Microplastics in freshwater sediments of Atoyac River basin, Puebla City, Mexico

Trace elements and heavy metal(loid)s triggering ecological risks in a heavily polluted river-reservoir system of central Mexico: Probabilistic approaches

The contamination of trace elements and heavy metal(loid)s in water bodies has emerged as a global environmental concern due to their high toxicity at low concentrations to both biota and humans. This study aimed to evaluate the ecological risk associated with the occurrence and spatial distribution of Mn, Fe, Co, Cd, Ni, Zn, Sb, As, Tl, Cu, Pb, U, and V in the heavily polluted waters of an important river-reservoir system (Atoyac River Basin) in central Mexico, using two-level tired probabilistic approaches: Risk Quotient based on Species Sensitivity Distribution (RQSSD) and Joint Probability Curves (JPCs). The concentrations of these elements varied widely, ranging from 0.055 μg L-1 to 9200 μg L-1 and from 0.056 μg L-1 to 660 μg L-1, in both total and dissolved fractions, respectively. Although geogenic and anthropogenic sources contribute to the presence of these elements in waters, the discharge of untreated or poorly treated industrial wastewater is the main source of contamination. In this regard, the RQSSD results indicated high ecological risk for Mn, Fe, Co, Ni, Zn, and Sb, and medium or low ecological risk for As, Tl, U, and V at almost all sampling sites. The highest RQSSD values were found downstream of a large industrial corridor for Co, Zn, Tl, Pb, and V, with Tl, Pb, and V escalating to higher risk levels, highlighting the negative impact of industrial contamination on biota. The JPC results for these elements are consistent with the RQSSD approach, indicating an ecological risk to species from Mn, Fe, Co, Ni, Zn, and Sb in waters of the Atoyac River Basin. Therefore, the results of this study offer a thorough assessment of pollution risk, providing valuable insights for legislators on managing and mitigating exposure.

Microplastic evidence assessment from water and sediment sampling in a shallow tropical lake

Microplastics (MPs) severely threaten inland waterbodies due to the direct impact of human activities. In the present study, spatial and temporal patterns of MPs in a shallow tropical lake were assessed, describing their size, morphology, and polymer types. Water and sediment samples were collected from Lake Chapala during three seasons, and MPs were quantified with a stereomicroscope. The structure, elemental composition, and polymeric composition were determined via environmental scanning electron microscopy and Fourier transform infrared spectroscopy. The highest average concentration of microplastics in Lake Chapala was detected during the low-water period in April 2022 (2.35 items/L), exceeding the July 2022 rainy season concentration (1.8 items/L) by 0.25 items/L, and sediment concentrations were also higher in April 2022 (219 items/kg) compared to July 2022 (210 items/kg). This study highlights the significant pollution of Lake Chapala with microplastics, emphasizing the need for urgent measures to manage plastic waste and mitigate its environmental impact on aquatic ecosystems. PRACTITIONER POINTS: Microplastic contamination was evaluated in Lake Chapala. The distribution profiles of microplastics were different in each area. Heavy metals osmium, tellurium, and rhodium were found associated with the PMs. Polymers were found in this study.

Understanding and addressing microplastic pollution: Impacts, mitigation, and future perspectives

Improper disposal of household and industrial waste into water bodies has transformed them into de facto dumping grounds. Plastic debris, weathered on beaches degrades into micro-particles and releases chemical additives that enter the water. Microplastic contamination is documented globally in both marine and freshwater environments, posing a significant threat to aquatic ecosystems. The small size of these particles makes them susceptible to ingestion by low trophic fauna, a trend expected to escalate. Ingestion leads to adverse effects like intestinal blockages, alterations in lipid metabolism, histopathological changes in the intestine, contributing to the extinction of vulnerable species and disrupting ecosystem balance. Notably, microplastics (MPs) can act as carriers for pathogens, potentially causing impaired reproductive activity, decreased immunity, and cancer in various organisms. Studies have identified seven principal sources of MPs, including synthetic textiles (35%) and tire abrasion (28%), highlighting the significant human contribution to this pollution. This review covers various aspects of microplastic pollution, including sources, extraction methods, and its profound impact on ecosystems. Additionally, it explores preventive measures, aiming to guide researchers in selecting techniques and inspiring further investigation into the far-reaching impacts of microplastic pollution, fostering effective solutions for this environmental challenge.

Distribution, flux, and risk assessment of microplastics at the Anzali Wetland, Iran, and its tributaries

Microplastic pollution has raised significant concerns among scientific communities and society in recent years due to its increase and lesser-known effects on the environment. To improve the knowledge of microplastic pollution in freshwater, we investigated microplastics in Anzali Wetland, a Ramsar site in northern Iran, as well as its nine main entering rivers. The extracted microplastics were characterized via visual identification, SEM-EDX, and μ-Raman methods. Microplastics (size range: 50-5000 μm) were found in all water and sediment samples with concentration of fibrous particles as well as polypropylene and polyethylene polymers. The mean concentration of microplastics in bottom sediment and surface water samples of the wetland was 301 ± 222 particles∙kg-1 d.w. and 235 ± 115 particles∙m-3 (0.23 particles∙L-1), respectively. The microplastic concentration in the central and eastern parts of the wetland was higher than in other areas; however, the mean concentrations revealed homogeneity across the wetland area. Water properties (dissolved oxygen, pH, temperature, electrical conductivity, and salinity in water) did not affect the concentration of microplastic particles, though correlational analysis revealed a strong positive association between microplastic quantity and turbidity. There was a significant positive relationship between microplastic concentration and the percentage of clay in sediment samples. The quantity of microplastics in river water was higher than in wetland water, but the difference between the results was not significant. However, the quantity of microplastics in the river's littoral sediment was higher than in the bottom sediment of the wetland where the difference between the results was significant. Microplastic ecological risk assessment showed high potential ecological risk. The findings underscore the importance of effective management strategies and the implementation of policies to mitigate the negative impact of MP pollution on ecosystems and human health.

Potential ecological risk assessment of microplastics in environmental compartments in Mexico: A meta-analysis

Microplastic (MP) environmental contamination has been widely studied in Mexico; however, the evaluation of the associated risk to MP in environmental compartments is scarce. Therefore, this study addresses this issue using diverse indicators such as the Pollution Load Index (PLI), the Polymer Risk Index (PRI), and the Potential Ecological Risk Index (PERI). The results of a meta-analysis revealed high MP contamination levels in most of the studied compartments, which included marine and estuarine waters, beach sand, freshwater, sediments, and biota. Regarding the risk assessment indicators, PLIs indicated low (56%), dangerous (22%), moderate (12%), and high (10%) levels across compartments. Meanwhile, PRIs displayed concerning values, with 36%, 35%, 20%, and 9% exhibiting dangerous, high, moderate, and low levels, respectively. Thus, high PRI values emphasized the significant rise in MP pollution, largely attributed to high-hazard polymer compositions. Otherwise, PERIs showed low (56%), very dangerous (29%), moderate (6%), high (5%), and dangerous (4%) levels. Thus, the ecological risk in Mexico is widespread and mainly linked to MP abundance, polymer type, environmental matrix, and organisms' characteristics. This study represents the first attempt at MP ecological risk assessment in Mexico, providing crucial insights for developing mitigation strategies to address concerns about MP contamination.

Microplastics pollution in tropical lakes: water, zooplankton, and fish in Central Mexico

The presence of microplastics in freshwater systems can have harmful effects on the food chain. Zooplankton, especially suspension and filter feeders, can ingest microplastics, which can cause adverse effects and transfer them to higher trophic levels. Here, we analyze the presence, abundance, and distribution of microplastics in surface water, zooplankton, and fish in two tropical lakes in central Mexico. We collected water samples in triplicate at three sites in each lake and 120 fish of the genus Chirostoma. From each water sample, 300 rotifers and 150 microcrustaceans were randomly isolated and processed independently. Of the particles found in the water, zooplankton, and fish from both lakes, the fragments were the predominant ones. The total abundance of microplastics in the water column of both lakes varied between 1.2 and 17.0 items L-1. In zooplankton, fragments were found predominantly with up to 0.1 items ind-1, while in fish, up to 4.5 items ind-1 was recorded. Our results confirm the presence of microplastics in different compartments of the food webs of freshwater bodies, water column, zooplankton, and fish. Further work is required on the possible effects of these stressors at the different trophic levels.

