Identification and Quantification of Microplastics in the Marine Environment Using the Laser Direct Infrared (LDIR) Technique.

Here, we evaluate for the first time the performances of the newly developed laser direct infrared (LDIR) technique and propose an optimization of the initial protocol for marine microplastics (MPs) analysis. Our results show that an 8 µm porosity polycarbonate filter placed on a Kevley slide enables preconcentration and efficient quantification of MPs, as well as polymer and size determination of reference plastic pellets of polypropylene (PP), polyethylene (PE), polystyrene (PS), polyvinyl chloride (PVC), and polyethylene terephthalate (PET), with recoveries ranging from 80-100% and negligible blank values for particle sizes ranging from 200 to 500 µm. A spiked experiment using seawater, sediment, mussels, and fish stomach samples showed that the method responded linearly with significant slopes (R2 ranging from 0.93-1.0; p < 0.001, p < 0.01). Overall, 11 polymer types were identified with limited handling and an analysis time of ca. 3 h for most samples and 6 h for complex samples. Application of this technique to Mediterranean marine samples (seawater, sediment, fish stomachs and mussels) indicated MP concentrations and size distribution consistent with the literature. A high predominance of PVC (sediment, fish stomachs) and PE and PP (seawater, mussels) was observed in the analyzed samples.

Insights into seafloor litter spatiotemporal dynamics in urbanized shallow Mediterranean bays. An optimized monitoring protocol using towed underwater cameras.

Monitoring of marine litter at the sea surface, the beaches and the seafloor is essential to understanding their sources, pathways and sinks and design effective clean-up programs or increase public awareness for reducing litter waste. Up until today, seafloor litter is the least exploited component of marine litter. Although the protocols for recording and assessing seafloor litter in the deep-sea environments are currently being actively defined and practiced, shallow seafloor litter survey protocols are still notably under-developed. Moreover, trawling for fishing, which is the main means for collecting seafloor litter data, needs to be phased out in the coming years due to its high environmental footprint and be replaced by less destructive ways based on underwater imagery. In this paper we propose an integrated approach for assessing in detail the spatiotemporal distribution and composition of seafloor litter in shallow coastal environments, using common towed underwater cameras. Effort has been put to correctly estimating spatial litter densities regarding the true coverage of the visualized area, which was efficiently extracted through photogrammetric reconstruction of the seafloor. Interpretation of the spatial distribution of litter was aided by auxiliary bathymetric and swath sonar backscatter datasets, to determine the seabed geomorphological features that control their dispersion and composition. Local geo-morphology, along with any reported coastal anthropogenic activity, are correlated to seafloor litter densities to investigate the temporal and spatial dynamics that control their distribution and temporal trends in Syros Island, Cyclades, Greece. There, in the context of LIFE DEBAG project, monitoring of an urbanized shallow bay for 3 consecutive years has been performed to assess the impact of an intensive local awareness raising campaign to the local environment. A significant reduction of litter densities under the impact of this campaign has been documented, while links between the seafloor litter transport dynamics and the seabed micro- and macro-topography were made evident. Monitoring litter densities on the seafloor of urbanized shallow bays proved to be a prospective way of tracking marine litter pressures on the local marine environment.

Are FADs a significant source of marine litter? Assessment of released debris and mitigation strategy in the Mediterranean sea.

