Homogenization of microplastics in alpine rivers: Analysis of microplastic abundance and characteristics in rivers of Qilian Mountain, China

Correcting microplastic pollution and risk assessment in Chinese watersheds

Microplastics (MPs) are emerging pollutants that are attracting attention because of their potential threats posed and their widespread presence in the environment. MP pollution in Chinese watersheds requires assessment; however, existing risk models face data-scale biases. By compiling 2,474 samples from 165 articles, we constructed a national dataset on MPs and propose a novel framework that integrates rescaled MP concentrations with MP characteristics to recalibrate MP pollution and ecological risks. The results showed that MP concentrations show substantial variability across seven orders of magnitude, and corrected data offered a more accurate representation of environmental concentrations. MP shapes, polymers, and colors differed among river basins, and population density and precipitation were important drivers of variations in MP concentrations. MP shapes, colors, and sizes that were not previously considered are now included in the risk assessment of MPs. Furthermore, 50 % of the sampling sites were in the dangerous and extremely dangerous ecological risk classes. The concentrations measured at 16.98 % of the sampling sites exceeded the risk threshold, therefore posing ecological and toxicological risks. The assessment framework may provide overall insights into the differences in MP pollution in river basins.

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.

Comprehensive analysis of microplastics at typical outlets around Hainan Island: From spatial distribution to flux estimation and correlation analysis

Previous studies on microplastics (MPs) distribution have predominantly focused on water bodies within specific regions, with limited emphasis on the contributions of MPs directly discharged from functional zones surrounding isolated island. This study addressed this gap by investigating the occurrence and distribution of MPs in water and sediment directly discharged into the adjacent coast of Hainan Island, a geographically isolated and ecologically sensitive region in the South China Sea. Based on the sampling from 40 typical sewage outlets (affiliated to five functional zones, i.e., wastewater treatment plants (WWTP), industrial area (ID), residential area (RA), aquaculture area (QA), estuary (EST)) around the Hainan Island, we analyzed the MPs abundance and composition in water and sediment. Our findings revealed significant contributions of land-derived MPs, with an average abundance of 15,900 items/m3 in water and 3171 items/kg in sediment. Annually, approximately 61.6 trillion MPs were discharged into the South China Sea via rivers from Hainan Island, highlighting its role as a major land-derived source of MPs pollution in this critical marine ecosystem. Risk assessments indicated the H and PLI level of Hainan Island as II and I, respectively, with H-water level highest in WWTP and EST as III and H-sediment level highest in WWTP, RD and QA as II, and this indicated the critical function of WWTP to control the release of land-derived MPs and reduce the environmental risks. Correlation analysis underscored the influence of natural factors (currents, tides, waves, and drifts), socio-economic factors (population density, regional area, and agricultural output), and anthropogenic activity (tourism development) on coastal MPs pollution. On the basis of existing timely MPs prevention and control measures in Hainan province, such as intercepting the MPs via WWTP and prohibiting the direct discharge of aquaculture wastewater to the surrounding sea, this study re-underscored the urgency of MPs management on the protection of the South China Sea's eco-environmental quality in view of the pivotal role of Hainan Island on the isolated geographic position and the South China Sea's ecological health. Overall, this study offered scientific insights to support source-oriented strategies for coastal MPs pollution control by providing fundamental data for predicting land-derived MPs contributions on an island-scale.

Machine Learning Advancements and Strategies in Microplastic and Nanoplastic Detection

Microplastics (MPs) and nanoplastics (NPs) present formidable global environmental challenges with serious risks to human health and ecosystem sustainability. Despite their significance, the accurate assessment of environmental MP and NP pollution remains hindered by limitations in existing detection technologies, such as low resolution, substantial data volumes, and prolonged imaging times. Machine learning (ML) provides a promising pathway to overcome these challenges by enabling efficient data processing and complex pattern recognition. This systematic Review aims to address these gaps by examining the role of ML techniques combined with spectroscopy in improving the detection and characterization of NPs. We focused on the application of ML and key tools in MP and NP detection, categorizing the literature into key aspects: (1) Developing tailored strategies for constructing ML models to optimize plastic detection while expanding monitoring capabilities. Emphasis is placed on harnessing the unique molecular fingerprinting capabilities offered by spectroscopy, including both infrared (IR) and Raman spectra. (2) Providing an in-depth analysis of the challenges and issues encountered by current ML approaches for NP detection. This Review highlights the critical role of ML in advancing environmental monitoring and improving our further, deeper investigation of the widespread presence of NPs. By identifying current key challenges, this Review provides valuable insights for future direction in environmental management and public health protection.

