Risk Assessment Of Microplastics Research Articles

Accumulation characteristics and ecological risk evaluation of microplastics in sediment cores from the artificial reef area and surrounding seas of Haizhou Bay, north China

One significant “sink” for microplastic (MP) pollution is the sediments. There's a considerable lack of reliable data regarding the historical status of MPs contamination in sediments within marine ranching. In this research, the study area encompassed Haizhou bay marine ranching and adjacent seas. The primary objective was to explore the potential relationships between the accumulation of MPs and both the sample depth and sediment characteristics within the cores. The results unveiled significant contamination of MPs within the sediment cores. The average MPs concentration of sediment was 1.01 ± 1.28 n/g. Fibrous polymers and particles smaller than 1000 μm were frequently found in the sediment. The abundance of MPs exhibited a tendency to decrease with an increase in sediment depth. Artificial reefs and currents affected on MPs distribution in sediment cores. The accumulation of MPs showed a significant correlation (P < 0.05) with the sediment content of different particle sizes, suggesting that the composition of sediment can serve as an indicator of the abundance of MPs. The risk of MP pollution in the sediments of the study area was assessed by establishing a risk assessment model using concentration data of MPs and polymer types. Due to the higher hazard score of polymers (PA and PET) in MPs, the Polymer hazard index (PHI) was elevated to grade II. However, it had a Pollution load index (PLIzone) value of 1.95 (level I). This suggested that contamination was minimal, yet the ecological risk remained relatively high. The ecological risk assessment of MPs served as the foundation for gaining a detailed understanding of the distribution characteristics of MPs. It also furnished essential data support for conducting a comprehensive assessment, developing feasible management strategies, and establishing water quality standards related to plastic waste.

Occurrence Characteristic and Risk Assessment of Microplastics in Sishui River (Xingyang Section)

Urban rivers are the main receptors and transporters of microplastic pollution. Understanding the occurrence and environmental risk of microplastics in urban rivers can provide theoretical basis for further control of microplastic pollution. The Sishui River, a tributary of the Yellow River, was selected as the research object. A total of nine water samples were collected from sewage outlets of the Sishui River (Xingyang section). The microplastics in the collected samples were characterized by their sizes, shapes, and colors using a microscope. It was found that microplastics were mostly in the form of transparent fibers and fragments in the water body of sewage outlets, of which the size below 500 μm was relatively high. In addition, PET and PE polymers were identified as the main types using a laser infrared imager. The correlation analysis showed that there was a significant correlation between the PET and PE, indicating that they were similar in origin. The results of the environmental risk assessment showed that the type of microplastics was the main factor affecting the assessment results, whereas the risk values of six sewage samples containing PVC were high. However, the value of pollution load index revealed a low risk level of pollutants in the study area.

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

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

Microplastics and heavy metals in the sediment of Songkhla Lagoon: distribution and risk assessment

Heavy metal and microplastic (MP) contamination of aquatic systems is a major environmental issue that affects human health globally. Songkhla lagoon, the largest lagoon in Thailand, also faced with the environmental issues. Here, this study reported the occurrence of heavy metal and MP in 10 sites of sediment in the Songkla lagoon. From the microplastic separation, fibers were found at all stations at 68.24% (15.15 items/g) and fragments were found at 31.76% (7.05 items/g). The highest number of MP particles was found at the area near the mouth of the lagoon (5.4 items/g). The average concentrations (mg/kg) of heavy metal at all sites showed the following trend: Mg (732.54 ± 247.04) &amp;gt; Mn (176.74 ± 83.68) &amp;gt; Zn (29.36 ± 39.47) &amp;gt; Cu (12.31 ± 24.58) &amp;gt; Pb (11.07 ± 7.60) &amp;gt; As (5.64 ± 3.30) &amp;gt; Co (2.90 ± 1.38) &amp;gt; Cd (0.22 ± 0.17). Regarding the overall risk assessment of MPs in lagoon sediment in this study, the risk was categorized as high for the polymer hazard index. The ecological risk index found Cd and As to have high ecological risk. High EF values were observed for As and Cd, which indicated severe enrichment. Based on the Igeo calculation, the majority of sampling stations were unpolluted to moderately contaminated (Pb, Zn, Mg, and Co). Furthermore, there was no significant correlation between MPs and heavy metals, except for Zn (r = 0.697) and Cu (r = 0.61) (both p&amp;lt; 0.05). The results of this study might provide valuable data to develop conservation policies for coastal lagoon areas.

