How well-protected are protected areas from anthropogenic microplastic contamination? Review of analytical methods,current trends,and prospects

Microplastics have sparked global concern due to their negative effects on organisms' health and the environment. Microplastics research in protected areas (marine and freshwater) has recently gained prominence and is expected to grow in the coming years. This review of 36 published studies examines current progress and identifies future research challenges. It begins with an overview of microplastic evaluation methodologies, followed by a discussion of recent advances in the abundance of microplastics in water, sediment, biota, wet and dry deposition, and particulate matter. Current quality assurance and control measures are also summarized. The majority of studies (44 %) examined sediment samples. In biota, the gastrointestinal system was the most evaluated for microplastics. Digestion (using H₂O₂ and KOH) and density separation (using NaCl) are the most common microplastic extraction methods. We found that microplastic contamination is pervasive in all the surveyed protected areas, with varying levels of abundance geographically, and over 50 % of the biota ingest microplastics. The methodological discrepancies amongst the investigations, from sampling to microplastics characterization, make it difficult to compare the results and generate baseline data on microplastic contamination levels. Close monitoring and a standardized approach are thus required to determine the extent to which microplastics might enter and persist in protected area environments, as well as to devise effective mitigating strategies.     

A review on analytical performance of micro- and nanoplastics analysis methods

Micro- and nanoplastics have been detected in diverse matrices. Recent studies have suggested their health impact on humans, animals, plants, and environment which depends on the size, concentration, chemical nature, and the mode of interaction of the plastic particles. Detection and quantification of these particles are often challenging due to their small size and complexity of the matrix in which they exist. The concentration and size of the particles combined with the nature of the matrix determines an analytical method to be followed. In recent years, many review articles focusing on origin, fate, and health effects of micro- and nanoplastics are already published. A systemic review focusing on analytical performance of currently available micro- and nanoplastics analysis methods would be useful for the scientific community. In this article, we reviewed papers and reports published in recent decades focusing on the sampling, concentration, detection, and chemical identification methods. We also reviewed the emerging new methods for microplastic analysis. Finally, we provide advantages and limitations of the methods and future perspectives on microplastic analysis.     

Methods for the extraction of microplastics in complex solid,water and biota samples

The widespread distribution of plastics, their persistence and ability to act as a vector of toxic chemicals has rendered them concerning emergent pollutants. The quantification of these contaminants is highly relevant for the evaluation of anthropogenic impacts on aquatic and terrestrial ecosystems and dependent of the efficacy of methods to separate microplastics from environmental matrices. Little information is available about the microplastic extraction methods on complex samples – i.e. samples with multiple types of matrices. Herein, methods for the separation of microplastics from complex samples are summarized and discussed based on their advantages and drawbacks focused on a comparative analysis of their efficiency on organic matter removal, polymer recovery and preservation of plastic integrity. The efficiency on microplastic recovery and organic matter reduction, as well as the examination of the effects of treatments on plastics are closely linked to the density and digestion approaches selected, the polymer features and the environmental matrix analyzed. High-density salt solutions are more effective for density separation, while oxidative methods have recurrently shown better rates of organic matter reduction (particularly in vegetal-rich samples) and plastic recovery, with little impact on plastics, while 10 % KOH has been described as highly efficient in samples containing animal organic matter. This comparative analysis highlights the benefits and limitations of different approaches for the analysis of microplastics in complex samples which may be helpful for the optimization and harmonization of the methods.     

Influence of Different Microplastic Forms on pH and Mobility of Cu2+ and Pb2+ in Soil

Microplastics, due to their surface properties, porosity and electrostatic interactions have a high affinity for cations sorption from the aqueous phase. As soil is a complex matrix, interactions between microplastics, soil constituents and heavy metals (HM) may modify the soil microenvironment for heavy metal mobilization/immobilization processes. In order to better understand the problem, three commonly found forms of microplastics in soil (fibers, fragments and microbeads) were mixed with Cu²⁺- or Pb²⁺-contaminated soil and incubated at 22 °C for 180 days. In soil samples pH and the content of water and acid exchangeable species of metals were analyzed. The results of this study showed that the presence of microplastics in HM-contaminated soil affected metal speciation, increasing the amount of easily exchangeable and potentially bioavailable forms of Cu²⁺ or Pb²⁺ in the tested soil. Soil pH also increased, confirming that microplastic particles affect soil properties relevant to the sorption/desorption process of metal cations. Overall, the smallest microplastic particles (≤1 mm), such as fibers or glitter microbeads, had a greater impact on the change in the sorption and desorption conditions of metals in tested soil than larger particles. The findings of our study show that microplastic form, shape and size should be considered as important factors that influence the soil properties and mobility of heavy metals in soil.     

