Separation and identification of microplastics in marine organisms by TGA-FTIR-GC/MS: A case study of mussels from coastal China

Reducing microplastics in tea infusions released from filter bags by pre-washing method: Quantitative evidences based on Raman imaging and Py-GC/MS

Microplastics released from plastic-based filter bags during tea brewing have attracted widespread attention. Laser confocal micro-Raman and direct classical least squares were used to identify and estimate micron-sized microplastics. Characteristic peaks from pyrolysis-gas chromatography/mass spectrometry of polyethylene terephthalate, polypropylene, and nylon 6 were selected to construct curves for quantification submicron-sized microplastics. The results showed that microplastics released from tea bags in the tea infusions ranged from 80 to 1288 pieces (micron-sized) and 0 to 63.755 μg (submicron-sized) per filter bag. Nylon 6 woven tea bags released far fewer microplastics than nonwoven filter bags. In particular, a simple strategy of three pre-washes with room temperature water significantly reduced microplastic residues with removal rates of 76 %-94 % (micron-sized) and 80 %-87 % (submicron-sized), respectively. The developed assay can be used for the quantitative evaluation of microplastics in tea infusions, and the pre-washing reduced the risk of human exposure to microplastics during tea consumption.

Polystyrene Nanoplastics Induce Lipid Metabolism Disorder by Activating the PERK-ATF4 Signaling Pathway in Mice

In recent years, the study of microplastics (MPs) and nanoplastics (NPs) and their effects on human health has gained significant attention. The impacts of NPs on lipid metabolism and the specific mechanisms involved remain poorly understood. To address this, we utilized high-throughput sequencing and molecular biology techniques to investigate how endoplasmic reticulum (ER) stress might affect hepatic lipid metabolism in the presence of polystyrene nanoplastics (PS-NPs). Our findings suggest that PS-NPs activate the PERK-ATF4 signaling pathway, which in turn upregulates the expression of genes related to lipid synthesis via the ATF4-PPARγ/SREBP-1 pathway. This activation leads to an abnormal accumulation of lipid droplets in the liver. 4-PBA, a known ER stress inhibitor, was found to mitigate the PS-NPs-induced lipid metabolism disorder. These results demonstrate the hepatotoxic effects of PS-NPs and clarify the mechanisms of abnormal lipid metabolism induced by PS-NPs.

Identification and morphological characterization of different types of plastic microparticles

The knowledge of the polymeric composition of microplastics (MPs) is interesting because offers useful information on the resistance, durability, and degradability of these materials, also allowing progress in the control of this contamination. However, there is currently a lack of reliable standardized methods for the identification, and characterization of the plastic microparticles. This work uses different techniques in a complementary manner for the identification, and characterization of MPs that more frequently are found in the environment. A total of 10 types of plastics were collected (polystyrene (PS), polyethylene terephthalate (PETE), polyethylene (PE), high- and low-density polyethylene (HDPE and LDPE, respectively), polyvinyl chloride (PVC), polypropylene (PP), polytetrafluoroethylene (PTFE), Polyamide (PA, Nylon 6,6) and poly-carbonate (PC)) and their chemical identification were analyzed by reflectance-attenuated infrared (FTIR-ATR). Furthermore, the samples were observed using light microscopy, and scan-ning electron microscopy (SEM). Also, staining with 12 different dyes was performed to improve the identification of microplastics. The results of this study revealed that PETE, PE, HDPE and LDPE, whose SEM images exhibited smoothness and flat uniformity of their surface, were not (or less) susceptible to adsorb staining solutions while PP, PA, PVC, and PTFE, were capable of adsorbing the dye solutions.

Effects of arsenic on the transport and attachment of microplastics in porous media

Understanding the impact of arsenic (As(III), inorganic pollutant widely present in natural environments) on microplastics (MPs, one type of emerging contaminants) mobility is essential to predict MPs fate and distribution in soil-groundwater systems, yet relevant research is lacking. This study explored the effects of As(III) copresent in suspensions (0.05, 0.5, and 5 mg/L) on MPs transport/attachment behaviors in porous media containing varied water contents (θ = 100 %, 90 %, and 60 %) under different ionic strengths (5, 10, and 50 mM NaCl) and flow rates (2, 4, and 8 m/day). Despite solution ionic strengths, flow rates, porous media water contents, sizes, and surface charges of MPs, with coexisting humic acid, and in actual water samples, As(III) of three concentrations increased MPs transport in quartz sand and natural sandy soil. The increased electrostatic repulsion between MPs and sand caused by the altered MPs surface charge via the adsorption of As(III) together with steric repulsion from As(III) in solution contributed to the promoted MPs mobility in porous media. The occupying attachment sites by As(III) partially contributed to the increased mobility of MPs with negative surface charge in porous media. Clearly, As(III) coexisting in suspensions would enhance MPs transport in porous media, increasing MPs environment risks.

In situ profiling reveals spatially metabolic injury in the initiation of polystyrene nanoplastic-derived intestinal epithelial injury in mice

Despite increasing concerns regarding the harmful effects of plastic-induced gut injury, mechanisms underlying the initiation of plastic-derived intestinal toxicity remain unelucidated. Here, mice were subjected to long-term exposure to polystyrene nanoplastics (PS-NPs) of varying sizes (80, 200, and 1000 nm) at doses relevant to human dietary exposure. PS-NPs exposure did not induce a significant inflammatory response, histopathological damage, or intestinal epithelial dysfunction in mice at a dosage of 0.5 mg/kg/day for 28 days. However, PS-NPs were detected in the mouse intestine, coupled with observed microstructural changes in enterocytes, including mild villous lodging, mitochondrial membrane rupture, and endoplasmic reticulum (ER) dysfunction, suggesting that intestinal-accumulating PS-NPs resulted in the onset of intestinal epithelial injury in mice. Mechanistically, intragastric PS-NPs induced gut microbiota dysbiosis and specific bacteria alterations, accompanied by abnormal metabolic fingerprinting in the plasma. Furthermore, integrated data from mass spectrometry imaging-based spatial metabolomics and metallomics revealed that PS-NPs exposure led to gut dysbiosis-associated host metabolic reprogramming and initiated intestinal injury. These findings provide novel insights into the critical gut microbial-host metabolic remodeling events vital to nanoplastic-derived-initiated intestinal injury.

