Microplastic contamination in groundwater of rural area, eastern part of Korea

Methods to optimize the collection, pretreatment, extraction, separation, and examination of microplastics in soil, groundwater, and human samples

Microplastics (MPs) in soil, groundwater, and human (SGH) present a significant global challenge due to their ecological and human health impacts. However, current protocols for detecting MPs in these environments and humans are limited, inconsistently applied, and vary significantly, particularly during the pretreatment stages of MP analysis. Moreover, no study has investigated the impact of methodological flaws on MP detection. This study conducted a thorough global assessment of the existing soil and groundwater (SG) pretreatment methods, using statistical tests to evaluate their effectiveness. It also reviewed filtration and analytical techniques for MPs in SGH samples. The analysis included research articles from PubMed, Google Scholar, Scopus, and Web of Science published between 2015 and 2024. Findings show that pretreatment using more than 100 g of soil can impact MP quantification, likely due to soil heterogeneity, while groundwater volume did not significantly affect MP quantification, likely due to the homogeneity of groundwater. During SGH pretreatment, various salts (e.g., ZnCl2 and NaCl) can be used for density flotation. Fenton's reagent was found to be a better choice than H2O2 for organic material removal because less heat was released. Post treatment MPs in SGH samples can be analyzed using various instruments and resolutions such as FTIR down to 1-5 µm, ATR-FTIR down to 2 µm, micro-Raman down to 500 nm, and LDIR down to 1 µm. This study lays the foundation for developing an effective MP analysis in SGH.

Nano and Microplastics: Unveiling Their Profound Impact on Endocrine Health

Plastics are extensively used materials with a long environmental lifespan, posing significant risks to human health and the environment. Global plastic consumption has surged, with plastic waste expected to triple by 2060. The primary concern is the breakdown of plastics into nano and micro-sized particles, which can enter the body and have been detected in various organs and tissues.This review systematically examines the effects of micro and nanoplastics (MNPs) on the endocrine system using in vitro and in vivo experimental models. Following PRISMA guidelines, articles were sourced from databases like PubMed, Web of Science, and Scopus. After screening for relevance and removing duplicates and non-English articles, 103 articles focusing on the endocrine effects of MNPs were selected.MNPs can disrupt endocrine functions, altering reproductive hormones and gene expression patterns. In vivo exposure to MNPs increases inflammatory markers such as TNF-α, IL-6, IL-1β, and NF-κB, leading to apoptosis, inflammation, and oxidative stress. These disruptions impact the gonads, thyroid glands, and hormone secretion from the pituitary and hypothalamus. Most studies focus on terrestrial animals, with polystyrene being the most commonly used polymer.Future research should explore various plastic polymers, longer exposure durations, a broader range of concentrations, and human-level studies to better understand the toxicity of plastic particles. Reducing exposure to these pollutants requires legal changes, consumer behavior adjustments, and increased public awareness. Understanding the underlying processes can help propose methods to mitigate risks and protect human health.

Application of high-resolution site characterisation tools and sampling methods for assessing microplastic migration beneath MSW dumpsites

The study addresses a significant environmental issue: the accumulation of microplastics (MPs) in municipal solid waste (MSW) dumpsites and their migration into deeper soil and groundwater (GW). Given the global increase in plastic production and limited waste management, this topic is highly relevant. Furthermore, many studies lack robust methodologies for tracking MP movement through complex soil strata. This study presents an innovative approach, employing advanced site characterisation and sampling techniques, including cone penetration test (CPT), hydraulic profiling tool (HPT), continuous soil sampling, and discrete GW sampling. This integrated method facilitates the identification of high-permeability zones, enabling large-depth sampling while reducing cross-contamination risk. Key findings reveal a substantial MSW layer containing plastics, textiles, and metals in specific zones, while natural soils dominate other areas. Unsaturated zones are mainly sandy, with occasional low-compressibility clay layers. MP concentrations are notably high at the MSW-soil interface 6600-8800 items/kg and decrease significantly with depth to 300-700 items/kg in saturated zones. Smaller MPs (<500 µm), mainly polyethylene, polypropylene, polyamide, and polyester, dominate soil samples. In GW, MP levels range from 26 to 171 items/L, with fibers (<250 µm) comprising about 80 % of MPs, highlighting subsurface soils as partial barriers to MP migration.