Metal-Organic Framework-based Wood Aerogel for Effective Removal of Micro/Nano Plastics

The large amount of microplastic pollution in the aquatic environment has been regarded as a major challenge facing the world. Although some traditional water treatment processes can effectively remove microplastics in the millimeter range, research is still needed to solve the problem of removing smaller microplastics. Here, we made a durable zinc metal-organic framework-based composite material ZIF-8@Aerogel by in situ growing ZIF-8 on wood aerogel fibers, which can successfully remove microplastics in simulated water and seawater. The removal efficiencies on micro/nano plastics including poly(1,1-difluoroethylene)(60-110 nm) and polystyrene(90-140 nm) reached 91.4% and 85.8%, respectively. This work is expected to provide a new and efficient way to remove small-sized microplastic particles in the environment.     

土壤样品中微塑料的分析方法研究进展

微塑料作为一种新型污染物,因其粒径小、难以降解、本身含有多种污染物、且易吸附疏水性有机污染物和重金属等产生复合污染,已成为国内外学者研究的热点问题。微塑料广泛存在于土壤环境中,进入土壤中的微塑料会影响土壤理化性质,同时影响土壤动物生长、植物生长和微生物活动等,并且,微塑料会在土壤中发生迁移或沿食物链传递从而对人类健康构成潜在风险。高效、统一、准确的微塑料分析方法是研究微塑料在土壤中分布、迁移、归趋和生态风险的基础。本文对近年来土壤中微塑料的采集、分离提取、鉴定量化和分析方法的质量保证等方面的研究进展进行了评述,比较了各个方法的优缺点及应用范围。最后,结合国内外微塑料污染最新研究进展,针对目前土壤微塑料分析方法存在的问题,对今后土壤微塑料分析技术的发展趋势进行了展望。     

Quality assessment for methodological aspects of microplastics analysis in soil

Over the last several years, a number of studies have concentrated on the occurrence, potential sources, and ecological implications of soil systems. However, the studies’ methodological aspects have received little attention. Thus, this study performed a quality assessment for the methodological aspects of soil microplastics studies by adopting the Criteria for Reporting and Evaluating Ecotoxicity Data (CRED) evaluation method. A total of 35 soil microplastic studies have been evaluated in terms of methodological aspects using 13 criteria, namely, sampling methods and strategy, sample processing and storage, sample size, laboratory preparation, clean air conditions, chemical purity, negative control, positive control, sample pre-treatment, microplastics particle data, particle size, particle shape and polymer type identification. The quality assessment findings indicated that no study scored a maximum of two in all criteria, reiterating the urgent need for enhanced quality assurance for future soil microplastics studies. The average quality assessment scores in soil microplastics studies also indicated that the conditions requiring the most improvement involve both the criteria of positive controls and the criteria of clean air conditions. With a value of zero in 13 assessed criterion, the relevance of the study’s findings in environmental risk assessment was restricted, suggesting that future studies should consider strengthening the implementation and reporting of QA/QC protocol. Adoption of proper quality assurance and contamination control measures will guarantee high data quality and establish confidence in the study’s findings, which allow for reproducibility and comparability as well as acceptability to be utilized in risk assessments.     

微塑料介导重金属在陆生植物中迁移及生物效应的影响

随着地膜在现代化农业中的广泛应用,微塑料在土壤中的残留问题日益严重。环境中释放的微塑料可能会与先前存在的重金属相互作用,导致生物效应(生物积累/毒性),并对人类健康和农产品安全构成威胁。目前,大多数研究集中于单一影响因素在土壤系统中的暴露和转化分析,有关微塑料和共存金属对环境联合影响的相当有限。本文综述了微塑料与重金属来源、相互作用机理与影响因素的研究现状,阐述了陆生植物对二者联合污染的生理响应。此外,未来的研究还应重点探讨微塑料与重金属共同在植物上暴露的具体分子机制、通过食物链对人类健康的影响、与其他混合污染物联合作用及微塑料老化过程对重金属迁移动态变化过程的影响。     

土壤微塑料污染及生态环境效应研究进展

微塑料作为一种新的污染物,具有粒径小、疏水性强、性质稳定、可以吸附多种污染物等特点,近年来受到了广泛的关注.目前关于微塑料的研究主要集中在水环境中,土壤环境中的微塑料研究相对滞后.土壤与人类生活息息相关,但土壤微塑料污染的现状却不容乐观,土壤微塑料的环境效应需要重视.本文综述了土壤微塑料的来源、分离和鉴定方法、微塑料在...     

