Abundance, characteristics, and ecological risks of microplastics in the riverbed sediments around Dhaka city

Occurrence and risk assessment of microplastics in surface water, sediment, and biota of Surma River, Bangladesh

Pollution from microplastics (MPs) has become a major environmental concern worldwide, impacting ecosystems severely. Bangladesh is one of the developing nations, with concerning issues of improper plastic trash handling by poor recycling infrastructure. The present study focuses on MPs pollution in the Surma River, which is in the northeastern part of the country. MPs in the water, sediment, and biota sample were observed in the study. Density separation, microscopic observations, and Fourier transform infrared spectroscopy (FTIR) analysis have been conducted for MPs identification and quantification. MPs concentrations were observed at 5-20 items/L in surface water, 360-960 items/kg in sediment, and 2-3.6 items/species in biota. Fiber shapes, 1-2 mm sizes, and transparent colored MPs were the most prevalent type in surface water. While fragment shape, 1-2 mm sizes, and black MPs were most common in sediment samples. For biota samples, fiber shape, 1-2 mm sizes, and black MPs were the most prevalent. Moreover, risk assessment indices were examined for the individual sites, including contamination factors (CF), polymeric hazard assessment (PHA), pollution risk index (PRI), and pollution load index (PLI). PLI recorded for surface water and sediment are 1.92 and 2.69, respectively, indicating substantial contamination in the Surma River. This study provides the first multi-compartment analysis of microplastic pollution in the Surma River. The findings can inform future mitigation strategies, waste management policies, and contribute to global efforts in combating the pervasive issue of MPs pollution.

Potential Biological Impacts of Microplastics and Nanoplastics on Farm Animals: Global Perspectives with Insights from Bangladesh

Microplastics (MPs) and nanoplastics (NPs), formed through the degradation of larger plastic materials, are emerging pollutants of significant concern. While their impact on aquatic ecosystems is well documented, their effects on terrestrial, especially farm animals remain underexplored. This review assesses the potential threats of MPs and NPs to Bangladesh's livestock sector by analyzing the results of experimental models and environmental studies. In Bangladesh, MPs and NPs have been detected in agricultural soils, air, water bodies, and aquatic organisms, indicating possible entry into animal systems through contaminated feed, water, and inhalation. Once internalized, these particles may trigger oxidative stress, inflammation, and tissue damage, impairing vital biological systems. Documented health consequences include reduced fertility, hematotoxicity, gut microbiota imbalance, gut-brain axis disruption, skeletal disorders, and metabolic dysfunction. Additionally, MPs and NPs can induce genomic changes, including altered gene expression and DNA hypomethylation, intensifying physiological damage and reducing productivity. Therefore, managing plastic contamination is vital in protecting animal health, ensuring food safety, and preserving human well-being around the globe, especially in vulnerable regions like Bangladesh. Given the critical role of livestock and poultry in ensuring food security and public health, the findings highlight an urgent need for comprehensive research and mitigation strategies.

Notable ecological risks of microplastics to Minjiang River ecosystem over headwater to upstream in Eastern Qinghai-Tibetan Plateau

Microplastics (MPs) in aquatic environments has been observed globally. However, the ecological risks of MP pollution in riverhead prior to highly urbanized region remain poorly understood. This study investigated MP pollution related to microbiome in sediments, and ecological risks of MPs in riverhead prior to urbanized area over 291 km of Minjiang River (MJR) in Qinghai-Tibetan Plateau (QTP). MPs in river water and sediments were averagely 245±128 items/L and 124±67 items/kg, respectively, over the investigated river range. The MP distribution indicated that MP abundance is low in headwater section and elevated in middle section and down section with increase of urbanized area. The MPs were found mainly in film, fragments, and fiber morphotypes, with size < 500 μm in both river water and sediments. The polymers of MPs were contributed by polyethylene (PE), polypropylene (PP), polyethylene terephthalate (PET), polyvinyl chloride (PVC), and polycarbonate (PC) at 41.7 %, 22.7 %, 17.9 %, 1.8 %, and 1.2 % in river water, and 32.6 %, 15.0 %, 29.3 %, 3.1 %, and 0.8 % in sediments, respectively. Microbiome analyses of sediments revealed that the majority of microorganisms were aerobic bacteria, which contained potential plastic-degrading bacterial genes. Ecological risk assessment indexes of pollution load, polymeric risk assessment and pollution risk indicated that MPs in MJR river water and sediments displayed noticeable pollution levels, i.e., river water exhibited medium to very high pollution risk levels, and sediments showed from low to very high pollution risk levels in riverhead. Monte Carlo simulation revealed that PVC and PC MPs were considered as priority control pollutants although they were not the most abundant polymers identified due to their intrinsic chemical toxicity. Compared with risk levels of global rivers, the results indicate prominent ecological risks caused by MPs in MJR riverhead areas, and thus raise a warning sign.

