Occurrence Of Microplastics Research Articles

Unseen riverine risk: Spatio-temporal shifts of microplastic pollution and its bioavailability in freshwater fish within the Ikopa River urban system.

Growing concern over microplastic pollution, driven by their widespread accumulation in the environment, stresses the need for comprehensive assessments. This study investigates the spatial and temporal distribution of microplastics in the Ikopa River (Antananarivo - Madagascar), which flows through a densely populated area, and examines their correlation with contamination levels in local fish species. By analyzing upstream and downstream stations across wet and dry seasons, only a notable increase in microplastic concentration downstream during the wet season was observed, ranging from 138.6 ± 9.0 to 222.0 ± 24.5 particles m-3, with polyethylene-co-vinyl acetate being the predominant polymer at 62.3 ± 5.13% of the total sampled polymers. This distribution underlines the impact of urban activities on pollution levels. Fish species, gambusia and Nile tilapia, were assessed for microplastic occurrence in gills and gastrointestinal tracts. Higher contamination rates were found in gambusia, enlightening the influence of feeding behaviour and fish habitat on microplastics contamination. Ingestion of microplastics directly from the water column was evident in both species, with the detection of high-density plastics such as polytetrafluoroethylene and polyvinyl chloride suggesting likely sediment contamination. This research highlights the widespread contamination of aquatic environments and its direct impact on local wildlife, pointing to a clear requirement for effective pollution management strategies.

Bridging the gap between microplastic research and social awareness of microplastic pollution through science communication: A call for action

The ubiquitous occurrence of microplastics (MPs) in the environmental matrices including soil, water, air, animals, and humans has gained increased attention globally from researchers, the public, industries, and regulators in recent decades. There is an enormous number of studies conducted to determine the presence, fate, behavior, and toxicity of MPs across the countries in the world. However, the gap between scientific evidence and social awareness of the issue of the MPs remains inadequately addressed. This paper aimed to identify the gap between MP research and social awareness of the MP issue while also emphasizing strategies to bridge this gap.

Microplastics in wild fish in the Three Gorges Reservoir, China: A detailed investigation of their occurrence, characteristics, biomagnification and risk

Microplastics (MPs) pollution in freshwater poses a risk to various ecosystems and health security. In 2018, the Chinese government banned fishing since 2018 in the Three Gorges Reservoir (TGR), but the fate and risk of MPs in wild fish remain unclear. Therefore, a detailed investigation was conducted into the occurrence of MPs in 18 wild fish species in the TGR using a Micro Fourier Transform Infrared Spectrometer, and the trophic transfer and risks were assessed. MPs in fish were aged, with abundances ranging from 0.68 ± 0.98 to 4.00 ± 2.12 items/individual. Most particles were less than 1 mm in size (73.4 %), with fibers being the dominant shape (48.9 %) and transparent as the dominant color (35 %). Polyethylene (PE) was the most prevalent type. The bioconcentration factor (BCF), bioaccumulation factor (BAF), trophic magnification factor (TMF) and polymer hazard index (PHI) were low, suggesting no trophic transfer and a low risk of MPs. The BAF may provide a more reasonable description of the degree of enrichment of MPs, and ‘items/individual’ or ‘g/individual’ can be used to describe MPs concentrations in fish. This study proposes new insights and prospectives that can help researchers better understand MPs enrichment in fish across various trophic levels.