Separation and Identification of Microplastics in Digestive System of Bivalves

A pretreatment method was established for separating microplastics from digestive system of bivalve sample. Qualitative and quantitative analysis of microplastics was carried out by micro-Fourier transformed infrared (μ-FT-IR) spectroscope and Stereo microscope. The method was applied to analyze the microplastics in the digestive system in Chlamys farreri and Mytilus galloprovincialis. The results showed that the digestion system of using 10% KOH had high digestion efficiency. With this digestion system, the recoveries of polypropylene (PP), polyethylene (PE), polystyrene (PS) and polyvinyl chloride (PVC) ranged from 96.7% to 98.6%, with relative standard deviation (RSD, n = 3) of ≤ 3.19%. We collected Chlamys farreri from local markets (n = 50) and Mytilus galloprovincialis from both local markets (n = 50) and wild environments (n = 15) in Qingdao, China. The results showed that microplastics were found in over 80% of the individuals purchased from the market and 40% of the wild collected individuals. The average abundance of microplastics in Chlamys farreri purchased from different markets varied between 5.2 and 19.4 items/individual or between 3.2 and 7.1 items g^?1 (wet weight of digestive system), while in Mytilus galloprovincialis, the numbers varied between 1.9 and 9.6 items/individual or between 2.0 and 12.8 items g^?1. Farmed mussels (Mytilus galloprovincialis) contained more microplastics (average 1.9 items per individual, 3.17 items g^?1) than wild mussels (average 0.53 items individual, 2.0 items g^?1). Three shapes of microplastics, including fibers, fragments and granules were separated from the samples above. Among which, fibrous microplastics, being the most dominant ones, took up 84.11% of total microplastics. The average size of fibrous microplastics ((0.66 ± 0.70) mm) was larger than that of the other two shapes of microplastics. The number of microplastics decreased with increasing microplastic sizes. Microplastics of less than 500 μm coming from different markets were in the range of 26% to 84%. And it was found that the most common polymer component in the samples was cellophane (CP), followed by polypropylene (PP). The method has some advantages such as simplicity, high efficiency, and low damage to the microplastics in the sample, and can be used to detect and analyze microplastics in seafood.     

水环境中微塑料的样品采集与分析进展

微塑料在环境中难以降解,可在水体、沉积物等环境介质中长期存在,并在水生生物体内积累,成为人们高度关注的环境问题之一。有关水环境中微塑料的污染研究尚处于起步阶段,快速、高效、准确的检测技术是水环境中微塑料研究的重要环节,对于优化研究路线、分析研究结果、总结微塑料污染规律至关重要。本文结合国内外微塑料污染研究进展,介绍了微塑料污染现状,并通过对环境样品中微塑料的采样、预处理以及定性定量分析方法的系统比较,总结了现行各种检测方法的优缺点及各自应用范围,最后指出了进一步研究的方向。     

Organic pollutants adsorbed on microplastics: Analytical methodologies and occurrence in oceans

The massive use of plastics in several products has generated microplastic debris worldwide. Besides their negative effect on marine organisms by ingestion, microplastics are a contamination vector due to their capacity to transport organic pollutants around our planet. To evaluate the magnitude of this issue, it is necessary to know what kinds of contaminants are adsorbed on microplastics, as well as their concentrations. In order to assess the adsorption and desorption of pollutants from microplastics, effective and reliable extraction procedures are required. In this overview, literature reports, in which extraction, separation and determination methods have been applied to analyse the organic pollutants adsorbed on microplastics, are revised and discussed. Furthermore, the worldwide occurrence of organic compounds found on microplastics in oceans is reviewed and the results obtained from different geographical areas and their global distribution trends are compared. Priority organic pollutants, such as polycyclic aromatic hydrocarbons, hexachlorocyclohexanes, polychlorinated benzenes, perfluoroalkyl substances or bisphenol analogues, have been widely found on microplastic samples. Future research that focuses on different kinds of emerging pollutants is required.     