Comparison of ATR-FTIR and NIR spectroscopy for identification of microplastics in biosolids

Biosolids are considered a potentially major input of microplastics (MPs) to agricultural soils. Our study aims to identify the polymeric origin of MPs extracted from biosolid samples by comparing their Attenuated Total Reflection (ATR) - Fourier-transform infrared (FTIR) spectra with the corresponding near-infrared (NIR) spectra. The reflectance spectra were preprocessed by Savitzky-Golay (SG), first derivative (FD) and compared with analogous spectra acquired on a set of fifty-two selected commercial plastic (SCP) materials collected from readily available products. According to the results portrayed in radar chart and built from both ATR-FTIR and NIR spectral datasets, the MPs showed high correlations with polymers such as polyethylene (LDPE, HDPE), polyethylene terephthalate (PET), polystyrene (PS), polypropylene (PP) and polyamide (PA), determined in SCP samples. Each unknown MP sample had on average three or more links to several types of SCP, according to the correlation coefficients for each polymer ranging from 0.7 up to 1. The comparison analysis classified the majority of MPs as composed mainly by LDPE/HDPE, according to the top correlation coefficients (r > 0.90). PP and PET were better identified with NIR than ATR-FTIR. In contrast to ATR-FTIR analysis, NIR was unable to identify PS. Based on these results, the primary sources of MPs in the biosolids could be identified as discarded consumer packaging (containers, bags, bottles) and fibers from laundry, disposable glove, and cleaning cloth. SYNOPSIS: Microplastics (MPs) are considered contaminants of emerging concern. This study compares two simple and fast spectroscopy techniques to identify microplastics in the biosolid matrix.

Emerging isolation and degradation technology of microplastics and nanoplastics in the environment

Microplastics (MPs, less than 5 mm in size) are widely distributed in surroundings in various forms and ways, and threaten ecosystems security and human health. Its environmental behavior as pollutants carrier and the after-effects exposed to MPs has been extensively exploited; whereas, current knowledge on technologies for the separation and degradation of MPs is relatively limited. It is essential to isolate MPs from surroundings and/or degrade to safe levels. This in-depth review details the origin and distribution of MPs. Provides a comprehensive summary of currently available MPs separation and degradation technologies, and discusses the mechanisms, challenges, and application prospects of these technologies. Comparison of the contribution of various separation methods to the separation of NPs and MPs. Furthermore, the latest research trends and direction in bio-degradation technology are outlooked.

Visual detection of microplastics using Raman spectroscopic imaging

As a new type of pollutant in the marine environment and terrestrial ecosystems, microplastics have attracted widespread attention. Assessing the ecological risk of microplastics relies on accurately detecting small-sized particles in the environment. Microplastics exhibit unique "fingerprint" characteristics in Raman spectroscopy, making them suitable for rapid identification. In this study, we achieved visualization of microplastics through pseudo-color images generated by Raman spectroscopy imaging. Pseudo-color imaging maps were generated by selecting characteristic peaks and the classical least-squares fitting method was used to visually represent the distribution of different microplastics. The study explored the potential of Raman spectroscopy and its mapping mode in distinguishing various types of mixed microplastics and demonstrated that this approach can identify microplastics in complex environmental samples. Specifically, a cloud-point extraction followed by membrane filtration method was successfully applied to identifying mixed-component microplastics. In summary, the category, quantity, location, and differentiation of microplastics can be accurately analyzed by Raman spectroscopy, which provides a basis for assessing their ecological risk.

When microplastics meet electroanalysis: future analytical trends for an emerging threat

Microplastics are a major modern challenge that must be addressed to protect the environment, particularly the marine environment. Microplastics, defined as particles ≤5 mm, are ubiquitous in the environment. Their small size for a relatively large surface area, high persistence and easy distribution in water, soil and air require the development of new analytical methods to monitor their presence. At present, the availability of analytical techniques that are easy to use, automated, inexpensive and based on new approaches to improve detection remains an open challenge. This review aims to outline the evolution and novelties of classical and advanced methods, in particular the recently reported electroanalytical detectors, methods and devices. Among all the studies reviewed here, we highlight the great advantages of electroanalytical tools over spectroscopic and thermal analysis, especially for the rapid and accurate detection of microplastics in the sub-micron range. Finally, the challenges faced in the development of automated analytical methods are discussed, highlighting recent trends in artificial intelligence (AI) in microplastics analysis.

Contribution of free hydroxyl radical to the formation of micro(nano)plastics and release of additives during polyethylene degradation in water

The omnipresence of secondary microplastics (MPs) in aquatic ecosystems has become an increasingly alarming public health concern. Hydrogen peroxide (H2O2) is an important oxidant in nature and the most stable reactive oxygen species occurred in natural water. In order to explore the contribution of free ˙OH generated from H2O2-driven Fenton-like reactions on the degradation of polyethylene (PE) and generation of micro- and nano-scale plastics in water, a batch experiment was conducted over a period of 620 days in water treated with micromolar H2O2. The incorporation of H2O2 in water induced the formation of flake-like micro(nano)-sized particles due to intensified oxidative degradation of PE films. The presence of ˙OH significantly enhanced the generation of both micro- and nano-scale plastics exhibiting a higher proportion of particles in the range of 200-500 nm compared to the Control. Total organic carbon in the H2O2 treated solution was nearly 174-fold higher than that of the Control indicating a substantial liberation of organic compounds due to the oxidative degradation of native carbon chain of PE and subsequent decomposition of its additives. The highly toxic butylated hydroxytoluene detected from the gas chromatography-mass spectrometry (GC-MS) analysis implied the toxicological behavior of secondary micro(nano)plastics influenced by the oxidation and decomposition processes The findings from this study further expand our understanding of the role of ˙OH in degrading PE micro-scale plastics into nanoparticles as an implication of naturally occurring H2O2 in aquatic environments. In the future, further attention should be drawn to the underlying mechanisms of H2O2-driven in-situ Fenton reaction mediated by natural environmental conditions targeting the alternation of light and darkness on the oxidative degradation of plastics.