Quantification and polymeric characterization of microplastics in composts and their accumulation in lettuce

Organic fertilizers have become a vector for the transport of microplastics (MPs), which pose human health concerns through the food chain. This study aimed to quantify and characterize MPs in eight different compost samples of various raw materials and their subsequent translocation to lettuce (Lacuta sativa) grown on contaminated composts. The results revealed that the MP abundance ranged from 3810 to 16530 MP/kg. Municipal solid waste compost (MSWC) had highest abundance (16082 ± 632 MP/kg), followed by leaf compost (LC) and organic compost (OC) (6299 ± 1011 and 3680 ± 419 MP/kg, respectively). MPs of <100 μm in size were most dominant in MSWC and LC. Fragments and fibers were the prevalent shape types, with white/transparent colored MPs being more abundant. Polyethylene (PE), polypropylene (PP) and polyethylene terephthalate (PET) were the dominant polymers. MPs accumulation in the lettuce leaves was greatest in the lettuce plants grown on MSWC, followed by those grown on LC and OC, indicating that MSWC grown lettuce is not suitable for human consumption. The decrease in the growth (leaf length, number of leaves, leaf fresh and weights) and physiological (membrane stability index, relative water contents) parameters of lettuce was in line with the trend of MP accumulations. Hence, it is highly important to regulate the plastic contents in compost because it is a threat to ecosystems and human health.

Influence of ongoing discharge from multiple wastewater treatment plants on microplastic patterns in small-scale receiving rivers

As widely acknowledged, wastewater treatment plants (WWTPs) stand as significant contributors to the presence of microplastics in surface water. Nonetheless, there exists a notable research gap regarding the extent of potential pollution resulting from the concurrent and uninterrupted discharges originating from multiple WWTPs into small-scale receiving water bodies. This study endeavors to address this knowledge deficit by conducting a thorough investigation into the prevalence of microplastics in surface water. The research encompasses seven distinct locations within the Changzhou section of the Beijing-Hangzhou Grand Canal and the effluent of three WWTPs situated along the tributary. The results indicate differences in the distribution of microplastics in surface waters of mainstream and tributaries. While the microplastic abundance and composition showed little variation along the main stream, the tributaries displayed an overall increasing trend in microplastic abundance from upstream to downstream. Notably, the major contributors to this increase were fragments, fiber particles, and microplastics with particle sizes ranging from 100 to 300 μm. Considering that the primary distinction between the tributaries and the mainstream is the presence of the three WWTPs along the tributaries, the study conducted a correlation analysis between river surface water and effluents from these plants. The results indicated a stronger correlation between the tributaries and the effluents, suggesting that WWTPs are one of the primary factors contributing to the elevated levels of microplastics in the tributaries. Finally, a comparative analysis of microplastic abundance in the Beijing-Hangzhou Grand Canal's Changzhou section and other regions was conducted. The findings revealed that the microplastic pollution level in the Beijing-Hangzhou Grand Canal's Changzhou section is higher than that in most other rivers. Therefore, the issue of microplastic pollution in the Beijing-Hangzhou Grand Canal's Changzhou section warrants our attention, particularly with regard to the effectiveness of microplastic removal by the WWTPs along its course.

Microplastics and environmental effects: investigating the effects of microplastics on aquatic habitats and their impact on human health

Microplastics (MPs) are particles with a diameter of <5 mm. The disposal of plastic waste into the environment poses a significant and pressing issue concern globally. Growing worry has been expressed in recent years over the impact of MPs on both human health and the entire natural ecosystem. MPs impact the feeding and digestive capabilities of marine organisms, as well as hinder the development of plant roots and leaves. Numerous studies have shown that the majority of individuals consume substantial quantities of MPs either through their dietary intake or by inhaling them. MPs have been identified in various human biological samples, such as lungs, stool, placenta, sputum, breast milk, liver, and blood. MPs can cause various illnesses in humans, depending on how they enter the body. Healthy and sustainable ecosystems depend on the proper functioning of microbiota, however, MPs disrupt the balance of microbiota. Also, due to their high surface area compared to their volume and chemical characteristics, MPs act as pollutant absorbers in different environments. Multiple policies and initiatives exist at both the domestic and global levels to mitigate pollution caused by MPs. Various techniques are currently employed to remove MPs, such as biodegradation, filtration systems, incineration, landfill disposal, and recycling, among others. In this review, we will discuss the sources and types of MPs, the presence of MPs in different environments and food, the impact of MPs on human health and microbiota, mechanisms of pollutant adsorption on MPs, and the methods of removing MPs with algae and microbes.

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.

From pollution to solutions: Insights into the sources, transport and management of plastic debris in pristine and urban rivers

River systems are important recipients of environmental plastic pollution and have become key pathways for the transfer of mismanaged waste from the land to the ocean. Understanding the sources and fate of plastic debris, including plastic litter (>5 mm) and microplastics (MPs) (<5 mm), entering different riverine systems is essential to mitigate the ongoing environmental plastic pollution crisis. We comprehensively investigated the plastic pollution in the catchments of two rivers in the Yangtze River basin: an urban river, the Suzhou section of the Beijing-Hangzhou Grand Canal (SZ); and a pristine rural river, the Jingmen section of the Hanjiang River (JM). The abundance of plastic pollutants in SZ was significantly higher than in JM: 0.430 ± 0.450 items/m3 and 0.003 ± 0.003 items/m3 of plastic litter in the water; 23.47 ± 25.53 n/m3 and 2.78 ± 1.55 n/m3 MPs in the water; and 218.82 ± 77.40 items/kg and 5.30 ± 1.99 items/kg of MPs in the sediment, respectively. Plastic litter and MPs were closely correlated in abundance and polymer composition. Overall, the polymer type, shape and color of MPs were dominant by polypropylene (42.5%), fragment (60.4%) and transparent (40.0%), respectively. Source tracing analysis revealed that packaging, shipping, and wastewater were the primary sources of plastic pollutants. The mantel analysis indicated that socio-economic and geospatial factors play crucial roles in driving the hotspot formation of plastic pollution in river networks. The composition of the MP communities differed significantly between the sediments and the overlying water. The urban riverbed sediments had a more pronounced pollutant 'sink' effect compared with the pristine rivers. These findings suggested that the modification of natural streams during urbanization may influence the transport and fate of plastic pollutants in them. Our results offer pivotal insights into effective preventive measures.

Microplastic pollution in urban stormwater inlet sediments influenced by land use type of runoff drainage area

Since the urban stormwater inlet (USI) acts as a link in the migration of microplastics (MPs) in stormwater, sufficient information on MPs in USI sediments is very important for understanding urban diffuse microplastic pollution. In this study, the abundance and characteristics of MPs in the USI sediments of Ma'anshan City, China, were analyzed based on urban land use type. MPs were prevalent in the USI sediments, with the average abundances of 536.77 ± 313.92 items·kg-1 for commercial areas, 505.64 ± 400.82 items·kg-1 for campuses, 694.71 ± 219.95 items·kg-1 for industrial areas, 526.41 ± 152.34 items·kg-1 for residential areas, and 1107.75 ± 422.10 items·kg-1 for main roads, indicating a high microplastic pollution in the USI sediments from main roads. The microplastic polymers were mainly polypropylene (PP), polyethylene (PE), polyethylene terephthalate (PET), and polystyrene (PS), accounting for 46.75 %-100.00 %, with PP MPs being the most abundant. Fiber MPs had the highest proportion in USI sediments from both campuses (35.30 %) and industrial areas (38.19 %), while film MPs were the most abundant for both commercial areas (39.91 %) and residential areas (35.65 %). The average proportions of fiber (27.29 %), fragment (29.18 %), and film (28.68 %) were almost equal for main roads, unlike other land use types. Except for campuses, transparent MPs were the most common for all land use types, with average proportions of 29.60 %-42.70 %. The proportions of MPs with sizes of <1000 μm were 72.54 % for commercial areas, 77.11 % for campuses, 76.05 % for industrial areas, 70.76 % for residential areas, and 74.29 % for main roads, respectively, with a consistent result with previous study that the MPs of <1000 μm are the predominant in the environment. This study enriches the knowledge of microplastic pollution in USI sediments and will benefit the mitigation of diffuse microplastic pollution.

