A Simple Sample Preparation Method to Significantly Improve Fourier Transform Infrared (FT-IR) Spectra of Microplastics

Release of microplastics from polymeric ultrafiltration membrane system for drinking water treatment under different operating conditions

Drinking water has emerged as an important route for microplastics (MPs) to enter the human body, prompting concerns about their adverse health impacts. Membrane filtration technology is widely recognized as an effective treatment solution for combating MP pollution in water. However, recent research disputes that polymeric membrane systems may serve as additional sources of MPs in drinking water. The aim of this research is to investigate MP release from ultrafiltration membrane systems under different operating conditions by providing concrete evidence, identifying the operational factors contributing to the release, and elucidating the underlying possible mechanisms. Two key pieces of evidence were found to support the assertion that MPs were released from membrane systems, i.e., negative removal efficiency and an alteration in MP compositions observed between feed and permeate samples. Surprisingly, the MPs released from the membrane system originated not only from the membrane material and its additives but also from plastic-made equipment and even the other polymers used in the system. Overall results reveal that destructive activities such as shear stress, mechanical abrasion, and chemical oxidation processes, along with the carrying of MPs from external sources, are identified as potential mechanisms driving the concentration increase and polymer composition shift of MPs in permeate water. This study enhances an understanding of MP pollution in drinking water caused by membrane technology, potentially spurring the development of mitigation strategies for this issue.

Microplastics in aquatic environments: detection, abundance, characteristics, and toxicological studies

Microplastics (MPs) are fragments with a diameter of less than 5 mm that have been directly manufactured or formed by the degradation of plastic waste. MPs are not only prone to bioaccumulation in the environment, but they also lead to the spread of micropollutants in the environment, thereby threatening human health ecological environment. The useful detection method of MPs and understanding their abundance, characteristics and toxicity are great essential for MPs removal and control. This work presented the current methods of MPs' detection, compared the abundance and characteristics of MPs in water, and reviewed MPs' toxicity to organisms. Furthermore, detailed policies intervention for plastics and MPs' mitigation have been focused which delineate for application of science and policy together with scientific evidence. Lastly, this study suggests more attention should be paid to the content of MPs in freshwater and organisms closely related to human life, as well as the toxicological toxicity of MPs in mammals.

Vertical transfer of microplastics in nearshore water by cultured filter-feeding oysters

Microplastics (MPs) are widely distributed in the sea, but the vertical transfer of MPs by marine organisms in coastal area is still poorly understood. In this study, we used laser direct infrared (LDIR) spectroscopy to determine the number and characteristics of MPs deposited by cultured oyster Crassostrea gigas and further compared the differences between MPs of natural deposit and biodeposit in field environments. The amounts of MPs found in the biodeposit of cultured oysters were 3.54 times greater than that in the natural deposition. The polymer types of biodeposit MPs also differed from those of natural deposition. It was estimated that a single oyster can deposit 15.88 MPs per day, which is a figure much higher than the initial results, and hotspots of MPs deposition may be formed within the oyster aquaculture area. We used generalized linear mixed model (GLMM) to further infer the sources of MPs in sediments and found that distance to shore, cultured zone and urban center were important predictors of MPs abundance in sediments of aquaculture area. The above results suggest that cultured bivalves have an important capacity for MPs biodeposition and will further change the vertical distribution pattern of MPs in coastal environments.

Identification Tools of Microplastics from Surface Water Integrating Digital Image Processing and Statistical Techniques

The primary objective of this study was to demonstrate the potential of digital image analysis as a tool to identify microplastic (MP) particles in surface waters and to facilitate their characterisation in terms of 2D and 3D morphology. Digital image analysis preceded by microscopic analysis was used for an exhaustive quantitative and qualitative evaluation of MPs isolated from the Vistula River. Using image processing procedures, 2D and 3D shape descriptors were determined. Principal Component Analysis was used to interpret the relationships between the parameters studied, characterising MP particle geometry, type and colour. This multivariate analysis of the data allowed three or four main factors to be extracted, explaining approximately 90% of the variation in the data characterising MP morphology. It was found that the first principal component for granules, flakes and films was largely represented by strongly correlated with 2D shape descriptors (area, perimeter, equivalent area diameter) and 3D shape descriptors (Corey Shape Factor, Compactness, Dimensionality). Considering the scraps, principal component PC1 was represented by only five of the above descriptors, and the Compactness variable had the largest contribution to principal component PC2. In addition, for granules, flakes and films, a relationship between 2D shape and the colour of their particles could be observed. For the most numerous MP group identified of multicoloured scraps, no such association was found. The results of our study can be used for further multivariate analysis regarding the presence of microplastic floating on the river surface, with a particular focus on particles of secondary origin. This is of key importance for optimising future efforts in conducting small-scale and multidimensional monitoring of and reducing plastics in the aquatic environment.