A poorly known form of marine litter known as Abandoned, Lost or otherwise Discarded Fishing (ALDFG) derives from fishing activities using FADs (Fish Aggregating Devices). In the Mediterranean Sea, this activity is widespread in southern Italy, Tunisia, Malta and Majorca (Spain). The way of constructing FADs, from a functional point of view, is very similar throughout the Mediterranean and consists mainly of the use of different materials for the floats and for the cables and blocks for anchoring. Every year, for at least 30 years, about 60,000 FADs have been placed at sea and in most cases are not recovered. In this study, through analysis of the scientific and grey literature, a historical reconstruction of the use of FADs in the Mediterranean Sea was made, including their spatial distribution, the number of objects and the materials used to build the devices. It has been estimated that approximately 1.6 million FADs were abandoned in the Mediterranean Sea between 1961 and 2017. The largest fishing areas are off Malta (34,465 km2) and Tunisia (23,033 km2). The greatest numbers of abandoned plastic sheets (452,742) and concrete blocks (905,483) were estimated to be around Tunisia, while the greatest amount, in terms of length, of polyethylene cable (399,423 km) was estimated to be around Sicily. About 30% of FADs used all over the world are used in the Mediterranean and are only of the anchored type (corresponding to about 90% of those anchored used worldwide). The legislation on the use of Mediterranean FADs is still poor and does not address environmental issues. An analysis of the possible environmental impacts of the FAD litter was made. Overall, reducing the number of FADs and introducing new types of FADs equipped with specific technological systems appear to be the most suitable strategies to mitigate the impact of FADs on the environment and resources, as well as measures and incentives to involve fishermen in their better management.

Phthalate Release from Plastic Fragments and Degradation in Seawater.

Plastic debris in the environment contains plasticizers, such as phthalates (PAEs), that can be released during plastic aging. Here, two common plastic materials, an insulation layer of electric cables (polyvinyl chloride, PVC-cables) and plastic garbage bag (polyethylene, PE-bags), were incubated in natural seawater under laboratory conditions, and the PAE migration to the seawater phase was studied with varying light and bacterial conditions over a 90-day time course. Free PAEs diluted in seawater were also studied for bacterial degradation. Our results showed that, within the first month of incubation, both plastic materials significantly leached out PAEs into the surrounding water. We found that di-isobutyl phthalate (DiBP) and di- n-butyl phthalate (DnBP) were the main PAEs released from the PE-bags, with the highest values of 83.4 ± 12.5 and 120.1 ± 18.0 ng g-1 of plastic, respectively. Furthermore, dimethyl phthalate (DMP) and diethyl phthalate (DEP) were the main PAEs released from PVC-cables, with mass fractions as high as 9.5 ± 1.4 and 68.9 ± 10.3 ng g-1, respectively. Additionally, we found that light and bacterial exposure increased the total amount of PAEs released from PVC-cables by a factor of up to 5, whereas they had no influence in the case of PE-bags.

White tides: The plastic nurdles problem.

The proliferation of plastic pollution, particularly from nurdles (small plastic pellets used in manufacturing), poses significant environmental and ecological risks. Originating with the invention of Bakelite in 1907 and escalating post-World War II with advanced petrochemical technologies, nurdles are the second largest source of primary microplastic pollution globally. Each year an estimated 445,970 tonnes of nurdles enter the environment worldwide. Nurdle spills, such as those along Spain's Galician coast and other global incidents, underline the need for improved spill response, preventive measures, and international regulatory coordination. The environmental impact of nurdles, compared to more visible oil spills, is insidious and long-lasting due to their persistence and widespread dispersion. Current regulations, like the International Maritime Organization's (IMO) guidelines, reveal gaps in enforcement and fail to fully address the long-term consequences of spills. Recent technological innovations and policy interventions aim to mitigate risks, but there's an urgent need for coordinated global action, stricter controls, and investment in biodegradable alternatives to safeguard marine environments and ensure ecological sustainability.

The geological footprint of plastics.

The significant impact of plastics on Earth's environments has transformed from being a symbol of modern innovation to a major ecological concern. This perspective paper explores the integration of plastics into geological contexts, emphasizing their role in contemporary sedimentary processes. It examines the lifecycle of plastics, from production to disposal, and their subsequent interaction with natural sedimentary cycles. The production and usage of plastics have led to considerable environmental repercussions. One of these, is their incorporation into geological systems and the formation of novel geological materials. Such a phenomenon challenges traditional geological concepts and necessitates a multidisciplinary approach encompassing geology, chemistry, and environmental science.