Effect of cooking on structural changes in the common black bean (Phaseolus vulgaris var. Jamapa)

The cooking process is fundamental for bean consumption and to increase the bioavailability of its nutritional components. The study aimed to determine the effect of cooking on bean seed coat through morphological analyses with different microscopy techniques and image analyses. The chemical composition and physical properties of raw black bean (RBB) and cooked black bean (CBB) seeds were determined. The surface and cross-sectional samples were studied by Optical microscopy (OM), environmental scanning electron microscopy (ESEM), atomic force microscopy (AFM) and confocal laser scanning microscopy (CLSM). The composition of samples showed significant differences after the cooking process. OM images and gray level co-occurrence matrix algorithm (GLCM) analysis indicated that cuticle-deposited minerals significantly influence texture parameters. Seed coat surface ESEM images showed cluster cracking. Texture fractal dimension and lacunarity parameters were effective in quantitatively assessing cracks on CBB. AFM results showed arithmetic average roughness (Ra) (121.67 nm) and quadratic average roughness (Rq) (149.94 nm). The cross-sectional ESEM images showed a decrease in seed coat thickness. The CLSM results showed an increased availability of lipids along the different multilayer tissues in CBB. The results generated from this research work offer a valuable potential to carry out a strict control of bean seed cooking at industrial level, since the structural changes and biochemical components (cell wall, lipids and protein bodies) that occur in the different tissues of the seed are able to migrate from the inside to the outside through the cracks generated in the multilayer structure that are evidenced by the microscopic techniques used.

Characteristics and ecological risks of microplastic pollution in a tropical drinking water source reservoir in Hainan province, China

Microplastic (<5 mm) pollution has become a pressing environmental concern in recent years. The present study investigated the occurrence characteristics and assessed the ecological risk of microplastics in the surface water and sediment of the Chitian Reservoir, a drinking water source in Hainan province (China). The results indicated that microplastics were detected in the surface water and sediment of the Chitian Reservoir and its surrounding areas. The overall abundance of microplastics in the water was 3.05 ± 1.16 items per L and in the sediment was 0.15 ± 0.06 items per g dry weight, which is relatively low compared to other reservoirs in China. The dominant components of microplastics detected in the Chitian Reservoir were polypropylene (PP), rayon, and polyester. Physical morphology analysis of microplastics showed that fibers with small particle sizes (<1 mm) and white color were the predominant characteristics in both the surface water and sediment. The domestic sewage from surrounding residents and agricultural wastewater may be the primary sources of microplastics in the reservoir. Ecological risk assessment revealed that the overall pollution load index (PLI) in the surface water (0.65) and sediment (0.51) of the Chitian Reservoir and its surrounding area is at a low level. The potential ecological hazards (RI) of microplastics (0.13 to 336.78 in water; 0.23 to 465.93 in sediment) in most sites fall within the scope of level I, but those in a few sites are at level II due to the presence of polyvinyl chloride (PVC). This study enriches the data on microplastic pollution in inland reservoir systems, providing fundamental reference information for future ecotoxicological studies and the management of microplastic pollution control.

Temporal and spatial variation of microplastics in the urban rivers of Harbin

This study was to investigate temporal and spatial variation of microplastics in surface water and sediment in the urban rivers of Harbin during dry and wet season. Water samples (n = 25) in Xinyi River (n = 13) and Ashe River (n = 12) were collected from the selected sampling points. Microplastics in urban rivers in Harbin included polyethylene (PE), polypropylene (PP), polystyrene (PS), polyamide (PA), polyvinyl chloride (PVC) and polyethylene terephthalate (PET). The results show that urban rivers in Harbin had relatively mild microplastic abundance with most fragments in shape and colorless in color. PP and PE were the major polymers in surface water samples, while PVC and PET were the major polymers in sediment, which were dominated by large-size and granulate shape microplastics. Source apportionment demonstrate that the main sources of microplastics in Xinyi River and Ashe River during dry season were domestic wastewater and effluent from rainfall, while the main sources of microplastics in Xinyi River and Ashe River during wet season were wastewater, atmospheric sedimentation, and agricultural source. The morphology of microplastics in surface water and sediment in urban rivers of Harbin was negatively correlated with water velocity and positively correlated with the concentration of suspended matter, dissolved oxygen, and conductivity. Riparian vegetation on the sides of Xinyi and Ashe River decreased migration process of microplastics by vegetal purification and then resulted in low abundance of microplastics. In conclusion, this study highlighted the occurrence characteristics, source apportionment and environmental influencing factors of microplastics in urban rivers of Harbin, which may develop new insights into the reduction of abundance of microplastics in the urban rivers.

Evaluation of niche, diversity, and risks of microplastics in farmland soils of different rocky desertification areas

The occurrence, sources, effects, and risks of microplastics (MPs) in farmland soils have attracted considerable attention. However, the pollution and ecological characteristics of MPs in farmland soils at different levels of rocky desertification remain unclear. We collected and analyzed farmland soil samples from rocky desertification areas in Guizhou, China, ranging from no to heavy risks. We explored differences and migration of MPs across these areas, unveiled the relationship between diversity, niche, and risks of MPs, and determined influencing factors. The average abundance of soil MPs was 8721 ± 3938 item/kg, and the abundance and contamination factor (CF) of MPs escalated with the increase in rocky desertification level. Diversity, niche, and risk of soil MPs in different rocky desertification areas were significantly different. Rocky desertification caused both MP community differences and linked MP communities at different sites. Diversity and niche significantly affected MP risk (p < 0.05). Environmental factors with significant correlations (p < 0.05) with the abundance and ecological characteristics of MPs varied significantly in soils of different rocky desertification areas. This study advances our comprehension of MP pollution in farmland soils within rocky desertification areas, offering essential data and theoretical insights for the development of control strategies.

Microplastics in Ecuador: A review of environmental and health-risk assessment challenges

Pollution from plastic debris and microplastics (MPs) is a worldwide issue. Classified as emerging contaminants, MPs have become widespread and have been found not only in terrestrial and aquatic ecosystems but also within the food chain, which affects both the environment and human health. Since the outbreak of COVID-19, the consumption of single-use plastics has drastically increased, intensifying mismanaged plastic waste in countries such as Ecuador. Therefore, the aim of this review is to 1) summarize the state of MP-related knowledge, focusing on studies conducted with environmental matrices, biota, and food, and 2) analyze the efforts by different national authorities and entities in Ecuador to control MP contamination. Results showed a limited number of studies have been done in Ecuador, which have mainly focused on the surface water of coastal areas, followed by studies on sediment and food. MPs were identified in all samples, indicating the lack of wastewater management policies, deficient management of solid wastes, and the contribution of anthropogenic activities such as artisanal fishing and aquaculture to water ecosystem pollution, which affects food webs. Moreover, studies have shown that food contamination can occur through atmospheric deposition of MPs; however, ingredients and inputs from food production, processing, and packaging, as well as food containers, contribute to MP occurrence in food. Further research is needed to develop more sensitive, precise, and reliable detection methods and assess MPs' impact on terrestrial and aquatic ecosystems, biota, and human health. In Ecuador specifically, implementing wastewater treatment plants in major cities, continuously monitoring MP coastal contamination, and establishing environmental and food safety regulations are crucial. Additionally, national authorities need to develop programs to raise public awareness of plastic use and its environmental effects, as well as MP exposure's effects on human health.

Analysis of microplastics in ships ballast water and its ecological risk assessment studies from the Persian Gulf

Transport of ballast water is considered a significant vector for dispersion of different pollutants, including microplastics (MPs), throughout the world's oceans. However, there is limited information on MPs in ballast water. Size distribution, polymer type, and ecological risks of MPs in ballast water were investigated for the first time in this study. The mean levels of MPs in ballast water and seawater samples were 12.53 and 11.80 items/L, respectively. MPs with a size category of 50-300 μm was the most abundant. Fiber, black, and polycarbonate (PC) were the predominant shape, color, and polymer type of identified MPs in ballast water and seawater, respectively. The pollution load index (PLI), hazard index (HI), and risk quotient (RQ) indicated high levels of MP pollution, potentially indicating an ecological risk. These findings increase our understanding of the major sources (such as ballast water), transportation routes, and related ecological risks of MPs to marine ecosystems.