Recognition and detection technology for microplastic, its source and health effects

Microplastic (MP) is ubiquitous in the environment which appeared as an immense intimidation to human and animal health. The plastic fragments significantly polluted the ocean, fresh water, food chain, and other food items. Inadequate maintenance, less knowledge of adverse influence along with inappropriate usage in addition throwing away of plastics items revolves present planet in to plastics planet. The present study aims to focus on the recognition and advance detection technologies for MPs and the adverse effects of micro- and nanoplastics on human health. MPs have rigorous adverse effect on human health that leads to condensed growth rates, lessened reproductive capability, ulcer, scrape, and oxidative nervous anxiety, in addition, also disturb circulatory and respiratory mechanism. The detection of MP particles has also placed emphasis on identification technologies such as scanning electron microscopy, Raman spectroscopy, optical detection, Fourier transform infrared spectroscopy, thermo-analytical techniques, flow cytometry, holography, and hyperspectral imaging. It suggests that further research should be explored to understand the source, distribution, and health impacts and evaluate numerous detection methodologies for the MPs along with purification techniques.

The fate of microplastics from municipal wastewater in a surface flow treatment wetland

Microplastics (MPs) are an anthropogenic pollutant of emerging concern prominent in both raw and treated municipal wastewater as well as urban and agricultural run-off. There is a critical need for the mitigation of both point- and diffuse sources, with treatment wetlands a possible sustainable nature-based solution. In this study, the possible retention of MPs in treatment wetlands of the widely used surface flow (SF) type was investigated. In- and outflow water, as well as atmospheric deposition, at a full-scale reed-based SF wetland (operating as a polishing phase of municipal wastewater treatment) was analyzed for MPs in a size range of 25-1000 μm. FPA-based μFT-IR spectroscopic imaging was used in combination with automated data analysis software, allowing for an unbiased assessment of MP numbers, polymer types and size distribution. Inflow water samples (secondary treated wastewater) contained 104 MPs m-3 and 56 MPs m-3 in sampling campaigns 1 and 2, respectively. Passage through the SF wetland increased the MP concentration in the water by 92 % during a rain intense period (campaign 1) and by 43 % during a low precipitation period (campaign 2). The MP particle numbers, size and polymer type distribution varied between the two sampling campaigns, making conclusions around the fate of specific types of MPs in SF wetlands difficult. Atmospheric deposition was measured to be 590 MPs m-2 week-1 during the rain-intense period. Our findings point towards atmospheric deposited MPs as an important factor in the fate of MPs in SF wetlands, causing an increase of MP concentrations, and potentially explaining the variations observed in MP concentrations in wetland effluent and removal efficiency. Furthermore, atmospheric deposition might also be a reason for the considerable inter-study variation regarding MPs removal efficiency in SF wetlands found in the available literature.

Polymer Characterization of Submerged Plastic Litter from Lake Tahoe, United States

Monitoring plastic litter in the environment is critical to understanding the amount, sources, transport, fate, and environmental impact of this pollutant. However, few studies have monitored plastic litter on lakebeds which are potentially important environments for determining the fate and transport of plastic litter in freshwater basins. In this study, a self-contained underwater breathing apparatus was used for litter collection at the lakebed along five transects in Lake Tahoe, United States. Litter was brought to the surface and characterized by litter type. Plastic litter was subsampled, and polymer composition was determined using attenuated total reflection Fourier transform infrared spectroscopy. The average plastic litter from the lakebed for the five dive transects was 83 ± 49 items per kilometer. The top plastic litter categories were other plastic litter (plastic litter that did not fall in another category), followed by food containers, bottles <2 L, plastic bags, and toys. These results are in line with prior studies on submerged litter, and intervention approaches or ongoing education are needed. The six polymers most frequently detected in the subsamples were polyvinyl chloride, polystyrene/expanded polystyrene, polyethylene terephthalate/polyester, polyethylene, polypropylene, and polyamide. These observations reflect global plastic production and microplastic studies from lake surface water and sediments. We found that some litter subcategories were primarily comprised of a single polymer type, therefore, in studies where the polymer type cannot be measured but litter is categorized, these results could provide an estimate of the total polymer composition for select litter categories.

