Marine Pollution from Plastics and Microplastics

The threat of plastic waste in the environment has evoked rising concern over the past decades. While these versatile and incredibly popular polymer materials undoubtedly fulfil unprecedented services, their extreme durability and alleged toxicity represent major downsides, once in the environment. As plastics break down into smaller microplastics (MP) they evidently pollute almost every thinkable habitat on the globe today. While an estimated 5–12 million tons of plastic end up in the oceans every year, rivers are important pathways, carrying an annual freight of 0.41–4 million tons downstream. The Rhine River, one of Europe’s main streams and one of the World’s busiest waterways, reportedly holds substantial amounts of MP in its near-surface waters and sediments. However, little is known about potential MP sources, seasonal dynamics and the MP pollution of benthic sediments of this major river. In my dissertation I address three pivotal knowledge gaps about MP in the Rhine River and investigate a new type of method to safely and efficiently separate MP from surrounding environmental sample matrices. The surface water MP pollution of the Rhine River was earlier characterised by the distinct appearance of vast amounts (~60%) of rigid polystyrene microbeads of unknown origin and former purpose. In a sustained investigation of a defined river stretch in the Lower Rhine downstream Cologne, we managed to narrow down the entry region of these pollutants and close-to-certainly unveil the particle’s former purpose as ion-exchange resin beads used in diverse fluid purification applications. As more data on MP in rivers emerges, an interesting gap opens: empirical field studies tend to generate temporally restricted snapshot data while modellers, laudably seeking the bigger picture, are confronted with enormous uncertainties in their results. In a bid to reduce this void we embarked on a quadruplicate surface water MP observation in the Rhine catchment during 2016–2017. The investigation included three nival discharge regime tributaries and the Rhine in Switzerland as well as a pluvial Rhine River section towards the German-Dutch border. It became evident that despite a coherent increasing MP concentration gradient downstream, reflecting average discharge and catchment size, overall variability in environmental MP data was large. This hampers clear-cut estimations about concentration fluctuations but at the same time reinforces the theory of high MP seasonal pollution fluxes in the European winter months, when Rhine discharge is highest. Seeking to contribute to the very scarce knowledge of MP and benthic sediment interaction in large dynamic rivers, we took a diving bell and a dredging vessel to the riverbed at two previously identified surface MP hotspots at the German Middle and Lower Rhine. Due to expected water turbulence and flow velocity, substantial settling of MP in such stretches is not necessarily anticipated. Interestingly, it showed that even the Rhine riverbed is not spared from vast MP pollution. The applied research technology allowed for reliable detection of MP down to particle sizes of 11 μm and yielded strongly varying concentrations of 260–11,000 MP kg^–1, with a strongly skewed size class distribution towards the smallest MP particles. Experience showed us that environmental sample preparation for MP research can be a tedious and resource-intensive enterprise – including health and environmental hazards. Instead of attacking the unwanted portions in a sample (e.g. biogenic residue to isolate MP), a more efficient approach is to select the MP specifically. We refined a proposed lipophilicity-based separation technique and broadened its scope by successfully testing it to four different types of environmental matrices. This one-for-all approach may present a promising means for quicker, cheap, safe and efficient MP data compilation. The method was successfully applied for the seasonal surface MP investigation presented in this dissertation.

A few times a year, volunteers fan out along the causeway that links the South Carolina mainland with the seashore community of Folly Beach to clean up plastic bottles, straws, bags, and other debris from along the road and the salt marsh. Some of this debris has come from cities miles away. On windy days, litter is often blown off city streets into waterways. During rainstorms, debris floats into drains that empty into rivers. Other trash probably came from places closer to home. “I see bags and other plastic flying off the beds of pickup trucks going down the causeway,” says Marty Morganello, who organizes the cleanups for the Charleston-area chapter of the nonprofit Surfrider Foundation. “I see them coming out the open windows of cars and out the backs of garbage trucks and even recycling trucks. This material is lightweight, and if you don’t secure it, it will fly away.” By one estimate, the volume of plastic debris going into the world’s oceans could more than double by 2025, assuming current trends in coastal development and plastics use. Some countries have begun identifying ways to improve management of plastic ... Beach cleanups yield enormous amounts of trash, with plastic items a major constituent.1 Although the human health impacts of this marine plastic pollution remain poorly characterized, it is widely seen as an emerging problem that deserves much more research attention.2 Likewise, there is a growing urgency among industry, government, nongovernmental organizations, and environmental groups to develop tools and policies to track, capture, and recycle plastic waste before it reaches the ocean.