Navigating between socio-economic viability and environmental impacts: The sachets and sticks paradox.

Sachets and plastic sticks, single-use packaging primarily constructed from polyethylene terephthalate (PET), have proliferated globally for their convenience and multilayered construction that ensures product integrity. Especially prominent in emerging markets and amplified by pandemic-driven demand for hygiene products, these formats contribute significantly to fossil fuel industry revenue, aligning closely with petrochemical infrastructure developments such as fracking. While providing producers risk mitigation and cost-effective branding opportunities, these packaging types impose significant environmental tolls. The multimaterial layered composition of these materials hampers recycling efforts, and incineration releases toxins, exacerbating pollution. The plastics industry thus becomes an economic support for fossil fuel sectors facing declining oil demand. The growth of this sachet-stick economy represents a precarious balance between immediate economic benefits and long-term environmental ramifications. As global attention increasingly turns toward sustainability and pollution reduction, it becomes crucial to analyze the true environmental and socioeconomic costs of sachet and stick packaging.

Addressing the global challenge of coastal sewage pollution.

Coastal environments, essential for about half of the world's population living near coastlines, face severe threats from human-induced activities such as intensified urbanization, aggressive development, and particularly, coastal sewage pollution. This type of pollution, comprising untreated sewage discharging nutrients, pathogens, heavy metals, microplastics, and organic compounds, significantly endangers these ecosystems. The issue of sewage in coastal areas is complex, influenced by factors like inadequate sewage systems, septic tanks, industrial and agricultural runoff, and natural processes like coastal erosion, further complicated by oceanic dynamics like tides and currents. A global statistic reveals that over 80 % of sewage enters the environment without treatment, contributing significantly to nitrogen pollution in coastal ecosystems. This pollution not only harms marine life and ecosystems through chemical contaminants and eutrophication, leading to hypoxic zones and biodiversity loss, but also affects human health through waterborne diseases and seafood contamination. Additionally, it has substantial economic repercussions, impacting tourism, recreation, and fisheries, and causing revenue and employment losses. Addressing this issue globally involves international agreements and national legislations, but their effectiveness is hindered by infrastructural disparities, particularly in developing countries. Thus, effective management requires a comprehensive approach including advanced treatment technologies, stringent regulations, regular monitoring, and international cooperation. The international scientific community plays a crucial role in fostering a collaborative and equitable response to this pressing environmental challenge.

The collateral effects of COVID-19 on coastal and marine environments.

The COVID-19 pandemic has generated a global health and economic crisis, significantly impacting coastal and marine environments. Lockdowns and restrictions, while necessary for public health, led to both positive and negative environmental consequences. Reduced human activity resulted in decreased pollution and habitat disruption, allowing for ecosystem recovery and improved water quality. However, the surge in single-use plastics and personal protective equipment (PPE) during the pandemic exacerbated plastic pollution. Additionally, the economic downturn severely affected coastal communities reliant on tourism and fisheries, highlighting the need for sustainable recovery strategies. This Special Issue explores these collateral effects, emphasizing the importance of adaptive management and resilient governance in safeguarding coastal and marine ecosystems against future crises.

Rethinking plastic entrapment: Misconceptions and implications for ecosystem services in coastal habitats.

This study addresses the pressing issue of plastic pollution in coastal and marine ecosystems, challenging the misconception that the entrapment of plastics can be considered as an ecosystem service. We differentiate between essential natural processes that sustain ecological balance and biodiversity and the detrimental accumulation of synthetic polymers. The pathways through which plastics enter these environments-from terrestrial to maritime sources-are examined, alongside their pervasive impacts on crucial ecosystem services such as habitat quality, the vitality of marine species, and nutrient cycling. Our findings highlight the paradox of resilience and vulnerability in these ecosystems: while capable of accumulating substantial amounts of plastic debris, they suffer long-lasting ecological, socio-economic, and health repercussions. We argue for a paradigm shift in management strategies aimed at reducing plastic production at the source, improving waste management practices, conducting targeted cleanup operations, and rehabilitating impacted ecosystems. Emphasizing a comprehensive understanding of plastic pollution is vital for framing effective solutions and necessitates a reevaluation of societal, industrial, and regulatory frameworks. This shift is imperative not only to address current pollution levels but also to safeguard and sustain the functionality of coastal ecosystems, ensuring their ability to continue providing essential services and supporting biodiversity.