Riverine microplastics in the Mount Everest region affected by glacier meltwater

Understanding the distribution and drivers of microplastics (MPs) in remote and sensitive environments is essential for assessing their ecological impacts and devising mitigation strategies. This study investigates the distribution and characteristics of MPs in streams and sediments of the Mt. Everest region. Results show that microplastic (MP) abundance during the non-monsoon season was 2-4 times higher than in the monsoon season. MPs were predominantly fragments, composed of specific polymer types (PA, PET), and fell within the 10-30 µm size range. An ecological risk assessment was conducted to better evaluate MP pollution in the Mt. Everest region. The study found that recharge sources of streams influenced MP distribution, with streams receiving non-glacial recharge exhibiting higher MP concentrations during the monsoon season, likely due to the dilution effect of glacier meltwater. Principal component analysis highlighted correlations between MP abundance and environmental factors such as wind speed, dissolved oxygen, stream order, and elevation. These findings advance our understanding of MP pollution dynamics in high-altitude streams, establish a foundation for evaluating their ecological impacts, and offer valuable insights for developing mitigation strategies. This study provides a critical reference for further exploring MP contamination in high-elevation ecosystems and addressing its challenges.

First evidence of microplastics in the Quilca-Vítor-Chili river basin, Arequipa region, Peru

The Chili, Vitor and Quilca rivers and their tributaries in Peru serve as a vital water resource for both irrigation and domestic use in the surrounding communities and agricultural areas. The purpose of this study was to establish, for the first time, the presence, abundance, distribution and chemical identity of polymer microparticles in aqueous samples from these river basins. The results showed that, on average, filaments were the most dominant (71.4 %), followed by fragments (17.2 %) and film (6.74 %). Identification of the polymer types revealed that the most abundant type of MPs is polyethylene (40.8 %), followed by polypropylene (23.8 %), synthetic fibres (15.8 %), and other synthetic polymers. All samples showed the occurrence of microplastics, with a mean concentration of 35.34 MPs/m3, a maximum value of 172.70 MPs/m3 and a minimum value of 3.59 MPs/m3. The results reported in this study establish a baseline for the study area for the first time; in addition, the areas were established with a Pollution Indicator, and the Pollutant Load Index (PLI) was calculated, which reinforced the proposed identification, alerting the need to control clandestine urban and rural landfills, as well as the indiscriminate use of PE big bags in the agricultural catchment.

Investigation of microplastic pollution index in the urban surface water: A case study in west Godavari district, Andhra Pradesh, India

Microplastics (MPs) are a growing environmental issue because of their widespread prevalence and their long-term effects on ecosystems and human health. Global studies have identified MPs in various aquatic environments, such as lake, rivers, estuaries, wastewater, and oceans. Although most MPs originate from urban surface water sources, the specific intensity, characteristics, and associated risk assessments remain unclear. This study focuses on west Godavari region of India, specifically analyzing MPs in surface water samples Godavari River and two water treatment plants (WTPs). A total of 330 MPs found in the surface water and 121 MPs in theWTP. In surface water, MPs were predominantly blue and transparent fibers, with the majority measuring less than 500 μm in size. Conversely, at the WTP, larger MPs, primarily in blue fiber form and exceeding 3000 μm, were observed. Additionally, μ-Raman spectroscopy analysis identified the presence of various polymers, including PP, PVC, PC, Nylon, and PET, among others. The risks associated with MPs, including their concentration and chemical composition, were assessed across all sample types using various indices such as Contamination Factor (CFi), Pollution Load Index (PLI), Polymer Risk Index (H), Potential Ecological Risk Index (RI), and Estimated Intake (EI) (daily, annually, and lifetime). The risk assessment revealed that the type of polymer poses a greater risk of MP pollution than the concentrations of MPs themselves. These findings provide critical insights into MP contamination patterns and risks, emphasizing the need for targeted mitigation strategies in this region.