What to monitor? Microplastics in a freshwater lake – From seasonal surface water to bottom sediments

Marine microplastics have received considerable attention, and efforts are underway to develop standardised methods for sampling, sample treatment, and analysis, while the observation of freshwater ecosystems remains relatively overlooked. To address this understudied environment, we present a comprehensive case study on microplastics in an urban lake from Baltic region of Northern Europe covering the seasonal dynamics of microplastics in surface water, deposition rate throughout one year in sediment traps and distribution of microplastics in dated sediment archive to determine the most representative environmental compartment for microplastic pollution monitoring. The following well-established microplastic research methods have been used: Manta trawling for surface water, trapping for assessing microplastics sedimentation rate and coring for sediments. Attenuated total reflection and micro-Fourier transform infrared spectroscopy methods were used to investigate the synthetic nature of identified particles. The sediment core chronology was based on 210Pb and Bayesian Plum model revealing sediment layers to represent even the time before the beginning of plastic mass production (approximately 1950). The surface water microplastic concentrations were higher in summer (5.71 particles/m3) and gradually decreased towards winter (0.75 particles/m3); they were almost 25 times higher in more recent (2018) sediments than in the deeper layers referring to years prior to 1890. Surprisingly, microplastic particles were found in sediments before the year 1950. The microplastic deposition rate was 9.47 particles/cm2/year or 4.31 µg/cm2/year. The most abundant polymers were polyethylene, polystyrene and polypropylene, and the prominent particle shapes were fibres in surface water and fragments in sediments. Our results provide a baseline for evaluating future contamination level changes in highly urbanized area. We recommend the combination of surface water filtering with net and sediment trapping methods for monitoring microplastics in lakes since this method requires little time and financial resources for sampling and processing and produces information on temporal microplastic occurrence and deposition.

Impact of COVID-19 pandemic on microplastic occurrence in aquatic environments: A three-year study in Taihu Lake Basin, China

The impact of the Coronavirus Disease 2019 (COVID-19) pandemic on microplastic (MP) occurrence in aquatic environments deserves an in-depth study. In this study, the occurrence of MPs and environmental flux of plastics before (2019) and during (2020 and 2021) the pandemic were comparatively investigated in various aquatic compartments in the Taihu Lake Basin in China. The field-based investigations from 2019 to 2021 for Taihu Lake have shown that, at the onset of the outbreak, the MP abundance declined at a rate of 62.3 %, but gradually recovered to the pre-pandemic level. However, the amount of plastics being released into aquatic environments showed a declining trend in 2020 and 2021 compared to those in 2019, with decrease rates of 13.7 % and 15.8 %, respectively. Characterization analysis of MP particles and source apportionment framework implied that while the contributions of tire abrasion and domestic waste to MP occurrence were depleted owing to the reduction in human activity during the pandemic, weathering and fragmentation of retained plastics contributed to the recovery of stored MPs. This study provides insights into the anthropogenic influences on MP occurrence, and supports policymakers in managing and controlling plastic contamination in large freshwater systems in the “new normal” phase.

Microplastics in honey from Türkiye: Occurrence, characteristic, human exposure, and risk assessment

In this study, honey samples produced in Türkiye in 2023 were analyzed to assess occurrence of microplastics. The microplastics were physically and chemically characterised by stereomicroscope and FT-IR, respectively. Microplastic exposure by honey consumption was also calculated and risk assessment was done. The mean microplastic concentration was 314±353 (0–1280) particles/kg in 32 honey samples analyzed. The microplastics with four different polymers (EVA, PE, PP, and Nylon–6), two different shapes (fiber and fragment), and six different colors (black, brown, green, red, yellow, and transparent) were detected. The daily microplastic intake by consumption of monofloral and multifloral honey was calculated as 1.20 and 0.85 particles/day, respectively. The mean polymer hazard index and microplastic load index levels for all honey samples analyzed were 16.7±16 and 6.70±1.0, respectively. Result of this study confirmed that honey in Türkiye was contaminated with variety of microplastics. Considering to potential health risks of microplastics and associated chemicals to human health, production process should be improved by producers and urgent strategies and controls should be developed and applied by decision makers to eliminate the intake of microplastics through food.