Characterization and risk assessment of microplastics in shoreline sediments of the Yellow River Delta

As the intersection of river, sea, and land, river deltas are hotspots for the accumulation of microplastics (MPs). This study investigated the abundance and characteristics of MPs in surface sediments from shoreline area of the Yellow River Delta in northern China, elucidated their sources, and assessed their risk. The MPs isolated from sediment samples were detected and characterized using optical microscopy and micro-Fourier transform infrared spectroscopy (μ-FTIR). The results showed that MPs were abundant (360-2160 items/kg) in the area, and occurred mainly in small sizes (<250 μm), as fibers (20.2-50.0%), filament (4.8-21.5%), and granules (8.5-20.6%), and in transparent (27.8-40.3%), blue (11.2-31.6%), or black (7.9-26.5%) color. Polyethylene terephthalate (26.08%), polyethylene (20.47%), polypropylene (13.49%), and polyvinyl chloride (10.71%) were the dominant polymer types for the MPs. The pollution load indices (1-6) indicated that all sampling sites were polluted by MPs, while the polymeric hazard indices (65.14-91.44) suggested that MPs pollution of the area was in medium range. Overall, the ecological risk indices (91.44-475.38) of the sampling sites indicated that MPs in shoreline sediments of the Yellow River Delta posed low to considerable potential ecological risk. While the dominance of polymers with medium polymeric risk scores rendered the MPs in the shoreline sediments with relatively low risk, the majority of MPs occurred in small sizes, which complicates the actual risk posed by MPs in shoreline sediments of the Yellow River Delta and deserves attention.

Characteristics, Contamination Levels, and Ecosystem Risk Assessment of Microplastics in Surface Water of a Highly Urbanized River from a Developing Country

Microplastic (MP) contamination poses significant risks to ecosystems and human health. However, the absence of standardized protocols, detailed polymer identification, and sources identification hinders the development of targeted mitigation strategies, particularly in developing nations. There is a scarcity of comprehensive data on MP distribution, sources, and transport mechanisms in freshwater environments. This study aimed to fill these gaps by comprehensively characterizing MP contamination, elucidating distribution patterns, identifying sources, and assessing ecological risks in an urban river adjacent to a megacity. This was accomplished using stereomicroscopy, Fourier-transform infrared(FTIR) spectroscopy, and a range of risk assessment indices. The analyses revealed spatial variations in MP levels, ranging from 350 to 660 items/m3 across different sampling stations along the river. Analysis of variance(ANOVA) highlighted significant differences in the average number of MPs among the stations (F = 16.93, p ≪ 0.01), with station S3 exhibiting the highest count and station S4 the lowest. Factors such as point sources of domestic and municipal waste, as well as river navigation, likely contribute to these variations. The predominant types, colors, and sizes of MPs observed were fiber, transparent, and <0.5 mm, respectively. Notably, 80% of the MPs consisted of polyethylene (PE) and polypropylene (PP), commonly associated with land-based sources like packaging materials. Despite minor ecological risks indicated by ecosystem risk assessment indices such as the risk index(RI) and pollution load index (PLI), which recorded values of 9.04 and 1.87, respectively, the potential hazard index(PHI) rose to hazard category V, posing a substantial threat to the river ecosystem. PCA facilitated the identification of trends linked to specific pollution sources, while cluster analysis categorized MPs with similar characteristics, thereby enhancing the understanding of their distribution patterns. These findings provided novel insights into the pervasive presence and pathways of plastic pollution in developing nations, offering important considerations for international efforts to address public health and environmental challenges associated with MPs.

Multifaceted analysis of microplastic pollution dynamics in the Yamuna river: Assessing anthropogenic impacts and ecological consequences

Microplastics (MPs) are pervasive contaminants that pose significant ecological and human health risks, emerging as one of the most widespread anthropogenic pollutants in natural environments. This study investigates the abundance, characteristics, and distribution of microplastics (MPs) in the Yamuna River, encompassing 29 sampling points across urban, rural, and industrial zones in and around Delhi, Mathura, Haryana, and Agra. Microplastics were identified and quantified using Nile red dye staining and Micro-Raman spectroscopy, with particle size distribution predominantly between 2 μm to 80 μm and the largest detected particle measuring 256.5 μm. The average MPs concentration was 14,717 ± 4444 L-1, with a significant abundance of hazardous polymers such as polyethylene terephthalate (PET), polypropylene (PP), and polystyrene (PS). The study found that MPs were predominantly fragments and films (65.6 %) and fibers (30.6 %), with transparent particles being the most prevalent. The Pollution Load Index (PLI) consistently indicated high-risk levels (PLI > 100) at all sampling sites, highlighting substantial MP contamination. These results underscore the urgent need for continuous monitoring and the development of robust management strategies to address microplastic pollution in the Yamuna River. This study provides valuable insights into MPs spatial distribution and persistence, contributing to an improved understanding of their environmental impacts and guiding future mitigation and regulatory efforts.