Occurrence, ecological and health risk assessment of phthalates in a polluted urban river used for agricultural land irrigation in central Mexico

The escalating global concern on phthalate esters (PAEs) stems from their status as emerging contaminants, marked by their toxicity and their potential to harm both the environment and human health. Consequently, this study aimed to evaluate the occurrence, spatial distribution, and ecological and health risks associated with PAEs in the Atoyac River, an urban waterway in central Mexico that receives untreated and poorly treated urban and industrial wastewater. Of the 14 PAEs analyzed in surface water samples collected along the river mainstream, nine were detected and quantified by GC-MS. The concentration of each detected PAE ranged from non-detected values to 25.7 μg L-1. Di (2-ethylhexyl) phthalate (DEHP) and di-n-hexyl phthalate (DnHP) were detected in all sampling sites, with concentrations ranging from 8.1 to 19.4 μg L-1 and from 6.3 to 15.6 μg L-1, respectively. The cumulative Σ9PAEs concentrations reached up to 81.1 μg L-1 and 96.0 μg L-1 in sites downstream to high-tech industrial parks, pinpointing industrial wastewater as the primary source of PAEs. Given that the river water is stored in a reservoir and used for cropland irrigation, this study also assessed the ecological and human health risks posed by PAEs. The findings disclosed a high ecological risk to aquatic organisms exposed to di-n-octyl phthalate (DOP), dicyclohexyl phthalate (DCHP), benzyl butyl phthalate (BBP), DEHP, and DnHP. Additionally, a high carcinogenic (CR > 10-4) and noncarcinogenic (HQ > 10) risk for the DEHP exposure through ingestion of crops irrigated with river water was identified for both children and adults. These data on PAEs provide valuable insights for the Mexican government's future strategies in regulating these pollutants in water bodies, thereby minimizing the environmental and human health risks that they pose.

A systematic review on the current situation of emerging pollutants in Mexico: A perspective on policies, regulation, detection, and elimination in water and wastewater

Emerging pollutants (EPs) emerged as a group of new compounds whose presence in the environment has been widely detected in Mexico. In this country, different concentrations of pharmaceutical compounds, pesticides, dyes, and microplastics have been reported, which vary depending on the region and the analyzed matrix (i.e., wastewater, surface water, groundwater). The evidence of the EPs' presence focuses on the detection of them, but there is a gap in information regarding is biomonitoring and their effects in health in Mexico. The presence of these pollutants in the country associated with lack of proper regulations in the discharge and disposal of EPs. Therefore, this review aims to provide a comprehensive view of the current environmental status, policies, and frameworks regarding Mexico's situation. The review also highlights the lack of information about biomonitoring since EPs are present in water even after their treatment, leading to a critical situation, which is high exposure to humans and animals. Although, technologies to efficiently eliminate EPs are available, their application has been reported only at a laboratory scale thus far. Here, an overview of health and environmental impacts and a summary of the research works reported in Mexico from 2014 to 2023 were presented. This review concludes with a concrete point of view and perspective on the status of the EPs' research in Mexico as an alert for government entities about the necessity of measures to control the EPs disposal and treatment.

Impact of soil structure and texture on occurrence of microplastics in agricultural soils of karst areas

The impact of microplastics (MPs) on soil ecosystems has attracted widespread attention; however, the effects of soil structure and texture on the occurrence of MPs are not fully understood. In this study, we investigated the effects of soil structure and texture on the abundance of MPs and their potential mechanisms in agricultural soils of karst areas in Guizhou, China. The results showed the average abundance of MPs was 2948 items/kg. The soil texture in the study area can be categorized into seven types such as powdered-light clay, the range of total soil porosity was 39.05-69.22 % and the range of soil bulk density was 0.66-1.51 g/cm3. Soils with a powdered-light clay, low soil porosity, and low soil bulk density showed higher MPs pollution. The percentage of pellet MPs in agricultural soils with a powdered-light clay was 84 %, which was higher than that of the other soil textures. The direct effects of soil texture, soil porosity, and soil bulk density on MPs abundance were much lower than the indirect effects, with soil texture having the highest effect on MPs abundance. We speculated that karst geology may affect the accumulation and distribution of MPs in soil by affecting soil texture and structure, which, in turn, affects the fragmentation and migration of MPs. These findings will help to better understand the mechanisms of soil MPs pollution and provide a scientific basis for the development of relevant control strategies.

Removal characteristics of microplastics in sewage flowing through a long-term operation surface flow wetland

Microplastics (MPs) in sewage pose significant threats to aquatic system. Surface flow wetland (SFW) is a common natural wetland type, and is also used as a cheap and easy-to-build sewage treatment system for small and scattered settlements. However, seasonal variation patterns of MPs in sewage removed by SFW are still limited. Therefore, a field investigation was conducted in an SFW that has been operated for 17 years. The concentration of microplastics in the influent of the SFW (CMPs, in) ranged from 56 ± 6 to 250 ± 14 items L-1. The dominant plastic types were fibers and polyethylene terephthalate (PET). CMPs, in were high in summer and winter, significantly related to the seasonal dressing habits. The removal efficiencies of MPs in SFW were 48.03-92.32 % in different seasons, and the mechanisms of MP removal were different with traditional pollutants. Before flowing out occasionally or by heavy precipitation, MPs were primarily trapped in the SFW and underwent certain oxidation. Simulation experiments demonstrated that 47.5-92.9 % of MPs would be trapped in the SFW, and plants would significantly enhance the trapping capacities. This study sheds light on the seasonal variation characteristics and patterns of MPs in actual sewage, and clarifies the fate of MPs in a long-term operation SFW.

Study of soil microplastic pollution and influencing factors based on environmental fragility theory

Soil microplastics (MPs) pollution is a global concern, but the distribution of MPs and the factors affecting the distribution of MPs in different ecologically fragile karst areas remain poorly understood. Here, we investigated the spatial distribution, characteristics, and composition of MPs in different ecologically fragile karst areas of Guizhou Province and explored the relationship between ecosystem fragility and MPs. Structural equation models combined with robust random forest (RF) models were used to clarify the effects of karst soil properties on MPs and quantify their relative contributions. The abundance of soil MPs in ecologically fragile karst areas was 2949 item kg-1, and the risk of MPs contamination was highest in medium-fragile areas. The robust RF models precisely predicted the abundance of soil MPs in different fragile areas, and the mean root mean square error and R2 were 0.21 and 0.93, respectively. The contribution of karst soil properties to the abundance of MPs was estimated. Some soil chemical properties had a significant effect (p < 0.05) on MPs pollution in ecologically fragile karst areas. The results of our study suggest that the fragile ecological environment may exacerbate MPs pollution. Our study also contributes to establish a scientific theoretical foundation for the utilization of plastics and the prevention and control of microplastics pollution in karst ecosystems.

Distribution of microplastics in shoreline water and sediment of the Ganges River Basin to Meghna Estuary in Bangladesh

This study focused on the distribution of microplastics in the water and sediment of the Ganges River Basin to the Meghna Estuary in Bangladesh. Thirty points were sampled from Chapainawabganj district (India-Bangladesh border) to Chandpur district (Meghna Estuary). The morphological appearances were recognized by stereomicroscope and SEM-EDX analysis. Potential ecological risks were also measured. The average microplastic concentration in upstream and downstream water was 50.9 ± 24.4 particles/L and 64.1 ± 26.3 particles/L, respectively, and the sediment concentration was 2953.49 ± 1670.52 particles/kg in upstream sediment and 4014.66 ± 1717.59 particles/kg in downstream sediment. In upstream water, the most dominant morphological appearance was fragment shape, blue colour and 1-2 mm in size. The appearance of downstream water was fragments shape, red colour and 0.1-0.5 mm in size. In upstream sediment, the most dominant morphological appearance was fragment shape, red colour and < 0.1 mm in size. The appearance of downstream sediment was fibre shape, red colour and < 0.1 mm in size. Seven polymer types were discovered in water, dominated by low-density polyethylene (LDPE), and eight polymer types in sediment, dominated by polyamide (PA). The correlation between the size and shape of particles was analyzed using principal component analysis. The overall pollution load index of the Ganges River Basin to the Meghna Estuary was 1.86, higher than the other studies done in Bangladesh. Surprisingly, the nemerow pollution index (NPI), contamination factor (CF), pollution load index (PLI), polymer hazard index (PHI), and potential ecological risk (Ei)- all five ecological risk indicators had low to very high water and sediment pollution in the Ganges River Basin due to microplastic exposure. The data produced through this study will drive increasing awareness regarding microplastic pollution in the vast river ecosystem. Given the widespread presence of this pollution, it highlights the necessity for continuous national monitoring of microplastics.