Microplastic accumulation in water from protected areas in Western Forest Complex of Thailand

Microplastics (MPs) are emerging as ubiquitous environmental pollutants worldwide. However, no research has been conducted in freshwater ecosystems within Thai protected areas (PAs), where biodiversity and natural resources are safeguarded for human well-being. The aim of this study was to explore the occurrence and abundance of potential MPs in the water of freshwater ecosystems in Thai PAs and to examine factors affecting their presence in the Western Forest Complex in Thailand (WEFCOM). Seventy water samples were collected from eight PAs in WEFCOM using a 20 μm plankton net. The water samples underwent digestion, density separation, and filtration. Potential MPs were visually identified under a stereomicroscope, and their chemical composition was further characterized using FTIR. The results revealed a 98.57 % potential MP prevalence in the water samples, with an average abundance of 0.30 ± 0.32 item·L−1. The quantities of potential MPs among PAs were significantly different (H = 17.88, p = 0.01). Fibers (68.93 %) were the most frequently identified potential MPs, with the dominant colors being blue (22.40 %) and black (20.03 %), mostly small-sized MPs (0.05–0.5 mm; 41.80 %). The major chemical plastic types included low-density polyethylene, polyethylene, polyethylene terephthalate, polypropylene, polyethylene/polypropylene copolymer, polyester, and natural fibers. The abundance of potential MPs varied significantly among PAs, shapes, colors, and sizes (p < 0.01). Furthermore, potential MP abundance correlated with the number of tourists (p < 0.05). Proximity to open waste dumping (p < 0.01) and lower elevation (p < 0.05) tended to accumulate more potential MPs. This research suggests potential sources of microplastics in Thai PAs from wastewater effluent, human activities, and recreational activities, highlighting the urgent need for research to develop appropriate waste management technologies in Thai PAs and to raise awareness among local people and tourists about microplastic pollution.

Occurrence of Micro-Plastics in Tigris River Water in Middle of Iraq

Abstract Microplastics, which are emerging pollutants in the environmental world, have become a source of concern for researchers and the public by virtue of the increasing use of plastic and mismanagement of plastic waste. Currently, research focuses on marine environments, with less attention to freshwater environments, especially urban rivers. In this study, 11 samples were taken from surface water along the Tigris River in the city of Baghdad and from the Kut Dam. The process of chemical digestion using H2O2 (30%) was used to digest natural organic materials, separation by density to get rid of unwanted materials, and then examination under an optical microscope and FTIR. The abundance of plastic materials ranged from 27to74 particles/sample size. Polypropylene, polyethylene and polystyrene were common types of microplastics as they represented (66.92%) of the samples. Fibers and fragments were the dominant microplastic forms in all samples. White color is the dominant characteristic of all samples. It has been shown that hydrodynamic conditions and the locations of urban cities and industrial facilities affect the concentrations of microplastics. The study’s results at S9, S10, and S11 show that microplastics are accumulating in the dam, indicating that the dam might act as a sink for microplastics.

Contamination by microplastics and sorbed organic pollutants in the surface waters of the Tietê River, São Paulo-SP, Brazil

Microplastics (MPs) are particles between 1 μm and 5 mm in size, originating mainly from poor solid waste and effluent management, that can reach water bodies from various sources. In freshwater environments, the occurrence, distribution, and characterization of this new class of pollutants are still little explored, especially in Brazil. The aim of this study was to assess the occurrence of MPs, as well as the presence and concentration of polychlorinated biphenyls (PCBs) sorbed to these particles in the surface waters of the Tietê River - SP. Surface water samples were collected in duplicate during the dry and wet seasons. The identification and characterization of the MPs was carried out through visual inspection and the chemical identity of the particles was verified using Fourier transform infrared spectroscopy with attenuated total reflectance (FTIR-ATR). For the analysis of PCBs adsorbed to the MPs, the sample extracts were analyzed by gas chromatography coupled with mass spectrometry (GC-MS). The MPs were found in concentrations ranging from 6.67 to 1530 particles m−3, with a predominance of the polymers polyethylene (PE, with 58.17 %) and polypropylene (PP, with 23.53 %). The main morphological categories identified were fragments (56.63 %), fibers (28.42 %), and transparent films (13.06 %). Higher abundances of PCBs were observed in the lower size range, between 0.106 and 0.35 mm. The total concentrations of PCBs in MPs ranged from 20.53 to 133.12 ng g−1. The results obtained here are relevant for understanding the dynamics and level of contamination of MPs and organic pollutants sorbed to these particles in the Tietê River, as well as helping with mitigation measures for the restoration and preservation of this ecosystem.