Characteristics, drivers and ecological risk assessment of microplastics in the surface water of urban rivers in Guangdong-Hong Kong-Macao Greater Bay Area cities - A case study of Dongguan city

In the Guangdong-Hong Kong-Macao Greater Bay Area (GBA), microplastic pollution in urban rivers is a prominent problem due to the developed economy and high industrial intensity. Using the Xiaohai River, Hanxi River and Dongguan Canal in Dongguan City, an important node city in the GBA, as an example, microplastic characteristics, drivers and ecological risks in the surface water of three rivers were investigated. Results showed that the average abundance of rivers in the wet period (1646.22 ± 154.73 items/m3) was 4.7 times higher than that in the dry period (351.09 ± 34.2 items/m3). Microplastics were mainly in the form of fragments and fibers, with a size range of 30-500 μm, and appeared transparent with white color. The microplastic polymer types PE, PP, PET and PA accounted for more than 70%. There are large differences in the characteristics of microplastic pollution during different hydrological periods. Redundancy analysis showed that the distribution of plastics, chemical materials, packaging and printing industries along the rivers dominated the differences in microplastic abundance. The electronic information industry contributed most to the composition of microplastic polymer types. The polymer hazard index, pollution load index, and potential ecological risk index for rivers indicate a medium-high risk classification or higher. Therefore, the industrial layout along the urban rivers should be rationalized, the disposal of microplastics in wastewater should be increased, and the use of green plastic products should be promoted. This study provides support for the management of microplastic pollution in urban surface water in the GBA.

Delving into South China Sea microplastic pollution: Abundance, composition, and environmental risk

Understanding marine pollution in the South China Sea is crucial for preserving marine ecosystems and biodiversity. Despite extensive research on pollutants, there is a significant gap in knowledge about microplastics (MPs) in the archipelago region. This study focused on four typical islands, examining MPs in seawater and sediments, their distribution, and environmental risks. Most MPs (>90 %) were smaller than 2.5 mm, with black fiber-shaped polyethylene terephthalate MPs being predominant. MPs in seawater had lower abundance (5-12 items/L) compared to sediment (100-2600 items/kg) but showed richer polymer composition. Pollution load index (PLI) and risk index analysis indicated all regions were contaminated (PLI > 1), with the Zhongsha islands being the most polluted. Correlation analysis highlighted black, fibrous PET-like polymers with large particle sizes (>0.5 mm) as major contributors. This study could help to understand the MPs distribution and pollution in the archipelago region of the South China Sea.

Abundance, characteristics and ecological risks of microplastics from South Yellow Sea Mudflat

Microplastic (MP) pollution in global marine environments has been extensively reported and attracted significant concerns, but MP distribution in mudflat has rarely been studied. In this paper, the abundance, features and ecological risk of MP in South Yellow Sea Mudflat were investigated comprehensively. MP were both detected in waters (5.4 ± 0.38-11.3 ± 0.78 items/L) and sediments (5.1 ± 0.36-10.1 ± 0.69 items/g) from South Yellow Sea Mudflat. There existed different MP abundance tendencies from sampling Group I (coastal estuary or port) and II (purely coastal mudflat), while MP abundance in water from Group II was lower than that from Group I generally, but MP abundance in sediment from Group I was lower than that from Group II generally. This suggested that MP abundance in mudflat water could be associated with frequent human activities significantly, and disturbance might not be beneficial to MP accumulation in sediments. Fragments, transparent, polyethylene (PE), polypropylene (PP) and polystyrene (PS) were major MP features in mudflat water and sediment, and maximum proportion of size of MP was 0.001-0.25 mm in both water and sediment. Furthermore, the primary risk assessment indicated that MP pollution load for mudflat was low level. However, potential MP ecological risk for mudflat could reach dangerous level to very dangerous level by calculating and evaluating polymer risk index (PRI) and potential ecological risk index (PERI), which could be caused by high proportions of polyvinyl chloride (PVC) and polyacrylonitrile (PAN) with high hazard score. For the first time, reference data about MP pollution from South Yellow Sea Mudflat were supplied in this paper, which would be helpful for management and control of MP in mudflat.

