Microplastic pollution in urban Lake Phewa, Nepal: the first report on abundance and composition in surface water of lake in different seasons

Microplastic pollution levels in the surface water and sediment of Orontes basin: Urgent risk for endangered species

Freshwater environments are a significant source of microplastics in the oceans, but, little is known about the distribution of microplastics in rivers and lakes. This study was undertaken to investigate the abundance and composition of microplastics (MPs) in the surface water and sediment of Karasu Creek, Gölbaşı Lake and Orontes River which are critical habitats for many endangered species. The mean microplastic abundance in the surface water and sediment of the Orontes Basin was determined to be 3.2 ± 4.0 MPs/L and 456 ± 318 MPs/kg, respectively. Due to the similar socioeconomic status and anthropogenic activities in the vicinity of stations, there wasn't any temporal variation in the microplastic abundance depending on stations. However, microplastic abundance in the surface water was drastically increased during flood periods. A correlation between microplastic abundance in the surface water and sediment was not detected due to insufficient data representing the hydrodynamic properties of the study area. Morphologically, fiber MPs were dominant (89 %), followed by fragments (9 %). The majority of the extracted MPs were <1 mm. This led to an increase in the number of individuals and species likely to be negatively affected by MPs. In terms of color, majority of the MPs were black (44 %) followed by blue (21 %), red (18 %), transparent and white (9 %). Results obtained in this study proved the ubiquity and dominance of the microplastics in both surface water and sediment. Therefore, the findings clearly show a remarkable ecological risk and indicate the need for mitigation strategies in the Orontes Basin ecosystem. This study provided critical data for local and national authorities to take necessary precautions to manage microplastic pollution in the Orontes Basin. However, more comprehensive understanding of the long-term impacts of pollution from MPs on endemic species is crucial for effective conservation strategies.

Microplastics monitoring in freshwater systems: A review of global efforts, knowledge gaps, and research priorities

The escalating production of synthetic plastics and inadequate waste management have led to pervasive microplastic (MP) contamination in aquatic ecosystems. MPs, typically defined as particles smaller than 5 mm, have become an emerging pollutant in freshwater environments. While significant concern about MPs has risen since 2014, research has predominantly concentrated on marine settings, there is an urgent need for a more in-depth critical review to systematically summarize the current global efforts, knowledge gaps, and research priorities for MP monitoring in freshwater systems. This review evaluates the current understanding of MP monitoring in freshwater environments by examining the distribution, characteristics, and sources of MPs, alongside the progression of analytical methods with quantitative evidence. Our findings suggest that MPs are widely distributed in global freshwater systems, with higher abundances found in areas with intense human economic activities, such as the United States, Europe, and China. MP abundance distributions vary across different water bodies (e.g., rivers, lakes, estuaries, and wetlands), with sampling methods and size range selections significantly influencing reported MP abundances. Despite great global efforts, there is still a lack of harmonized analyzing framework and understanding of MP pollution in specific regions and facilities. Future research should prioritize the development of standardized analysis protocols and open-source MP datasets to facilitate data comparison. Additionally, exploring the potential of state-of-the-art artificial intelligence for rapid, accurate, and large-scale modeling and characterization of MPs is crucial to inform effective strategies for managing MP pollution in freshwater ecosystems.

The abundance and analytical characterization of microplastics in the surface water of Haryana, India