The seasonal variation and ecological risk of microplastics in the Lower Ganges River, Bangladesh.

Microplastic (MP) pollution has gained considerable attention in various ecosystems; however, it has received relatively less attention in freshwater-riverine environments than in other ecosystems. The Ganges River Delta, one of the world's most densely populated areas, is a potential source of MP pollution in the freshwater ecosystem. MPs were identified throughout the year in the lower Ganges River water. Seasonally, the highest abundance was observed during the monsoon (14.66 ± 2.06 MPs/L), followed by the pre-monsoon (13.46 ± 1.75 MPs/L) and post-monsoon (11.50 ± 0.40 MPs/L). Throughout the year, MP discharge was estimated at 4.12 × 1012 to 2.17 × 1013 MPs/year. Fourier transformed infrared spectroscopy identified plastic polymers in the water, like ethylene vinyl acetate, polystyrene, polypropylene, polyethylene, and nylon. Moderate contamination by MPs was assessed throughout the year. Significant correlations between MP abundance and both rainfall and discharge were observed. It is essential to implement preventative measures in the Ganges River Basin to mitigate MP pollution before the situation worsens. PRACTITIONER POINTS: Throughout the year, MP concentration ranged from 10.67 to 20.33 MPs/L The highest MP occurrence was observed in the monsoon season (14.66 ± 2.06 MPs/L) The lowest abundance was detected in the post-monsoon period (11.50 ± 0.40 MPs/L) There was a moderate level of MP contamination in the lower Ganges River water It was shown that discharge and rainfall were correlated with MP abundance.

Occurrence and analysis of microplastics in municipal wastewater, Poland

Microplastics are a growing environmental threat and wastewater treatment plants have been identified as significant conduits for these pollutants. This study addresses microplastic loading in the influent of a large urban wastewater treatment plant, presenting a detailed analysis of their prevalence and characteristics. Our findings reveal a concentration of 4.09 microplastic particles per litre in the tributary. We performed a detailed statistical comparison of the microplastic particles, categorising them by shape, size, colour, and polymer type. Using Fourier transform total reflectance infrared spectroscopy, we identified 13 different polymer types, with polyethylene terephthalate, rubber, and polyethylene predominating. The analysis showed that textile fibres, mainly from clothing, are the most prevalent form of microplastic in wastewater, followed by fragments from the breakdown of larger plastic objects and films. This research highlights the critical need for strategic interventions to mitigate microplastic pollution at municipal sources.

Characteristics, sources and potential ecological risk of atmospheric microplastics in Lhasa city

Atmospheric microplastics are important contributors to environmental contamination in aquatic and terrestrial systems and pose potential ecological risks. However, studies on atmospheric microplastics are still limited in urban regions of the Tibetan Plateau, a sentinel region for climate and environmental change under a warming climate. In this study, the occurrence and potential ecological risk of atmospheric microplastics were investigated in samples of suspended atmospheric microplastics collected in Lhasa city during the Tibetan New Year in February 2023. The results show that the average abundance of atmospheric microplastics in Lhasa was 7.15 ± 2.46 MPs m−3. The sizes of the detected microplastics ranged from 20.34 to 297.18 μm, approximately 87% of which were smaller than 100 μm. Fragmented microplastics (95.76%) were the dominant shape, followed by fibres (3.75%) and pellets (0.49%). The primary polymer chemical components identified were polyamide (68.73%) and polystyrene (16.61%). The analysis of meteorological data and the backwards trajectory model indicated the air mass in Lhasa mainly controlled by westwards, and the atmospheric microplastics mainly originated from long-distance atmospheric transport. The potential ecological risk index assessment revealed that the atmospheric microplastic pollution in Lhasa was relatively low. This study provides valuable insights and a scientific foundation for future research on the prevention and control of atmospheric microplastic pollution in Lhasa and other ecologically sensitive cities.