Microplastics in groundwater: Environmental fate and possible interactions with coexisting contaminants

Microplastics (MPs) are emerging environmental pollutants which represent a serious threat to ecosystems and human health and have received significant attention from the global community. Currently, a growing number of studies have found the presence of MPs in groundwater. This study exhaustively reviewed varying degrees of recent publications in Web of Science database and investigated the characteristics of MPs (concentration, types, sizes and shapes) in groundwater ecosystems, their migration characteristics, and interactions with co-occurring contaminants. Results suggested that current global research on MPs in groundwater has primarily focused on countries such as India, South Korea, China, Italy and United States. Pollution levels of MPs in groundwater show significant variability, ranging from 0 to 6832 n/L. The predominant plastic polymer types include PP, PE, PS, PA, PET and PVC. The sources of MPs in groundwater are primarily classified as associated with natural processes and anthropogenic activities. The physical, chemical and biological properties can influence the migration of MPs into groundwater. Furthermore, MPs can act as carriers, interacting with co-occurring contaminants, thereby enhancing their migration and toxicity, potentially posing a threat to groundwater ecosystems and human health. Consequently, the major challenges and associated recommendations for forthcoming research on MPs in groundwater are proposed.

Current research status on the distribution and transport of micro(nano)plastics in hyporheic zones and groundwater

Micro(nano)plastics, as an emerging environmental pollutant, are gradually discovered in hyporheic zones and groundwater worldwide. Recent studies have focused on the origin and spatial/temporal distribution of micro(nano)plastics in regional groundwater, together with the influence of their properties and effects of environmental factors on their transport. However, the transport of micro(nano)plastics in the whole hyporheic zone-groundwater system and the behavior of co-existing substances still lack a complete theoretical interpretation. To provide systematic theoretical support for that, this review summarizes the current pollution status of micro(nano)plastics in the hyporheic zone-groundwater system, provides a comprehensive introduction of their sources and fate, and classifies the transport mechanisms into mechanical transport, physicochemical transport and biological processes assisted transport from the perspectives of mechanical stress, physicochemical reactions, and bioturbation, respectively. Ultimately, this review proposes to advance the understanding of the multi-dimensional hydrosphere transport of micro(nano)plastics centered on groundwater, the microorganisms-mediated synergistic transformation and co-transport involving the intertidal circulation. Overall, this review systematically dissects the presence and transport cycles of micro(nano)plastics within the hyporheic zone-groundwater system and proposes prospects for future studies based on the limitations of current studies.

Occurrence, sources, and ecological risk of microplastics in groundwater: Impacts by agricultural activities and atmospheric deposition

Although microplastic (MP) pollution in groundwater is a serious issue, its potential sources and environmental risks are poorly understood. This study identified the sources of MPs in groundwater from a megacity in China. It estimated the environmental risks of MPs using a combination of the pollution load index (PLI), the polymer hazard index (PHI), and the potential ecological risk index (PERI). The groundwater in Shanghai showed high MP abundances, ranging from 3 ± 3 particles/L to 99 ± 19 particles/L. A total of 43 polymer types were detected, of which polypropylene (PP) and polyethylene (PE) were the main polymer types. Groundwater in agricultural areas has the highest level of MP pollution, with >50 % of MPs being identified as PP. Plastic woven bags used in agricultural activities were the primary sources. Similar characteristics of MPs in groundwater from open wells and atmospheric deposition samples suggested that atmospheric deposition was a significant source of MPs in groundwater from open wells. Landfills and construction activities were also recognized as potential MP pollution sources in groundwater. Based on PLI, PHI and PERI analysis, the groundwater in Shanghai exhibited a high MP pollution load, a middle polymer hazard, and a high potential ecological risk level, respectively. The PERI analysis, a comprehensive assessment compared to the PLI and PHI analyses, indicated an overall high ecological risk of MPs in agricultural groundwater. This study advances the knowledge of MP sources and their ecological risks in groundwater, allowing for better MP pollution control in areas with high MP abundance and high risk levels.

