. Thus, the sampling methodology is considered as a basic factor influencing MPs abundance. In this baseline, a total of 67 investigations were chosen to conduct a quantitative analysis between two sampling methods: Trawl and bulk. The aim is to report a general overview of the MPs abundance and characteristic differences based on the sampling procedures and provide methodological recommendations. MPs abundance reported by bulk studies is 3500 higher than trawl studies. Furthermore, the morphological types and polymers abundances were statistically affected by the type of sampling tool. Conversely, MPs size ranges were significantly different between sampling procedures, suggesting that trawling underestimates the smaller MPs fractions. The analysis confirms that the sampling methods should be selected based on the research objectives. In this sense, it is recommended to combine both types of sampling procedures to obtain comprehensive data.

Heavy metals contamination and associated health risks in food webs-a review focuses on food safety and environmental sustainability in Bangladesh

Heavy metals occur naturally in very small amounts in living organisms, but exposure to their higher concentrations is hazardous. Heavy metals at hazardous levels are commonly found in foodstuffs of Bangladesh, mainly due to the lack of safety guidelines and poor management of industrial effluents. Several lines of evidence suggest that the level of heavy metals in foodstuffs of Bangladesh is higher than the acceptable limits set by World Health Organization/Food and Agriculture Organization. Literature survey revealed that the sources and transport pathways of heavy metals in the ecosystem and the abundance of heavy metals in the food products of Bangladesh are potential threats to food safety. However, an extensive assessment of the toxicity of heavy metals in food webs is lacking. Although widespread heavy metal contamination in various foodstuffs and environmental matrices have been summarized in some reports, a critical evaluation regarding multi-trophic transfer and the health risk of heavy metal exposure through food chain toxicity in Bangladesh has not been performed. This systematic review critically discussed heavy metal contamination, exposure toxicity, research gaps, existing legislation, and sustainable remediation strategies to enhance Bangladesh's food safety. In particular, this study for the first time explored the potential multi-trophic transfer of heavy metals via food webs in Bangladesh. Furthermore, we recommended a conceptual policy framework to combat heavy metal contaminations in Bangladesh.

Macro marine litter survey of sandy beaches along the Cox's Bazar Coast of Bay of Bengal, Bangladesh: Land-based sources of solid litter pollution

Macro-sized marine litter (>2.5 cm) was collected, characterized, and enumerated along the Cox's Bazar Coast, Bangladesh. Marine litter abundance was converted to density (number of items/m²). Beach cleanliness was evaluated using the clean-coast index (CCI). Plastic polythene bags were the most abundant litter items, followed by plastic cups. Total marine litter abundance was 54,401 ± 184 items. Major sources of marine litter were from tourism, fishery and residential activities. Of 10 sites surveyed, two were classified as dirty, two were moderate, four were clean and two were very clean using the CCI. Marine litter pollution along the Cox's Bazar Coast represents a potential threat to coastal and marine environments. This baseline study will help to establish mitigation strategies that are urgently required to reduce marine litter pollution along the Cox's Bazar Coast.

Hydrological distribution of physicochemical parameters and heavy metals in surface water and their ecotoxicological implications in the Bay of Bengal coast of Bangladesh

Accumulation of heavy metals in the coastal ecosystem has become a prodigious problem in any developing countries like Bangladesh. The impact of human activities on some physicochemical parameters and heavy metals was studied in surface water of the Bengal coast, Bangladesh. For ease of description, the fourteen study stations were categorized into four regions of the coastal sites of Bangladesh to determine physicochemical parameters and nine heavy metals like chromium (Cr), nickel (Ni), copper (Cu), arsenic (As), cadmium (Cd), lead (Pb), iron (Fe), manganese (Mn), and zinc (Zn) in water samples. The mean concentrations for water physico-chemistry are temperature (27.7±1.2 °C), pH (7.4±0.27), electrical conductivity (EC) (41.8±6.6 mS/cm), dissolved oxygen (DO) (6.7±0.69 mg/L), turbidity (58.5±12.0 NTU), fluoride (1.4±1.2 mg/L), chloride (126±66.3 mg/L), sulfate (120±90.5 mg/L), nitrate (4.7±2.5 mg/L), and phosphate (4.7±2.5 mg/L). While the mean concentrations of Cr, Ni, Cu, As, Cd, Pb, Fe, Mn, and Zn were 150±58.3, 40.2±10.1, 186±114, 77.3±31.3, 32.7±20.7, 66.7±32.5, 871±268, 178±41.4, and 222±100 μg/L, respectively. As a whole, average concentration of studied metals in surface water followed the decreasing order of Fe > Zn > Cu > Mn > Cr > Pb > As > Ni > Cd. Heavy metals in water samples were much higher than the water quality guidelines for freshwater quality criteria for protection of aquatic life and drinking, indicated that the water of the study areas may create health hazard. The outcomes of the contamination factor (CF), pollution load index (PLI), Nemerow's pollution index (NPI), degree of contamination (C_d), and modified degree of contamination (mC_d) varied spatially and most of the water samples were moderately to heavily polluted.