Microplastic Pollution in the Gastrointestinal Tract and Gills of Some Teleost and Sturgeon Fish from the Caspian Sea, Northern Iran

The increasing microplastic pollution in the marine environment has raised global concern. The main risk of microplastics in aquatic ecosystem is their bioaccumulation in aquatic organisms. A few studies have reported microplastic pollution in the digestive system of Caspian Sea fish species, but there is no research on sturgeon species, nor on fish gills. We investigated the occurrence of microplastics in the gastrointestinal tract (GIT) and gills of 62 specimens belonging to four species including three teleosts (Cyprinus carpio, Rutilus kutum, and Chelon aurata) and one sturgeon (Acipenser persicus, a valuable endangered species) from the Caspian Sea between January and March 2022. Fish tissues were removed, exposed for 24 h to 10% KOH, and then dried on filter paper. Particles were observed under a stereomicroscope and analyzed by Raman microspectrometry, scanning electron microscopy, and energy-dispersive spectroscopy. A total of 91 microplastics were detected in the GIT (average of 1.46 ± 1.17 items/individual) and 63 microplastics in the gills (average of 1.01 ± 0.62 items/individual). A significant correlation was not found between the number of microplastics found in both tissues and fish body length, body weight, GIT weight, and gill weight (p > 0.05), except between microplastics isolated from gills and gill weight in C. carpio (rs  = 0.707, p = 0.022). The abundance of microplastics in fish followed the order of A. persicus > C. aurata > R. kutum > C. carpio. The microplastics were in the size range of 45 to 5000 µm, with particles of 300 to 1000 µm being the most prevalent; 74.68% of the particles were shaped like fibers, 30.53% were red, and 70.6% were composed of nylon polymer. Environ Toxicol Chem 2023;42:2453-2465. © 2023 SETAC.

Microplastic contamination in Indian rural and urban lacustrine ecosystems

This study investigates the microplastics (MPs) pollution of the lacustrine ecosystems of Tamil Nadu, South India. It examines the seasonal distribution, characteristics and morphology of MPs and assesses the risk posed by MPs pollution. MPs abundance in the 39 rural and urban lakes studied varies from 16 ± 2.69 to 118.17 ± 22.17 items/L (water) and 19.50 ± 4.75 to 156.23 ± 36.41 items/kg (sediment). The water and sediment of urban lakes show average MPs abundances of 88.06 items/L and 115.24 items/kg respectively, while the rural lakes exhibit average MPs abundances of 42.98 items/L and 53.29 items/kg. The results demonstrate that study areas with more residential and urban centers with higher population density and larger discharge of sewage have greater MP abundance. Urban zones have greater MP diversity integrated index (MPDII = 0.73) than rural zones (MPDII = 0.59). Fibres are the dominant group and polyethylene and polypropylene are the most commonly found polymers, possibly gaining entry through land-based plastic litter and urban activities in this region. The weathering index values, 50 % of MPs exhibit high degree of oxidation (WI >0.31) with an age of >10 years. SEM-EDAX results reveal that the weathered MPs from urban lakes have a wider variety of metal elements (Al, Cr, Mn, Co, Ni, Cu, Zn, As, Sr, Hg, Pb and Cd) than those from rural lakes (Na, Cl, Si, Mg, Al, Cu). Though PLI shows low risk (<10) in terms of abundance, PHI reflects pollution status III (10-100) and IV (100-1000) in rural areas and IV and V (>1000) in urban areas based on the toxicity score of the polymer. Ecological risk assessment shows minor risks (<150) at present. The assessment indicates the risk posed by the MPs to the lakes studied and emphasizes the necessity for best MP management practices in future.

Plastic rain-Atmospheric microplastics deposition in urban and peri-urban areas of Patna City, Bihar, India: Distribution, characteristics, transport, and source analysis

Evidence of atmospheric microplastics (MPs) deposition in India is scarce though reports of MPs pollution in other environmental media exist. Henceforth, this study for the first time examines and compares the abundance, characteristics, transport, and source analysis of atmospheric MPs in the urban and peri-urban areas of Patna city, Bihar, India. Wet atmospheric fallout samples were collected and analyzed for MPs deposition rate. The results showed that the mean MPs concentrations at each site were 1959.6 ± 205 (urban) and 1320.4 ± 126 (peri-urban) MPs/m²/day. The deposited MPs were mainly transparent fibers and fragments with a mean size of 347.9 ± 189.2 µm. Polyethylene terephthalate and polypropylene were the most abundant polymer found at both sites. Morphological characteristics revealed surface degradation and deposition of metal contaminants on the identified MPs. Meteorological parameters (wind direction and rainfall intensity) were significantly associated with the distribution of atmospheric MPs in the study area. The cluster mean backward trajectory suggested vehicular emissions, construction activities, and waste mismanagement as the potential sources of MPs. Findings of the present work necessitates future studies in gaining a deeper understanding of the fate, movement, and potential health hazards associated with atmospheric MPs.

Source, occurrence, distribution, fate, and implications of microplastic pollutants in freshwater on environment: A critical review and way forward

The generation of microplastics (MPs) has increased recently and become an emerging issue globally. Due to their long-term durability and capability of traveling between different habitats in air, water, and soil, MPs presence in freshwater ecosystem threatens the environment with respect to its quality, biotic life, and sustainability. Although many previous works have been undertaken on the MPs pollution in the marine system recently, none of the study has covered the scope of MPs pollution in the freshwater. To consolidate scattered knowledge in the literature body into one place, this work identifies the sources, fate, occurrence, transport pathways, and distribution of MPs pollution in the aquatic system with respect to their impacts on biotic life, degradation, and detection techniques. This article also discusses the environmental implications of MPs pollution in the freshwater ecosystems. Certain techniques for identifying MPs and their limitations in applications are presented. Through a literature survey of over 276 published articles (2000-2023), this study presents an overview of solutions to the MP pollution, while identifying research gaps in the body of knowledge for further work. It is conclusive from this review that the MPs exist in the freshwater due to an improper littering of plastic waste and its degradation into smaller particles. Approximately 15-51 trillion MP particles have accumulated in the oceans with their weight ranging between 93,000 and 236,000 metric ton (Mt), while about 19-23 Mt of plastic waste was released into rivers in 2016, which was projected to increase up to 53 Mt by 2030. A subsequent degradation of MPs in the aquatic environment results in the generation of NPs with size ranging from 1 to 1000 nm. It is expected that this work facilitates stakeholders to understand the multi-aspects of MPs pollution in the freshwater and recommends policy actions to implement sustainable solutions to this environmental problem.

Microplastic pollution in riverine ecosystems: threats posed on macroinvertebrates

Microplastics (MPs) are pollutants of emerging concern that have been reported in terrestrial and aquatic ecosystems as well as in food items. The increasing production and use of plastic materials have led to a rise in MP pollution in aquatic ecosystems. This review aimed at providing an overview of the abundance and distribution of MPs in riverine ecosystems and the potential effects posed on macroinvertebrates. Microplastics in riverine ecosystems are reported in all regions, with less research in Africa, South America, and Oceania. The abundance and distribution of MPs in riverine ecosystems are mainly affected by population density, economic activities, seasons, and hydraulic regimes. Ingestion of MPs has also been reported in riverine macroinvertebrates and has been incorporated in caddisflies cases. Further, bivalves and chironomids have been reported as potential indicators of MPs in aquatic ecosystems due to their ability to ingest MPs relative to environmental concentration. Fiber and fragments are the most common types reported. Meanwhile, polyethylene, polypropylene, polystyrene, polyethylene terephthalate (polyester), polyamide, and polyvinyl chloride are the most common polymers. These MPs are from materials/polymers commonly used for packaging, shopping/carrier bags, fabrics/textiles, and construction. Ingestion of MPs by macroinvertebrates can physically harm and inhibit growth, reproduction, feeding, and moulting, thus threatening their survival. In addition, MP ingestion can trigger enzymatic changes and cause oxidative stress in the organisms. There is a need to regulate the production and use of plastic materials, as well as disposal of the wastes to reduce MP pollution in riverine ecosystems.

