Quantification and characterization of microplastics in coastal environments: Insights from laser direct infrared imaging

Laser Direct Infrared Spectroscopy: A cutting-edge approach to microplastic detection in environmental samples

Microplastic pollution has emerged as a significant global environmental concern, affecting marine, terrestrial, and atmospheric ecosystems. As microplastic contamination continues to intensify, the need for precise, efficient, and scalable detection method is growing. This review highlights recent advancements in microplastic detection technologies, with a particular focus on Laser Direct Infrared (LDIR) spectroscopy. Utilizing a Quantum Cascade Laser (QCL), LDIR offers rapid, sensitive, and automated detection capabilities. It significantly reduces analysis time compared to conventional techniques such as Fourier Transform Infrared (FTIR) and Raman spectroscopic techniques, making it ideal for large-scale environmental monitoring. Its ability to identify particles as small as 10 μm, combined with enhanced wavelength accuracy, positions LDIR as a promising tool for microplastic analysis across various environmental matrices. Despite some limitations, such as a narrower spectral range, LDIR's superior speed and precision make it a critical advancement for understanding and addressing the global microplastic crisis.

Assessment of microplastics and associated ecological risk in the longest river (Godavari) of peninsular India: A comprehensive source-to-sink analysis in water, sediment and fish

Persistent microplastics (MPs) accumulation in the aqueous environments is considered a threat to the ecosystem, potentially harming aquatic species and human health. In view of the escalating problem of MPs pollution in India, a comprehensive investigation of MPs accumulation in major riverine systems is necessary. The current study aims to estimate MPs abundance in surface water, sediment, and fish samples along the entire stretch of Godavari, the largest river in peninsular India. Average MPs concentrations in water lie in the range of 311-939 MPs/m3 and 2-144 MPs/kg d.w. for sediment. Urban regions and dam reservoirs showed elevated MPs abundance, emphasizing the impact of anthropogenic activities. The μ-Raman analysis revealed PE and PP were the abundantly occurring polymers in all matrices. Polymer and ecological risk index identify most sampling sites as extremely high-risk zones, posing a potential threat to aquatic ecosystems and human health. Plotted t-SNE (t-distributed Stochastic Neighbour Embedding) revealed similarities in MPs morphology and compositions among water, sediment and fish samples. Examined MPs in edible (flesh+skin) and inedible parts (GIT and gills) of seven different fish species showed a higher average MPs abundance in edible parts (10.7 ± 14.9 MPs/fish) than gills (7 ± 8.1 MPs/fish) and GIT (6.6 ± 5.5 MPs/fish). This suggests that removing gills and GIT from fish doesn't eliminate the consumer's risk of MPs intake. Overall, our work highlights the significant MPs pollution in the Godavari River, further providing essential data on the ecological risk of MPs to guide municipal action plans, improve waste management, target high-risk areas, and raise awareness to mitigate impacts.

Establishment and application of standard analysis methods for microplastic samples: Urban sewage and sewage sludge as a source of microplastics in the environment

The widespread use of plastics has led to the ubiquitous presence of microplastics (MPs) in the environment, posing risks to ecosystems and human health. Wastewater treatment plants (WWTPs), which often fail to completely remove MPs during treatment, have become a significant source of pollution. However, inconsistencies in sampling, pretreatment, and identification methods hinder comparative studies. This study developed a standardized method for MP analysis in WWTP water and sludge samples. Metal filters and ultrasound-assisted transfer improved desorption efficiency, while NaI flotation achieved nearly complete MP recovery. A two-step digestion method combining Fenton reagent and cellulase effectively removed organic matter (weight loss of 54.21 ± 2.00%) while maintaining 100% MP recovery. By tailoring the method to variables such as treatment processes, water volume, and pollution sources, a "gold standard" approach was designed to evaluate the environmental abundance of MPs in various WWTPs. Application of this method revealed MP concentrations of 2530-18,240 MP/L in influent and 650-1700 MP/L in effluent, with an estimated daily discharge of 1.42 × 108 MP/d into the environment. Primary sedimentation and skimming removed 57.07% of MPs, with secondary and advanced treatments enhancing removal. MPs primarily transferred to sludge, averaging 38.6-104.5 MP/g (dry weight). The most abundant MPs in influent were PU, PET, and PTFE, while PA, PU, and PET dominated in effluent. MPs smaller than 0.5 mm accounted for 98%, with regular particles increasing in effluent. This efficient method establishes a "gold standard" for MP analysis in WWTPs.