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.

Interconnected impacts of water resource management and climate change on microplastic pollution and riverine biocoenosis: A review by freshwater ecologists

The relationship between river hydrology and microplastic (MP) pollution is complex: increased discharge does not always mobilize more MPs, but floods can effectively flush out MPs from river catchments. Climate change and water resource management further influence MP pollution and its fate by altering river hydro-sedimentary regimes. This review investigates the interconnected impacts of these factors from a comprehensive perspective, focusing on how they affect MP concentration in freshwater ecosystems, particularly in regulated rivers and associated reservoirs. Our review reveals a scarcity of studies that jointly analyze the interrelated issues of MP pollution, water resource management, and climate change. Key findings indicate that variations in river discharge significantly influence MP mobilization, mainly depending on catchment land use, channel morphology, position within the catchment, and MP characteristics. Reservoirs function as both sinks and sources of MPs, underscoring their complex role in MP dynamics and the need for sustainable sediment management strategies. The increasing frequency of extreme weather events, driven by climate change, along with prolonged droughts intensified by water management practices, exacerbates MP pollution. These changes contribute to the local concentration of MPs, posing direct physical threats to aquatic organisms, particularly benthic species, through pollution and habitat alterations. Current policies on plastic pollution, water resources and climate change are underdeveloped, as these topics have been treated separately so far. In conclusion, this review provides perspectives on future research and policy directions to address challenges posed by MPs and to preserve rivers against multiple stressors.

Application of metal-organic frameworks for photocatalytic degradation of microplastics: Design, challenges, and scope

Microplastics (MPs), plastic particles smaller than 5 mm, are pervasive pollutants challenging wastewater treatment due to their size and hydrophobicity. They infiltrate freshwater, marine, and soil environments, posing ecological threats. In marine settings, MPs ingested by organisms cause cytokine release, cellular and DNA damage, and inflammation. As MPs enter the food chain and disrupt biological processes, their degradation is crucial. While biodegradation, pyrolysis, and chemical methods have been extensively studied, the use of metal-organic frameworks (MOFs) for MP pollution mitigation is underexplored. In this study, we explored the photocatalytic degradation mechanisms of MPs by MOFs in aquatic environments. We analyzed the hydrolysis, oxidation, and adsorption processes, while focusing on the environmentally friendly and cost-effective photocatalytic approach. Additionally, we analyzed the literature on MP decomposition for various types of MOFs, providing a detailed understanding of the degradation mechanisms specific to each MOF. Furthermore, we evaluated the degradation efficiencies of different MOFs and discussed the challenges and limitations in their application. Our study highlights the need for an integrated approach that involves the application of MOFs while considering environmental factors and safety concerns to develop effective MP degradation models. This review provides a framework for developing reliable photocatalytic materials with high MP removal and degradation efficiencies, thereby promoting the use of MOFs for marine plastic pollution mitigation.

Heterogenization of microplastic communities in lakes of the Qinghai-Tibetan Plateau driven by tourism and transport activities

The Qinghai-Tibetan Plateau has a booming tourism industry and an increasingly sophisticated road system. There is a paucity of studies quantifying the contributions of anthropogenic and natural factors to microplastic pollution in remote plateau areas. In this study, water and sediment samples were collected from eight lake tourist attractions and four remote lakes in northern and southern regions of the Qinghai-Tibetan Plateau. Microplastics were detected in all samples, with a mean abundance of 0.78 items/L in water and 44.98 items/kg in sediment. The abundance of microplastics in the study area was lower than previously observed in more populated areas of China. Small-sized (<1 mm and 1-2 mm), fiber, and transparent microplastics were predominant, with polyethylene and polypropylene microplastics as the primary polymer types. The compositions of microplastic communities indicated that tourism and road networks were the major sources of microplastics in the lakes. Distance-decay models revealed greater influence of environmental distances on microplastic community similarity than geographic distance. Compared to climate factors, urban spatial impact intensity and traffic flow impact played a leading role in the structuring of microplastic communities in lake water and sediment. Our findings provide novel quantitative insights into the role of various factors in shaping the distribution patterns of microplastic communities in plateau lakes.