Pretreatment methods for monitoring microplastics in soil and freshwater sediment samples: A comprehensive review

This paper reviews the currently used pretreatment methods for microplastics (MPs) analysis in soil and freshwater sediments, primarily sample processing, pretreatment, and characterization methods for MPs analysis. In addition, analytical tools (e.g., lab instruments), MPs characteristics, and MPs quantity, are included in this review. Prior to pretreatment, soil and sediment samples are typically processed using sieving and drying methods, and a sample quantity of <50 g was mostly used for the pretreatment. Density separation was commonly performed before organic matter removal. Sodium chloride (NaCl) and zinc chloride (ZnCl₂) were most often used for density separation, and hydrogen peroxide (H₂O₂) oxidation was most frequently used to remove organic matter. Although advantages of each pretreatment method have been investigated, it is still challenging to determine a universal pretreatment method due to sample variability (e.g., sample characteristics). Furthermore, it is highly required to establish standard pretreatment methods that can be used for various environmental matrices, including air, water, and wastes as well as soil and sediment.

Distribution and risk assessment of microplastics in Liujiaxia Reservoir on the upper Yellow River

Microplastics (MPSs) distribution in global freshwater systems is extensively reported, but the distribution of MPSs in reservoirs of the Yellow River has rarely been studied. To fill in this gap, we systematically investigated the distribution of MPSs in surface water and bank sediments gleaned from Liujiaxia Reservoir of the upper Yellow River for the first time and conducted an ecological risk assessment in succession in this work. The results showed that the main polymer types of MPSs in the surface water and bank sediments of Liujiaxia Reservoir were polyethylene terephthalate (PET), polystyrene (PS), and polypropylene (PP), and the abundance of MPSs in the reservoir surface water and bank sediments ranged from 4.48 to 12.09 item/L and 447.27 to 1543.80 item/kg (dry weight), respectively. Further physical morphology analysis of MPSs in the samples revealed that MPSs in the surface water and bank sediments of Liujiaxia Reservoir were predominantly fibrous with small particle sizes (<1 mm), and there was abundant color, mainly exhibiting transparent, black, and blue. The results of the MPS pollution load index (PLI>1) and the hazard ranking of MPSs (H_Zone = 10.20 for surface water and H_Zone = 14.06 for bank sediments) yielded a hazard class II for MPS pollution in Liujiaxia Reservoir, the combined pollution risk index (PRI_Zone = 17.05 for surface water and PRI_Zone = 31.25 for bank sediments) stated clearly the potential ecological risk in the Liujiaxia Reservoir. Briefly, this study supplemented and enriched the data on the distribution of MPSs in the reservoirs of the Yellow River basin, and provide a benchmark for future pollution control and management in the reservoir area.

Mechanisms of microplastics trapping in river sediments: Insights from the Arno river (Tuscany, Italy)

Rivers efficiently convey microplastics to the sea, but during this transfer microplastic can be temporary stored in sediments, where they undergo further fragmentation due to biological and physical processes. Aiming at shedding light on mechanisms governing microplastic sedimentation in rivers, we analyse deposits accumulated in alternate bars of the Arno River (central Italy). Specifically, we considered microplastics associated with floating plant debris, and those trapped in clastic suspended and bedload deposits. The overall concentration of microplastic ranges between 0.44 and 5.68 items per gram, and is comparable with that of some highly-polluted rivers in the world. Fibers are prevalent among the recovered items, and composition is dominated by nylon. Our measurements reveal that microplastics can be easily trapped by floating plant debris, and stored on bar top zones and river banks. Microplastics are also trapped in gravel and sand deposits. Sand incorporates microplastics both when it is transported at the river bottom under tractional conditions and during the waning flood stage, when settling processes contribute to bed aggradation. Gravels do not entraps microplastics when they move on the river bed, but they are extremely efficient in trapping microplastics during recessional flood stages, when water infiltrates between larger clasts, where it drops suspended microplastics. Further studies based on application of principles of fluvial sedimentology will provide crucial insights to understand mechanisms controlling transport and storage of MPs in river sediments.

Aquatic plants entrap different size of plastics in indoor flume experiments

Plastics accumulate in the environment affecting biota and ecosystems. Although rivers are vectors of land-based plastics to the sea, macroplastics and microplastics in rivers are recently studied. Most studies focused on floating plastic transport to the sea through rivers considering only abiotic hydromorphological factors. In this view, among biotic factors, vegetation has recently been found to entrap plastics. Indeed, the role of vegetation is pivotal in affecting riverine plastic transport. While marine vegetation blocking plastics has been studied, research in freshwater ecosystems is neglected. Since hydrological factors have a pivotal role in riverine plastic transport and few is known on plant entrapment, the interaction between hydrological variables and plastic entrapment by vegetation has not yet been investigated. Given that the composition, transport, and fate of "submerged" plastics in the water column are neglected, we aimed at investigating the behaviour of plants in entrapping plastics within a specific laboratory flume tank. Specifically, we assessed whether (i) aquatic plants block different plastic sizes within the water column and (ii) different factors (e.g. water level, density of plants) affect plastic entrapment. Our results showed that, according to plant density, the higher the plant density the higher the entrapment of plastics by plants - independently of plastic size. Considering the water level, macro-, meso-, and microplastics were trapped similarly. Moreover, Potamogeton crispus blocked fewer microplastics compared with Myriophyllum spicatum. Our results might have impact as plants acted as temporary plastic trappers and can be used as tools for mitigating plastic pollution. Future research might investigate if this laboratory approach can be applied in field for recollecting plastics and consequently mitigating the problem. In conclusion, good management of plants in watercourses, canals, and rivers should be ideal for enhancing river functionality and ecosystem services for human well-being (i.e. the plastic entrapment service by plants).

Occurrence and distribution of microplastics in wetlands

Presence of microplastic particles has been reported in all over the world, even in remote areas with no human activities. Wetlands are important transitional areas between terrestrial and aquatic systems. However, microplastic pollution in wetlands is less studied than other aquatic ecosystems. In this review, documented researches about microplastic occurrence and distribution in different components of wetland systems (except constructed wetlands) were investigated. In this regard, all available articles from different science databases with the keywords microplastic, wetland and lagoon in title were examined and results were proposed by text, table and diagram, after standardization of data express units. Based on results, wetland ecosystems are prone to microplastic pollution. Based on particle properties, PE/PP and fiber/fragment were the most dominant reported chemical composition and particle shapes, respectively.

Investigation of ecological risk of microplastics in peatland areas: A case study in Vietnam

This study aims to investigate the distribution and ecological risk assessment of microplastics (MPs) in peatland areas located in Long An province, Vietnam's Mekong Delta. In general, polyvinyl chloride (60.7%), polyethylene (25.8%), and polypropylene (11.9%) were the most abundant polymers determined in the thirty sediment samples. The hazard index (HI) remarked a level of III for MPs contamination in Tan Thanh and Thanh Hoa districts. The pollution load index (PLI) and potential ecological risk index (RI) indicated that the contamination risk of MPs polymer types in the studied sites is relatively high. According to PLI values, MPs levels of peatlands in Tan Thanh and Thanh Hoa are high and moderate, respectively, while the peatland sediments in Duc Hue district are less contaminated. Furthermore, ecological risk indexes in the peatland areas were relatively high, with PLI_overall (level III); HI_overall (level V), and RI_overall (extreme danger). Hence, this study proposed a SWOT framework for challenges of MPs pollution in order to manage peatlands appropriately and minimize ecological risks. As a result, several practical strategies and appropriate approaches have been recommended to reduce microplastics towards a circular economy. These findings provide the initial quantitative assessment insights into hazard levels and ecological impacts of MPs in Vietnam's Mekong Delta peatlands.

Evaluating community science sampling for microplastics in shore sediments of large river watersheds

A community science project in the Ottawa River Watershed in Canada interacted with an existing volunteer base to collect sediment from 68 locations in the watershed over approximately 750 km. Ninety-one percent of the distributed kits were returned with 42 volunteers taking part in the project. After analysis, particle concentrations were relatively low compared to previous freshwater microplastic sediment research, with contributing factors including (but not limited to) the large size of the watershed, a lower population base compared to other researched freshwater watersheds, the relative size and discharge of the Ottawa River and the large seasonal fluxes experienced in the river basin. Utilising community science for sampling large freshwater watersheds demonstrated its advantages in the research, especially spatially. However, careful consideration to research design and implementation is essential for community science projects examining microplastics in freshwater sediments. Research teams should ensure they are responsible for strict quality assurance and quality control protocols, especially in the laboratory with sample preparation and processing. Nonetheless, community science is potentially an extremely useful approach for researchers to use for microplastic sampling projects over large spatial areas.