More than just sweet: current insights into microplastics in honey products and a case study of Melipona quadrifasciata honey.

Honey, traditionally known as a pure and natural substance, has become an unexpected reservoir for microplastic contamination. This study consisted of an experimental investigation to assess the occurrence of microplastics in honey produced by Melipona quadrifasciata, a native bee species in Brazil. Our investigation covers eight areas (one sample per area), including built and vegetated areas located in São Paulo city, Brazil, to understand the distribution of microplastics in these environments. Honey samples (10 mL) were collected using a syringe and sent to the laboratory for further analysis. Microplastics extracted from honey samples were characterized under a stereomicroscope to determine their size, color, and morphology. Also, the polymer type was determined by FTIR analysis. All honey samples (100%) showed microplastics. The predominant particles displayed a fiber shape with a size below 299 μm and a transparent color and were primarily composed of polypropylene. Their concentrations ranged from 0.1 to 2.6 particles per mL of honey, raising concerns about their potential impact on bee populations and human consumers. This study underscores the need for further research on the sources and implications of microplastic contamination in Melipona quadrifasciata honey, shedding light on the broader issue of environmental plastic pollution and its impact on pollinators.

Occurrence of microplastics in the headwaters of Yellow River on the Tibetan Plateau: Source analysis and ecological risk assessment

The widespread occurrence of Microplastics (MPs) has aroused increasing concerns. However, the fate of MPs in remote areas remains poorly understood. Here, the spatial distribution, potential sources, and environmental risks of MPs were analyzed in the headstream of the Yellow River on the eastern Tibetan Plateau. The average MP abundances are (464.3 ± 200.9) items /m3 and (63.6 ± 34.7) items /kg in the water and sediment, respectively, with both majority polymer is polypropylene (PP) (water: 28.7 %; sediment: 25.2 %). The structural equation modeling and conditional fragmentation model were used in this study to analyze the source and impact factors of riverine MPs. According to the models, MPs were influenced by water quality parameters and anthropogenic activities. Furthermore, the source analysis through MP characteristics and statistical analysis showed that the main sources of MPs include domestic sewage, plastic waste disposal, and the use of agricultural plastic film. Moreover, the differences in MP sources along the river were distinguished by the conditional fragmentation model. The potential ecological risks of MPs were evaluated, resulting in relatively medium-to-low levels. Our findings will serve as important references for improving the understanding of the plateau environmental impacts of MP distribution in the headwaters of large rivers.

Occurrence and abundance of microplastics in surface water of Songkhla Lagoon.