Rethinking geological concepts in the age of plastic pollution.

This paper attempts to reevaluate traditional geological classifications from sedimentology to stratigraphy as well as the concept of the Holocene/Anthropocene epochs, characterized by the widespread integration of plastics into sedimentary environments. This paper presents a set of novel insights into the interactions between synthetic materials and natural geological processes. We illustrate how plastics not only disrupt sedimentary dynamics and alter the composition of rocks and soils, creating new forms of pollution and also pose escalated threats to marine biodiversity through altered erosion, transport, and deposition patterns. We highlight the emerging role of plastics as distinctive stratigraphic markers, providing a different perspective on human environmental impacts. This analysis challenges the traditional perception of rocks as solely natural, inorganic formations and highlights the critical need for interdisciplinary approaches that meld geology, chemistry, and environmental science. The document calls for intensified research to develop effective strategies for managing these impacts and promotes innovative conservation techniques that address both the symptoms and sources of plastic pollution.

What, where, and when: Spatial-temporal distribution of macro-litter on the seafloor of the western and central Mediterranean sea.

The progressive increase of marine macro-litter on the bottom of the Mediterranean Sea is an urgent problem that needs accurate information and guidance to identify those areas most at risk of accumulation. In the absence of dedicated monitoring programs, an important source of opportunistic data is fishery-independent monitoring campaigns of demersal resources. These data have long been used but not yet extensively. In this paper, MEDiterranean International Trawl Survey (MEDITS) data was supplemented with 18 layers of information related to major environmental (e.g. depth, sea water and wind velocity, sea waves) and anthropogenic (e.g. river inputs, shipping lanes, urban areas and ports, fishing effort) forcings that influence seafloor macro-litter distribution. The Random Forest (RF), a machine learning approach, was applied to: i) model the distribution of several litter categories at a high spatial resolution (i.e. 1 km2); ii) identify major accumulation hot spots and their temporal trends. Results indicate that RF is a very effective approach to model the distribution of marine macro-litter and provides a consistent picture of the heterogeneous distribution of different macro-litter categories. The most critical situation in the study area was observed in the north-eastern part of the western basin. In addition, the combined analysis of weight and density data identified a tendency for lighter items to accumulate in areas (such as the northern part of the Tyrrhenian Sea) with more stagnant currents. This approach, based on georeferenced information widely available in public databases, seems a natural candidate to be applied in other basins as a support and complement tool to field monitoring activities and strategies for protection and remediation of the most impacted areas.

Comparative analysis of microplastics detection methods applied to marine sediments: A case study in the Bay of Marseille.

An intercomparison exercise on "microplastics in sediment" was carried out by five laboratories using samples collected in the Bay of Marseille in September 2021. The results from different extraction and identification methods varied depending on the type and size classes of MPs, and was better than 80 % for the size class >300 µm and for the fragments. The variability in recovery rates can be attributed to the choice of reagents and extraction protocols. Recovery rates per laboratory were between 47 % and 113 % and the use of ZnCl2 and NaI increased recovery rates by an average of 70 %. The lowest recovery rates (47 and 53 %) were attributed to the reference methods (FTIR and LDIR), conversely the highest (80 and 87 %) were attributed to identification by Nile Red. The average ranged between 23 and 53 items /50 g d.w. with decreases offshore and at greater depth.

Plastics in the Anthropocene: A multifaceted approach to marine pollution management.