Micro(nano)plastics in commercial foods: A review of their characterization and potential hazards to human health

Micro (nano)plastics (MNPs) are pollutants of worldwide concern for their ubiquitous environmental presence and associated impacts. The higher consumption of MNPs contaminated commercial food can cause potential adverse human health effects. This review highlights the evidence of MNPs in commercial food items and summarizes different sampling, extraction, and digestion techniques for the isolation of MNPs, such as oxidizing digestion, enzymatic digestion, alkaline digestion and acidic digestion. Various methods for the characterization and quantification of microplastics (MPs) are also compared, including μ-Raman spectroscopy, μ-Fourier transform infrared spectroscopy (FTIR), thermal analysis and Scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDX). Finally, we share our concerns about the risks of MNPs to human health through the consumption of commercial seafood. The knowledge of the potential human health impacts at a subcellular or molecular level of consuming mariculture products contaminated with MNPs is still limited. Moreover, MNPs are somewhat limited, hard to measure, and still contentious. Due to the nutritional significance of fish consumption, the risk of exposure to MNPs and the associated health effects are of the utmost importance.

Recent Study of Separation and Identification of Micro- and Nanoplastics for Aquatic Products

Micro- and nanoplastics (MNPs) are polymeric compounds widely used in industry and daily life. Although contamination of aquatic products with MNPs exists, most current research on MNPs focuses on environmental, ecological, and toxicological studies, with less on food safety. Currently, the extent to which aquatic products are affected depends primarily on the physical and chemical properties of the consumed MNPs and the content of MNPs. This review presents new findings on the occurrence of MNPs in aquatic products in light of their properties, carrier effects, chemical effects, seasonality, spatiality, and differences in their location within organisms. The latest studies have been summarized for separation and identification of MNPs for aquatic products as well as their physical and chemical properties in aquatic products using fish, bivalves, and crustaceans as models from a food safety perspective. Also, the shortcomings of safety studies are reviewed, and guidance is provided for future research directions. Finally, gaps in current knowledge on MNPs are also emphasized.

Development of a solubility parameter calculation-based method as a complementary tool to traditional techniques for indoor dust microplastic determination and risk assessment

Herein, a method based on solubility parameter calculation was first used to analyze microplastics in indoor dust. The limit of quantification (LOQ) reached 0.2 mg/g, and the result of reference material SRM 2585 (n = 3) was 14.8 mg/g ± 1.8 %, suggesting satisfying sensitivity and precision. Recoveries of spiking experiments were > 80 % with no obvious matrix interferences observed, except ethylene propylene diene monomer (EPDM) MPs. Further, 69 indoor dust samples were analyzed to verify the method and to assess exposure scenarios for graduate students in Tianjin, China. EPDM was identified in an indoor environment for the first time as the second most widely detected type after PET in this work. The mass-based result is complementary to the outcomes from thermogravimetric analysis-gas chromatography-mass spectrometry and laser direct infrared imaging. Significant correlations were found between total organic carbon (TOC), microplastics, and BDE-209 concentrations, indicating microplastics important contaminant vectors in indoor dust. Dormitory stays and PET contributed the most to health risks among the three exposure scenarios and detected four polymers, respectively. This work provides an approach with the potential for the standardized determination of microplastics in complex environmental matrices and reveals exposure characteristics of indoor dust microplastics.

Mass concentration and distribution characteristics of microplastics in landfill mineralized refuse using efficient quantitative detection based on Py-GC/MS

Landfilling is the most traditional disposal method of domestic waste. Plastic waste in landfill sites could degrade to microplastics (MPs) and diffuse to the surrounding environment with leachate. However, MPs pollution in landfill mineralized refuse has not been well recognized. In the present research, a detection method for mixed MPs of polyethylene (PE), polypropylene (PP), and polystyrene (PS) based on Py-GC/MS was established and verified. The method is suitable for the rapid quantitative detection of large-batch of complex solid matrix samples, with an average deviation of less than 10%. Based on the method, samples from a landfill site in South China were studied, where PE was found to be the main component. The total concentration of MPs in mineralized refuse was 7.62 kg/t in the old area and 5.49 kg/t in the young area. Further analysis showed that the content of MPs was correlated with that of plastic waste and the landfill age, indicating that a considerable proportion was secondary MPs. The reserves of MPs in landfill sites may have reached an alarming number. In the absence of adequate safeguards, quantities of MPs may spread from the landfill sites, resulting in serious pollution of the surrounding soil and groundwater.

Microplastics in food - a critical approach to definition, sample preparation, and characterisation

The ubiquity of microplastics (MPs) is a more and more frequently brought up topic. The fact that such particles are present in food raises particular concern. Information regarding the described contamination is incoherent and difficult to interpret. Problems appear already at the level of the definition of MPs. This paper will discuss ways of explaining the concept of MPs and methods used for its analysis. Isolation of characterised particles is usually performed using filtration, etching and/or density separation. Spectroscopic techniques are commonly applied for analysis, whereas visual evaluation of the particles is possible thanks to microscopic analysis. Basic information about the sample can be obtained by the combination of Fourier Transform Infrared spectroscopy or Raman spectroscopy and microscopy or using the thermal method combined with spectroscopy or chromatography. The unification of the research methodology will allow a credible assessment of the influence of this pollution coming from food on health.