Persistent organic pollutants sorbed in plastic resin pellet — “Nurdles” from coastal areas of Central Chile

The haphazard disposal of plastic waste has become a severe environmental problem. The low degradability of plastics in nature has resulted in the production of tiny plastic fragments by physical and chemical degradation of large plastic debris, and fragments in the range of 1 to 1000 μm are known as microplastics (MPs). MPs can be considered one of the worst forms of plastic waste damaging the environment. Their sorption and desorption of both organic and inorganic pollutants leads to bioaccumulation via food chains and can cause detrimental effects. In addition, MPs function as vectors of certain chemical pollutants, including persistent organic pollutants (POPs), perfluoroalkyl substances (PFAS), phthalate esters, pharmaceuticals, and heavy metals. It has been identified that the type of polymer, crystallinity, size of plastic particles, pH of the medium, age, and degree of weathering of plastic debris influence the interaction of chemical pollutants with MPs. MP-bound pollutants can desorb from plastic to organisms, causing various issues when those organisms ingest plastics. This chapter will elaborate on the interaction of chemical contaminants with MPs, mechanisms driving the interaction, and future approaches for handling environmental issues related to MPs.

Since the Second World War, scientists have identified certain chemical contaminants that exhibit toxic characteristics and are persistent in the environment, bioaccumulative, prone to long-range atmospheric transboundary migration and deposition, and expected to impose serious health effects on humans, wildlife, and marine biota adjacent to and distant from their origin of emission. These chemical pollutants are referred to as persistent organic pollutants (POPs) (Ashraf et al. 2015). POPs have long half-lives in soils, sediments, air and biota. No consensus exists on how long the half-life in a given medium should be for the word “persistent� to be applicable; nevertheless, the half-life of a POP might be years or decades in soil/sediment and a number of days in the atmosphere. Several thousand POP chemicals are known. Many of them are members of a definite series or “families� of chemicals. For instance, 209 diverse groups of polychlorinated biphenyls have been identified; they differ from each other by the level of chlorination and the substitution position (Jones and Voogt 1999). The carbon-chlorine bond is very stable toward hydrolysis and larger numbers of chlorine substitution and/or functional groups lead to greater resistance to biological and photolytic degradation. Because POPs break down very slowly, they will be present in the environment for a long time, even if all new sources are immediately eliminated (Chu et al. 2006). POPs in the environment are transported at low concentrations by movement of fresh and marine waters; in addition, because they are semi-volatile, POPs are transported over long distances in the atmosphere. The result is widespread distribution of POPs across the globe, including regions where they have never been used (Buccini et al. 2003). The POP levels observed in the Arctic region are surprising to many people because some of these pollutants have been banned from the USA and Canada for many years. POPs travel toward colder areas such as Alaska and then sink because of the colder temperatures. The settled contaminants remain in the area for a long period because the temperature does not allow them to easily breakdown. Consequently, they move from the air and water to soil and plants and then to animals and humans with ease. The persistence of contaminants in the Arctic from distant sources first came to light in the late 1970s when pesticides were found in polar bear fat tissue. The reality of atmospheric POPs and their effects on wildlife and human health then became evident. In addition to the Arctic, researchers have begun to search for evidence of airborne POPs in other cold ecosystems and mountain environments (Zhao et al. 2007). POPs are usually hydrophobic (i.e., “water-hating�) and lipophilic (i.e., “fat-loving�) chemicals. In marine and terrestrial systems, they bind strongly to solids, particularly organic matter, evading the aqueous segment. They also enter the lipids of organisms more easily than the inside of the aqueous medium of cells and are stockpiled in fatty tissue. This stockpiling in fatty tissue allows the compounds to persevere in biota, where the metabolism rate is low. Consequently, POPs may climb the food chain. POPs tend to move in the gas phase under environmental temperatures. Therefore, they may volatilize from soils, vegetation, and aquatic systems into the air and, because of their resistance to breakdown reactions in air, migrate long distances before being re-deposited. The sequence of volatilization and condensation can be repeated frequently; as a consequence, POPs are detected in regions far removed from where they were used or discharged. POPs can partition between particles and aerosols in the air and are reliant on ambient temperature and the physico-chemical characteristics of the substances. In summary, the combination of permanency and the tendency to form a gas under suitable environmental conditions causes POPs to migrate long-range atmospheric distances. The combined effects of confrontation, metabolism, and lipophilicity result in the accumulation of POPs in food chains (Jones and Voogt 1999).