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.

Significance of Morphology in Characterizing Human Health Risk from di(2-ethylhexyl) Phthalate in Polyvinyl Chloride Microplastics in Groundwater

In this study, a human health risk assessment was performed on the ingestion route of groundwater containing polyvinyl chloride (PVC) microplastics (MPs), and the carcinogenic and non-carcinogenic risks of di(2-ethylhexyl) phthalate (DEHP), a representative additive, were determined. In particular, the impact of volume diversity according to the shape (morphology) of PVC MP (fragment, fiber, film) on the risk characterization was intensively explored. Firstly, a continuous particle size distribution following a power function was derived using the abundance ratio of PVC MPs by size in the investigated groundwater, and human health risk assessment for DEHP in the PVC MPs was performed through the volume distribution according to the shape of MPs. DEHP human health risk assessment showed an excess cancer risk (ECR) of below 10-6 for a 95% cumulative probability for all MP shapes, but the values varied depending on the shape. Sensitivity analysis showed that the parameter that most affected human health risk was MP volume, second to concentration, which is dependent on MP shape. Therefore, it is necessary to consider the variety of MP shapes during human health risk assessment, and it can be achieved through probabilistic risk assessment utilizing the probability distribution for size and shape of MPs.

Advanced characterisation of groundwater contamination at a dumpsite: Methodology and assessment - Case study of a municipal solid waste dumpsite in India

Groundwater (GW) contamination due to municipal solid waste (MSW) disposal in open dumpsites is a pressing global issue. Traditional GW assessment studies are limited to single-depth sampling from nearby wells/handpumps, providing limited insights into subsurface soil characteristics and are prone to cross-contamination. The present study introduces an innovative methodology integrating advanced techniques: Cone Penetration Testing (CPT), Hydraulic Profiling Tool (HPT), Continuous Soil Sampling, and Discrete GW Sampling. Conducted at an operational dumpsite in New Delhi, India, from January to February 2023, the site investigation program covered seven distinct locations to incorporate the entire dumpsite area. The investigation proceeded in stages, starting with subsurface soil characterisation using CPT and HPT, followed by extracting soil and GW samples using CPT and HPT data. Due to restrictions in the northeast direction, GW samples were directly extracted from borewells. The results revealed maximum and minimum concentrations of 171 items/l and 26 items/l of MPs, while ionic concentration reached 13,200 ppm for Cl- and 4437 ppm for SO4-2. A maximum of 0.721 ppm, 0.663 ppm and 0.948 ppm concentration was observed for Ni, Cu and Mo in GW samples. Spearman correlation and principal component analysis underscore the influence of Ec, TDS, Na+1 and Cl-1 on GW quality. This integrated approach effectively identifies high-permeability layers, which are crucial for understanding contaminant dispersion, and ensures precise sampling at various depths with minimal cross-contamination. This research demonstrates the proposed methodology's effectiveness in providing more profound and precise insights into GW contamination dynamics and suggests its utility in forming the basis for more effective remediation and regulatory strategies.

Global distribution, drivers, and potential hazards of microplastics in groundwater: A review

Since microplastics (MPs) were first detected in groundwater, an increasing number of studies have focused on groundwater pollution by MPs. However, knowledge of the global properties of groundwater MPs: distribution, concentration, composition, and morphology remains limited, while potential factors regulating their transport and distribution in groundwater, especially the hydrogeological background and climate warming conditions, have been omitted from most analyses. Furthermore, previous field investigations did not assess the risks posed by groundwater MPs to the environment and to human health, a necessary preliminary to remediation. In this work, to promote future MP pollution studies and remediation policies, we assimilated and synthesized the current knowledge on this topic. We reviewed current data on global groundwater pollution by MPs, analyzed the driving factors of their transport and distribution, and summarized the ecological and health hazards posed by MPs, before discussing current knowledge limits and suggesting perspectives for future work.