Microplastics pollution in salt pans from the Maheshkhali Channel, Bangladesh

Microplastics (MP) were recognized as an emergent pollution problem due to their ubiquitous nature and bioaccumulative potential. Those present in salt for consumption could represent a human exposure route through dietary uptake. The current study, conducted in Bangladesh, reports microplastics contamination in coarse salt prepared for human consumption. Sea salt samples were collected from eight representative salt pans located in the country's largest salt farming area, in the Maheshkhali Channel, along the Bay of Bengal. Microplastics were detected in all samples, with mean concentrations ranging from 78 ± 9.33 to 137 ± 21.70 particles kg^-1, mostly white and ranging in size from 500-1000 µm. The prevalent types were: fragments (48%) > films (22%) > fibers (15%) > granules and lines (both 9%). Fourier transform mid-IR and near-IR spectra (FT-MIR-NIR) analysis registered terephthalate (48%), polypropylene (20%), polyethylene (17%), and polystyrene (15%) in all samples. These results contribute to the MP's pollution knowledge in sea salts to understand and reduce this significant human exposure route and environmental pollution source in the future.

Personal protective equipment (PPE) pollution driven by the COVID-19 pandemic in Cox's Bazar, the longest natural beach in the world

The extensive use of personal protective equipment (PPE) driven by the COVID-19 pandemic has become an important contributor to marine plastic pollution. However, there are very few studies quantifying and characterizing this type of pollution in coastal areas. In the present study, we monitored the occurrence of PPE (face masks, bouffant caps, and gloves) discarded in 13 sites along Cox's Bazar beach, the longest naturally occurring beach in the world. The vast majority of the items were face masks (97.9%), and the mean PPE density across sites was 6.29 × 10^-3 PPE m^-2. The presence of illegal dumping sites was the main source of PPE, which was mainly located on touristic/recreational beaches. Fishing activity contributed to PPE pollution at a lower level. Poor solid waste management practices in Cox's Bazar demonstrated to be a major driver of PPE pollution. The potential solutions and sustainable alternatives were discussed.

Levels and health risk assessment of heavy metals in dried fish consumed in Bangladesh

As a cheap source of high-quality protein, healthy fats and essential nutrients, dried fish is a common item in the daily diet of the Bangladesh populace. In this study, ten types of widely consumed dried fish (H. neherius, T. lepturu, P.chinensis, P. affinis, A. mola, P. microdon, I. megaloptera, C. dussumieri, L. calcarifer, and G. chapra) were analyzed for Cr, Mn, Fe, Co, Cu, Zn, Se, Rb, Hg, Pb, Ni and As by using an Energy Dispersive X-ray Fluorescence (EDXRF) technique. The concentration of the studied metals was found in the order Fe > Zn > Hg > Cu > Se > Cr > Mn > Co > Rb > Pb, while As and Ni were below the limit of detection. All fish species showed moderate to high pollution, where the species H. Neherius and P. Chinensis are the most and least polluted ones, respectively. The probable source of contamination is the leaching from the drying pans into the fish samples, atmospheric deposition, anthropogenic contamination, etc. of the water body where these fish were harvested. The calculated hazard index for the general population was below the maximum limiting value (i.e., < 1) except for Hg to children. The carcinogenic risk showed values lower than the acceptable limit for cancer risks (10^–6 to 10^–4). Periodic monitoring of trace metals in the aquatic organisms along with fish is recommended to avoid any unexpected health hazards caused by the toxic heavy metals via fish consumption.