Algae- and bacteria-based biodegradation of phthalic acid esters towards the sustainable green solution

Phthalic acid esters are widely used worldwide as plasticizers. The high consumption of phthalates in China makes it the world's largest plasticizer market. The lack of phthalic acid ester's chemical bonding with the polymer matrix facilitates their detachment from plastic products and subsequent release into the environment and causes serious threats to the health of living organisms. Thus, environmentally friendly and sustainable solutions for their removal are urgently needed. In this context, both natural and engineered bacterial and algal communities have played a crucial role in the degradation of various phthalic acid esters present in water and soil. When algae-bacteria co-culture is compared to a singular algae or bacteria system, this symbiotic system shows superior performance in the removal of dibutyl phthalates and diethyl phthalates from synthetic wastewater. This review provides an optimistic outlook for co-culture systems by in-depth examining single microorganisms, namely bacteria and algae, as well as algae-bacterial consortiums for phthalates degradation, which will draw attention to species co-existence for the removal of various pollutants from the environment. In addition, further development and research, particularly on the mechanisms, genes involved in the degradation of phthalic acid esters, and interactions between bacterial and algal species, will lead to the discovery of more adaptable species as well as the production of targeted species to address the environmental pollution crisis and provide a green, efficient, and sustainable approach to environmental protection. Discrepancies in knowledge and potential avenues for exploration will enhance the existing body of literature, enabling researchers to investigate this field more comprehensively.

Morphometric characteristics and spatiotemporal heterogeneity of microplastics on the north-east coast of India

The study analysed microplastics (MPs) in surface waters along the north-east coast of India and focused on the spatiotemporal distribution and morphometric characteristics of 800 particles for environmental insights. The MPs were consistently present in all water masses, with an average abundance of 0.67 ± 0.66 particles/m3 during the monsoon and 0.12 ± 0.08 particles/m3 post-monsoon. Fragments and fibers were dominant in both seasons, comprising over 83 % and 12 %, respectively. In terms of colours, blue was significantly dominant during the post-monsoon (H, χ2 (5) = 15.38, p < 0.01); however, such variation was absent during the monsoon. Spatially, significant variance in abundance (F4, 34 = 8.542; p < 0.01) and across colours and forms during the monsoon was correlated with land-based inputs from the Hooghly River. FTIR analysis revealed ten polymer types, predominantly polyethylene (44 %). SEM observations indicated that 80 % of particles exhibited polymer ageing from oxidative weathering. The size distribution of MPs varied notably, with a higher proportion of < 0.3 mm (16.7 %) during the monsoon, possibly due to increased particle disintegration. The study noted MPs had low to moderate circularity, with increased irregularity during the monsoon due to heavy precipitation and river flushing. An initial risk assessment of MP pollution in surface waters on the north-east coast revealed a low-risk state. Acrylonitrile butadiene styrene (ABS) was identified as the most hazardous MP polymer. A wide range of toxic trace elements were found in MPs in these waters. The findings from the study deepen our knowledge of MPs and their fate in the pelagic zone, which supports the development of science-based policies that effectively reduce MP pollution.

Distribution characteristics and relationship of microplastics, phthalate esters, and bisphenol A in the Beiyun River basin of Beijing

Urban rivers are closely related to human life, and due to the widespread use of plastic products, rivers have become important carriers of pollutants such as microplastics (MP), phthalate esters (PAEs), and bisphenol A (BPA). However, our understanding of the distribution characteristics and relationships of MP, PAEs, and BPA in rivers is limited. In this study, MP, six PAEs and BPA were detected in the water and sediments of the Beiyun River basin. Polyvinyl chloride (PVC) was the most abundant type of microplastic, while di(2-ethylhexyl) phthalate (DEHP) and dibutyl phthalate (DBP) were the most abundant PAEs. MP, PAEs, and BPA in both water and sediment showed positive correlations, with stronger correlations and higher pollution levels in sediment than in water. The tendency for PAE congeners to partition into sediments increased with a higher octanol-water partition coefficient (Kow). There was a significant positive correlation between the distribution tendency of ∑6PAEs and TOC in sediments with a pearson correlation coefficient of 0.717. Rivers with more frequent human activities and higher levels of urbanization in the vicinity had a higher abundance of various pollutants and a greater diversity of MP types.