Microplastic (MP) contamination has become a serious environmental concern that affects terrestrial environments, aquatic ecosystems, and human health. The current study assesses the presence, abundance, and morphology of MPs present in the surface water of Rohtak district, Haryana, India, which is rapidly undergoing industrialization. While the morphological studies of MPs were conducted through stereo microscopy and field emission-scanning electron microscopy (FE-SEM), the elemental composition of polymers was analyzed through attenuated total reflectance-Fourier transform infrared (ATR-FTIR). The results revealed that the surface water was significantly contaminated by polyethylene, polypropylene, and polystyrene. Moreover, the abundance of MPs was found to be 16-28 particles/L with an average value of 23 particles/L. Most of the MPs had fibrous morphology with the specifics being, fibers (43.9%), fragments (23.7%), films (17%), and pellets (15.4%). The MPs exhibited a size range of 0.61-4.87 mm, with an average size measured at 2.03 ± 0.04 mm. Also, the MP pollution load index values for the surface water bodies were found to be below 10, indicating a low risk category. Though currently designated as "low risk," it is important that mitigation strategies be brought over at this juncture to further prevent the deterioration of quality of water. Thus, this study not only intends to bring forth the impact of human activities, industrial waste, open waste dumping, and inadequate municipal waste management practices on increasing MP concentration but also highlights the sustainable alternatives and strategies to address this emerging pollutant in urban water systems. For further prevention, the implementation of stringent regulations and on-site plastic waste segregation is a critical component in preventing the disposal of plastic waste in surface water bodies. RESEARCH HIGHLIGHTS: The abundance of MPs was found to be 16-28 particles/L, with an average value of 23 particles/L. The surface water bodies in Rohtak district fall into the hazard categories of low risk with values less than 10. The overall MP concentration in water, across all five areas, based on color was in order: white/transparent (39.1%), black (15%), gray (9.1%), green (8.7%), blue (7.8%), red (7.8%), orange (6.3%), and yellow (6.1%). The dominant polymers were polyethylene (PE) (42%) and polypropylene (41%) as determined by FTIR spectroscopy.

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.

Migration characteristics of microplastics in riparian soils and groundwater

Investigations have revealed the presence of microplastics in both soil and groundwater, but the migration characteristics from soil to groundwater remain incompletely understood. In this study, two sampling sections consisting of soil-groundwater-river water were established near Lianxi Bridge and Xilin Bridge along the Jiuxi River in Xiamen. A total of 22 soil samples, 36 groundwater samples, and 18 river water samples were collected. Microplastics were detected in all samples with an abundance range of 392-836 n/kg in soil (mean, 655 ± 177 n/kg), 0.58-2.48 n/L groundwater (mean, 1.23 ± 0.42 n/L), and 0.38-1.80 n/L in river water (mean, 0.86 ± 0.41 n/L). Flakes predominantly constituted the shape of microplastics found in soil, while fibers dominated those present in water. Black, yellow, and red were the dominant color types. Polyamide (PA) and polyethylene (PE) were the main components of microplastics within soils, whereas polyethylene terephthalate (PET), polypropylene (PP), and PA prevailed within water. Microplastic particle sizes ranged from 39 to 2498 μm in soils, mainly from 29 to 3394 μm in water. The upstream section displayed higher abundances of microplastic compared to the downstream, revealing the soil particles having an intercepting effect on microplastics. The distribution and migration of microplastics in soil and groundwater are affected by many factors, including natural and anthropogenic factors, such as soil depth, soil properties, pore structure, hydrodynamics, hydraulic connections between groundwater and surface water, the extensive utilization and disposal of plastics, irrational exploitation of groundwater, and morphology and types of microplastics. These research findings contribute to a better understanding of the pathways, migration capacity, and influencing factors associated with microplastic entry into groundwater, thereby providing valuable technical support for the development of strategies aimed at controlling microplastic pollution.