Cellular effects of microplastics are influenced by their dimension: Mechanistic relationships and integrated criteria for particles definition.

The definition of microplastics (MPs) is nowadays too generic from a biological perspective, since different characteristics of these particles might influence their effects. To provide experimental evidence that size is an important factor to be considered, Mediterranean mussels Mytilus galloprovincialis were exposed to five size classes of polyethylene fragments (PE-MPs, 20–50 μm, 50–100 μm, 100–250 μm, 250–500 μm, 500–1000 μm). After 10 days of exposure, MPs ingestion and mechanistic relationships between particles size and cellular effects were analysed through a wide panel of biological alterations, including immune system responses, cholinergic function, antioxidant system, lipid metabolism and peroxidation. Results were further elaborated through a Weight of Evidence approach, summarizing the overall biological significance of obtained results in a hazard index based on the number and magnitude of variations and their toxicological relevance. PE-MPs 500–1000 μm were identified as the less biologically reactive size class due to the limited ingestion of particles coupled with the lack of biological effects, followed by PE-MPs 250–500 μm, which slightly altered the cholinergic function and lysosomal membranes. Conversely, PE-MPs smaller than 250 μm provoked a more consistent onset of biological alterations in terms of immune system composition and functioning, redox homeostasis, and lipid metabolism. The overall findings of this study highlight the importance of considering the size of particles for monitoring and risk assessment of MPs, introducing a more integrated evaluation of plastic pollution that, beside particles concentration, should adequately weigh those characteristics triggering the onset of biological effects.

The pollution characteristics and risk assessment of microplastics in mollusks collected from the Bohai Sea

Microplastics (MPs) pollution in the marine environment has become a global problem. In this study, a number of 21 mollusk species (n = 2006) with different feeding habits were collected from 11 sites along the Bohai Sea for MPs uptake analysis. The MPs in mollusk samples were isolated and identified by micro-Fourier Transform Infrared Spectroscopy (μ-FTIR), and an assessment of the health risks of MPs ingested by mollusk consumption is also conducted. Approximately 91.9 % of the individuals among all the collected species inhaled MPs, and there was an average abundance of 3.30 ± 2.04 items·individual−1 or 1.04 ± 0.74 items·g−1 of wet weight. The shape of MPs was mainly fiber, and a total number of 8 polymers were detected, of which rayon had the highest detection rate (58.3 %). The highest abundance, uptake rate and polymer composition of MPs was observed in creeping types, suggesting that they might ingest these MPs from their food. The gastropod Siphonalia subdilatata contains the highest levels of MPs, which may increase the risk of human exposure if consumed whole without removing the digestive gland. The polymer risk level of MPs in these mollusks was Level III (H = 299), presenting harmful MPs such as polyvinyl chloride. In terms of human exposure risk, the average risk of human exposure to MPs through consumption of Bohai mollusks is estimated to be 3399 items·(capita·year)−1 (424–9349 items·(capita·year)−1). Overall, this study provides a basis for the ecological and health Risk assessment of MPs in mollusks collected from the coastline of China.

Occurrence characteristics and risk assessment of microplastics in agricultural soils in the loess hilly gully area of Yan' an, China

Large amounts of microplastics accumulated in the soil of agricultural fields with the rapid development of mulch agriculture. The enrichment of microplastics endangered the growth of crops and food security, and it also posed ecological risks. In this study, we investigated microplastics in a typical agriculture area of Yan' an City, in the loess hilly gully area of China. The characteristics of microplastics including their abundances, sizes, and types were measured through laser direct infrared spectrometer. The potential sources of microplastics were analyzed and the risk of soil microplastic pollution was evaluated. It was elaborated that the average abundances of microplastics in soil, water, and fertilizer were 4505 ± 435 n·kg−1, 91 ± 27 n·L−1, and 39,629 ± 10,114 n·kg−1, respectively. Microplastics with particle sizes < 100 μm accounted for >90 %. The smaller the particle size, the higher the content of microplastics. The top three polymers were polyethylene (PE, 37.4 %), polyethylene terephthalate (PET, 15.0 %), and ethylene vinyl acetate (EVA, 8.9 %), respectively. Agricultural mulch, plastic film, domestic waste, surface water irrigation, and organic compost were probably the potential sources of soil microplastics. The ecological risk evaluation showed that overall sampling sites had a minor ecological risk of microplastic pollution based on their abundance, while the polymer type showed a relatively high ecological risk for the investigated agricultural soils. Polyvinylchloride (PVC) and polymethylmethacrylate (PMMA) contribute considerably to the ecological risk, and their inputs to the farmland environment should be strictly limited. There was no significant carcinogenic risk to humans. This study would provide the basic reference for the current situation and risk assessment of farmland soil microplastics pollution in the loess hilly gully area of China.