Nano and microplastics occurrence in wastewater treatment plants: A comprehensive understanding of microplastics fragmentation and their removal

Nano/microplastic (NP/MP) pollution is a growing concern for the water environment. Wastewater treatment plants (WWTPs) are considered the major recipients of MP before discharging into local waterbodies. MPs enter WWTPs mainly from synthetic fibers through washing activities and personal care products. To control and prevent NP/MP pollution, it is essential to have a comprehensive understanding of their characteristics, fragmentation mechanisms, and the effectiveness of the current treatment processes used in WWTPs for NP/MP removal. Therefore, the objectives of this study are to (i) understand the detailed mapping of NP/MP in the WWTP, (ii) understand the fragmentation mechanisms of MP into NP, and (iii) investigate the removal efficiency of NP/MP by existing processes in the WWTP. This study found that fiber is the dominant shape of MP, and polyethylene, polypropylene, polyethylene terephthalate, and polystyrene are the major polymer type of MP in wastewater samples. Crack propagation and mechanical breakdown of MP due to water shear forces induced by treatment facilities (e.g., pumping, mixing, and bubbling) could be the major causes for NP generation in the WWTP. Conventional wastewater treatment processes are ineffective for the complete removal of MPs. Although these processes are capable of removing ∼95% of MPs, they tend to accumulate in sludge. Thus, a significant number of MPs may still be released into the environment from WWTPs on a daily basis. Therefore, this study suggested that using DAF process in the primary treatment unit can be an effective strategy to control MP in the initial stage before it goes to the secondary and tertiary stage.

Comprehensive analysis of common polymers using hyphenated TGA-FTIR-GC/MS and Raman spectroscopy towards a database for micro- and nanoplastics identification, characterization, and quantitation

Environmental contamination by micro- and nanoplastics (MNPs) is well documented with potential for their increased accumulation globally. Growing public concern over environmental, ecological, and human exposure to MNPs has led to exponential increase in publications, news articles, and reports (Casillas et al., 2023). Significant knowledge gap exists in standardized analytical methods for the identification and quantification of MNPs from real world environmental samples. Here, we report comprehensive datasets utilizing thermogravimetric analyzer (TGA) coupled to a Fourier transformed infrared spectrometer (FTIR) and a gas chromatography/mass spectrometer (GC/MS) with corresponding Raman spectral data for the most common polymers documented to be present in the environment (35 plastics of 12 polymer types), to serve as a base line reference for the identification and quantitation of MNPs. Various parameters for TGA-FTIR-GC/MS data acquisition were optimized. Commercial consumer plastic product compositions were identified using this analytical database. Case studies to showcase the utility of the method for polymer mixtures analysis is included. This dataset would serve towards the development of a collaborative, global, comprehensive, and curated public database for the identification of various MNPs and mixtures.

Microplastics identification in water by TGA-DSC Method: Maharloo Lake, Iran

Nowadays, one of the biggest challenges is the lack of coordination between the microplastic identification methods used by researchers. To advance our global understanding of microplastic contamination and address the knowledge gaps, we require acceptable or similar identification methods or instruments designed to support the quantitative characterization of the microplastics data. In the current study, we focused on the thermogravimetric analysis (TGA) with differential scanning calorimetry (DSC) method which is usually used experimentally by other researchers, while we tried to look at this method in a real aquatic environment, Maharloo Lake and its Rivers. A number of 22 sites were chosen for sampling microplastics from water. The mean and median of total organic matter percentage for rivers samples (mean = 88%;median = 88%) was similar to the Maharloo lake (mean = 88.33%; median = 89%), suggesting the existence of a robust potential sink. The differentiation of the organic matter part into labile (e.g., carbon aliphatic and polysaccharides), recalcitrant (e.g., aromatic compounds and most plastics), and refractory fractions was implemented and the results indicated that labile organic matter was dominant in both the lake and the rivers, while recalcitrant and refractory fractions were lower. The river's average labile and refractory fractions were similar to the lake. Although the overall results of the study show combining TGA techniques with other analytical procedures can improve the technical quality of polymers, interpreting the complex information of those measurements requires a high level of expertise and the technology is still maturing.

Nanoelectromechanical Infrared Spectroscopy with In Situ Separation by Thermal Desorption: NEMS-IR-TD

We present a novel method for the quantitative analysis of mixtures of semivolatile chemical compounds. For the first time, thermal desorption is integrated directly with nanoelectromechanical infrared spectroscopy (NEMS-IR-TD). In this new technique, an analyte mixture is deposited via nebulization on the surface of a NEMS sensor and subsequently desorbed using heating under vacuum. The desorption process is monitored in situ via infrared spectroscopy and thermogravimetric analysis. The resulting spectro-temporal maps allow for selective identification and analysis of the mixture. In addition, the corresponding thermogravimetric data allow for analysis of the desorption dynamics of the mixture components. As a demonstration, caffeine and theobromine were selectively identified and quantified from a mixture with a detection limit of less than 6 pg (about 30 fmol). With its exceptional sensitivity, NEMS-IR-TD allows for the analysis of low abundance and complex analytes with potential applications ranging from environmental sensing to life sciences.

Mass spectrometry-based multimodal approaches for the identification and quantification analysis of microplastics in food matrix

Background

Microplastics (MPs) and nanoplastics (NPs) have become emerging contaminants worldwide in food matrices. However, analytical approaches for their determination have yet to be standardized. Therefore, a systematic study is urgently needed to highlight the merits of mass spectrometry (MS) based methods for these applications.

Purpose

The aim of the study is to review the current status of MS-based multimodal analysis for the determination of MPs in food matrices.