Effects of 3D microstructure of porous media on DNAPL migration and remediation by surface active agents in groundwater

Aquifers composed of porous granular media are important to human beings because they are capable of storing a large amount of groundwater. Contaminant migration and remediation in subsurface environments are strongly influenced by three-dimensional (3D) microstructures of porous media. In this study, fractal models are developed to investigate contaminant transport and surfactant-enhanced aquifer remediation (SEAR) for the regular tetrahedron microstructure (RTM) and right square pyramid microstructure (RSPM). The relationships of permeability and entry pressure are derived for these two kinds of 3D microstructures of granular porous media. Afterward, the difference in perchloroethylene (PCE) migration and SEAR efficiency between RTM and RSPM is investigated by the numerical simulation based on a synthetic heterogeneous granular aquifer. Results indicate that PCE penetrates faster and spreads farther in RSPM-based aquifers compared with RTM-based aquifers. Further, SEAR in RTM-based aquifers can achieve remediation efficiencies of 66.129%-92.214% with a mean of 84.324%, which is clearly lower than the SEAR efficiency of 70.149%-94.773% (with a mean of 89.122%) in RSPM-based aquifers. Findings are significant for understanding the 3D microstructure of porous media and how the microstructure of porous media affects macroscopic contaminant behaviors and remediation.

Characterization of microplastics in soil, leachate and groundwater at a municipal landfill in Rayong Province, Thailand

Recent years have witnessed a dramatic increase in global plastic production, leading to heightened concerns over microplastics (MPs) contamination as a significant environmental challenge. MP particles are ubiquitously distributed across both continental and marine ecosystems. Given the paucity of research on MPs in Thailand, particularly regarding MPs contamination in terrestrial environments, this study focused on investigating the distribution and characteristics of MPs in a landfill area. We collected 15 soil samples, 2 leachate samples, and 7 groundwater samples from both inside and outside a municipal landfill situated in the urbanized coastal region of Rayong Province. Our findings revealed variability in MPs concentration across different sample types. In soil, the MP count ranged from 240 to 26,100 pieces per kg of dry soil, 58.71 % of all sample sizes are lower than 0.5 mm. Similarly, the size found in the leachate sample, and the average MP in the leachate samples was 139 pieces per liter of MPs. The groundwater samples showed a fluctuation in MPs count from 18 to 94 pieces per liter, and the size of MPs ranged mostly from 0.5 to 1 mm. The predominant forms of MPs identified were sheets, followed by fragments, fibers, and granules. According to μ-FTIR analysis, the majority of the MPs were composed of polyethylene and polypropylene, commonly used in plastic packaging and ropes. The observed high concentrations and extensive distribution of MP contamination underscore the urgency for further studies and effective management strategies to mitigate the adverse impacts of this pollution on various organisms and ecosystems.

Limits, challenges, and opportunities of sampling groundwater wells with plastic casings for microplastic investigations

Investigating microplastics (MPs) in groundwater suffers from problems already faced by surface water research, such as the absence of common protocols for sampling and analysis. While the use of plastic instruments during the collection, processing, and analysis of water samples is usually avoided in order to minimize unintentional contamination, groundwater research encompassing MPs faces unique challenges. Groundwater sampling typically relies on pre-existing monitoring wells (MWs) and water wells (WWs) that are often constructed with polyvinyl chloride (PVC) casings or pipes due to their favorable price-performance ratio. Despite the convenience, however, the suitability of PVC casings for MP research is questionable. Unfortunately, the specifics of these wells are often not detailed in published studies. Current literature does not indicate significant pollution risks from PVC casings, suggesting these wells might still be viable for MP studies. Our preliminary analysis of the existing literature indicates that if PVC exceeds 6 % of the total MP concentration, it is likely that casings and pipes made of PVC are a source of pollution. Above this threshold, additional investigations in MWs and WWs with PVC casings and pipes are suggested.