Microplastics (MPs) have become a critical pollutant, accumulating in aquatic ecosystems and posing significant environmental and human health risks. Approximately 5.25 trillion plastic particles float in global oceans, releasing up to 23,600 metric tonnes of dissolved organic carbon annually, which disrupts microbial dynamics. MPs arise from the breakdown of larger plastics, degraded by photodegradation, thermal degradation, and biological processes, which are influenced by polymer type and environmental factors. As carriers, MPs absorb and transport contaminants such as heavy metals, per- and polyfluoroalkyl substances (PFAS), and persistent organic pollutants (POPs) across trophic levels, thereby increasing toxicity within food webs. Key aquatic organisms, including microalgae, molluscs, and fish, experience cellular toxicity, oxidative stress, and disruptions in essential functions due to MP ingestion or adhesion, raising concerns about their bioaccumulation in humans through ingestion, inhalation, and dermal contact. The complex surface chemistry of MPs enhances their pollutant adsorption, a process modulated by environmental pH, salinity, and contamination levels, while aging and structural attributes further impact their bioavailability and toxicity. This review consolidates knowledge on MPs’ occurrence, transformation, pollutant interactions, and methodologies for sampling and analysis, emphasizing advancements in spectroscopy and imaging techniques to improve MP detection in aquatic environments. These insights underscore the pressing need for standardized analytical protocols and comprehensive toxicological research to fully understand MPs’ effects on ecosystems and human health, informing future mitigation strategies and policy development.Graphical abstract

Emerging threats of microplastics on marine environment: A critical review of toxicity measurement, policy practice gap and future research direction

Wastewater treatment facilities can filter out some plastics before they reach the open environment, yet microplastics often persist throughout these systems. As they age, microplastics in wastewater may both leach and sorb pollutants and fragment to provide an increased surface area for bacterial attachment and conjugation, possibly impacting antimicrobial resistance (AMR) traits. Despite this, little is known about the effects of persistent plastic pollution on microbial functioning. To address this knowledge gap, we deployed five different artificially weathered plastic types and a glass control into the final maturation pond of a municipal wastewater treatment plant in Ōtautahi-Christchurch, Aotearoa/New Zealand. We sampled the plastic-associated biofilms (plastisphere) at 2, 6, 26, and 52 weeks, along with the ambient pond water, at three different depths (20, 40, and 60 cm from the pond water surface). We investigated the changes in plastisphere microbial diversity and functional potential through metagenomic sequencing. Bacterial 16S ribosomal RNA genes composition did not vary among plastic types and glass controls (P = 0.997) but varied among sampling times [permutational multivariate analysis of variance (PERMANOVA), P = 0.001] and depths (PERMANOVA, P = 0.011). Overall, there was no polymer-substrate specificity evident in the total composition of genes (PERMANOVA, P = 0.67), but sampling time (PERMANOVA, P = 0.002) and depth were significant factors (PERMANOVA, P = 0.001). The plastisphere housed diverse AMR gene families, potentially influenced by biofilm-meditated conjugation. The plastisphere also harbored an increased abundance of genes associated with the biodegradation of nylon, or nylon-associated substances, including nylon oligomer-degrading enzymes and hydrolases.IMPORTANCEPlastic pollution is pervasive and ubiquitous. Occurrences of plastics causing entanglement or ingestion, the leaching of toxic additives and persistent organic pollutants from environmental plastics, and their consequences for marine macrofauna are widely reported. However, little is known about the effects of persistent plastic pollution on microbial functioning. Shotgun metagenomics sequencing provides us with the necessary tools to examine broad-scale community functioning to further investigate how plastics influence microbial communities. This study provides insight into the functional consequence of continued exposure to waste plastic by comparing the prokaryotic functional potential of biofilms on five types of plastic [linear low-density polyethylene (LLDPE), nylon-6, polyethylene terephthalate, polylactic acid, and oxygen-degradable LLDPE], glass, and ambient pond water over 12 months and at different depths (20, 40, and 60 cm) within a tertiary maturation pond of a municipal wastewater treatment plant.