Methods

Web of Science and Google Scholar databases were searched and screened until Jan. 2023. Inclusion criteria: “publication years” was set to the last decades, “English” was selected as the “language,” and “research area” was set to environmental chemistry, food analysis and polymer science. The keywords were “microplastics,” “nanoplastics,” “determination,” “identification/quantification,” and “mass spectrometry.”

Results

Traditional spectrometry techniques offer good abilities to conduct the multimodal analysis of MPs in terms of color, shape and other morphologies. However, such technologies have some limitations, in particular the relatively high limits of detection. In contrast, MS-based methods supply excellent supplements. In MS-based methods, gas chromatographic-mass spectrometry (GC-MS), and LC-MS/MS were selected as representative methods for determining MPs in the food matrices, while specialized MS methods (i.e., MALDI-ToF MS and ToF-SIMS) were considered to offer great potential in multimodal analysis of MPs especially when interfaced with the imaging systems.

Significance

This study will contribute to gaining a deeper insight into the assessment of the exposure levels of MPs in human body, and may help build a bridge between the monitoring studies and the toxicology field.

Quantification of polyethylene terephthalate micro- and nanoplastics in domestic wastewater using a simple three-step method

Concerns about impact of small plastic particles, known as microplastics (<5 mm) and nanoplastics (<1 μm), together abbreviated as MNP, on the environment and on human health have increased in recent years. Polyethylene terephthalate (PET) microplastics have been detected previously in different environmental samples including freshwater and wastewater sludge. In the present study, we target all small plastic particles of PET with a diameter smaller than 5 mm ('PET MNP'). A simple three-step method of drying, (in matrix) PET depolymerization in ethylene glycol and liquid chromatography-mass spectrometry (LC-MS) analysis, was applied for the quantification of PET MNP in influents and effluents collected from ten Dutch wastewater treatment plants. The PET recovery was 98 % in the wastewater matrix. The limits of detection (LOD) for PET in influents and effluents were 2.0 μg/L and 1.2 μg/L, respectively. PET MNP was detected in all the influents (ranging from 24.9 μg/L to 680 μg/L) and most of the effluents (ranging from <LOD to 23.1 μg/L). The results of the present study confirmed that WWTP effluents can be a source of PET MNP in the environment.

A short review on the recent method development for extraction and identification of microplastics in mussels and fish, two major groups of seafood

The prevalence of microplastics in the marine environment poses potential health risks to humans through seafood consumption. Relevant data are available but the diverse analytical approaches adopted to characterise microplastics have hampered data comparison among studies. Here, the techniques for extraction and identification of microplastics are summarised among studies of marine mussels and fish, two major groups of seafood. Among the reviewed papers published in 2018-2021, the most common practice to extract microplastics was through tissue digestion in alkaline chemicals (46 % for mussels, 56 % for fish) and oxidative chemicals (28 % for mussels, 12 % for fish). High-density solutions such as sodium chloride could be used to isolate microplastics from other undigested residues by flotation. Polymer analysis of microplastics was mainly carried out with Fourier-transform infrared (FTIR) spectroscopy (58 % for both mussels and fish) and Raman spectroscopy (14 % for mussels, 8 % for fish). Among these methods, we recommend alkaline digestion for microplastic extraction, and the automated mapping approach of FTIR or Raman spectroscopy for microplastic identification. Overall, this study highlights the need for a standard protocol for characterising microplastics in seafood samples.

Prevalence and risk assessment of microplastics in the Nile Delta estuaries: "The Plastic Nile" revisited

Recent research is directed toward studying plastic pollution in rivers, and estuaries due to the importance of freshwater bodies in all aspects of life. The river deltas and estuaries are interesting for studying the flux of plastics into the oceans. The Nile River has been identified as a hot spot of plastic litter flux in the eastern Mediterranean basin. In addition, it was nicknamed "Plastic Nile", yet this major river is largely unexplored with a lack of field measurements and adequate surveys. The current study was based on bridging this scientific gap. Three trips were conducted, covering 30 km in the Rosetta branch and 23 km in the Damietta branch, during the high water level in summer 2021, and 10 km off the inlet of Lake Burullus, in spring 2021. Microplastics in surface water ranged from 761 ± 319 to 1718 ± 1008 MPs/m³, and from 167 ± 137 to 1630 ± 1303 MPs/kg of dry sediments. Land use/ land cover mapping using Sentinel-2 images showed several sources of pollution that contribute to plastic contamination in the study area. Thermal analysis indicated seven plastic polymers; including, PE, PP, PET, PEVA, and PTFE, using discarded plastic products as reference materials. Microplastics were composed of colored and glossy fragments of sizes <500 μm, originating from land-based sources. Pollution load, polymer risk assessment, and ecological risk indices were calculated. Based on field observations macro-plastics were retained within the extensive network of infrastructure and dam systems. 80-106 billion MPs/year were estimated to flux from the Nile estuaries into the Mediterranean Sea. The current situation urges the development of binding plans to reduce plastic waste in the Nile Delta, as well as setting environmental monitoring points along the Deltaic coast.

Mass Spectrometry as an Analytical Tool for Detection of Microplastics in the Environment

Plastic particles smaller than 5 mm accumulate in aqueous, terrestrial, and atmospheric environments and their discovery has been a serious concern when it comes to eco-toxicology and human health risk assessment. In the following review, the potential of mass spectrometry (MS) for the detection of microplastic (MP) pollutants has been elaborately reviewed. The use of various mass spectrometric techniques ranging from gas chromatography–mass spectrometry (GC-MS), liquid chromatographic mass spectrometric (LC-MS) to matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS), including their variants, have been reviewed. The lapses in the detection system have been addressed and future recommendations proposed. The challenges facing microplastics and their detection have been discussed and future directions, including mitigation methods, have been presented.