The retention of plastic particles by macrophytes in the Amazon River, Brazil

This study evaluated the presence of plastics and microplastics in macrophytes in an urbanized sector of the Amazon River. A total of 77 quadrats in 23 macrophyte banks were sampled during the dry (September 2020) and rainy (June 2021) season. Five species were identified: Paspalum repens, Pontederia rotundifolia, Pistia stratiotes, Salvinia auriculata and Limnobium laevigatum, with P. repens being dominant during the dry season (47.54%) and P. rotundifolia during the rainy season (78.96%). Most of the plastic particles accumulated in Paspalum repens (49.3%) and P. rotundifolia (32.4%), likely due to their morphological structure and volume. The dry season showed a higher accumulation of plastic particles than the rainy season. Microplastics were found in most samples, during both the dry (75.98%) and rainy seasons (74.03%). The upstream macrophyte banks retained more plastic particles compared to the downstream banks. A moderate positive correlation was observed between the presence of plastic particles and macrophyte biomass, and a weak positive correlation between the occurrence of microplastics and mesoplastics. White and blue fragments, ranging from 1 to 5 mm were the most common microplastics found in the macrophyte banks. Green fragments and green and blue fibers were identified as polypropylene, blue and red fragments as polyethylene, and white fragments as polystyrene. Therefore, the results of this study highlight the first evidence of the retention of plastic particles in macrophytes of the Amazon and highlight a significant risk due to the harmful effects that this type of plastic can cause to the fauna and flora of aquatic ecosystems.

Microplastic pollution in high-altitude Nainital lake, Uttarakhand, India

Microplastics (MPs) contamination has been reported in all environmental compartments, but very limited information is available at higher-altitude lakes. Nainital Lake, located at a high altitude in the Indian Himalayas, has various ecosystem services and is the major source of water for Nainital town, but the MP abundance is still unknown. This study presents the first evidence of the abundance and distribution of MP in Nainital Lake. Surface water and sediment samples were analysed from 16 different sites in and around the catchment area of Nainital Lake. The MP were observed in all the samples, and their abundance in surface water was 8.6-56.0 particles L-1 in the lake and 2.4-88.0 particles L-1 in hotspot sites. In the surface sediment, MP abundance ranged from 0.4-10.6 particles g-1, while in the hotspot sediment, the mean abundance was 0.6 ± 0.5 particles g-1. Fibers were the dominant MP, while 0.02-1 mm were the predominant size of MP particles. The results of chemical characterization showed the presence of six polymers, among which high-density polyethylene was the most abundant. The Polymer Hazard Index assessment classified the identified polymers as low-to high-risk categories, with a higher abundance of low- (polypropylene) and medium- (polyethylene)-risk polymers. Tourist activities and run-off catchments can be considered the major sources of MP, which can affect the ecosystem. Minimal concentrations of MP were observed in the tube well and drinking water, which depicts the direct risks to humans and, thus, the need for remedial measures to prevent MP contamination in drinking water. This study improves the knowledge of MP contamination in the higher-altitude freshwater lake, which can be the major pathway for the transport of MP to the rivers, and also emphasizes the need for waste management in Nainital town.

Microplastics research in Nepal: Present scenario and current gaps in knowledge

The topic of microplastics has drawn considerable scholarly interest in recent times. The objective of this study is to provide an overview of the current state of microplastic pollution research in Nepal and to make future research recommendations. To achieve the objective, three popular databases (Web of Science, SCOPUS and Google Scholar) were used. The results showed that the current scenario for microplastic research in Nepal is in its early stage, which commenced in 2020. A total of six papers were recorded over the period from 2020 to 2023. The research conducted in the fields were rivers, lakes, snow, and sediments. Studies have provided evidence of the occurrence of microplastics in diverse aquatic ecosystems. Lakeshore sediments show concentrations of 100.5 ± 58.6 items/kg dry weight, while shoreline sediments of Phewa lake exhibit variability between 55 and 122.5 items/kg. The lake water in winter records 2.96 ± 1.83 Microplastics per Liter (MPs/L), river water indicates 202 ± 100 items/m3, and snow demonstrates 30 MP/L. In freshwater ecosystems, microplastics, specifically fibers, were found to be the prevailing type, while fragments were recorded in road dust. The study conducted in Nepal provided evidence of the presence of a wide range of polymers. The polymers encompassed polypropylene (PP), polyethylene (PE), polyethylene terephthalate (PET), polyamide, polystyrene (PS), and polyester. Microplastic research in Nepal, initiated in 2020, covered rivers, lakes, snow, and sediments. Diverse aquatic ecosystems reveal microplastic presence, emphasizing the need for continued study and awareness. Although extensive research has been carried out on the subject of microplastic contamination and its effects on various creatures on a global scale, an examination of the implications of microplastics on animals, plants, and humans in Nepal has not been found in any scholarly publications. There exists a noticeable deficit of research investigating the consumption of microplastics by human.