<p>This study reports on the amount of plastic wastes in five river mouths discharging to Manila Bay, a natural harbor which drains approximately 17,000 km<sup>3</sup> of watershed area. Of the 17 rivers discharging to the Bay, five rivers which run through the densely populated and highly urbanized Metropolitan Manila are included in the study namely, Pasig, Cañas, Tullahan, Meycauyan and Parañaque. A Waste Analysis and Characterization Study (WACS) was conducted to investigate the composition of the wastes that were on the river banks. Samples were taken from the wastes that were found lying on the banks. The wastes collected in each study site varied from each other, although plastic wastes and yard wastes were gathered from all areas. Based on their % wet weight, plastics alone comprised 28% of wastes in Cañas, 46% of wastes in Meycauayan, 42% of wastes in Parañaque, 37% of wastes in Pasig and 27% of wastes in Tullahan. The disposed plastics collected were also characterized and categorized into different types: hard plastic (PP, HDPE), film plastic (PP, PE), foam (PS, PUR) and other type (PVC, PET). In Cañas River, film plastics (79%) were the most ubiquitous type of plastic waste which primarily consist of different sachets of household products and single-use plastic bags. Few hard plastics and other types of plastic such as PVC and PET were collected. Meycauayan River and Parañaque River had almost the same plastic type distribution wherein the most dominant plastic type were hard plastics. These hard plastics collected were mostly composed of bottles of detergents and toiletries. Meycauayan River has relatively fewer establishments near its river mouth, indicating that the sources of the accumulated plastic wastes came from the mid and upstream of the river where the urbanized and industrialized areas were located. Furthermore, even though hard plastics represented 38% of wastes in Paranaque, numerous plastic straw ropes were collected as fishermen use these straws to tie up their boats to the docking area. Significant amount of foams  and PET bottles were also amassed in these rivers. Plastic wastes from the Pasig River were mostly comprised of both film plastics (39%) and hard plastics (30%). The plastic wastes taken were all household products directly dumped by the those residing by the Pasig River mouth. Notable quantity of foams and other types of plastic were fetched from the sampling area. Tullahan River has abundant amount of film plastics (35%) and foams (33%) in its river mouth. Some of these plastic wastes are stuck to the rafts tied up along the bank of the river. Sachets of household products were dominantly present. Few hard plastics and other type of plastic were extracted from the site. Substantial amount of plastic wastes in each of the river mouths signifies poor waste management infrastructure, lack of materials recovery facilities, and lack of discipline of people as these plastics are found to be directly dumped into the water bodies.  </p>

Microplastics (MPs) have attracted much attention in recent years, due to the difficulty of degradation and threats to ecological systems and humans. Based on the analysis of 1429 articles on MPs in soil, we found that we know little about the behavior and fate of manure-born MPs from the livestock and poultry production systems to agriculture soils. This review summarizes the analytical methods for sampling, separation, and identification and the occurrence of MPs in livestock and poultry manure, mainly based on 7 surveys related to manure-born MPs. Then, the sources, fate, and environmental risks of MPs in livestock and poultry manure are discussed. MPs, heavy metals, pathogens, antibiotic resistance genes, and persistent organic pollutants are common pollutants in livestock and poultry manure. Worse, manure-born MPs will become smaller, rougher, and more numerous and could easily form more toxic compound pollution after complicated processes of manure treatment, which seriously threatens agricultural soil safety. Finally, an outlook is offered for future research. We hope this article to attract attention to the risks of MPs in livestock and poultry manure and provide a reference for future research.