Microplastics contributed much less than organic matter to the burial of polycyclic aromatic hydrocarbons by sediments in the past decades: a case study from an urban lake

The role of microplastics in burying hydrophobic organic compounds remains largely unknown. Sediment cores collected from the center of a typical urban lake (Lake Qianhu) in China were chosen to explore the contribution of microplastics to the burial of polycyclic aromatic hydrocarbons (PAHs) by sediments, and to elucidate how this contribution changed with microplastic composition and the hydrophobicity of PAHs on a decade scale. Our results showed that the concentration of individual PAHs adsorbed by microplastics varied from detection limit (LOD) to 7.2 mg g^-1 MP, which was much higher than the LOD to 31.0 μg g^-1 TOC buried by total organic carbon. However, the amount of individual PAHs adsorbed by microplastics only contributed to 0-34.2% of that in sediments. Changes in the composition of microplastics, including the increased proportion of polyethylene and polypropylene : polyethylene polymer in sediments, resulted in the average microplastic sediment burial ratios (MSBRs) of most PAHs increasing by 0.13% to 2.7% in the period from 1997 to 2018 compared with those in the period from 1975 to 1996. The average MSBRs varied with the hydrophobicity of PAHs, which increased with log K_ow value if it varied from 3.45 to 5.20, but decreased with log K_ow if it was in the range of 5.30 to 6.50. Our study provides novel knowledge on the contribution of microplastics to the burial of PAHs by sediments.

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).

Micro-contaminant, but immense impact: Source and influence of diethyl phthalate plasticizer on bottom-dwelling fishes

Sustainable plastic-waste management is becoming increasingly challenging as enormous loads of plastic debris regularly accumulate in susceptible ecosystems. The microplastic (MP) particles generated from these plastic wastes are imposing additional threats to these ecosystems due to their small size as well as their ability to adsorb and carry toxic chemicals. The current investigation deals with one such MP-originated toxicant, diethyl phthalate (DEP), and its impact on two species of freshwater loaches from the Western Ghats of India, Lepidocephalichthys thermalis and Indoreonectes evezardi. The MP samples were collected from the sediments of the Mula River and characterized using spectroscopic methods and scanning electron microscopy. Polymers, such as polyvinyl chloride and polypropylene, were identified in the collected MPs. GC-MS analysis of the MP extracts revealed the presence of DEP, confirming the MP waste as a potential source of DEP pollution. Further, to evaluate the effect of DEP on survival of selected loaches, L. thermalis and I. evezardi were exposed to DEP concentrations (18.75-300 mg L^-1) and the lethal DEP dose (LC₅₀) was estimated to be 44.53 mg L^-1 for L. thermalis and 34.64 mg L^-1 for I. evezardi. Fishes were further exposed to sub-lethal DEP concentration for one day (Short term exposure: STE) or eight days (Long term exposure: LTE) to analyze the histological condition and oxidative status of the liver in response to DEP treatment. Histology revealed congestion of sinusoids and vacuolization after the LTE. Higher lipid peroxidation levels were also measured in the livers of both species treated with DEP, which indicated DEP-mediated oxidative damage. The antioxidant enzymes including superoxide dismutase, catalase, peroxidase and glutathione-S-transferase displayed elevated activities in response to STE and LTE of DEP. Collectively, the results demonstrate that MPs in the Mula River are a potential source of DEP. The findings also show that DEP exposure can be fatal to freshwater fishes such as loaches, possibly by causing increased oxidative damage to the hepatic system.

Occurrence and distribution of microplastics in peatland areas: A case study in Long An province of the Mekong Delta, Vietnam

Vietnam is known as one of the high plastic consumption countries in Southeast Asia. This study initially determined characteristics of microplastics (MPs) including morphology, polymer type, and abundance at peatland areas in Mekong Delta in Vietnam. The MPs level was found with an average abundance of 192.3 ± 261.3 items kg^-1. In details, those values at Thanh Hoa, Duc Hue, and Tan Thanh were observed at 57.0 ± 110.4 items kg^-1, 7.0 ± 10.6 items kg^-1, and 513.0 ± 186.9 items kg^-1, respectively. The results indicated that MP particle contaminations in peatland sediments are significant among sampling sites (p < 0.001). Also, FT-IR analysis indicated that polyvinyl chloride is the primary polymer (46.2 %), followed by polyethylene (20.9 %), and polypropylene (9.2 %) in peatland samples and their composition varies in different regions significantly. The fragments (67.0 %) and films (24.6 %) were the most common shapes, followed by fibers (7.6 %) and foams (0.9 %). Small MPs with particle size (300-1000 μm) was the most abundant in sediment samples. Moreover, the most popular colors observed in peatland sediments were aqua (26.6 %), white (25.6 %), blue (25.4 %), and green (12.7 %). Our findings indicated that anthropogenic factors and environmental processes that caused the transformation/transportation and accumulation, leading to rising MP contaminant concerns in peatland areas in Mekong Delta in Vietnam, mainly in terms of the spatial distribution of MPs. In summary, this study provided an in-depth knowledge of microplastic pollution in peatland areas, which is crucial for the building sustainable development strategies in these areas.

Microplastics as Contaminants in Water Bodies and Their Threat to the Aquatic Animals: A Mini-Review

Microplastics (MPs), which are particles with a diameter of less than 5 mm, have been extensively studied due to their serious global pollution. Typically, MPs in water originate from terrestrial input. A number of studies have reported the presence of MPs as a stressor in water environments worldwide, and their potential threat to the aquatic animals, affecting the growth, oxidative stress responses, body composition, histopathology, intestinal flora, and immune and reproduction systems. During the plastic degradation process, a large variety of toxic substances are released. MPs have been proposed to be the carriers of toxic chemicals and harmful microorganisms. A study of the literature on MP pollution and stress on the aquatic animals associated with MPs was carried out.

Investigation of microplastic pollution in Torghabeh River sediments, northeast of Iran

Rivers are the route of transfer of microplastics from upstream to downstream areas and seas. Microplastic tracing in river sediments can provide a better reflection of long-term microplastic pollution. This study aimed to investigate the occurrence and distribution of microplastic contamination in the Torghabeh River sediments in Khorasan Razavi (Iran). Sediment samples were collected from four sites along the river. Microplastic particles were classified according to type, shape, and color. The average microplastic concentration was 8 ± 2.82 particles per 100 g of dry sediments. Most of the microplastics detected in river sediments were in the form of filaments and fragments. A total of 32 polymers were identified and isolated from sediments. According to Raman spectroscopy results, polystyrene had the highest abundance compared to polyester, polyethylene, and other polymers. The predominant shape of the microplastics in the river sediment was filament and fragmented. It can be concluded that the areas that were exposed to human activity contained more microplastic contamination. The present investigation can also provide baseline information for the study of riverine ecosystems.

Review on invasion of microplastic in our ecosystem and implications

Today the world is going through the "Plastic Age." Nowadays, it is difficult to find a commonly used convenient item that is nonplastic. Plastic production and consumption, thus, increased exponentially and plastic emerged as one of the major concerns for waste management. Recent studies confirmed a faster rate of plastic degradation than previously believed under various conditions (e.g. saltwater, UV, soil interaction) that microplastic has become a new type of health-hazardous pollution source. Much research has been conducted since the discovery of the "Pacific Garbage Patch," and the scope has expanded from marine to soil, groundwater, air, and food chain. This article underwent a substantial amount of literature review to verify the degree of microplastic pollution progression in major pillars of the environment (aqueous, terrestrial, airborne, bio-organism, and human). Multiple kinds of literature indicated a high possibility of vigorous interaction among the pillars that microplastic is not stationary at the point of contamination but travels across the nation (transboundary) and medium (transmedium). Thus, only the waste reduction policy (i.e. production and consumption reduction) would be effective through a single national or local effort, while pollution and contamination management require more of a collective, if not global, approach. For these characteristics, this article proposes two most urgently required actions to combat microplastic pollution: (a) global acknowledgement of microplastic as transboundary and transmedium pollution source that require international collective action and (b) standardization of microplastic related research including basic definition and experimental specification to secure global comparativeness among data analysis. Without resolving these two issues, it could be very difficult to obtain an accurate global status mapping of microplastic pollution to design effective and efficient global microplastic pollution management policies.