Spectro-Microscopic Techniques for Studying Nanoplastics in the Environment and in Organisms

Nanoplastics (NPs), small (<1 μm) polymer particles formed from bulk plastics, are a potential threat to human health and the environment. Orders of magnitude smaller than microplastics (MPs), they might behave differently due to their larger surface area and small size, which allows them to diffuse through organic barriers. However, detecting NPs in the environment and organic matrices has proven to be difficult, as their chemical nature is similar to these matrices. Furthermore, as their size is smaller than the (spatial) detection limit of common analytical tools, they are hard to find and quantify. We highlight different micro-spectroscopic techniques utilized for NP detection and argue that an analysis procedure should involve both particle imaging and correlative or direct chemical characterization of the same particles or samples. Finally, we highlight methods that can do both simultaneously, but with the downside that large particle numbers and statistics cannot be obtained.     

Analysis of Microplastics in Takeaway Food Containers in China Using FPA-FTIR Whole Filter Analysis

With the rapid development and popularization of the internet and smartphone industry for ordering and delivery, the consumption of takeaway food is increasing globally, especially in China. However, there is little information about microplastics in takeaway food containers, so their potential risks to human health remain unknown. This study explored the possibility of using focal plane array (FPA)-based micro-FT-IR imaging to detect microplastics released from food containers and evaluated their contents using an automated database matching analysis method. We investigated microplastics in seven types of food containers widely used in China. The most common plastic types observed were polyamide (PA), polyurethane (PU) and polystyrene (PS), which were found to comprise 22.8%, 18.2%, and 8.5% (number of particles) of all microplastics, respectively. Microplastics were found in all seven types of food containers, and the content excluding cellulose was 29–552 items/container. Our research shows that microplastics in takeaway food containers might originate from atmospheric sediment or flakes from the inside surface of the container. According to the content of microplastics in takeaway food containers, people who order takeaway food 5–10 times a month might consume 145–5520 microplastic pieces from food containers.     

Integrated sample-pretreatment strategy for separation and enrichment of microplastics and primary aromatic amines in the migration of teabag

In this work, an integrated sample-pretreatment strategy for the separation and enrichment of microplastics and primary aromatic amines from the migration of teabag was developed. The migration solution of teabag was passed through a homemade device. The microplastics were firstly captured by a silver membrane, and then the primary aromatic amines were enriched by a solid-phase extraction column. The microplastics migrated from teabag were detected by attenuated total reflection-Fourier transform infrared spectrometer and Raman spectroscopy. The data showed the character, the number of particles, area ratio, and morphology of microplastics migrated from the teabag. Subsequently, after the enrichment procedure, a sensitive analytical method for primary aromatic amines was established followed by ultra-high performance liquid chromatography-tandem mass spectrometry. The method showed wide linear ranges with R² greater than 0.9915, low limits of detection (2–18 ng/L), and low limits of quantification (8–50 ng/L). The developed method was adopted to analyze microplastics and primary aromatic amines migrated from nylon and polyethylene terephthalate teabag under different temperatures and times. The integrated sample-pretreatment strategy displayed promising potentials in the one-step preparation of the microplastics and hazardous molecules in the sample of environment and food security.     

Identification and characterization of organic nanoparticles in food

Interest in nanoparticles (NPs) has increased explosively over the past two decades. Using NPs, high loadings of vitamins and health-benefit actives can be achieved in food, and stable flavors as well as natural food-coloring dispersions can be developed. Detection and characterization of NPs are essential in understanding the benefits as well as the potential risks of the application of such materials in food. While many such applications are described in the literature, methods for detection and characterization of such particles are lacking. Organic NPs suitable for application in food are lipid-, protein- or polysaccharide-based particles, and this review describes current analytical techniques that are used, or could be used, for identification and characterization of such particles in food products. We divide the analytical approaches into four sections: sample preparation; separation; imaging; and, characterization.We discuss techniques and reported applications for NPs or otherwise related particle compounds. The results of this investigation show that, for a successful characterization of NPs in food, at least some kind of sample preparation will be required. While a simple sample preparation may be satisfactory for imaging techniques for known analytes, for other techniques, a further separation using chromatography, field-flow fractionation or ion-mobility separation is necessary. Subsequently, photon-correlation spectroscopy and especially mass spectrometry techniques as matrix-assisted laser desorption/ionization combined with time-of-flight mass spectrometry, seem suitable techniques for characterizing a wide variety of organic NPs.     