A comprehensive review of urban microplastic pollution sources, environment and human health impacts, and regulatory efforts

Microplastic (MP) pollution in urban environments is a pervasive and complex problem with significant environmental and human health implications. Although studies have been conducted on MP pollution in urban environments, there are still research gaps in understanding the exact sources, regulation, and impact of urban MP on the environment and public health. Therefore, the goal of this study is to provide a comprehensive overview of the complex pathways, harmful effects, and regulatory efforts of urban MP pollution. It discusses the research challenges and suggests future directions for addressing MPs related to environmental issues in urban settings. In this study, original research papers published from 2010 to 2024 across ten database categories, including PubMed, Google Scholar, Scopus, and Web of Science, were selected and reviewed to improve our understanding of urban MP pollution. The analysis revealed multifaceted sources of MPs, including surface runoff, wastewater discharge, atmospheric deposition, and biological interactions, which contribute to the contamination of aquatic and terrestrial ecosystems. MPs pose a threat to marine and terrestrial life, freshwater organisms, soil health, plant communities, and human health through ingestion, inhalation, and dermal exposure. Current regulatory measures for MP pollution include improved waste management, upgraded wastewater treatment, stormwater management, product innovation, public awareness campaigns, and community engagement. Despite these regulatory measures, several challenges such as; the absence of standardized MPs testing methods, MPs enter into the environment through a multitude of sources and pathways, countries struggle in balancing trade interests with environmental concerns have hindered effective policy implementation and enforcement. Addressing MP pollution in urban environments is essential for preserving ecosystems, safeguarding public health, and advancing sustainable development. Interdisciplinary collaboration, innovative research, stringent regulations, and public participation are vital for mitigating this critical issue and ensuring a cleaner and healthier future for urban environments and the planet.

Migration characteristics of microplastics in riparian soils and groundwater

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

Microplastic accumulation in groundwater: Data-scaled insights and future research

Given that microplastics (MPs) in groundwater have been concerned for risks to humans and ecosystems with increased publications, a Contrasting Analysis of Scales (CAS) approach is developed by this study to synthesize all existing data into a hierarchical understanding of MP accumulation in groundwater. Within the full data of 386 compiled samples, the median abundance of MPs in Open Groundwater (OG) and Closed Groundwater (CG) were 4.4 and 2.5 items/L respectively, with OG exhibiting a greater diversity of MP colors and larger particle sizes. The different pathways of MP entry (i.e., surface runoff and rock interstices) into OG and CG led to this difference. At the regional scale, median MP abundance in nature reserves and landfills were 17.5 and 13.4 items/L, respectively, all the sampling points showed high pollution load risk. MPs in agricultural areas exhibited a high coefficient of variation (716.7%), and a median abundance of 1.0 items/L. Anthropogenic activities at the regional scale are the drivers behind the differentiation in the morphological characteristics of MPs, where groundwater in residential areas with highly toxic polymers (e.g., polyvinylchloride) deserves prolonged attention. At the local scale, the transport of MPs is controlled by groundwater flow paths, with a higher abundance of MP particles downstream than upstream, and MPs with regular surfaces and lower resistance (e.g., pellets) are more likely to be transported over long distances. From the data-scaled insight this study provides on the accumulation of MPs, future research should be directed towards network-based observation for groundwater-rich regions covered with landfills, residences, and agricultural land.