Microplastic (MP) pollution is now a global critical issue and has been the subject of considerable worry for multiple various types of habitats, notably in lagoons which are coastal areas connected to the ocean. MPs are of concern, particularly because floating MP in surface water can be ingested by a number of marine organisms. There are several lagoons along Southeast Asia's coastline, but Songkhla Lagoon is Thailand's only exit with a rich biodiversity. To date, there has been little research undertaken on MP in this lagoon, so there is a pressing need to learn more about the presence of MP in the lagoon's water. We investigate MPs in the surface water of Songkhla Lagoon, Thailand. Sampling took place at ten stations in the lagoon during the wet season in December 2022 and the dry season in February 2023. Samples were digested with hydrogen peroxide to remove organic matter followed by density separation using saturated sodium chloride. MPs were visually examined under a stereo microscope to describe and determine the shape, size, and color. Polymer type was identified using a micro Fourier transform infrared (FTIR) spectrometer. Moreover, the in-situ of water quality of the surface water was measured using a multi-parameter probe. A Mann-Whitney U test was performed to investigate the variations in MP levels and water quality parameters between the wet and dry seasons. Correlation analysis (Spearman rho) was used to determine the significance of correlations between MP and water quality (p < 0.05). MPs were detected at all ten of the sites sampled. The most abundant MPs were small size class (<500 µm, primarily consisting of fibers). Five types of polymers were seen in surface water, including polyethylene terephthalate, rayon, polypropylene, polyester, and poly (ethylene:propylene). Rayon and polyester were the dominant polymers. Additionally, the most dominant color of MPs in the wet and dry season was black and blue, respectively. The mean contents of MPs in the wet and dry season were 0.43 ± 0.18 and 0.34 ± 0.08 items/L, respectively. The Mann-Whitney U test suggested a significant difference between water quality in the wet and dry seasons (p < 0.05). Correlation analysis (Spearman rho) indicated a negative significant difference relationship between the MPs and the values of total dissolved solid (TDS) in the wet season (r = -0.821, p = <0.05), revealing that the large amounts of MPs may possibly be dispersed within surface water bodies with low TDS concentrations. Based on the overall findings, MP pollution in the surface water of the lagoon is not found to be influenced by the seasonal context. Rivers flowing into the lagoon, especially the U-Taphao River, may be a principal pathway contributing to increased MP pollution loading in the lagoon. The results can be used as baseline data to undertake further research work relevant to sources, fates, distribution, and impacts of MPs in other coastal lagoons.

First occurrence and risk assessment of microplastics in enteral nutrition formulas

Occurrence and characteristics of microplastics were evaluated in enteral nutrition formulas, for the first time. A total of 30 samples belonging to 9 brands were analysed. Physical and chemical characteristics of microplastics were identified by stereomicroscopy and micro-raman spectroscopy, respectively. The mean number of microplastics was 45 ± 63 MP/L. Two different shapes of microplastics were detected with fibres (62%) being the most common microplastics followed by fragments (38%). The most common color of microplastics was black (37%) followed by blue (26%), orange (15%), green (7%), red (7%), grey (4%) and multicolor (4%). The length of microplastics ranged from 10 to 2086 μm with an average of 548 ± 526 μm. Estimated mean daily microplastic intake for four different scenarios varied between 24 to 61 and 30 to 76 MPs/day for women and men, respectively. The mean polymer hazard index and microplastic load index levels were calculated as 380 and 1.30, respectively. The results of this study showed that microplastics are prevalent in enteral nutrition products. The presence of polymers with high hazard risk scores in enteral nutrition formulas may pose a risk to the health of patients with special nutritional needs.

Occurrence of microplastics in commercial fish species from the Ethiopian rift valley's Lake Hawassa, Ethiopia.

Microplastics (MPs) have recently been detected as emergent pollutants in the Ethiopian rift valley lakes located close to rapidly expanding towns. We provide the first study of MPs ingestion of commercial fish species from Lake Hawassa, Ethiopia: Catfish (Clarias gariepinus) and Nile Tilapia (Oreochromis niloticus). A total of 60 individual fish species was collected from three sampling sites of lake Hawassa in October 2020. Across all sampling sites, there was a significant difference in ingested MPs between benthic omnivore catfish and pelagic phytoplanktivorous Tilapia (χ2 = 15.864, p < 0.001). The most common size of ingested MPs (84.6%) was 0.5-1mm, with fragments (59.5%) dominating, followed by fibers (25.4%). On average, 4.03 ± 1.33 MPs with sizes ranging between 60μm and 10.53mm were detected per individual. White and yellow MPs were particularly numerous, accounting for 36.8% and 26.4% of the total, respectively. Because Lake Hawassa's fishery is so significant, the potential impact of MP pollution on the lake biota in general, and economically valuable fish species in particular, deserves attention, additional research, and, if possible, early mitigation.