Textural characteristics and abundance of microplastics in Tecolutla beach sediments, Gulf of Mexico

Abundance of microplastics in coastal sediments is considered an emerging pollution problem worldwide. In Mexico, studies focused on microplastics in coastal sediments are little. In this study, we analyzed the textural characteristics and investigated the abundance of microplastics in the Tecolutla beach sediments, SW Gulf of Mexico. The extraction of microplastics in sediments was done by density separation. Microplastics were identified by stereomicroscope and scanning electron microscopy, and were classified based on their morphology, color, length, texture, and abundance. Among 181 microplastics, fiber type is predominant (number of microplastics n = 166; 92%) and followed by film (n = 12; 6%) and fragment (n = 3; 2%) types. The most abundant color of microplastics is black (n = 81; 45%) and second dominant color is blue (n = 65; 36%); most of them are fiber type. Based on the textural characteristics of sediments, it was observed that microplastics were derived from the fluvial contribution of the Tecolutla River and were deposited in the coastal environment by ocean currents. This study revealed that the abundance of microplastics was high in fine-grained sediments and was directly proportional to skewness. The results of this study can act as a reference for understanding the abundance of microplastics in the Gulf of Mexico coastal sediments.

Spatial and temporal variations of microplastic concentrations in Portland's freshwater ecosystems

While microplastics are a pollutant of growing concern in various environmental compartments, less is known regarding the sources and delivery pathways of microplastics in urban rivers. We investigated the relationship between microplastic concentrations and various spatiotemporal factors (e.g., land use, arterial road length, water velocity, precipitation) in two watersheds along an urban-rural gradient in the Portland metropolitan area. Samples were collected in August, September, and February and were analyzed for total microplastic count and type. Nonparametric statistics were used to evaluate potential relationships with the explanatory variables, derived at both the subwatershed and near stream scales. In August, microplastic concentrations were significantly higher than in February. August concentrations also negatively correlated with flow rate, suggesting that lower flow rates may have facilitated the accumulation of microplastics. Smaller size microplastic particles (< 100 μm) were found more in August than September and February, while larger size particles were more dominant in February than the other months. Microplastic concentrations were positively related to 24-h antecedent precipitation in February. Negative correlations existed between wet season microplastic concentrations and agricultural lands at the near stream level. The results indicate that near stream variables may more strongly influence the presence and abundance of microplastics in Portland's waterways than subwatershed-scale variables. Fragments were the most commonly observed microplastic morphology, with a dominance of gray particles and the polymer polyethylene. The findings of this study can inform management decisions regarding microplastic waste and identify hotspots of microplastic pollution that may benefit from remediation.

Effect of land use on microplastic pollution in a major boundary waterway: The Arvand River

The occurrence of microplastics (MPs) was investigated in the Arvand River (Iran). The Arvand River (200 Km) is a major water body that flows through land with diverse use and it meets the Persian Gulf. This study constitutes the first assessment of MP pollution (prevalence and physico-chemical characteristics) in the Arvand river, both in the sediment and in the water. MP monitoring has been carried out in 24 stations located along the river. The MP pollution found ranged between 1 and 291 items·L^-1 and 70 to 15,620 items·kg^-1 (dw), in water and sediment, respectively. The majority of MPs were fibres, black/grey and yellow/orange in colour, and mainly 250-500 μm and >1000 μm in size. Polyethylene terephthalate (PET), polypropylene (PP), nylon (NYL), high-density polyethylene (HDPE), and polystyrene (PS) were found in sediment samples. All these polymers, except HDPE, were also identified in the water samples. PET and PP were dominant in the water samples; whereas PET and PS were the most abundant in the sediments. The vicinity of urban wastewater effluents could be behind MP pollution in both water and sediments. Significant differences (p < 0.05) of MP concentrations were affected by different land uses when comparing MP levels in undisturbed natural area with urban areas. A strong correlation between MP fibres and fragments found with PCA biplots revealed their similar distribution in water. In the sediment samples, fibre and fragment MP particles were significantly correlated with colloidal particles (e.g., clay and organic matter) suggesting a relevant role of colloidal particles in the aquatic ecosystem of the Arvand River in transporting MPs. This study contributes to the better understanding of the presence of MP in major rivers, which are systems that have been scarcely investigated for this type of pollution, and it can inform interventions to reduce MP inputs to the river and sea.

Effects of cascade dams on the occurrence and distribution of microplastics in surface sediments of Wujiang river basin, Southwestern China

The influence of cascade dams on the migration of microplastics (MPs) was conducted by analyzing the spatial distribution of MPs in sediments of the Wujiang river basin (Wujiang river basin) in Southwest China. The results showed that the abundance of MPs in Wujiang river basin sediments ranged from 310 to 2620 items/kg dw (mean: 1354 items/kg dw, a high level compared with aquatic sediments worldwide). The main chemical components of these MPs were polypropylene and polyethylene. High abundance of MPs in tributary sediments suggested that tributary inputs contributed to the main stream and reservoirs. Statistical analysis showed that gross domestic product (GDP) and the basin area of cascade reservoirs, rather than hydraulic retention time and reservoir age, were the dominating factors in the distribution of MPs in the Wujiang river basin. The accumulation of MPs in cascade reservoirs implied the interception effect of cascade dams. The rapid development of cascade dam systems and the interception effect of dams should be taken into account when predicting the flux of MPs from rivers to the ocean. Heavy metals found on the surface of the MPs showed the compound pollution of MPs and heavy metals in dammed rivers and cascade reservoirs. Our results deepen the understanding of the migration of MPs in rivers alongside intensive cascade hydropower development.

Assessment of microplastics in Irish river sediment

Microplastics (MPs) are environmental pollutants of growing concern, and awareness of MPs pollution in marine and freshwater environments has increased in recent years. However, knowledge of MPs contamination in riverine sediments in Ireland is limited. To address this, we collected and analysed sediment samples from 16 selected sites along the River Barrow. Microplastics were extracted through a density separation method, after which their size, colour, and shape were analysed under a stereo microscope (Optica SZM-2). Attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy was used to identify polymer types. A total of 690 MPs were recovered from the 16 sites, with fibres as the dominant MP type. The highest concentration of MPs was 155 MP fibres kg-1 wet sediment found in samples collected from Graiguenamanagh, Co. Kilkenny (GK). The majority of the recovered MPs were polyethylene (PE), polypropylene (PP), nylon, and cellulose acetate (CA) fibres. Overall, this study highlighted the presence of MPs in Irish river sediments and provided a baseline for future studies on MPs pollution. Further research is needed to better understand sources, distribution, and effects of MPs in freshwater ecosystems.

Embryotoxicity of polystyrene microplastics in zebrafish Daniorerio

In the recent years, increasing scientific and societal concern has been raised over the presence and accumulation of plastic debris in the environment and the effects of microplastics (MPs) that can easily interact with biota. In order to elucidate the impact of MPs at the critical development stages of freshwater fish species, a fish embryo toxicity test was herein performed on the zebrafish Danio rerio, exposed to 10 μm polystyrene MPs at 200 particles/mL for 120 hpf. After exposure, accumulation of MPs in larvae was measured, survival, hatching and larvae development were monitored and the oxidant/anti-oxidant responses and cellular detoxification evaluated. No impact on survival of developing zebrafish was revealed, but a moderate delay in hatching was observed. Alterations in larvae development were recorded with zebrafish exhibiting serious deformities, mainly at the level of column and tail, as well as a compromised integrity of the visual structure of the eyes. Moreover, increased levels of gene transcription involved in the oxidative stress (sod1, sod2 and cat) and in cellular detoxification (gst and cyp) were also detected in MPs-exposed zebrafish larvae. Overall, this research work provides new insights on the ecotoxicological impact of polystyrene MPs on the critical developmental stages of a freshwater fish species, therefore enhancing the current knowledge of the environmental risk posed by MPs to the aquatic ecosystem.