Plastic pollution has become a problem for many marine organisms. The omnipresent microplastics (MPs) are of particular concern due to their effect on a variety of species, including reef-building corals. Corals have been found to interact with MPs, ingest, and even incorporate them into their skeletons. However, knowledge on what affects the responses of coral polyps to these indigestible particles is still constrained. Here, we aimed to unravel factors influencing the feeding responses of coral polyps to MPs. Particularly, we (I) assessed coral feeding responses (i.e., reaction, ingestion, and incorporation) to different MP polymers and shapes in the presence vs. absence of a biofilm and food during feeding trials. We (II) characterized polymer-biofilm-associated compounds to infer potential mechanistic processes underlying the observed differences. We (III) evaluated effects of food availability on polyp activity under continuous MPs exposure. We found that the polymer type most strongly influenced the feeding response, and that MP shape additionally affected ingestion and incorporation. While we detected species-specific differences in responses, the presence of a biofilm and food had only minor effects. We identified 11 polymer-biofilm-associated compounds with potential stimulating and toxic influence. Polyp activity was not altered by the prevalence of natural food. These findings suggest that the particle recognition mechanisms of corals are, although generally well suited to differentiate between MPs and natural particles, rely primarily on chemoreception of substances leaching from MP polymers, with mechanoreception contributing to shape-specific responses. We conclude that future assessments of coral-MPs interactions should consider polymer- and shape-specific effects, as these appear to be the key driver of the coral feeding response to MPs.

Plastic pollution has become a global problem for marine ecosystems. Microplastics (MPs) are consumed by several marine organisms, including benthic and pelagic fish species that confuse them with food sources, thus contributing to bioaccumulation along the food chain. In addition to structural intestinal damage, ingestion of MPs represents a pathway for fish exposure to potentially hazardous chemicals, too. Most of them are endocrine disrupters, genotoxic or induce immune depression in fish.Accordingly, we assessed the combined toxicological effects of microplastics (MPs) and adsorbed pollutants by adding them to marine fish diet. European sea bass (Dicentrarchus labrax) juveniles were fed for 60 days with feeds containing polypropylene MPs, either virgin or contaminated with chemical pollutants (a blend of dichlorodiphenyldichloroethylene, chlorpyrifos, and benzophenone-3). The data demonstrated a synergic action of MPs and chemical pollutants to induce an inflammatory-like response in distal intestine of sea bass as shown by the up regulation of cytokine il-6 and tnf-α expression. Morphological analysis detected the presence of a focus of lymphocytes in anterior and posterior intestinal segments of fish fed with contaminants in the diet. With regard to microbiota, significant changes in bacterial species richness, beta diversity, and composition of gut microbiota were observed as a consequence of both pollutants and polluted MPs ingestion. These perturbations in gut microbial communities, including the reduction of beneficial lactic acid bacteria and the increase in potential pathogenic microorganism (Proteobacteria and Vibrionales), were undeniable signs of intestinal dysbiosis, which in turn confirmed the signs of inflammation caused by pollutants, especially when combined with MPs. The results obtained in this study provide, therefore, new insights into the potential risks of ingesting MPs as pollutant carriers in marine fish.

Microplastics pollution in freshwater fishes in the South of Italy: Characterization, distribution, and correlation with environmental pollutants

In a world where plastics have become an integral part of daily life, the ubiquitous presence of microplastics (MPs) is hardly surprising. However, the emergence of MPs in one of humanity’s most vital resources—groundwater—is concerning. This review explores the widespread reports of MPs in drinking water, examining their origins and the potential effects of their associated pollutants on human health. The exploration was facilitated through an exhaustive analysis of research contributions across the topic. Instances of MPs infiltrating drinking water have been documented across 42 countries, including Australia, Belgium, Brazil, Canada, China, Hong Kong, Iceland, Nepal, Nigeria, the United Kingdom, and the United States. The identification of the sources of these MPs is crucial, and this review clarifies several significant contributors. The sources encompass atmospheric contamination, the packaging and distribution processes associated with bottled water, effluents generated from laundry activities, fertilizers, and the domestic/industrial wastewater streams. Furthermore, the review emphasizes the role of MP particles as carriers, facilitating the transportation of heavy metals, persistent organic pollutants, and emergent contaminants into drinking water. While scientific evidence to definitively establish the impacts of MPs on human health remains an evolving field, it is paramount to recognize that their associated pollutants have tangible effects that warrant attention. Among the potential effects highlighted are anemia, brain cancer, hypertension, intestinal bleeding, methemoglobinemia, and liver cancer. Addressing the pressing need for actionable measures, this review offers practical strategies to counter the presence of existing MPs in drinking water and mitigate their further proliferation. The insights and recommendations presented herein are anticipated to provide valuable contributions toward the resolution of the menace posed by MP contamination in drinking water, as well as the broader challenge of plastic pollution at large.

Deciphering the seasonal dynamics of microplastic morphotypes and associated co-contaminants along the northwest coast of India