A review of microplastic threat mitigation in Asian lentic environments

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

Microplastic particles in river sediments and water of southwestern Nigeria: insights on the occurrence, seasonal distribution, composition, and source apportionment

Microplastics (MPs) are globally recognized as an emerging environmental threat, particularly in the aquatic environment. This study presents baseline data on the occurrence and distribution of MPs in sediments and surface water of major rivers in southwestern Nigeria. Microplastics were extracted by density separation and polymer identification using Fourier transformed infrared spectroscopy in attenuated total reflectance mode (FTIR-ATR). The abundance of MPs in surface sediment and water samples across all locations ranged from 12.82 to 22.90 particle/kg dw and 6.71 to 17.12 particle/L during the dry season and 5.69 to 14.38 particle/kg dw and 12.41 to 22.73 particle/L during the wet season, respectively. On average, fiber constituted the highest percentage of MP in sediments (71%) and water (67%) while foam accounted for the lowest values of 0.6% and 1.7%, respectively. Polypropylene (PP) and polyethylene (PE) were the main MPs across all locations based on Fourier transform infrared spectroscopy (FTIR). MPs of size < 1 mm were the most abundant (≥ 55%) on average in both water and sediments. The study identified run-off from human activities and industrial wastewater as potential sources of MP exposure based on positive matrix factorization. The study suggests assessing the impact of different land-use activities on MPs occurrence and distribution in addition to quantifying MPs in seafood as a way forward in food safety management systems for further studies. This study confirmed the occurrence and widespread distribution of MPs in surface water and sediments and provides a database on MP pollution in Nigeria.

What is hiding below the surface - MPs including TWP in an urban lake

Inland lakes play an important role as habitats for local species and are often essential drinking water reservoirs. However, there is limited information about the presence of microplastics (MPs) in these water bodies. Thirteen sediment samples were collected across a Danish urban lake to map MPs, including tyre wear particles (TWP). The lower size detection limit was 10 µm. MPs were quantified as counts, size, and polymer type by Fourier-transform infrared microspectroscopy (µFTIR) and mass estimated from the 2D projections of the MPs. As TWP cannot be determined by µFTIR, counts and sizes could not be quantified by this technique. Instead, TWP mass was determined by pyrolysis gas chromatography mass spectrometry (Py-GC/MS). The average MP abundance was 279 mg kg-1 (µFTIR), of which 19 mg kg-1 (Py-GC/MS) were TWP. For MPs other than tyre wear, the average MP count concentration was 11,312 counts kg-1. Urban runoff from combined sewer overflows and separate stormwater outlets combined with outflow from a wastewater treatment plant were potential point sources. The spatial variation was substantial, with concentrations varying several orders of magnitude. There was no pattern in concentration across the lake, and the distribution of high and low values seemed random. This indicates that large sampling campaigns encompassing the entire lake are key to an accurate quantification. No preferential spatial trend in polymer characteristics was identified. For MPs other than TWP, the size of buoyant and non-buoyant polymers showed no significant difference across the lake, suggesting that the same processes brought them to the sediment, regardless of their density. Moreover, MP abundance was not correlated to sediment properties, further indicating a random occurrence of MPs in the lake sediments. These findings shed light on the occurrence and distribution of MPs, including TWP, in an inland lake, improving the basis for making mitigation decisions.

