Plastic Debris Research Articles

High-Efficiency Degradation of PET Plastics by Glutathione S-Transferase under Mild Conditions.

Plastic pollution is a significant environmental concern globally. Plastics are normally considered chemically inert and resistant to biodegradation. Although many papers have reported enzyme-induced biodegradation of plastics, these studies are primarily limited to enzymes of microbial origin or engineered enzymes. This study reveals that poly(ethylene terephthalate) (PET, ∼6000 Da and 100 kDa) particles and plastic bottle debris (PBD, 24.9 kDa) can be efficiently degraded by a mammal-origin natural phase II metabolic isozyme, glutathione S-transferase (GST), under mild conditions. The degradation efficiency of PET plastics reached 98.9%, with a degradation rate of 2.6 g·L-1·h-1 under ambient or physiological conditions at 1 atm. PET plastics can be degraded by GST with varying environmental or biological factors (i.e., temperature, light irradiation, pH, and presence of humic acid or protein). We suggest a novel mechanism for PET degradation other than hydrolysis, i.e., the mechanism of cleavage and release of PET plastic monomers via nitridation and oxidation. This finding also reveals a novel function of GST, previously thought to only degrade small molecules (<1000 Da). This method has been successfully applied in real human serum samples. Additionally, we have tested and confirmed the ability to degrade PET of a mammal-origin natural digestive enzyme (trypsin) and a human-derived natural metabolic enzyme (CYP450). Overall, our findings provide a potential new route to plastic pollution control and contribute to our understanding of the metabolism and fate of plastics in organisms.

Beach litter deposition and turnover, effects of tides and weather, and implications for cleanup strategies: A case study in the Lofoten archipelago, Norway

Plastic pollution is ubiquitous in the marine environment. Beach cleanups are considered a cost-effective mitigative measure with generally few negative environmental impacts. Beached litter is not static, however, and may wash back out to sea or be buried, meaning it is only temporarily available for cleanup. We studied deposition and turnover of litter on three Arctic beaches in Lofoten, Norway, biweekly for 31 months. The mean estimated daily deposition rate was 10 items/100 m, with a median residence time of 99 days. Both processes were impacted by seasons and weather and varied both spatially and temporally. Strong winds during the fall increased litter influx and onshore winds contributed to its loss. Heavier objects and those higher on the beach persisted longer yet were still subject to turnover. Snow temporarily buries litter but protects it in the long run. Given the turnover of litter, frequent (albeit smaller) cleanups can readily remove 3–4 times more litter from circulation in the environment than larger, infrequent cleanups. With limited resources, it is recommended to prioritise late fall cleanups.

Marine Debris Harbor Unique, yet Functionally Similar Cryptofauna Communities.

Human-made debris is entering the ocean at alarming rates. These artificial structures are becoming habitats for small marine taxa known as cryptofauna. Cryptofauna are among the most essential reef taxa; however, little is known about these organisms, let alone their fate considering degrading coral reefs and increasing anthropogenic disturbance. The current study explores differences in naturally occurring cryptofauna biodiversity compared to those inhabiting benthic marine debris. To explore this difference, we measured invertebrate diversity from autonomous reef monitoring structures (ARMS) located on patch reefs along the middle Florida Keys reef tract. ARMS were used as a proxy for natural structure to compare to marine debris removed from five reef locations. Plastic debris was the most abundant of all the debris material collected. Wood and concrete were identified as covariates since they are sourced from wooden lobster traps. Taxa diversity varied significantly between ARMS and debris, indicating that each structural unit contained significantly different and diverse communities. The most influential taxa identified included commensal shrimps, hermit crabs, brittle stars, segmented worms, and several families of crabs. Additionally, while functional richness increased with taxa richness for ARMS communities, debris communities showed decreasing functional richness and high functional similarity, suggesting a specialization of debris-specific taxa. Overall, these data assist in better understanding of the marine community ecology surrounding anthropogenic marine debris for future debris removal and management practices for comprehensive reef health.