Spontaneous Imbibition Oil Recovery by Natural Surfactant/Nanofluid: An Experimental and Theoretical Study

Organic surfactants have been utilized with different nanoparticles in enhanced oil recovery (EOR) operations due to the synergic mechanisms of nanofluid stabilization, wettability alteration, and oil-water interfacial tension reduction. However, investment and environmental issues are the main concerns to make the operation more practical. The present study introduces a natural and cost-effective surfactant named Azarboo for modifying the surface traits of silica nanoparticles for more efficient EOR. Surface-modified nanoparticles were synthesized by conjugating negatively charged Azarboo surfactant on positively charged amino-treated silica nanoparticles. The effect of the hybrid application of the natural surfactant and amine-modified silica nanoparticles was investigated by analysis of wettability alteration. Amine-surfactant-functionalized silica nanoparticles were found to be more effective than typical nanoparticles. Amott cell experiments showed maximum imbibition oil recovery after nine days of treatment with amine-surfactant-modified nanoparticles and fifteen days of treatment with amine-modified nanoparticles. This finding confirmed the superior potential of amine-surfactant-modified silica nanoparticles compared to amine-modified silica nanoparticles. Modeling showed that amine surfactant-treated SiO₂ could change wettability from strongly oil-wet to almost strongly water-wet. In the case of amine-treated silica nanoparticles, a strongly water-wet condition was not achieved. Oil displacement experiments confirmed the better performance of amine-surfactant-treated SiO₂ nanoparticles compared to amine-treated SiO₂ by improving oil recovery by 15%. Overall, a synergistic effect between Azarboo surfactant and amine-modified silica nanoparticles led to wettability alteration and higher oil recovery.

Micro(nano)plastics in food system: potential health impacts on human intestinal system

Micro(nano)plastics (MNPs) in human food system have been broadly recognized by researchers and have drawn an increasing public attention to their potential health risks, particularly the risk to the intestinal system regarding the long-term exposure to MNPs through food consumption. This study aims to review the environmental properties (formation and composition) of MNPs and MNPs pollution in human food system following the order of food production, food processing and food consumption. The current analytic and identical technologies utilized by researchers are also summarized in this review. In fact, parts of commonly consumed food raw materials, processed food and the way to take in food all become the possible sources for human MNPs ingestion. In addition, the available literatures investigating MNPs-induced intestinal adverse effect are discussed from in vitro models and in vivo mammalian experiments, respectively. Particle translocation, cytotoxicity, damaged gut barrier, intestinal inflammation as well as microbial alteration are mostly reported. Moreover, the practical remediation strategies for MNPs pollution are also illustrated in the last section. This review is expected to provide a research insight for foodborne MNPs and arouse more public awareness of MNPs pollution in food and potential risk for human intestinal health.

The Optimal Concentration of Nanoclay Hydrotalcite for Recovery of Reactive and Direct Textile Colorants

Concerns about the health of the planet have grown dramatically, and the dyeing sector of the textile industry is one of the most polluting of all industries. Nanoclays can clean dyeing wastewater using their adsorption capacities. In this study, as a new finding, it was possible to analyze and quantify the amount of metal ions substituted by anionic dyes when adsorbed, and to determine the optimal amount of nanoclay to be used to adsorb all the dye. The tests demonstrated the specific amount of nanoclay that must be used and how to optimize the subsequent processes of separation and processing of the nanoclay. Hydrotalcite was used as the adsorbent material. Direct dyes were used in this research. X-ray diffraction (XRD) patterns allowed the shape recovery of the hydrotalcite to be checked and confirmed the adsorption of the dyes. An FTIR analysis was used to check the presence of characteristic groups of the dyes in the resulting hybrids. The thermogravimetric (TGA) tests corroborated the dye adsorption and the thermal fastness improvement. Total solar reflectance (TSR) showed increased radiation protection for UV-VIS-NIR. Through the work carried out, it has been possible to establish the maximum adsorption point of hydrotalcite.

Extensive investigation and beyond the removal of micro-polyvinyl chloride by microalgae to promote environmental health

Microplastics (MPs) remediation via algae could be a prospective strategy to address MPs pollution concerns. In this study, Chlorella sp. GEEL-08 was exposed to different gradient concentrations ranging from 0 to 200 mg L^-1 of polyvinyl chloride (PVC_0.2μm). Microalgal growth, total nitrogen (TN), total phosphorus (TP), and cations (Cu, Zn, Na, and K) removal were investigated. The oxidative stress enzymes such as superoxide dismutase (SOD) and malonaldehyde (MDA) were also assessed. The addition of 50 mg L^-1 mPVC resulted in the highest growth along with >99% removal of nutrients (TN and TP) and >80% removal of cations. However, the addition of 100-200 mg L^-1 mPVC inhibited microalgal growth by 8.8-12.3%. The stress-induced by mPVC was highly observed at 200 mg L^-1 mPVC on the 4th d with 70.8 U mg_prot^-1 and 62.3 nmol mg_prot^-1 of SOD and MDA, respectively. Fourier-transform infrared spectroscopy (FTIR) spectra confirmed that microalgal biomass retained mPVC. Thermogravimetric analysis/derivative thermogravimetric analysis (TGA/DTG) spectra showed that the organic matter of microalgal biomass attached with mPVC was decomposed faster than control, indicating the possibilities of using this biomass for pyrolysis and the formation of bio-products.