The Anthropocene, defined by human-induced environmental transformations, presents a critical challenge: plastic pollution. This complex problem, particularly prominent in coastal and marine environments, requires integrated and adaptive responses. This opinion paper examines global efforts across policy interventions, scientific innovations, and public education, highlighting both advancements and hurdles in managing this problem. These include enforcement limitations in policy implementation, scalability and cost issues in scientific innovations, and challenges in effecting large-scale behavioral change through public education. The complexities inherent in managing plastic litter in coastal and marine environments are further discussed, emphasizing the necessity for an integrated approach. This approach involves interdisciplinary collaboration, adaptive management, stakeholder engagement, policy integration, sustainable financing, resilience building, capacity enhancement, technological innovation, policy reform, ecosystem-based management, disaster risk reduction, and advocacy. The management of plastic pollution in the Anthropocene requires strategic planning, innovative thinking, and unified global efforts, ultimately providing an opportunity to redefine our relationship with the planet and steer toward a more sustainable future.

Discussion about suitable applications for biodegradable plastics regarding their sources, uses and end of life.

This opinion paper offers a scientific view on the current debate of the place of biodegradable plastics as part of the solution to deal with the growing plastic pollution in the world's soil, aquatic, and marine compartments. Based on the current scientific literature, we focus on the current limits to prove plastic biodegradability and to assess the toxicity of commercially used biobased and biodegradable plastics in natural environments. We also discuss the relevance of biodegradable plastics for selected applications with respect to their use and end of life. In particular, we underlined that there is no universal biodegradability of plastics in any ecosystem, that considering the environment as a waste treatment system is not acceptable, and that the use of compostable plastics requires adaptation of existing organic waste collection and treatment channels.

Oceanographic and anthropogenic variables driving marine litter distribution in Mediterranean protected areas: Extensive field data supported by forecasting modelling.

Marine litter concentration in the Mediterranean Sea is strongly influenced both by anthropogenic pressures and hydrodynamic factors that locally characterise the basin. Within the Plastic Busters MPAs (Marine Protected Areas) Interreg Mediterranean Project, a comprehensive assessment of floating macro- and microlitter in the Pelagos Sanctuary and the Tuscan Archipelago National Park was performed. An innovative multilevel experimental design has been planned ad-hoc according to a litter provisional distribution model, harmonising and implementing the current sampling methodologies. The simultaneous presence of floating macro- and microlitter items and the potential influences of environmental and anthropogenic factors affecting litter distribution have been evaluated to identify hotspot accumulation areas representing a major hazard for marine species. A total of 273 monitoring transects of floating macrolitter and 141 manta trawl samples were collected in the study areas to evaluate the abundance and composition of marine litter. High mean concentrations of floating macrolitter (399 items/km2) and microplastics (259,490 items/km2) have been found in the facing waters of the Gulf of La Spezia and Tuscan Archipelago National Park as well in the Genova canyon and Janua seamount area. Accordingly, strong litter inputs were identified to originate from the mainland and accumulate in coastal waters within 10-15 nautical miles. Harbours and riverine outfalls contribute significantly to plastic pollution representing the main sources of contamination as well as areas with warmer waters and weak oceanographic features that could facilitate its accumulation. The results achieved may indicate a potentially threatening trend of litter accumulation that may pose a serious risk to the Pelagos Sanctuary biodiversity and provide further indications for dealing with plastic pollution in protected areas, facilitating future management recommendations and mitigation actions in these fragile marines and coastal environments.

A critical review on the evaluation of toxicity and ecological risk assessment of plastics in the marine environment.

The increasing production of plastics together with the insufficient waste management has led to massive pollution by plastic debris in the marine environment. Contrary to other known pollutants, plastic has the potential to induce three types of toxic effects: physical (e.g intestinal injuries), chemical (e.g leaching of toxic additives) and biological (e.g transfer of pathogenic microorganisms). This critical review questions our capability to give an effective ecological risk assessment, based on an ever-growing number of scientific articles in the last two decades acknowledging toxic effects at all levels of biological integration, from the molecular to the population level. Numerous biases in terms of concentration, size, shape, composition and microbial colonization revealed how toxicity and ecotoxicity tests are still not adapted to this peculiar pollutant. Suggestions to improve the relevance of plastic toxicity studies and standards are disclosed with a view to support future appropriate legislation.