Reshaping the plastisphere upon deposition: Promote N2O production through affecting sediment microbial communities in aquaculture pond

Microplastics (MPs) could provide vector for microorganisms to form biofilm (plastisphere), but the shaping process of MPs biofilm and its effects on the structure and function of sedimentary microbial communities especially in aquaculture environments are not reported. For this, we incubated MPs biofilm in situ in an aquaculture pond and established a sediment microcosm with plastisphere. We found that the formation of MPs biofilm in surface water was basically stable after 30 d incubation, but the biofilm communities were reshaped after deposition for another 30 d, because they were more similar to plastisphere communities incubated directly within sediment but not surface water. Moreover, microbial communities of MPs-contaminated sediment were altered, which was mainly driven by the biofilm communities present on MPs, because they but not sediment communities in proximity to MPs had a more pronounced separation from the control sediment communities. In the presence of MPs, increased sediment nitrification, denitrification and N2O production rates were observed. The K00371 (NO2-⇋NO3-) pathway and elevated abundance of nxrB and narH genes were screened by metagenomic analysis. Based on structural equation model, two key bacteria (Alphaproteobacteria bacterium and Rhodobacteraceae bacterium) associated with N2O production were further identified. Overall, the settling of MPs could reshape the original biofilm and promote N2O production by selectively elevating sedimental microorganisms and functional genes in aquaculture pond.

The consequences of reduced anthropogenic activities during the COVID-19 pandemic on microplastic abundance in a tropical estuarine region: Goa, India

Plastic pollution is pervasive, as it has infiltrated every corner of the planet and the COVID-19 pandemic has caused a depletion in the production, consumption, and disposal of plastics. To find out the effect of the COVID-19 pandemic, a comparative assessment of microplastics (MPs) observed before and after the pandemic was evaluated in surface water and sediment from the major rivers of Goa, i.e. Mandovi and Zuari. To comprehend the relative difference in the abundance, characteristics, and source of MPs, samples were examined in both the dry and wet seasons. We found a sharp decrease in the concentration of MPs immediately after the isolated pandemic. During the dry and wet seasons, two to seven times less concentration of MPs was recorded for water and sediments after the pandemic period compared to the prior pandemic. MPs size, >300 μm were relatively abundant after the pandemic period in contrast to the prior pandemic (<300 μm sized MPs were more). Polyamide (PA), polyvinyl alcohol (PVAL), and polyvinyl chloride (PVC) were the dominant polymers after the pandemic whereas earlier the dominant polymers were polyacetylene, polyacrylamide (PAM), and polyvinyl pyrrolidone (PVP). The risk assessment of MPs in sediments (Polymer load index) was higher prior to the pandemic. The water quality parameters also indicated an improvement in the water quality during the pandemic. The present study clearly exhibited that due to the reduction of overall anthropogenic activities during the COVID-19 pandemic period, a sharp decline of plastic waste and MP abundance in the coastal water body in Goa, west coast of India was found. This study unveils the controlling factors (such as total solid waste generation, plastic waste, tourism activities, and the effect of monsoon) which influence the abundance and distribution of macro- and microplastics.