Investigation of microplastics in urban rivers of Eastern China in summer: abundance, characteristics and ecological risk assessment

Microplastics (MPs) are increasingly becoming recognized as worldwide environmental contaminants, exerting a substantial impact on the safety of city rivers. This study explored the abundance and characteristics of MPs in summer 2023, including June and August, representing plum rain and typhoon rain seasons. The Qinhuai River exhibits more spatial fluctuations in six sampling sites with average concentrations of 470 ± 119.56 items per L, and the abundance increases with the water flows in the river. Downstream had the highest MP abundance of 484 ± 121.34 items per L, which were positive with the concentration of suspended solids (SS). Transparent and green MPs were more even in the sampling sites, and the shapes of fragments were predominant in the summer. Interestingly, the proportion of fiber and small-sized (38-75 μm) microplastics was predominant in the plum rain seasons, while the percentage of large-sized (270-5000 μm) and polymers of PE occurred in the typhoon rain seasons. The index of hazard scores of plastic polymers (H) revealed that the studied river had a severe pollution level (IV), which was highly influenced by PVC and PC. Besides, the pollution load index PLI value of different rain seasons was slightly polluted (I), while the PLI in autumn rain seasons was relatively higher than that in other seasons due to the higher variance of MPs. Therefore, the ecological risk of microplastics of PVC and PC in the Qinhuai River during varying seasons should be seriously considered. Our research is expected to provide valuable assistance in improving the management of urban rivers.

Historical and dispersal processes drive community assembly of multiple aquatic taxa in glacierized catchments in the Qinghai-Tibet plateau

Understanding the relative role of dispersal dynamics and niche constraints is not only a core task in community ecology, but also becomes an important prerequisite for bioassessment. Despite the recent progress in our knowledge of community assembly in space and time, patterns and processes underlying biotic communities in alpine glacierized catchments remain mostly ignored. To fill this knowledge gap, we combined the recently proposed dispersal-niche continuum index (DNCI) with traditional constrained ordinations and idealized patterns of species distributions to unravel community assembly mechanisms of different key groups of primary producers and consumers (i.e., phytoplankton, epiphytic algae, zooplankton, macroinvertebrates, and fishes) in rivers in the Qinghai-Tibet Plateau, the World's Third Pole. We tested whether organismal groups with contrasting body sizes differed in their assembly processes, and discussed their applicability in bioassessment in alpine zones. We found that community structure of alpine river biotas was always predominantly explained in terms of dispersal dynamics and historical biogeography. These patterns are most likely the result of differences in species-specific functional attributes, the stochastic colonization-extinction dynamics driven by multi-year glacier disturbances and the repeated hydrodynamic separation among alpine catchments after the rising of the Qilian mountains. Additionally, we found that the strength of dispersal dynamics and niche constraints was partially mediated by organismal body sizes, with dispersal processes being more influential for microscopic primary producers. Finding that zooplankton and macroinvertebrate communities followed clumped species replacement structures (i.e., Clementsian gradients) supports the notion that environmental filtering also contributes to the structure of high-altitude animal communities in glacierized catchments. In terms of the applied fields, we argue that freshwater bioassessment in glacierized catchments can benefit from incorporating the metacommunity perspective and applying novel approaches to (i) detect the optimal spatial scale for species sorting and (ii) identify and eliminate the species that are sensitive to dispersal-related processes.

Engineered biochar combined clay for microplastic biodegradation during pig manure composting

This study pursued to regulate bacterial community succession pattern and expedited biodegradation of microplastics (MP) during pig manure (PM) composting employing walnut shell biochar (WSB) and montmorillonite (M). The WSB with concentration of 0%, 2.5%, 5%, 7.5%, 10% and 12% along with 10% M participated into PM for 42 days compost to search the optimal solution. The results confirmed the most prosperous bacterial phylum consisted of Firmicutes (3.02%-91.80%), Proteobacteria (2.08%-48.54%), Chloroflexi (0-44.62%) and Bacteroidetes (0.85%-40.93%). The addition of biochar has dramatically arranged bacterial community at different stages of composting. Energy Dispersive Spectrometer (EDS) revealed that carbon element in MPs decreased since the chemical bond fracture, under the intervention of high-temperature composting and WSB, the carbon content of MPs was maximum reduced by 20.25%. Fourier transform infrared spectrum indicated that CC, C-O, C-H and -COOH abundance of MPs in 10% and 12% dose biochar addition sharply reduced, interestingly, explicating WSB and composting made MP biodegradable. This experiment possesses affirmatory practical meaning for elimination of potential hazards by composting.