The bioadhesion and effects of microplastics and natural particles on growth, cell viability, physiology, and elemental content of an aquatic macrophyte Elodea canadensis

Microplastics in the aquatic environment can interact with aquatic plants, but the consequences of these interactions are poorly understood. Therefore, the aim of this study was to investigate the effects of microplastics commonly found in the environment, namely polyethylene (PE) fragments, polyacrylonitrile (PAN) fibres, tire wear (TW) particles under a relevant environmental concentration (5000 particles/L) on the growth, cell viability, physiology, and elemental content of the aquatic macrophyte Elodea canadensis. The effects of microplastics were compared to those of natural wood particles. The results showed that all types of microplastics adhered to plant tissues, but the effect on leaves (leaf damage area) was greatest at PE > PAN > TW, while the effect of natural particles was comparable to that of the control. None of the microplastics studied affected plant growth, lipid, carbohydrate, or protein content. Electron transport system activity was significantly higher in plants exposed to PAN fibres and PE fragments, but also when exposed to natural particles, while chlorophyll a content was negatively affected only by PE fragments and TW particles. Elemental analysis of plant tissue showed that in some cases PAN fibres and TW particles caused increased metal content. The results of this study indicated that aquatic macrophytes may respond differently to exposure to microplastics than to natural particles, likely through the combined effects of mechanical damage and chemical stress.

Microplastic pollution in Kolavai Lake, Tamil Nadu, India: quantification of plankton-sized microplastics in the surface water of lake

The prevalence of microplastics (MP) (< 5 mm) in aquatic habitats has recently raised concerns owing to their influence on humans and aquatic organisms, as they absorb organic pollutants and pathogens from the surrounding media because of their higher surface-to-volume ratio. Freshwater systems are severely affected by the increased intake of discarded waste from diverse sources. This study focused on the microplastic-to-zooplankton ratio and its potential impact on the environment's food chain. The sampling sites of Kolavai Lake were divided into three zones (18 stations) to investigate the spatial distribution of microplastics and zooplankton biota. The average microplastic abundance was 6.1 ± 2.5 particles/L. Fourier transform infrared spectroscopy (FTIR) and SEM analysis were performed to understand the chemical composition and surface morphology of microplastics. Water samples collected along the Central and Southern Zones revealed a high abundance of microplastics, which might be due to anthropogenic activities. A negative correlation was observed between the abundance of microplastics and zooplankton. The microplastic-to-zooplankton ratio was found to range from 0.05 to 0.74. Furthermore, the impact of microplastics in the lake ecosystem was analysed using the size and shape descriptors for both zooplankton and microplastics. These findings suggest that microplastics built up in aquatic environments, particularly those with rich biota, could be a severe concern because of their capacity to infiltrate the food web.

Microplastic pollution in lakeshore sediments: the first report on abundance and composition of Phewa Lake, Nepal

Microplastic pollution in a freshwater environment has captured the attention of the scientific world in recent years. Microplastic is a new area of research in the freshwater of Nepal. Hence, the present study aims to examine the concentration, distribution, and characteristics of microplastic pollution in the sediments of Phewa Lake. Twenty sediment samples were collected from 10 sites to cover the vast area (5.762 km²) of the lake. The mean abundance of microplastic was 100.5 ± 58.6 items/kg dry weight. The average abundance of microplastics in five sections of the lake showed a significant difference (test statistics = 10.379, p < 0.05). Fibers (78.11%) dominated the sediments of Phewa Lake in all sampling sites. Transparent was the prominent color observed followed by red and altogether 70.65% of the microplastics detected were found at 0.2-1 mm size class. Fourier transform infrared spectroscopy (FTIR) analysis of visible microplastic particles (1-5 mm) confirmed polypropylene (PP) (42.86%) as the dominant polymer type followed by polyethylene (PE). This study can help to bridge the knowledge gap regarding the microplastic pollution in freshwater shoreline sediments of Nepal. Furthermore, these findings would create a new research area to explore the impact of plastic pollution which has been ignored in Phewa Lake.