The role of microplastics in altering arsenic fractionation and microbial community structures in arsenic-contaminated riverine sediments

The ability of microplastics (MPs) to interact with environmental pollutants is of great concern. Riverine sediments, as sinks for multi-pollutants, have been rarely studied for MPs risk evaluation. Meanwhile, MPs generated from biodegradable plastics are questioning the safety of the promising materials. In this study, we investigated the effects of typical non-degradable polyethylene (PE) and biodegradable polylactic acid (PLA) MPs on sediment enzymes, arsenic (As) fractionation, and microbial community structures in As-contaminated riverine sediments. The results indicated that the presence of MPs (1% and 3%, w/w) led As transformed into more labile and bioavailable fractions in riverine sediments, especially under higher As and MPs levels. Analysis on microbial activities and community structures confirmed the strong potential of MPs in inhibiting microbial activities and shifting bacterial community succession patterns through enrichment of certain microbiota. Moreover, biodegradable PLA MPs presented stronger alterations in arsenic fractionation and microbial community structures than PE MPs did, which might be jointly attributed to adsorption behaviors, microbial alterations, and potential PLA degradation behaviors. The study indicated that MPs contamination increased As mobility and bioavailability, and shifted microbial communities in riverine sediments. Moreover, biodegradable MPs might lead to stronger microbial alterations and increases in As bioavailability, acting as a threat to ecological safety, which needed further exploration.

Advanced microplastic monitoring using Raman spectroscopy with a combination of nanostructure-based substrates

Micro(nano)plastic (MNP) pollutants have not only impacted human health directly, but are also associated with numerous chemical contaminants that increase toxicity in the natural environment. Most recent research about increasing plastic pollutants in natural environments have focused on the toxic effects of MNPs in water, the atmosphere, and soil. The methodologies of MNP identification have been extensively developed for actual applications, but they still require further study, including on-site detection. This review article provides a comprehensive update on the facile detection of MNPs by Raman spectroscopy, which aims at early diagnosis of potential risks and human health impacts. In particular, Raman imaging and nanostructure-enhanced Raman scattering have emerged as effective analytical technologies for identifying MNPs in an environment. Here, the authors give an update on the latest advances in plasmonic nanostructured materials-assisted SERS substrates utilized for the detection of MNP particles present in environmental samples. Moreover, this work describes different plasmonic materials-including pure noble metal nanostructured materials and hybrid nanomaterials-that have been used to fabricate and develop SERS platforms to obtain the identifying MNP particles at low concentrations. Plasmonic nanostructure-enhanced materials consisting of pure noble metals and hybrid nanomaterials can significantly enhance the surface-enhanced Raman scattering (SERS) spectra signals of pollutant analytes due to their localized hot spots. This concise topical review also provides updates on recent developments and trends in MNP detection by means of SERS using a variety of unique materials, along with three-dimensional (3D) SERS substrates, nanopipettes, and microfluidic chips. A novel material-assisted spectral Raman technique and its effective application are also introduced for selective monitoring and trace detection of MNPs in indoor and outdoor environments.

Differential staining lowers the false positive detection in a novel volumetric measurement technique of microplastics

A novel method for the volumetric detection of microplastics in various environmental (soil, water) and food (fish, meat) matrices was developed. The method is based on the Nile Red staining of microplastics while eliminating probable interference by other organic polymers such as lignin, chitin, cellulosic materials, and other organic substances using a mixture of three water-based dyes (Calcofluor White, Evans Blue, and 4,6-diamidino-2-phenylindole [DAPI]). The excitation/emission 'sweet spot' was determined for water based blue dyes to detect them in a single channel for effective elimination of probable contaminations. Detection of microplastic particles using the Nile Red method was validated by comparing with traditional detection of microplastics via Fourier transform infrared spectroscopy (FTIR). Volumetric measurements of the microplastics present in environmental samples were made possible using Z-stack confocal microscopy images backed by threshold-based 3D segmentation. Regularly shaped microplastic materials were used to validate the volumetric measurement method. The proposed volumetric determination method will be very useful for screening microplastics in diverse media and improving the prevailing method using FTIR.

Thermal Stability of Fluorescent Chitosan Modified with Heterocyclic Aromatic Dyes

Fluorescent biopolymer derivatives are increasingly used in biology and medicine, but their resistance to heat and UV radiation, which are sterilizing agents, is relatively unknown. In this work, chitosan (CS) modified by three different heterocyclic aromatic dyes based on benzimidazole, benzothiazole, and benzoxazole (assigned as IBm, BTh, and BOx) has been studied. The thermal properties of these CS derivatives have been determined using the Thermogravimetric Analysis coupled with the Fourier Transform Infrared spectroscopy of volatile degradation products. The influence of UV radiation on the thermal resistance of modified, fluorescent chitosan samples was also investigated. Based on the temperature onset as well as the decomposition temperatures at a maximal rate, IBm was found to be more thermally stable than BOx and BTh. However, this dye gave off the most volatile products (mainly water, ammonia, carbon oxides, and carbonyl/ether compounds). The substitution of dyes for chitosan changes its thermal stability slightly. Characteristic decomposition temperatures in modified CS vary by a few degrees (<10 °C) from the virgin sample. Considering the temperatures of the main decomposition stage, CS-BOx turned out to be the most stable. The UV irradiation of chitosan derivatives leads to minor changes in the thermal parameters and a decrease in the number of volatile degradation products. It was concluded that the obtained CS derivatives are characterized by good resistance to heat and UV irradiation, which extends the possibilities of using these innovative materials.

Tailoring moisture electroactive Ag/Zn@cotton coupled with electrospun PVDF/PS nanofibers for antimicrobial face masks

Face mask has become an essential and effective apparatus to protect human beings from air pollution, especially the air-borne pathogens. However, most commercial face masks can hardly achieve good particulate matters (PMs) and high bactericidal efficacy concurrently. Herein, a bilayer structured composite filter medium with built-in antimicrobial activities was constructed by combining cotton woven modified by magnetron sputtered Ag/Zn coatings and electrospun poly(vinylidene fluoride)/polystyrene (PVDF/PS) nanofibers. With the benefit of external moisture, an electrical stimulation was generated inside the composite fabric and thus endowed the fabric antimicrobial function. The resultant composite fabric presented conspicuous performance for integrated air pollution control, high filtration performance towards PM_0.3 (99.1%, 79.2 Pa) and exceptional interception ratio against Escherichia coli (99.64%) and Staphylococcus aureus (98.75%) within 20 min contact. The high efficiency contact sterilization function of the bilayer fabric could further potentially promote disinfection and reuse of the filter media. This work may provide a new perspective on designing high-performance face mask media for public health protection.