Occurrence of personal protective equipment (PPE) associated with the COVID-19 pandemic along the coast of Lima, Peru

The use and disposal of face masks, gloves, face shields, and other types of personal protective equipment (PPE) have increased dramatically due to the ongoing COVID-19 pandemic. Many governments enforce the use of PPE as an efficient and inexpensive way to reduce the transmission of the virus. However, this may pose a new challenge to solid waste management and exacerbate plastic pollution. The aim of the present study was to report the occurrence and distribution of COVID-19-associated PPE along the coast of the overpopulated city of Lima, Peru, and determine the influence of the activities carried out in each study site. In general terms, 138 PPE items were found in 11 beaches during 12 sampling weeks. The density was in the range of 0 to 7.44 × 10^-4 PPE m^-2. Microplastic release, colonization of invasive species, and entanglement or ingestion by apex predators are some of the potential threats identified. Recreational beaches were the most polluted sites, followed by surfing, and fishing sites. This may be because recreational beaches are many times overcrowded by beachgoers. Additionally, most of the PPE was found to be discarded by beachgoers rather than washed ashore. The lack of environmental awareness, education, and coastal mismanagement may pose a threat to the marine environment through marine litter and plastic pollution. Significant efforts are required to shift towards a sustainable solid waste management. Novel alternatives involve redesigning masks based on degradable plastics and recycling PPE by obtaining liquid fuels through pyrolysis.

Metals uptake and translocation in salt marsh macrophytes, Porteresia sp. from Bangladesh coastal area

Studies from around the world have suggested salt marshes or coastal wetlands can be used as sites for phytoremediation of metals. However, no investigations have been conducted to assess metal accumulation and translocation capabilities of salt marsh macrophytes from Bangladesh coastal area. The aim of this study was to evaluate the uptake and translocation of eight metals, Fe, Zn, Mn, Cu, Co, Rb, Sr, and Pb in Porteresia sp. from the six salt marsh sites of Bangladesh. The leaf, shoots and root tissues of Porteresia sp. samples were analyzed for metals by using the energy-dispersive X-ray fluorescence (EDXRF). The decreasing trend of metal concentrations was, in roots; Fe > Mn > Pb > Cu > Zn > Sr > Rb > Co, in shoots; Mn >Fe > Cu > Pb > Zn > Sr > Rb > Co, in leaves; Fe > Mn > Cu > Pb > Zn > Rb > Sr > Co. Generally, roots of the Porteresia sp. showed high accumulation of the metals when compared to shoots and leaves suggesting relevant availability in the sediment. Pb was the only metal with concentrations significantly higher in the leaves and shoots than in the root. Except for Pb, bioaccumulation concentration factor (BCF) for all metals was lower than 1 in plant organs indicating poor absorption and bioavailability of metals. Higher value (>1) of BCF for Pb infers the species can potentially be used for Pb phytoremediation. However, the translocation factor (TF) confirmed the diversified mobility of the metals from below-ground part to above-ground parts for all the measured metals in the salt marsh species. Highest mobility was observed for Mn and Pb. But it was hard to find any regular trends among all the metals and all the sites.

Data set on trace metals in surface sediment and water from a sub-tropical estuarine system, Bay of Bengal, Bangladesh

Meghna River Estuary, the largest estuarine system (GBM, Ganges-Brahmaputra-Meghna) in Bangladesh, is a major spawning ground of national fish, Hilsha shad. In this study, we collected 24 surface sediment and 24 water samples from the entire lower estuary (4 sites, 3 sampling points from each site, 2 replicas from each sampling point) to detect trace/heavy metals. Sediment samples were collected from the top surface soil (0–5 cm) using Ekman grab sampler and water samples from 5 cm below the surface layer using plastic water bottles. After collection, sediment and water samples were preserved as necessary using HNO₃ (for water). Immediately after reaching the laboratory, sediment samples were dried in an oven at 70°C until the constant weight gained. The metals were then analyzed using energy-dispersive X-ray fluorescence method (EDXRF) and calculated the metal concentrations. In total, 12 metals were detected and the average value (mg/Kg) of all metals for sediment samples followed the descending order of Fe > Ca > K >Ti >Sr >Zr >Rb> Cu > Zn >Pb >As > Ni, and for water the order (µg/mL) of Fe >Ti > Ca > Co >Mn > Ni > Zn >Sr > Cu > As > Se . Besides, several physicochemical parameters i.e. water pH, soil pH, temperature, salinity, dissolved oxygen, hardness, and alkalinity of the 12 sampling points were also measured in-situ using handheld instruments.