First report on microplastics contamination in a meteorite impact Crater Lake from India

Microplastic pollution is a worldwide concern affecting all environmental matrices, including pristine lakes. Lentic lakes operate as a sink for microplastics (MPs), which interfere with a biogeochemical cycle and, therefore, deserve immediate attention. We present a comprehensive assessment of MPs contamination in the sediment and surface water of a geo-heritage site, Lonar lake (India). It is the third largest natural saltwater lake and only basaltic crater in the world formed by meteoric impact around 52,000 years ago. Mean MPs abundance in lakeshore sediment and surface water was 14.44 particles/kg and 2.66 particles/L, respectively. Small-sized MPs dominate the hypersaline region of the lake. Transparent and green fragments and filaments morphotypes were abundant. Most of the MPs in Lonar lake were secondary in origin. FTIR-ATR analysis revealed 16 types of polymers in the lake, of which polypropylene, polyvinyl chloride, polyethylene, high-density polyethylene, low-density polyethylene, polystyrene, and polyester were the most common. The overall pollution load index (PLI) for Lonar lake sediment and water was 1.39 and 2.58, respectively. Although all sampling stations had significant MPs pollution (PLI > 1), there was noticeable station-specific variability, which could be linked to anthropogenic activities. Irresponsible tourist behavior and religious activities, coupled with poor waste management are the leading causes of MPs contamination in the lake. The current work fills a gap in the investigation of MP pollution in a crater lake formed by a meteorite impact by being the first to provide a precise estimate of the MPs contamination in the Lonar lake.

Microplastic contamination in the freshwater shrimp Macrobrachium amazonicum in Itacoatiara, Amazonas, Brazil

The present study analyzed the presence of microplastics (MPs) in the shrimp Macrobrachium amazonicum, which is an economically important food that is consumed in several regions of the Brazilian Amazon. A total of 600 specimens of M. amazonicum were captured at two sampling sites (urban and rural area). A total of 2597 MP particles were recorded in the shrimps, with a significant difference between the two sites. The presence of MPs in the body parts also differed significantly. No significant difference was found between MPs abundance and sex of the shrimps. The size of the MPs did not differ significantly between the collection sites and between the body parts. Dark blue fiber-type MPs were the most abundant. A positive correlation was observed between the abundance of MPs and the total weight of shrimps. Raman spectroscopy identified the dark blue fibers as polypropylene and the FTIR technique identified the light blue fragments as nylon. The results indicate that the presence of MPs in the M. amazonicum shrimp is associated with the capture sites near the urban area and is present in the diet of the Amazonian population that regularly consumes this crustacean in traditional dishes.

Chironomus sp. as a Bioindicator for Assessing Microplastic Contamination and the Heavy Metals Associated with It in the Sediment of Wastewater in Sohag Governorate, Egypt

The consequences of plastic waste pollution have imposed wide global concerns. One of these consequences is the production of micro- and nanosized particles (MNPLs) from aged plastics. The problem of MNPLs is magnified by their potential to transport various contaminants due to their large surface area and other variable physiochemical properties. From this point on, it is important to know the real concentration of MNPLs in our environment and their potential to internalize wild organisms as well as transfer contaminants that are completely highlighted. As a result, our study is the first to detect MP pollution in the upper Egypt wastewater environment. It could be utilized as a baseline to estimate MP wastes and develop management techniques, particularly in Sohag Governorate. The concentration and characterization of MPs in sludge, water, Chironomus sp. larvae, and their tubes were studied in this work. Chironomus sp. is a reliable bioindicator prevalent in such contaminated environments, and it was used to demonstrate how MPs invade biological barriers. Our results found that red and blue polyester fibers are much more prevalent than other polymers, colors, and shapes of MPs. While each dry kilogram of wastewater sludge contains 310 ± 84 particles, this amount is reduced to 1.55 ± 0.7 per liter in the water column. Biologically, the present study succeeded in detecting the MPs inside the wild organism, with concentrations reaching 71 ± 21 and 4.41 ± 1.1 particles per gram wet weight in Chironomus sp. larvae and their tubes (chironomid tubes), respectively. The potential hazard of MPs stems from their propensity to transfer pollutants. At this point, our findings revealed a corresponding and significant concentration of various heavy metals (Cu, Pb, Cd, and Ni) detected in MPs or Chironomus sp. versus sludge. In conclusion, our findings not only proved the presence of MPs in wastewater but also demonstrated their ability to internalize cross-wild organisms, allowing toxins to accumulate inside their bodies, raising concerns about the possible health impacts of plastic pollution.