Effects of groundwater sample volume on identified microplastics in groundwater of an agricultural area in Korea

Groundwater serves various purposes worldwide, including agricultural, drinking, domestic, and industrial uses. In the Republic of Korea, groundwater is used primarily for agricultural purpose. Understanding the quality of groundwater is crucial because microplastics (MPs) can enter groundwater through agricultural activities and potentially pose harm to humans. Therefore, groundwater sampling plays a vital role in determining the presence of MPs. However, the optimal volume of groundwater sampling required for accurate MP assessment remains uncertain. This study examined the optimal sample size for collecting MPs from groundwater in the heavy agricultural area of the Haean Basin, Korea. Groundwater sampling and MP analyses were conducted during the wet and dry seasons of 2022. A total of 500 L of groundwater was continuously sampled in increments of 100 L to 500 L (100, 200, 300, 400, and 500 L). Additionally, we investigated the land use surrounding the sampling wells and the predominant types of plastics used in agriculture. To ensure reliable MP analysis, precautions were taken to minimize plastic contact during sampling, pretreatment, and μ-FTIR analysis. The concentration of MPs in groundwater ranged from 0.04 to 17.77 particles/L during the wet season and from 0 to 0.56 particles/L during the dry season. The highest concentration of MPs was observed at the first 100 L sample volume, with concentrations decreasing as the sampling volume increased. Fragmented particles accounted for 86.3 % during the wet season and 91.5 % during the dry season, whereas fibers constituted 13.7 and 8.5 %, respectively. MPs in the size range of 20-100 μm were predominant in both seasons. The polymers identified in both seasons were polypropylene (PP), polyethylene (PE), polyvinyl chloride (PVC), and polyamide (PA). While some studies suggest that 500 L is the optimal sample volume for assessing MPs in groundwater, the findings of this study indicate that a larger sample volume may be necessary. This study was the first attempt to determine the optimum sample volume required to collect MPs from groundwater, emphasizing the importance of conducting further research to validate these findings.

Evaluation of niche, diversity, and risks of microplastics in farmland soils of different rocky desertification areas

The occurrence, sources, effects, and risks of microplastics (MPs) in farmland soils have attracted considerable attention. However, the pollution and ecological characteristics of MPs in farmland soils at different levels of rocky desertification remain unclear. We collected and analyzed farmland soil samples from rocky desertification areas in Guizhou, China, ranging from no to heavy risks. We explored differences and migration of MPs across these areas, unveiled the relationship between diversity, niche, and risks of MPs, and determined influencing factors. The average abundance of soil MPs was 8721 ± 3938 item/kg, and the abundance and contamination factor (CF) of MPs escalated with the increase in rocky desertification level. Diversity, niche, and risk of soil MPs in different rocky desertification areas were significantly different. Rocky desertification caused both MP community differences and linked MP communities at different sites. Diversity and niche significantly affected MP risk (p < 0.05). Environmental factors with significant correlations (p < 0.05) with the abundance and ecological characteristics of MPs varied significantly in soils of different rocky desertification areas. This study advances our comprehension of MP pollution in farmland soils within rocky desertification areas, offering essential data and theoretical insights for the development of control strategies.

Leaching of organic matter from microplastics and its role in disinfection by-product formation

Natural organic matter (NOM) is the primary precursor of disinfection by-products (DBPs). However, as emerging environmental contaminants continue to increase in natural waters, there is a possibility of new precursors of DBPs. We investigated the potential of microplastics (MPs), a growing environmental concern, for leaching organic matter (OM) and subsequent DBP formation. Two experimental setups were used, including chlorinated water containing MPs (Cl2-MP), and non-chlorinated water containing MPs (Non-Cl2-MP), using polyethylene (PE), polyethylene tetrahydrate (PET), polypropylene (PP), and polyvinyl chloride (PVC) as MP materials. The UV absorbance spectra of Cl2-PET/PP/PVC showed peaks at 218 nm, which were significantly correlated with dissolved organic carbon (DOC), indicating lower aromaticity of the leached OM. The DOC concentrations in Cl2-MP samples were several times higher than those in Non-Cl2-MP samples. The leached OM from MPs formed trihalomethanes (THMs) and haloacetic acids (HAAs) in Cl2-MP samples. Among the MPs tested, PVC showed the highest total THM formation after 7 days, followed by PET, PE, and PP. Brominated THMs were predominant, while HAAs were highly chlorinated. THM formation increased with contact time for PE, PET, and PVC, and decreased for PP. Compared to THMs, the concentration of HAAs was low (highest total THM = 185.5 μg/L per g-MP and highest total HAA = 120.7 μg/L per g-MP). Further, the total THM concentration decreased and the total HAA concentration increased over the reaction period, indicating the leaching of different types of OM with increasing contact time. Additionally, the differences in the pattern of DOC leaching and DBP formation among different MPs suggested changes in the leached OM.