Harmful algae and pathogens on plastics in three mediterranean coastal lagoons.

Plastic is now a pervasive pollutant in all marine ecosystems. The microplastics and macroplastic debris were studied in three French Mediterranean coastal lagoons (Prevost, Biguglia and Diana lagoons), displaying different environmental characteristics. In addition, biofilm samples were analyzed over the seasons to quantify and identify microalgae communities colonizing macroplastics, and determine potentially harmful microorganisms. Results indicate low but highly variable concentrations of microplastics, in relation to the period and location of sampling. Micro-Raman spectroscopy analyses revealed that the majority of macroplastic debris corresponded to polyethylene (PE) and low-density polyethylene (LDPE), and to a far lesser extent to polypropylene (PP). The observations by Scanning Electron Microscopy of microalgae communities colonizing macroplastic debris demonstrated differences depending on the seasons, with higher amounts in spring and summer, but without any variation between lagoons and polymers. Among the Diatomophyceae, the most dominant genera were Amphora spp., Cocconeis spp., and Navicula spp.. Cyanobacteria and Dinophyceae such as Prorocentrum cordatum, a potentially toxic species, were also found sporadically. The use of Primer specific DNA amplification tools enabled us to detect potentially harmful microorganisms colonizing plastics, such as Alexandrium minutum or Vibrio spp. An additional in situ experiment performed over one year revealed an increase in the diversity of colonizing microalgae in relation to the duration of immersion for the three tested polymers PE, LDPE and polyethylene terephthalates (PET). Vibrio settled durably after two weeks of immersion, whatever the polymer. This study confirms that Mediterranean coastal lagoons are vulnerable to the presence of macroplastic debris that may passively host and transport various species, including some potentially harmful algal and bacterial microorganisms.

The streaming of plastic in the Mediterranean Sea.

Plastic debris is a ubiquitous pollutant on the sea surface. To date, substantial research efforts focused on the detection of plastic accumulation zones. Here, a different paradigm is proposed: looking for crossroad regions through which large amounts of plastic debris flow. This approach is applied to the Mediterranean Sea, massively polluted but lacking in zones of high plastic concentration. The most extensive dataset of plastic measurements in this region to date is combined with an advanced numerical plastic-tracking model. Around 20% of Mediterranean plastic debris released every year passed through about 1% of the basin surface. The most important crossroads intercepted plastic debris from multiple sources, which had often traveled long distances. The detection of these spots could foster understanding of plastic transport and help mitigation strategies. Moreover, the general applicability and the soundness of the crossroad approach can promote its application to the study of other pollutants.

Chemical composition of microplastics floating on the surface of the Mediterranean Sea.

The Mediterranean Sea is one of the most studied regions in the world in terms of microplastic (MP) contamination. However, only a few studies have analysed the chemical composition of MPs at the Mediterranean Sea surface. In this context, this study aims to describe the chemical composition as a function of particle size, mass and number concentrations of MPs collected in the surface waters of the Mediterranean Sea. The chemical composition showed a certain homogeneity at the Mediterranean Sea scale. The main polymers identified by Fourier Transform Infra-Red (FTIR) spectroscopy were poly(ethylene) (67.3 ± 2.4%), poly(propylene) (20.8 ± 2.1%) and poly(styrene) (3.0 ± 0.9%). Nevertheless, discrepancies, confirmed by the literature, were observed at a mesoscale level. Thus, in the North Tyrrhenian Sea, the proportion of poly(ethylene) was significantly lower than the average value of the Mediterranean Sea (57.9 ± 10.5%). Anthropic sources, rivers, or polymer ageing are assumed to be responsible for the variations observed.