Quantification, characterization and risk assessment of microplastics from five major estuaries along the northern Bay of Bengal coast

Microplastics (MPs) as hazardous contaminants has drawn the rapid attention of the general public due to their omnipresence and adverse impacts on ecosystems and human health. Despite this, understanding of MPs contamination levels in the estuarine ecosystems along the Bay of Bengal coast remains very limited. This research focused on the presence, spatial distribution, morpho-chemical characteristics and ecological implications of MPs in water and sediment from five key estuaries (Meghna, Karnaphuli, Matamuhuri, Bakkhali, and Naf rivers) within the Bengal delta. Out of the five estuaries, the Meghna exhibited the least amount of MPs in both surface water (150.00 ± 65.62 items/m3) and sediment (30.56 ± 9.34 items/kg). In contrast, the highest occurrence of MPs was recorded in Karnaphuli river water (350.00 ± 69.22 items/m3) and Matamuhuri river sediment (118.33 ± 26.81 items/kg). ANOVA indicated a statistically significant distinction (p < 0.01) among the examined estuaries. Most identified MPs were fibers and < 0.5 mm in size in both water and sediment samples. Transparent MPs were dominant in both water (42.28%) and sediment (45.22%). Besides violet, red, blue, pink and green colored MPs were also observed. Various polymer types, including PE, PP, PET, PS, Nylon, EVA, and ABS, were detected, with PE being the dominant one. Based on the polymer risk index (PHI), the estuaries were classified as hazard level V, signifying a severe level of MP contamination. However, the potential ecological hazardous index (PHI), potential ecological risk index (RI), and pollution load index (PLI) indicated moderate pollution levels. This study offers initial insights into the pollution caused by MPs in major estuaries of Bengal delta, which policymakers can utilize to implement suitable management strategies.

Microplastics in the sediments along the eastern Arabian Sea shelf: Distribution, governing factors and risk assessment

Despite the omnipresence of microplastics (MPs), the studies around the western continental shelf of Indian Ocean (Eastern Arabian Sea-EAS) are uncovered and understudied. Thus, the present study was focused to understand the spatial distribution, characterization and risk assessment of MPs in sediment across seven coastal transects (10 to 50 m) all along the EAS shelf. The highest MPs concentration (MPs/kg d.w.) was detected in the northern EAS (NEAS; 2260 ± 1050) followed by central (CEAS; 1550 ± 1012) and southern (SEAS; 1300 ± 513) shelves. Among all distinct locations, the highest concentration of MPs (2500 ± 1042) was detected in the north coastal sediments off Mumbai, followed by off Mangalore (1480 ± 1169) in the center and off Kochi (1350 ± 212) in the south. MPs were found in the form of fibres, fragments and films with a predominance of fibres (~70–80 %). Approximately 74.6 % of the total MPs were in the size range of 300 μm to 5 mm. The surface of detected MPs was rough, irregular, and mechanical weathering features such as pits, grooves also observed and spotted with bacterial community structures. Polypropylene (PP; 34 %), polyisoprene (PIP; 19 %), butyl rubber (18 %), and low-density polyethylene (LDPE; 13 %) were dominant polymers. The pollution load index highlighted minor risk while the polymer hazard index exhibited a hazard level of V. Litter discharge, fishing activities, and active marine navigation are among the many high-risk sources of plastic contamination in this region. Due to the prevailing winds, currents, low sea surface height, and high precipitation, the conditions in the EAS are favorable for the accumulation of both sea-based and land-based particles. Hence, this study provides novel insights into the potential risks posed by MP to the IO rim and associated marine ecosystem which will enhance our knowledge of the ecological implications and consequences of MP pollution, ultimately aiding in developing effective management and mitigation strategies.

Characterization and risk assessment of microplastics in laver from the Yueqing Bay

Microplastics (MPs) pollution is regarded as a global challenge for ocean. As an important food source of human, macroalgae could suffer MP pollution and transmit MPs into human via food web. However, few studies have revealed the relationship of MP pollution between macroalgae and its habitat. In order to evaluate the trapping and accumulation of MPs in macroalgae and surface water, the present study investigated MP pollution in a typical aquaculture macroalgae species, laver (Porphyra haitanensis) in the Yueqing Bay. The results indicated MP abundance in laver (1.45 ± 0.26 items/g) was at a medium level while MP abundance in surface water (0.21 ± 0.15 item/m3) was at a relatively low level worldwide. Distribution trend and characteristics of MPs in laver and surface water showed highly similarity. Besides, heavy metal elements (Fe and Zr) were detected on the surface of MPs trapped by laver. Pollution load index (PLI) in surface water of the whole bay was low, indicating MP pollution was not serious in the Yueqing Bay. Due to the discharging of domestic sewage in recent years, fiber-shaped, textile MPs accounted for most in laver and surface water of the Yueqing Bay. These results indicated that MPs in surface water could be trapped by P. haitanensis, thus macroalgae cultivation might be a potential way to alleviate seawater MP pollution in the nearshore areas.