Distribution of microplastics in the catchment region of Pallikaranai marshland, a Ramsar site in Chennai, India

Microplastics are persistent toxic pollutants, detected in different environmental compartments. Numerous studies on the characteristics and distribution of microplastics present in different environmental matrices are being carried out. However, limited studies have been performed in environmental systems like eco-sensitive freshwater marshlands. Therefore, to enrich the existing knowledge and understanding, this current study has analysed the distribution and characteristics of microplastics present in the catchment region of Pallikaranai marshland, Chennai, India. Both surface water and sediment samples were contaminated with microplastics in the range of 740-2826 items/m³and 700 to 5833 items/kg of dry sediment, respectively. Compared to other shapes, fibrous microplastics were predominant in most of the surface water (n = 11) and sediment (n = 8) samples. The abundant presence of smaller microplastics (<1 mm) in the surface water suggests elevated impacts on the aquatic species owing to their higher bioavailability. Elevated anthropogenic activities and frequent movement of people in urban and residential areas were noted to possibly influence the spatial distribution of microplastics. Furthermore, heavy metals' occurrence on microplastics was investigated using X-Ray Fluorescence Analyser (XRF) and Zn, Fe, Ti, and Ni are the commonly detected (>50% of the samples) elements. The estimated average pollution load index of 2.5 indicates the polluted state of Pallikaranai catchment region.

Application of a microplastic trap to the determination of the factors controlling the lakebed deposition of microplastics

Microplastics (MPs) in aquatic environments are hard to degrade, easy to transport, and potentially hazardous to biota. Previous studies of MPs in lakes have shown that their deposition is a significant process controlling both their lateral dispersal from a source, and their concentration within the water column. However, the lakebed depositional rates of MPs have predominantly been determined using laboratory experiments and/or through model simulations that may not fully reflect field conditions. In this paper, lacustrine depositional rates in Lake Ulansuhai were documented using an MP trap that allowed for the assessment and quantification of the depositional rates of MPs of differing size, density, and shape at three sampling sites over five different time periods. The results showed that the downward flux for all types of MPs near the lakebed was correlated with wind speed. Higher wind speeds led to the resuspension of greater amounts of MPs in the lakebed sediments and the transport of greater amounts of MPs from the lake inlet to the lake interior and outlet along the hydrologic flow directions. Consequently, higher wind speeds increased the abundance of MPs at the sediment-water interface and intensified the vertical mixing of MPs in the lake water, resulting in a higher depositional flux of MPs. Particles of differing size, shape, and density exhibited different depositional rates. In general, fragmentary, larger size, and higher density MPs were more likely to be deposited. Thus, size and shape have a strong effect on the migration and deposition of HDMPs in Lake Ulansuhai.

Occurrence and Distribution of Microplastics from Nepal's Second Largest Lake

Due to its harmful impact on biota, microplastic pollution is the top priority research in many countries. However, there is hardly any research on microplastic pollution in Nepal's freshwater. Therefore, the present research was accomplished in Phewa Lake to evaluate the occurrence and distribution of microplastic contamination in shoreline sediments. The average abundance of microplastic varied from 55 to 122.5 items/kg dry weight (dw). The highest value appeared on densely populated eastern side of the lake and the western region reported the lowest concentration of microplastic. With regard to the shape, fibers dominated the sediments of Phewa Lake accounting for 62.03%. The dominant color was transparent (23.53%) followed by blue (21.39%). The size category 0.2-1 mm recorded the highest abundance of microplastic. Similarly, Fourier transform infrared spectroscopy (FTIR) reveal the dominant polymer type as polypropylene (PP) and polyethylene (PE). The outcome of this result adds a step toward filling the existing knowledge gap and providing a database on microplastic pollution in Nepal's freshwater.