Application of Infrared and Near-Infrared Microspectroscopy to Microplastic Human Exposure Measurements

Microplastic pollution is a global issue for the environment and human health. The potential for human exposure to microplastic through drinking water, dust, food, and air raises concern, since experimental in vitro and in vivo toxicology studies suggest there is a level of hazard associated with high microplastic concentrations. However, to infer the likelihood of hazards manifesting in the human population, a robust understanding of exposure concentrations is needed. Infrared and near-infrared microspectroscopies have routinely been used to analyze microplastic in different exposure matrices (air, dust, food, and water), with technological advances coupling multivariate and machine learning algorithms to spectral data. This focal point article will highlight the application of infrared and Raman modes of spectroscopy to detect, characterize, and quantify microplastic particles, with a focus on human exposure to microplastic. Methodologies and state-of-the-art approaches will be reported and potential confounding variables and challenges in microplastic analysis discussed. The article provides an up-to-date review of the literature on microplastic exposure measurement using (near) infrared spectroscopies as an analytical tool, highlighting the recent advances in this rapidly advancing field.

Sampling strategies and analytical techniques for assessment of airborne micro and nano plastics

The atmosphere is pervasively polluted by microplastics and nano plastics (M/NPs) released into indoor and outdoor areas. However, various methodologies and their limitations along with non-standardization make the comparison of information concerning their prevalence difficult. Such diversity in techniques greatly limits the interpretation of results. Herein, We extracted data from publications on PubMed and Embase database up to the year 2022 regarding sampling strategies, identification methods, and reporting data for M/NPs quantification. In this review, 5 major areas for measuring airborne M/NPs have been identified including pre-sampling/ sampling/ post-sampling/ analysis/ and contamination avoidance. There are many challenges specific to each of those sections that need to be resolved through further method development and harmonization. This review mainly focuses on the different methods for collecting atmospheric M/NPs and also the analytical tools which have been used for their identification. While passive sampling is the most user-friendly method, the most precise and reproducible approach for collecting plastic particles is an active method which is directly followed by visual counting as the most common physical analysis technique. Polymers collected using visual sorting are most frequently identified by spectroscopy (FTIR; Raman). However, destructive analytical techniques (thermal degradation) also provide precise chemical information. In all cases, the methods were screened for advantages, limitations, and fieldwork abilities. This review outlines and critiques knowledge gaps, and recommendations to support standardized and comparable future research.

Man-made natural and regenerated cellulosic fibres greatly outnumber microplastic fibres in the atmosphere

Atmospheric microplastics have been widely reported in studies around the world. Microfibres are often the dominant morphology found by researchers, although synthetic (i.e., plastic) microfibres are typically just a fraction of the total number of microfibres, with other, non-synthetic, cellulosic microfibres frequently being reported. This study set out to review existing literature to determine the relative proportion of cellulosic and synthetic atmospheric anthropogenic (man-made) microfibres, discuss trends in the microfibre abundances, and outline proposed best-practices for future studies. We conducted a systematic review of the existing literature and identified 33 peer-reviewed articles from Scopus and Google Scholar searches that examined cellulosic microfibres and synthetic microfibres in the atmosphere. Multiple analyses indicate that cellulosic microfibres are considerably more common than synthetic microfibres. FT-IR and Raman spectroscopy data obtained from 24 studies, showed that 57% of microfibres were cellulosic and 23% were synthetic. The remaining were either inorganic, or not determined. In total, 20 studies identified more cellulosic microfibres, compared to 11 studies which identified more synthetic microfibres. The data show that cellulosic microfibres are 2.5 times more abundant between 2016 and 2022, however, the proportion of cellulosic microfibres appear to be decreasing, while synthetic microfibres are increasing. We expect a crossover to happen by 2030, where synthetic microfibres will be dominant in the atmosphere. We propose that future studies on atmospheric anthropogenic microfibres should include information on natural and regenerated cellulosic microfibres, and design studies which are inclusive of cellulosic microfibres during analysis and reporting. This will allow researchers to monitor trends in the composition of atmospheric microfibers and will help address the frequent underestimation of cellulosic microfibre abundance in the atmosphere.