Abundance, characteristics and risk assessment of microplastics in aquatic sediments: A comparative study in the Yellow River and Yellow Sea

The occurrence of microplastics (MPs) in aquatic ecosystems has become an increasingly serious threat to public health. Marine sediments are considered the final recipients of all microplastic pollution from inland rivers, however, whether and how the MPs differ in these two ecosystems remains poorly known due to the divergent MPs detection methods employed in previous studies. Here, we investigated the abundance, size, and types of MPs in sediment samples from the Yellow River and Yellow Sea using laser direct infrared (LDIR), and assessed their ecological risks. The abundance of MPs in the Yellow Sea is 2.9 times higher than that in the Yellow River, with an average abundance of 54813.2 ± 19355.9 and 18780.2 ± 9951.8 particles·kg−1 (dry sediment), respectively. Notably, the predominant polymer types in both sediment environments were silicone, fluororubber, and polypropylene (PP). MPs with sizes < 100 μm accounted for > 90 % of the total MPs number. Risk assessment demonstrated all the sediment environments exhibited high ecological risks. The dominance of small MPs highlighted the importance of using a method with high resolution to delineate the truthful status of MP pollution.

Distribution Characteristics and Risk Assessment of Microplastics in Farmland Soil in Guyuan

The farmland ecosystem faces the emerging risk of microplastic pollution. To investigate the distribution characteristics of microplastics in agricultural soils in Guyuan City, the abundance, type, color, size, and shape of microplastics in Guyuan City agricultural soils were analyzed using field survey, microscopic observation, and Fourier transform infrared spectroscopy. In addition, the risk of microplastic pollution was assessed using the pollution load index method (PLI). The results showed that the microplastic abundance of agricultural soils (0-20 cm) in Guyuan City ranged from 186.32 to 1286.24 n·kg-1, and the microplastic abundance of soils in facility agriculture increased significantly by 35.56% and 228.91% compared with those in non-facility agriculture with and without film, respectively, and the microplastic abundance in the arable layer was 0.31 times higher than that in the plough pan layer. PE (26.42% to 62.83%) and PP (27.64% to 42.62%) were the main microplastic polymer types, and the number of soil polymer species was significantly greater in facility agriculture than that in non-facility agriculture. Microplastics <100 μm accounted for 32.21%-42.52%, whereas >1000 μm accounted for only 0.28%-12.31%. The particle size of microplastics in the arable layer was 47.39% higher than that in the plough pan layer, and the particle size of microplastics was the largest in facility agriculture and the smallest in non-facility film-free planting. Microplastics were mostly in the form of films, fibers, fragments, and microbeads, with the greatest abundance in the form of fibers and the second largest in the form of films. A total of seven colors of microplastics were monitored, mainly white and black. The overall risk of contamination in the study area was low, and the highest risk of microplastic contamination was found in the soil of facility agriculture. The results of the study will provide data reference for the assessment of microplastic contamination in agricultural soils and microplastic soil environmental behavior in China.

Distribution, Sources, and Risk Assessment of Microplastics in Surface Sediments of Yellow River Delta Wetland

Estuarine habitats are a critical zone of the Earth with strong land-sea interactions, that are strongly influenced by human activities. Microplastics (MPs) pollution in the Yellow River Delta (YRD) wetland, a typical young warm-temperate estuarine wetland, has not been comprehensively studied. The morphology, abundance, particle size, and polymer composition of MPs in the surface sediments of the YRD wetland were determined, and the pollution status and ecological risk in the study area were evaluated using the pollution load index (PLI) and potential pollution risk index (PRI). The results showed that the abundance of MPs in the YRD wetland was 20-520 n·kg-1, with a median value of 150 n·kg-1. The MPs were primarily fibers in shape and black in color, with particle size over 1 mm. The polymer components were primarily rayon, polyethylene, polyester, and polyethylene terephthalate. The PLI and PRI values of the MPs in the area were between 0.04-0.96 and 0.00-171.60, respectively, indicating that the pollution of MPs in the YRD wetland was at a slightly polluted level with low ecological risk.