Microplastics pollution in the Surma River, Bangladesh: A rising hazard to upstream water quality and aquatic life

The ecological health of freshwater rivers is deteriorating globally due to careless human activities, for instance, the emission of plastic garbage into the river. The current research was the first assessment of microplastics (MPs) pollution in water, sediment, and representative organisms (fish, crustacean, and bivalve) from the Surma River. Water, sediment, and organisms were sampled from six river sites (Site 1: Charkhai; Site 2: Golapganj; Site 3: Alampur; Site 4: Kazir Bazar; Site 5: Kanishail and Site 6: Lamakazi), and major water quality parameters were recorded during sampling. Thereafter, MPs in water, sediment, and organism samples were extracted, and then microscopically examined to categorize selected MPs types. The abundance of MPs, as well as size, and color distribution, were estimated. Polymer types were analyzed by ATR-FTIR, the color loss of MPs was recorded, the Pollution Load Index (PLI) was calculated, and the relationship between MPs and water quality parameters was analyzed. Sites 4 and 5 had comparatively poorer water quality than other sites. Microplastic fibers, fragments, and microbeads were consistently observed in water, sediment, and organisms. A substantial range of MPs in water, sediment, and organisms (37.33-686.67 items/L, 0.89-15.12 items/g, and 0.66-48.93 items/g, respectively) was recorded. There was a diverse color range, and MPs of <200 μm were prevalent in sampling areas. Six polymer types were identified by ATR-FTIR, namely Polyethylene (PE), Polyamide (PA), Polypropylene (PP), Cellulose acetate (CA), Polyethylene terephthalate (PET), and Polystyrene (PS), where PE (41%) was recognized as highly abundant. The highest PLI was documented in Site 4 followed by Site 5 both in water and sediment. Likewise, Sites 4 and 5 were substantially different from other study areas according to PCA. Overall, the pervasiveness of MPs was evident in the Surma River, which requires further attention and prompt actions.

Microplastic pollution characteristics and ecological risk assessment in the Wuding River Basin, China

Microplastics (MPs), as a new type of environmental pollutant, have attracted extensive attention in recent years. However, there has been relatively little research specifically focusing on MPs in the Yellow River Basin, China, particularly regarding MP migration patterns. Based on surface water and sediment samples from 19 sampling sites in the Wuding River (WDR), the abundances and characteristic distributions of MPs were analyzed, and the environmental factors affecting their distribution and potential ecological risks were evaluated. The results showed that the MP abundances in surface water and sediments of the WDR were significantly different (P < 0.05), with mean values of 2.98 ± 0.69 items/L and 419.47 ± 75.61 items/kg, respectively. In terms of MP characteristics, the most common size class was 0.1-0.5 mm in surface water. Polyethylene (PE, 32.50%) and polypropylene (PP, 27.50%) were the main polymer types of MPs in surface water. Although similar MP characteristics were observed in sediments, there were significantly more particles in the <0.1 mm particle size (P < 0.05), which was 15.0% higher than in surface water. Also, more high-density MP fragments were observed in sediment samples. The retention of MPs in sediments was influenced by the MP characteristics (density, shape, particle size) and sediment particle size. In contrast, the MP abundance in surface water was more closely related to the presence of other environmental pollutants, such as total phosphorus (WTP) and ammonia nitrogen (WAN). Temperature (T), agricultural land (AGR), and residential land (RES) only had significant effects on the distribution of MPs in surface water (P < 0.05). Potential ecological risk assessments revealed that MP pollution in sediments was more serious than in surface water, especially in the middle and lower reaches. The results of this study are important for understanding MP transport in a sandy river and for eliminating potential sources of MPs.