Densities of neuston often not elevated within plastic hotspots territory inside the North Pacific Garbage Patch

The North Pacific Garbage Patch, located in the eastern part of the North Pacific subtropical gyre, contains vast amounts of floating plastic debris. Research over the past decades has mainly focused on assessing the extent of plastic pollution in this oceanic region. However, the North Pacific subtropical gyre is also home to the surface-associated pelagic community known as neuston. To date, the dynamics of this ecosystem and its vulnerability towards environmental pollution and anthropogenic impacts remain poorly understood. While removing plastic debris afloat at sea can reduce negative impacts of plastic pollution on neuston and marine life in general, concerns have been raised that cleanup efforts could have an adverse effect on neuston due to potential co-accumulation of neuston and plastic at the sea surface. Here, we provide the most comprehensive assessment of neuston abundance in the eastern North Pacific Ocean and its relation to the distribution of floating plastic debris (0.05–5 cm in size) based on a first year-round survey. Our results reveal that neuston taxa inside the North Pacific Garbage Patch often show similar or lower abundances in areas with particularly high densities of floating plastic debris compared to the wider garbage patch. Targeting open-ocean cleanups on such plastic hotspot territories inside the garbage patch can therefore minimize interactions with neuston during cleanups, thus maximizing their net environmental gain. We further discover that neuston depicts substantial seasonal variability, which needs to be considered when assessing impacts on neuston.

Towards Solving the Beach Litter Problem: Ecosystem Service Assessments at North African Coasts

Towards Solving the Beach Litter Problem: Ecosystem Service Assessments at North African Coasts

From Sea Water to Salt Crystals: An Onsite Investigation of Microplastics in a Conventional Sea Salt Farming System.

This study investigated microplastic (MP) contamination in conventional sea salt farming systems. Various crude sea salt samples (n = 22) that were traditionally produced were collected from salt farms and local vendors. Salt water (n = 15), macroalgae (n = 6), and clay of pond floors (n = 6) were collected from ponds subjected to different production (stabilization, evaporation, and concentration and crystallization concentration) processes. All samples were analyzed for MP abundance and characteristics. The potential sources of MP contamination in the salt were also investigated. The mean abundance of MPs in the salt water and clay of pond floor increased progressively throughout the production process and reached its highest level in the concentration and crystallization ponds (7400 MP particles/m3 in salt water and 19,336 MP particles/m2 in the clay of the pond floor). A maximum of 26,500 MP particles/kg of macroalgal material indicated the potential sink of MPs on the surface of the algae. Approximately 34-2377 MP particles/kg salt were found in the crude sea salt samples. However, the mean abundance (378 MP particles/kg of salt) indicated nonsignificant impacts of different harvesting processes on MP contamination. Most MP size distributions, shapes and polymer types in the salts were similar to those found in the salt water, macroalgae and clay of the pond floor. Approximately 99% of the MPs were fragments that were suspected to be decomposed from larger plastic debris and plastic machinery and tools used at the salt farm. Similar patterns of polymer distribution, in which PP > PE > PET > PS, were found for all samples studied.

Toxicity of environmental and polystyrene plastic particles on the bivalve Corbicula fluminea: focus on the molecular responses.