Size- and surface charge-dependent hormetic effects of microplastics on bacterial resistance and their interactive effects with quinolone antibiotic

The facilitation of microplastics (MPs) on bacterial resistance has attracted wide concern, due to the widespread presence of MPs in environmental media and their ubiquitous contact with bacteria strains. Furthermore, MPs possibly co-exist with antibiotics to trigger combined stress on bacterial survival. Therefore, it is significant to reveal the dose-responses of MPs and MP-antibiotic mixtures on bacterial endogenous and exogenous resistance. In this study, 0.1 and 5 μm polystyrenes with no surface functionalization (PS-NF, no charge), surface functionalized with amino groups (PS-NH2, positive charge) and carboxyl groups (PS-COOH, negative charge) were selected as the test MPs, and norfloxacin (NOR) was set as the representative of antibiotics. It was found that six types of PS all inhibited the growth of Escherichia coli (E. coli) but induced hormetic dose-responses on the mutation frequency (MF) and conjugative transfer frequency (CTF) of RP4 plasmid in E. coli. Moreover, these hormetic effects exhibited size- and surface charge-dependent features, where 0.1 μm PS-NH2 (100 mg/L) triggered the maximum stimulatory rates on MF (363.63 %) and CTF (74.80 %). The hormetic phenomena of MF and CTF were also observed in the treatments of PS-NOR mixtures, which varied with the particle size and surface charge of PS. In addition, the interactive effects between PS and NOR indicated that the co-existence of PS and NOR might trigger greater resistance risk than the single pollutants. Mechanistic exploration demonstrated that the increase of cellular reactive oxygen species and the variation of cell membrane permeability participated in the hormetic effects of PS and PS-NOR mixtures on bacterial resistance. This study provides new insights into the individual effects of MPs and the combined effects of MP-antibiotic mixtures on bacterial resistance, which will promote the development of environmental risk assessment of MPs from the perspective of bacterial resistance.

Risk assessment of microplastics in fish assemblage based on ecological preferences in an interconnected and polluted river system

Risk assessment of microplastics (MPs) contamination in the assemblage of 15 important fish species with different feeding habits and microhabitats was studied in the River Ravi, Pakistan. Fishes with different feeding habits (omnivore, herbivore, and carnivore) and microhabitat preferences (surface, column, and bottom dweller) were sampled at Balloki and Sidhnai barrages during the post-monsoon seasons of 2019–2020. The gastrointestinal tract (GIT) of fish samples were found to be contaminated with MPs, with an average of 28.1 ± 20.7 MPs/individual and 26.8 ± 15.9 MPs/individual at Balloki and Sidhnai barrages, respectively. The surface dweller fish exhibited the highest MPs abundance, followed by the bottom dweller and column dweller. In addition, the highest MPs recovered from the omnivore generalist feeding group as compared to herbivores and carnivores. The fibers were the most abundant shape and generally made up of polyethylene terephthalate (PET) and polyethylene (PE). These PET and PE (low-density MPs) exhibit low hazard level, whereas high-density MPs with high hazard level and rarely present in GIT of sampled fishes. Based on MP polymer toxicity assessment, nine fish species were categorized in minor risk, two species in medium risk, and four species in highrisk group. Bottom dwelling fishes were at the highest plastic polymer risk level III due to the presence of a high density of MPs with high toxicity hazards. The high-risk prone fishes are under direct threat from MPs pollution, which may disrupt the ecological integrity of the river ecosystem and human health. The findings of the current study highlight the urgent need to address plastic pollution issues in River Ravi, and will be helpful for managers, researchers, and fisheries experts to mitigate this emerging challenge.speciesspecies

Environmental concentrations, characteristics and risk assessment of microplastics in water and sediment along the Western Cape coastline, South Africa