Environmental fate of microplastics in alpine and canyon-type river-cascade reservoir systems: Large-scale investigation of the Yalong River in the eastern Qinghai-Tibet Plateau

Reservoirs are regarded as potential collection sites for microplastics (MPs), and ample water resources in plateau regions provide favorable natural conditions for hydroelectric power generation. However, research on the impact of cascade reservoir construction in the plateau region on the fate of MPs within the watershed is limited. In this study, the Yalong River, an alpine canyon river in the eastern Qinghai-Tibet Plateau, was selected as the research area. This study explored the distribution of MPs at various depths in water, sediment, and riverbank soil as well as the formation of "MP communities" within the river-cascade reservoir system. Furthermore, the effects of dam construction on MPs' migration in different environments were analyzed. The results revealed that the abundance of MPs in the water and sediment within the cascade reservoir area (CRA) was significantly higher than that in the river area (RA) (P < 0.001). Additionally, the trend of increasing MPs in water with decreasing altitude was notably slower in CRA. Regarding shape, the proportion of fibers in the water within the CRA was significantly lower than that in the RA, with a smaller vertical migration rate in the water than in the sediment. The proportion of MPs < 500 μm in the water within the CRA was significantly higher than that in the RA. High-density MPs were notably deposited in the reservoir sediments. The analysis of the MP communities revealed that the construction of cascade dams led to relative geographical isolation between different sampling sites, reducing the similarity of MP communities in the CRA. This study established a theoretical foundation for understanding the impact of cascade dam construction on the fate characteristics of MPs and their potential risks in plateau areas.

Effects of lakeshore landcover types and environmental factors on microplastic distribution in lakes on the Inner Mongolia Plateau, China

Microplastic pollution in freshwater environments has received increasing attention. However, limited research on the occurrence and distribution of microplastics in plateau lakes. This study investigated the microplastic characteristics and influencing factors in lakes with different land cover types on the Inner Mongolia Plateau. Results showed that microplastic abundance ranged from 0.5 to 12.6 items/L in water and 50-325 items/kg in sediments. Microplastics in water were predominantly polypropylene (50.5%), fragments (40.5%), and 50-200 µm (66.7%). High-density (27.9%), fibrous (69.3%), and large-sized microplastics (47.7%) were retained primarily in lake sediments. The highest microplastic abundance in water was found in cropland lakes and grassland lakes, while that in sediments was in descending order of desert lakes > cropland lakes > grassland lakes > forest-grassland lakes. Differences among lake types suggest that agriculture, tourism, and atmospheric transport may be critical microplastic sources. Microplastic distribution was positively correlated with farmland and artificial surface coverage, showing that land cover types related to human activities could exacerbate microplastic pollution in lakes. Redundancy analysis showed that ammonia nitrogen and pH were the key physicochemical factors affecting microplastic distribution in lakes, indicating the potential sources of microplastics in lakes and the uniqueness of microplastic occurrence characteristics in desert saline-alkaline lakes, respectively.

Are algae a promising ecofriendly approach to micro/nanoplastic remediation?

How to reduce microplastic pollution in aquatic ecosystem has become the focus of the global attention. The re-removal of microplastics of wastewater treatment plant (WWTP) effluent is gradually being put on the agenda. Recently, algae have been used as an ecofriendly remediation strategy for microplastic removal. Microplastics in sewage can be removed by algae through interception, capture, and entanglement, and can also form heterogeneous aggregates with algae, thereby reducing their free suspensions. Algae can recover nitrogen and carbon from wastewater and can be made into biochar, biofertilizers, and biofuels. However, problematically, this technology has been in the laboratory research stage, and existing research results cannot provide effective basis for its application. Microplastic removal via algae is influenced by wastewater flow rate, microplastic types, and pollutants. Microplastics are only physically fixed by algae, and ensuring that microplastics do not re-enter the environment during resource and capacity recovery is also a key factor limiting the implementation of this technology. The topic of this paper is to discuss the performance of the current tertiary wastewater treatment process - algae process to remove microplastics. Algae can remove nitrogen and phosphorus pollutants in sewage and remove microplastics at the same time, which can realize energy recovery and reduce ecological risks of the effluent. Although algae combined tertiary sewage treatment is a green technology for microplastic removal, its application still needs to be explored. The key challenges that need to be addressed, from single laboratory conditions to complex conditions, from small-scale testing to large-scale simulations, lie ahead of the application of this friendly technology.