Microplastic-associated pathogens and antimicrobial resistance in environment

The ubiquitous use of microplastics and their release into the environment especially the water bodies by anthropogenic/industrial activities are the major resources for microplastic contamination. The widespread and often injudicious use of antimicrobial drugs or antibiotics in various sectors including human health and hygiene, agriculture, animal husbandry and food industries are leading to the release of antibiotics into the wastewater/sewage and other water bodies, particularly in urban setups and thus leads to the antimicrobial resistance (AMR) in the microbes. Microplastics are emerging as the hubs as well as effective carriers of these microbial pathogens beside their AMR-genes (ARGs) in marine, freshwater, sewage/wastewater, and urban river ecosystems. These drug resistant bacteria interact with microplastics forming synthetic plastispheres, the ideal niche for biofilm formations which in turn facilitates the transfer of ARGs via horizontal gene transfer and further escalates the occurrence and levels of AMR. Microplastic-associated AMR is an emerging threat for human health and healthcare besides being a challenge for the research community for effective management/address of this menace. In this review, we encompass the increasing prevalence of microplastics in environment, emphasizing mainly on water environments, how they act as centers and vectors of microbial pathogens with their associated bacterial assemblage compositions and ultimately lead to AMR. It further discusses the mechanistic insights on how microplastics act as hosts of biofilms (creating the plastisphere). We have also presented the modern toolbox used for microplastic-biofilm analyses. A review on potential strategies for addressing microplastic-associated AMR is given with recent success stories, challenges and future prospects.

Methods of Analyzing Microsized Plastics in the Environment

Microplastics are found in various environments with the increasing use of plastics worldwide. Several methods have been developed for the sampling, extraction, purification, identification, and quantification of microplastics in complex environmental matrices. This study intends to summarize recent research trends on the subject. Large microplastic particles can be sorted manually and identified through chemical analysis; however, sample preparation for small microplastic analysis is usually more difficult. Microplastics are identified by evaluating the physical and chemical properties of plastic particles separated through extraction and washing steps from a mixture of inorganic and organic particles. This identification has a high risk of producing false-positive and false-negative results in the analysis of small microplastics. Currently, a combination of physical (e.g., microscopy), chemical (e.g., spectroscopy), and thermal analyses is widely used. We aim to summarize the best strategies for microplastic analysis by comparing the strengths and limitations of each identification method.

Determination of nano and microplastic particles in hypersaline lakes by multiple methods

Microplastics and nanoplastics have a range of impacts on the aquatic environment and present major challenges to their mitigation and management. Their transport and fate depend on their composition, form, and the characteristics of the receiving environment. We explore the spatial and temporal dynamics of plastic particles in the world's second-largest hypersaline lake, combining information from microscopic, thermal gravimetric, and fractional methods. Studies on microplastic and nanoplastic pollution in these important environments are scarce, and there is limited understanding of their dynamics and fate. Our results for Urmia Lake (Iran) in 2016 and 2019 show a discrepancy in the composition and quantity of microplastics measured in river tributaries to the lake and the lake itself, suggesting an active microplastic sink. Potential sink mechanisms in hypersaline lakes are explored. The present study indicates that microplastics have different transport mechanisms and fate in these extreme environments, compared to lake and ocean environments.

Microplastics and Nanoplastics: Emerging Contaminants in Food

As current concerns about food safety issues around the world are still relatively serious, more and more food safety issues have become the focus of people's attention. What's more serious is that environmental pollution and changes in human lifestyles have also led to the emergence of contaminants in food, microplastics (MPs) and nanoplastics (NPs) being typical representatives. MPs and NPs (M/NPs) in food are gradually becoming recognized by regulatory authorities and the public. Most published reviews on M/NPs have been focused on the environmental ecosystems. In those papers, it is only sporadically mentioned that M/NPs can also appear in food. As far as we know, there has not been a systematic review of the pollution and existing status of M/NPs in food. This Review focuses on the harmfulness of M/NPs, the ways in which M/NPs contaminate food, the residual amount of M/NPs in food, and the current analysis and detection methods for M/NPs in food. Current analysis and detection methods have problems such as being time-consuming, involving cumbersome operation, and giving poor accuracy. In the future, it will be necessary to increase the research on methods for efficient and sensitive separation and detection of M/NPs in food. Finally, it is hoped that this Review will arouse more people's awareness of and attention to the seriousness of M/NPs in food.

Disparities in Methods Used to Determine Microplastics in the Aquatic Environment: A Review of Legislation, Sampling Process and Instrumental Analysis

Plastic particles smaller than 5 mm, i.e., microplastics, have been detected in a number of environments. The number of studies on microplastics in marine environments, fresh water, wastewater, the atmosphere, and the human body are increasing along with a rise in the amounts of plastic materials introduced into the environment every year, all contributing to a range of health and environmental issues. Although the use of primary microplastics has been gradually reduced by recent legislation in many countries, new knowledge and data on these problems are needed to understand the overall lifecycle of secondary microplastics in particular. The aim of this review is to provide unified information on the pathways of microplastics into the environment, their degradation, and related legislation, with a special focus on the methods of their sampling, determination, and instrumental analysis. To deal with the health and environmental issues associated with the abundance of microplastics in the environment, researchers should focus on agreeing on a uniform methodology to determine the gravity of the problem through obtaining comparable data, thus leading to new and stricter legislation enforcing more sustainable plastic production and recycling, and hopefully contributing to reversing the trend of high amounts of microplastics worldwide.