Occurrence of Microplastics in the Atmosphere: An Overview on Sources, Analytical Challenges, and Human Health Effects

The rapid spread and accumulation of microplastics (MPs) in environmental ecosystems result from extensive plastic usage. MPs have been found in both indoor and outdoor air. Outdoor MP levels vary widely across global cities, with reported ranges from 36 to 118 MPs m−2 day−1. However, differing measurement units complicate comparisons. Indoor MPs are particularly concerning due to the significant amount of time people spend indoors. For instance, MP concentrations in workplaces like reception areas and nail salons were found to be 309 ± 214 and 46 ± 55 MPs m−3, respectively. Technological limitations hinder the identification of MPs, with methods like µ-ATR-FTIR, µ-FTIR, and µ-Raman identifying MPs of different sizes. MPs smaller than 0.3 µm pose a health risk as they can be internalized in lung cells, while MPs larger than 10 µm are too large to enter alveolar macrophages. This review highlights the current understanding of airborne MPs, focusing on their sources, transport, and deposition mechanisms. It aims to provide a foundation for further studies to deeply assess the presence, abundance, and occurrence of MPs in aerosols, a subject that remains underexplored.

Occurrence and identification of microplastics retained in corrosion deposits of drinking water transmission pipes

The irregular structure and high porosity of corrosion deposits create suitable conditions for the retention, accumulation and adsorption of microplastics (MPs) and nanoplastics (NPs) transported by distributed water. Due to the low mass and continuous degradation of MPs, under certain conditions (e.g., changes in water composition or hydraulic conditions, network failures), these particles can be re-released into the water, causing secondary contamination. This paper presents preliminary results on the degree of MP contamination of sediments lining the inner surface of metal alloy pipes taken from a municipal drinking water distribution network. The isolated particles were assessed in terms of number, shape, residence time in the network, and origin. Plastic fragments classified as MPs and NPs were found in all analyzed corrosion deposits. Fragments smaller than 50 μm predominated, indicating a high level of plastic fragmentation associated with advanced degradation and prolonged residence in the environment. The predominant plastics identified were polyethylene (PE), polyethylene terephthalate (PET), and polyamides. High-carbon particles, most likely NP particles, whose presence in drinking water may pose a high health risk to consumers due to their potential to migrate into body tissues, were very abundant in the sediments but impossible to count with the techniques used. The results indicate the need to intensify research on the content of MPs and NPs not only in drinking water, but also in the sediments covering the interior of distribution pipes, and to identify factors that may cause their secondary release into bulk water.

Occurrence and emission characteristics of microplastics in agricultural surface runoff under different natural rainfall and short-term fertilizer application

Land-based microplastics (MPs) are considered the primary source of MPs in aquatic environments, with runoff being a major pathway for their transfer from soil to surface water. However, the transportation characteristics of MPs via agricultural surface runoff remain unclear. In this study, we investigated the occurrence and emission characteristics of MPs in agricultural surface runoff under various short-term fertilizer applications and natural rainfall events using laser direct infrared imaging analysis (LDIR). MPs from fertilizers and soils co-migrated with the agricultural runoff. The abundance and concentration of MPs in runoff were 145.90 ± 22.48–2043.38 ± 89.51 items·L−1 and 39.17 ± 21.94–523.04 ± 47.85 µg·L−1, respectively. Small and low-density MPs, such as polyethylene (PE), chlorinated polyethylene (CPE), and polyurethane (PU) in film/fragment form with 20–50 µm exhibited a higher mobility. No statistical differences were observed in the distribution of runoff MPs with the application of different fertilizers. There was a significant positive relationship between runoff MP abundance and rainfall intensity. The annual emission load in this study area was 116.73 g·hm−2, indicating that the transportation of MPs via agricultural surface runoff cannot be ignored. This study is conducive to understanding the migration behavior of MPs in soil-water environments in a better manner.