Solid‐phase microextraction for the human biomonitoring of environmental chemicals: Current applications and future perspectives

Sample preparation is one of the crucial steps in the analytical chemistry including human biomonitoring studies. Although there are several traditional approaches available, solid‐phase microextraction is emerged as one of the pioneering techniques due to its simplicity, rapidness, wide applicability, and miniaturization of traditional sample preparation (e.g., use of less or no organic solvents). There are few earlier review articles available on the advancements in solid‐phase microextraction and its use for the measurement of environmental chemicals in various types of environmental samples. However, a collective information on applicability and current usage of solid‐phase microextraction for the human biomonitoring of environmental chemicals are scarce, nonetheless, rising demands on innovative analytical approaches for human biomonitoring studies. Hence, in this review article, we covered the application of solid‐phase microextraction as extraction/purification methods for more than 15 classes of environmental chemicals to assess their respective exposure levels and associated health outcomes in various human population reported across the globe. Further, a detailed discussion on various types of matrix used, nature of coupled analytical instrumentations, and limitations and future perspectives of solid‐phase microextraction for human biomonitoring studies is presented in this review.     

Detection,characterization and quantification of inorganic engineered nanomaterials: A review of techniques and methodological approaches for the analysis of complex samples

The increasing demand of analytical information related to inorganic engineered nanomaterials requires the adaptation of existing techniques and methods, or the development of new ones. The challenge for the analytical sciences has been to consider the nanoparticles as a new sort of analytes, involving both chemical (composition, mass and number concentration) and physical information (e.g. size, shape, aggregation). Moreover, information about the species derived from the nanoparticles themselves and their transformations must also be supplied. Whereas techniques commonly used for nanoparticle characterization, such as light scattering techniques, show serious limitations when applied to complex samples, other well-established techniques, like electron microscopy and atomic spectrometry, can provide useful information in most cases. Furthermore, separation techniques, including flow field flow fractionation, capillary electrophoresis and hydrodynamic chromatography, are moving to the nano domain, mostly hyphenated to inductively coupled plasma mass spectrometry as element specific detector. Emerging techniques based on the detection of single nanoparticles by using ICP-MS, but also coulometry, are in their way to gain a position. Chemical sensors selective to nanoparticles are in their early stages, but they are very promising considering their portability and simplicity. Although the field is in continuous evolution, at this moment it is moving from proofs-of-concept in simple matrices to methods dealing with matrices of higher complexity and relevant analyte concentrations. To achieve this goal, sample preparation methods are essential to manage such complex situations. Apart from size fractionation methods, matrix digestion, extraction and concentration methods capable of preserving the nature of the nanoparticles are being developed. This review presents and discusses the state-of-the-art analytical techniques and sample preparation methods suitable for dealing with complex samples. Single- and multi-method approaches applied to solve the nanometrological challenges posed by a variety of stakeholders are also presented.     

Characterisation and determination of fullerenes: A critical review

A prominent sector of nanotechnology is occupied by a class of carbon-based nanoparticles known as fullerenes. Fullerene particle size and shape impact in how easily these particles are transported into and throughout the environment and living tissues. Currently, there is a lack of adequate methodology for their size and shape characterisation, identification and quantitative detection in environmental and biological samples. The most commonly used methods for their size measurements (aggregation, size distribution, shape, etc.), the effect of sampling and sample treatment on these characteristics and the analytical methods proposed for their determination in complex matrices are discussed in this review. For the characterisation and analysis of fullerenes in real samples, different analytical techniques including microscopy, spectroscopy, flow field-flow fractionation, electrophoresis, light scattering, liquid chromatography and mass spectrometry have been reported. The existing limitations and knowledge gaps in the use of these techniques are discussed and the necessity to hyphenate complementary ones for the accurate characterisation, identification and quantitation of these nanoparticles is highlighted.     

Specific use of electron microscopic techniques in the characterization of ABS polymers

The supermolecular structure of various types of ABS polymers was characterized by employing various preparation and electron-microscopic observation techniques. The results thus obtained were compared with the classical techniques of preparation of ultra-thin sections. The techniques were chosen so as to reveal the structure of the interior of the sample and the rubber particles (material contrast on cut surfaces, separation of particles by dissolving the matrix, fracture at low and high temperatures), the surface structure (surface etching) and the mechanism of the fracture process (fracture surface at room temperature). By treatment of the fracture surfaces (relaxation in vapours of the solvent of the matrix or OsO₄-staining), rubber particles on the fracture surface or adjacent to it can be revealed. The size distribution of rubber particles, determined by using one sample and most of the methods mentioned above, shows an agreement in the range of the most frequently occurring particles. Systematic deviations in the range of large particles (aggregates) are explained by differences between the individual preparation methods.