Plastic debris is accumulating in all environments globally and South Africa’s poor waste management plan has led to an increase in plastic contamination throughout the country. Information about microplastics (MPs) in urban and rural coastal environments in South Africa is poor. The aim of this study was to determine coastal MP concentrations in water (particles/L) and sediment (particles/kg). Sampling took place in summer of 2020 during low tide at 14 sites, along the coast of the Western Cape, South Africa. MPs were extracted and analysed based on shape, color, size and polymer type (using an ATR-FTIR). An ecological risk assessment was done to assess the potential risks posed by MPs in all sample types. Sediment MP concentrations (185.07 ± 15.25 standard error particles/kg) were higher than water (1.33 ± 0.15 particles/L). Gordon’s Bay (site 12) had the highest MP concentrations in sediment samples (360 ± 36.74 particles/kg), identifying harbors as the main source for MP contamination. Kalk Bay (site 9) displayed the highest concentration in water samples (4.97 ± 0.18 particles/L), suggesting that the source of MPs are from stormwater outfall pipes and human activities. Filaments were the most dominant MP shape (89%) for all samples, with black/grey (water) and transparent (sediment) being the most dominant colors (31% and 31% respectively). Dominant sizes were 1000–2000 μm in water and 2000–5000 μm in sediment. Polyethylene terephthalate (PET) (29%) was the most dominant polymer type recorded in water samples and natural fibres (mainly cotton) (32%) recorded in sediment. Based on the risk assessment, MPs recorded at Mouille Point (site 6) poses the greatest ecological risk associated with polymers. MP concentrations reported in this study provide a baseline for future studies along the Western Cape coastline of South Africa.

Distribution, abundance, and risks posed by microplastics in surface waters of the Yangtze River Basin, China

Microplastic (MP) pollution in the Yangtze River Basin, China, has become an environmental issue of great concern. However, most studies on MPs have focused on a part of the Yangtze River Basin, and still lack knowledge on the risk of MPs exposure in surface waters of the whole basin. This study overviews the differences in abundance and spatial distribution of MPs in surface waters basin-wide and comprehensively assesses the ecological risk of MPs exposure in surface waters of the Yangtze River Basin by considering the abundance and toxicity effects. The results showed that the MP abundance at the collected sampling sites ranged from 0 to 44,080 particles/m3, with a mean of 3441 particles/m3. MPs were unevenly distributed throughout the basin, with hotspots such as Three Gorges Reservoir, Yangtze River estuary, and some urban lakes showing relatively higher abundance than the surroundings. Based on the available toxicity data, chronic and acute predicted no-effect concentrations (PNECs) of 12.3 particles/L and 21 particles/L were derived for freshwater MPs exposure using constructed species sensitivity distributions (SSDs). The hazard quotient (HQ) method was used to compare the environmental exposure concentrations of MPs with PNECs, and the results showed that 71.8% of the sampling sites in the Yangtze River Basin had moderate chronic ecological risk, while 43% of the sampling sites had moderate acute ecological risk. Overall, the ecological risk of MPs in lake and reservoir water was higher than that in river water. Joint probability curves (JPCs) showed that the overall risk probability of MPs in the surface water of the Yangtze River Basin was lower than that of other basins in China and other countries. This research provides valuable information for the ecological risk assessment of MPs at the watershed scale.

Characteristics and Risk Assessment of Microplastics in Water and Mussels Sampled from Cape Town Harbour and Two Oceans Aquarium, South Africa

The aim of this study was to measure the characteristics and risk assessment of microplastics (MPs) in Cape Town Harbour (CTH) and the Two Oceans Aquarium (TOA) in Cape Town, South Africa from 2018 to 2020. Water and mussel MP samples were analyzed at 3 sites in CTH and TOA, respectively. Microplastics were mainly filamentous, black/grey and 1000–2000 μm in size. A total of 1778 MPs, averaging 7.50 (± 0.6 standard error of the mean, SEM) MPs/unit were recorded. Average MP concentrations were 10.3 ± 1.1 MPs/L in water and 6.27 ± 0.59 MPs/individual or, based on weight, 3.05 ± 1.09 MPs/g soft tissue wet weight in mussels. Average MPs in seawater in CTH (12.08 ± 1.3 SEM MPs/L) was significantly higher (4.61 ± 1.1 MPs/L) than inside the TOA (U = 536, p = 0.04). Various risk assessment calculations indicate that MPs in seawater poses a greater ecological risk than MPs in mussels at the sites sampled.