Evaluating the sources of microplastic contamination and quantifying its abundance in the Balu River, Dhaka, Bangladesh

Microplastics (MPs) are prevalent environmental pollutants due to their durable composition, extensive use, and improper disposal. Despite their widespread presence, rivers have received less attention in microplastic research than other water bodies. This study focused on investigating the origins, prevalence, spatial distribution, and physicochemical characteristics of microplastics in the surface waters of the Balu River, located in Dhaka, Bangladesh. Surface water samples were collected at six sampling sites of Balu River (each about 1-5 km apart) adjacent to the footwear industry, jute factory, textile mill, paper mill, agro and beverage factory, and cement plant. The study found that the average concentration of microplastics in the sampled water bodies was 102.5 ± 12.83 (items/l). Samples near the textile mill had the highest microplastic abundance (122 ± 18 items/l), while the cement plant had the lowest (58.5 ± 8 items/l). Analysis using a stereomicroscope revealed that fibers (29%), microplastics smaller than 100 µm (45%), and transparent microplastics (19%) were the most prevalent types observed in terms of shape, size, and color, respectively. Furthermore, scanning electron microscopy (SEM) observation suggested the potential for additional degradation of these microplastics into smaller particles, potentially reaching the nanoplastic scale. Additionally, Fourier transform infrared (FTIR) analysis identified 07 distinct polymer types among the microplastics: nylon (24%), polyvinyl chloride (19%), high-density polyethylene (17%), low-density polyethylene (14%), polystyrene (12%), polypropylene (7%), and nitrile (7%). The findings of this study serve as a crucial indicator of microplastic contamination, providing valuable insights into the sources and magnitude of microplastic pollution within the significant freshwater ecosystem of Balu River, Bangladesh, particularly focusing on its river systems.

Assessment of Microplastics and Potentially Toxic Elements in Surface Sediments of the River Kelvin, Central Scotland, United Kingdom

Contamination of the environment by microplastics (MPs), polymer particles of <5 mm in diameter, is an emerging concern globally due to their ubiquitous nature, interactions with pollutants, and adverse effects on aquatic organisms. The majority of studies have focused on marine environments, with freshwater systems only recently attracting attention. The current study investigated the presence, abundance, and distribution of MPs and potentially toxic elements (PTEs) in sediments of the River Kelvin, Scotland, UK. Sediment samples were collected from eight sampling points along the river and were extracted by density separation with NaCl solution. Extracted microplastics were characterised for shape and colour, and the polymer types were determined through attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy. Pollution status and ecological risks were assessed for both the microplastics and PTEs. Abundance of MPs generally increased from the most upstream location (Queenzieburn, 50.0 ± 17.3 particles/kg) to the most downstream sampling point (Kelvingrove Museum, 244 ± 19.2 particles/kg). Fibres were most abundant at all sampling locations, with red, blue, and black being the predominant colours found. Larger polymer fragments were identified as polypropylene and polyethylene. Concentrations of Cr, Cu, Ni, Pb and Zn exceeded Scottish background soil values at some locations. Principal component and Pearson's correlation analyses suggest that As, Cr, Pb and Zn emanated from the same anthropogenic sources. Potential ecological risk assessment indicates that Cd presents a moderate risk to organisms at one location. This study constitutes the first co-investigation of MPs and PTEs in a river system in Scotland.

Understanding microplastic pollution: Tracing the footprints and eco-friendly solutions

Microplastics (MPs) pollution has emerged as a critical environmental issue with far-reaching consequences for ecosystems and human health. These are plastic particles measuring <5 mm and are categorized as primary and secondary based on their origin. Primary MPs are used in various products like cosmetics, scrubs, body wash, and toothpaste, while secondary MPs are generated through the degradation of plastic products. These have been detected in seas, rivers, snow, indoor air, and seafood, posing potential risks to human health through the food chain. Detecting and quantifying MPs are essential to understand their distribution and abundance in the environment. Various microscopic (fluorescence microscopy, scanning electron microscopy) and spectroscopy techniques (FTIR, Raman spectroscopy, X-ray photoelectron spectroscopy) have been reported to analyse MPs. Despite the challenges in scalable removal methods, biological systems have emerged as promising options for eco-friendly MPs remediation. Algae, bacteria, and fungi have shown the potential to adsorb and degrade MPs in wastewater treatment plants (WWTPs) offering hope for mitigating this global crisis. This review examines the sources, impacts, detection, and biological removal of MPs, highlighting future directions in this crucial field of environmental conservation. By fostering global collaboration and innovative research a path towards a cleaner and healthier planet for future generations can be promised.

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

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