Recent advances in the relationships between biofilms and microplastics in natural environments

Plastic pollution in the form of microplastics (MPs), poses a significant threat to natural ecosystems, with detrimental ecological, social, and economic impacts. This review paper aims to provide an overview of the existing research on the interaction between microbial biofilms and MPs in natural environments. The review begins by outlining the sources and types of MPs, emphasizing their widespread presence in marine, freshwater, and terrestrial ecosystems. It then discusses the formation and characteristics of microbial biofilms on MPs surfaces, highlighting their role in altering the physicochemical properties of MPs and facilitating processes such as vertical transport, biodegradation, dispersion of microorganisms, and gene transfer. Different methods used to assess these interactions are discussed, including microbiological and physicochemical characterization. Current gaps and challenges in understanding the complex relationships between biofilms and MPs are identified, highlighting the need for further research to elucidate the mechanisms underlying these complex interactions and to develop effective mitigation strategies. Innovative solutions, including bioremediation techniques and their combination with other strategies, such as nanotechnology, advanced filtration technologies, and public awareness campaigns, are proposed as promising approaches to address the issue of MPs pollution. Overall, this review underscores the urgent need for a multidisciplinary approach to combating MPs pollution, combining scientific research, technological innovation, and public engagement to safeguard the health and integrity of natural ecosystems.

Polyester microfiber impacts on coastal sediment organic matter consumption

As plastic pollution continues to accumulate at the seafloor, concerns around benthic ecosystem functionality heightens. This research demonstrates the systematic effects of polyester microfibers on seafloor organic matter consumption rates, an important benthic ecosystem function connected to multiple reactions and processes. We used a field-based assay to measure the loss of organic matter, both with and without polyester microfiber contamination. We identified sediment organic matter content, mud content, and mean grain size as the main drivers of organic matter consumption, however, polyester microfiber contamination decoupled ecosystem relationships and altered observed organic matter cycling dynamics. Organic matter consumption rates varied across horizontal and vertical spaces, highlighting that consumption and associated plastic effects are dependent on environmental heterogeneity at both small (within sites) and larger (between sites) scales. Our results emphasize the important role habitat heterogeneity plays in seafloor organic matter consumption and the associated effects of plastic pollution on ecosystem function.

Revealing the long-term impact of photodegradation and fragmentation on HDPE in the marine environment: Origins of microplastics and dissolved organics

The extensive usage of high-density polyethylene (HDPE) materials in marine environments raises concerns about their potential contribution to plastic pollution. Various factors contribute to the degradation of HDPE in marine environments, including UV radiation, seawater hydrolysis, biodegradation, and mechanical stress. Despite their supposed long lifespans, there is still a lack of understanding about the long-term degradation mechanisms that cause weathering of seawater-exposed HDPE products. In this research, the impact of UV radiation on the degradation of HDPE pile sleeves was studied in natural as well as laboratory settings to isolate the UV effect. After nine years of exposure to the marine environment in natural settings, the HDPE pile sleeves exhibited an increase in oxygen-containing surface functional groups and more morphological changes compared to accelerated UVB irradiation in the laboratory. This indicated that combined non-UV mechanisms may play a major role in HDPE degradation than UV irradiation alone. However, UVB irradiation was found to release dissolved organic carbon and total dissolved nitrogen from HDPE pile sleeves, reaching levels of up to 15 mg/L and 2 mg/L, respectively. Our findings underscore the significance of taking into account both UV and non-UV degradation mechanisms when evaluating the role of HDPE in contributing to marine plastic pollution.