Microplastics, Volume 1, Issue 2 (June 2022) – 8 articles

Microplastics (MPs; <5 mm) are present throughout the marine environment and are recognized as an emerging threat to aquatic ecosystems. Filter feeding organisms, such as mussels, are considered as bioindicators of MP pollution and are useful to evaluate the potential risks of MPs to human health. The work presented shows data on potential MPs found in Mytilus galloprovincialis samples collected from the Adriatic Sea during two sampling sections (1st sampling: December 2019 and 2nd sampling: May 2020). The mussels were subjected to digestion with H₂O₂ individually and filtered and the MP elements found were observed using a stereomicroscope and ultimately categorized by shape, size class and color, with the aid of a digital camera and data acquisition software. The highest MP concentrations were observed in the mussels collected in December 2019 (1.11 microplastic items per gram wet weight of mussels’ tissue), highlighting the possible influence of the following two main factors: greater river discharges following adverse weather events and higher river water pollution due to industrial activities. Indeed, the second sampling was performed after the Italian lockdown, due to the COVID-19 emergency. MP fibers (50–80%) were the most abundant type of MPs identified, followed by fragments (10–40%), granules (1.5–2.5%), non-categorized shape (1–2%) and foam (<1%). The color black (50–70%) and sizes smaller than 500 µm were the most dominant characteristics recorded both in the 1st sampling (50–70%) and the 2nd survey (30–50%). These data could be overestimated, due to the lack of polymer identification. The results of this study provide further data on the importance of bivalves as environmental bioindicators with regard to the pollution of MPs in the Adriatic Sea, supporting their instrumental role as environmental bioindicators for MP pollution. Full article

This study reports on the presence of microplastics in the gastrointestinal tracts and livers of demersal fish (the mullet, Mullus spp.) from a Marine Protected Area (Porto Cesareo) along the Ionian Sea coast (Apulia, Southern Italy). The results showed microplastic ingestion in more than 60% of specimens analyzed with an average of three items per fish and average levels in red mullets being almost twice as high as the average in the congeneric striped red mullets. The dominant polymers identified by Attenuated Total ReflectanceFourier Transform Infrared spectroscopy (ATR-FTIR) and Prolysis Gas Chromatography/Mass Spectrometry (Py-GCMS) analysis were polyethylene and polystyrene. Results can be used to set baseline levels for the assessment of microplastic pollution useful for the implementation of the Marine Strategy Framework Directive (MSFD) descriptor 10 in the Italian coast of Ionian Sea. Full article

Plastic fragments, weathered into or released in the form of micro- and nanoplastics, are persistent and widespread in the environment, and it is anticipated that they have negative environmental impacts. This necessitates immediate efforts for management strategies throughout the entire plastics lifecycle. This opinion paper was initiated by the EU COST Action CA20101 PRIORITY, which focuses on the need to develop an effective global networking platform dealing with research, implementation, and consolidation of ways to address the worldwide challenges associated with micro- and nanoplastics pollution in the environment. Full article

The aim of this paper is to contribute to the investigation of microplastics reaching the Baltic Sea with freshwater input. The scope of the paper was to analyze samples from several locations with different environmental characteristics. First, samples from urban areas differing in their degree of urbanization, a forest, a river and its watercourse were examined. Secondly, the ageing quantitative and qualitative characterization is discussed. Spectral techniques are crucial in identifying polymers, but the signal itself constitutes a valuable source of the crystallinity and density parameters of the polyethylene materials. The study indicates that polypropylene, polyethylene, polycarbonate and polystyrene are the most common types of microplastics in the investigated areas. Full article

Inadvertent consumption of latent microplastics is a lethal challenge for developing creatures in aquatic environments. There are compelling needs to classify which kinds of plastics are most likely to be encountered by sea creatures and to develop mitigation strategies to reduce exposure. We analyzed an ensemble of microplastic particle fragments isolated from sea turtle post-hatchlings to identify their composition and other features and attributes. These microplastic particles were likely consumed by post-hatchlings because of the adsorbed biofilm formation mimicking normal food sources. Of the hundreds of particles that were collected, 30 were selected for analysis using differential scanning calorimetry (DSC), Fourier transform infrared (FTIR) spectroscopy and density assessment to identify them compared with other compositional libraries. These thermophysical measurements were also compared with observational assessments via optical microscopy. Of the particles tested, nearly all were polyolefins such as polyethylene and polypropylene. The melting points of the extracted polymers were typically lower than for product grades of these resins, indicative of some level of degradation. Spectral analysis by FTIR often showed absorption indicative of new chemistries likely from both hydrolysis and biofilm growth observed on the surface that was subsequently investigated through surface abrading. Separate assessments of density of these particles were conducted and tended to reinforce identification via FTIR and DSC. The density results can be misleading if additives, fillers or biofilms that form alter the particle density relative to those of the neat resins. We suggest that since post-hatchlings commonly feed in the neritic or nearshore environment, less dense polymers are more likely to convey, thereby threatening sea turtle hatchlings who consume them inadvertently. Full article

The histopathological effects of microplastics (MPs) in the gastrointestinal tracts of fish following long-term exposure and depuration are relatively understudied. This study investigated histomorphological damage in the small intestine of Oreochromis urolepis larvae following 65 d exposure to 38–45 μm of polyethylene microspheres (PE MPs) and after a recovery period of 60 d. Larval fish were assigned to each treatment group (control, 1, 10 and 100 PE MPs), where ingestion and degenerative changes in the small intestine were examined using a routine hematoxylin and eosin staining technique. The results highlighted significant PE MPs ingestion and retention proportional to exposure dose (χ² = 49.54; df = 2). Villi height and width and epithelial cell height were significantly affected and differed between treatment groups. Indices of damage to the small intestine organ (χ² = 47.37; df = 2; p < 0.05) and reaction patterns of villi, epithelial, goblet and cryptic glandular cells, leucocytic infiltration and blood congestion revealed significant occurrence of alteration as PE MPs exposure dose increased. After the recovery period, no PE MPs were observed, and villi height, width and epithelial cells showed recovery with no significant difference between treatment groups. Organ indices declined (χ² = 12; df = 2; p < 0.05) but remained significantly different between treatment groups, largely due to leucocytic infiltration (χ² = 9.08; df = 2; p < 0.05). The study demonstrated that microplastics induced small intestinal wall degeneration, but recovery in young fish occurred slowly. The damage likely compromised its digestive function, which may affect growth and reproduction. This requires further research. Full article

Pyrolysis-GC/MS is increasingly used to quantify microplastics (MP) in environmental samples. In general, prior to analysis, purification steps are carried out to reduce the environmental matrix in sediment samples. The conventionally used protocol of density separation followed by digestion of organic matter does not allow for complete isolation of MP from the associated organic and mineral matter. Among the pyrolysis products used as indicator compounds for plastic polymers, some may originate from other substances present in the environmental samples. In this paper, the indicator compounds are reviewed for the most common polymers: PE, PP, PS, PET and PVC and selected taking into account potential interactions with substances present in environmental matrices. Even after a purification step, a residual mineral fraction remains in a sediment sample, including matrix effects. This effect may be positive or negative, depending on the investigated polymer and is thus important to consider when using Pyr-GC/MS for the quantification of MP in sediment samples. It also shows that no external calibration can be used to reliably quantify MP in such samples and that the use of internal standards is compulsory. Full article