Preparation of composite coagulant for the removal of microplastics in water

In this work, a composite flocculant (polyferric titanium sulfate-polydimethyldiallylammonium chloride [PFTS-PDMDAAC]) with a rich spatial network structure was prepared for the treatment of simulated wastewater containing polystyrene (PS) micro-nanoparticles. Characterization results showed that the surface of the PFTS-PDMDAAC was a three-dimensional network polymer of chain molecules that exhibited good thermal stability and formed an amorphous polymer containing multiply hydroxyl-bridged titanium and iron. When n(OH- ) : n(Fe) = 1:2, n(PO4 3- ) : n(Fe) = 0.35, n(Ti) : n(Fe) = 1:8, n(DMDAAC) : n(Fe) = 5:100, and the polymerization temperature is 60°C, the prepared composite flocculant has the best effect. The effects of dosage, pH, and agitation intensity on the flocculation properties of PFTS-PDMDAAC were also studied. The optimal removal rates of PS-μm and haze by PFTS-PDMDAAC were 85.60% and 90.10%, respectively, at a stirring intensity of 200 rpm, a pH of 9.0, and a PFTS-PDMDAAC dosage of 20 mg/L. The flocs produced by the PFTS-PDMDAAC flocculation were large and compact in structure, and the flocculation mechanism was mainly based on adsorption bridging. Kaolin played a promoting role in the process of PS-μm removal by PFTS-PDMDAAC floc and accelerated the formation of large and dense flocs. This study provided a reference for the coagulation method to remove micro-nanopollutants in the actual water treatment process. PRACTITIONER POINTS: A composite flocculant with rich spatial network structure (PFTS-PDMDAAC) was prepared. PFTS-PDMDAAC can effectively remove micro-nano polystyrene (PS) in wastewater. The floc produced by PFTS-PDMDAAC is large and compact in structure. The flocculation mechanism of PFTS-PDMDAAC is mainly adsorption bridging.

The first evidence of microplastic occurrence in mine water: The largest black coal mining area in the Czech Republic

Climate change is creating new challenges for water supply worldwide, making the search for new sources of water vital. As mine water could serve as a potential source, this study investigated the presence of microplastics in water from terminated deep mines in the largest coal basin in the Czech Republic, as well as in water from nearby shallow wells. The particles found were analyzed for size, polymer composition, color and morphology using the ImageJ tool, infrared spectroscopy with Fourier transform (FTIR) and an optical stereomicroscope with a digital camera. Microplastics were detected in all tested sites. Their range accounted for 2.5-17.5 items/L for mine water samples and 2.5-20 items/L for well samples, with fibers being the dominant type. The average width of particles from mine water and wells amounted to 58 µm; 71 µm, length to 655 µm; 501 µm and area to 22,067 µm2; 28,613 µm2, respectively. Blue color was prevalent, among materials, in both cases, plastic coated paper was found dominant to Polyethylene terephthalate (PET), Polyester (PES), Tetrafluoroethylene-perfluoro (Propyl Vinyl Ether) - Copolymer (TFE-PPVE), and polypropylene (PP). The research provides the first evidence of microplastics' presence in underground waters from deep mines and shallow wells in the same area. The data suggest that it is almost impossible to find underground water sources free of microplastic contamination. In this context, atmospheric contamination from mine ventilation and infiltration through terminated mines were identified as potential sources, while infiltration through soil and rock formations is unlikely given the geological composition. The results of this study can serve as a relevant basis for further research on microplastics in mine waters. Additionally, the conclusions can advance the development in remediation technologies of microplastics from deep underground waters and their implementation in practice, particularly in light of upcoming legislation.