Among aquatic organisms, filter feeders are particularly exposed to the ingestion of microplastics (MPs) and nanoplastics (NPs). The present study investigates the effect of environmental microplastics (ENV MPs) and nanoplastics (ENV NPs) generated from macro-sized plastic debris collected in the Garonne River (France), and polystyrene NPs (PS NPs) on the freshwater bivalve Corbicula fluminea. Organisms were exposed to plastic particles at three concentrations: 0.008, 10, and 100 μg L-1 for 21 days. Gene expression measurements were conducted in gills and visceral mass at 7 and 21 days to assess the effects of plastic particles on different functions. Our results revealed: (i) an up-regulation of genes, mainly involved in endocytosis, oxidative stress, immunity, apoptosis, and neurotoxicity, at 7 days of exposure for almost all environmental plastic particles and at 21 days of exposure for PS NPs in the gills, (ii) PS NPs at the three concentrations tested and ENV MPs at 0.008 μg L-1 induced strong down-regulation of genes involved in detoxication, oxidative stress, immunity, apoptosis, and neurotoxicity at 7 days of exposure in the visceral mass whereas ENV MPs at 10 and 100 μg L-1 and all ENV NPs induced less pronounced effects, (iii) overall, PS NPs and ENV MPs 0.008 μg L-1 did not trigger the same effects as ENV MPs 10 and 100 μg L-1 and all ENV NPs, either in the gills or the visceral mass at 7 and 21 days of exposure. This study highlighted the need to use MPs and NPs sampled in the environment for future studies as their properties induce different effects at the molecular level to living organisms.

From riverbank to the sea: An initial assessment of plastic pollution along the Ciliwung River, Indonesia

This study presents the first comprehensive analysis of anthropogenic debris on the riverbanks of the Ciliwung River, covering upstream to downstream areas. The mean of debris found in each measurement was 32.79 ± 15.38 items/m2 with a weight of 106.00 ± 50.23 g/m2. Plastic debris accounted for over 50 % of all litter items identified and represents 55 % by weight, signifying a significantly high prevalence compared to global studies examining litter along riverbanks. The majority of the plastics found originated from Single-use applications and were predominantly made from Styrofoam. This investigation demonstrated the importance of actions to reduce single use applications and to improve waste management strategies. This can be achieved through proactive initiatives coupled with adaptable approaches, such as implementing effective urban planning and enhancing waste collection capacity.

Transitioning to Microplastic-Free Seed Coatings: Challenges and Solutions.

This review addresses the issue of replacing manufactured microplastics in seed coatings used in agriculture. Firstly, it focuses on the policy and regulatory actions taken on microplastics at a global level. There is no consensus within the scientific community on the definition of a microplastic and, more generally, on the classification of plastic debris. Nevertheless, several decision schemes have been proposed in an attempt to define the notion of microplastics. The different criteria relevant to this definition, such as the size, physical state, chemical structure, origin, and persistence of microplastics, are discussed, with a comparison being made between the REACH regulation and the scientific literature. Seed production and processing are also discussed, with the functions of seed coatings being explained in order to gain a better understanding of the properties to be considered in a substitution strategy for currently used microplastics. The main challenges are multiple; substitutes must provide the same performance as microplastics: (i) improving the adherence of the treatment to the seed, (ii) distributing the treatment more evenly over the seed, (iii) reducing the amount of dust-off when handling treated seed, and (iv) improving the seed flowability, which is particularly important during the sowing stage, all while preserving the physiological properties of the seed. Substitute polymers are proposed according to the desired performance and functional properties: two main chemical families of biopolymers were identified in the literature: polysaccharides and proteins. Among them, 13 and 6 polymers, respectively, complied with REACH regulation, demonstrating adhesion, dust reduction performances, and preservation of seed physiological quality in particular. This work aims to guide future studies on microplastic substitution in seed coatings, and to highlight research needs in this area. It is based on an analysis and discussion of the literature, identifying and listing potential substitutes.

What lies underneath: Comparison among beach litter in the underwater bathing area and exposed beach

The standard techniques for monitoring beach litter focus on the litter that is accumulated on beaches. Therefore, the underwater bathing area is usually overlooked. Our study aims to start the discussion about the litter in the bathing area, an important connection between the exposed beach and the ocean. We aimed to compare sampling methodologies between the underwater bathing area and the exposed beach. We highlighted litter's similarities and differences regarding the amount, material, possible sources, and interaction with the biota. We also performed a brand audit on the underwater bathing area litter. In the underwater region, 106 items were collected while 1706 items were collected from the exposed beach region. Plastic was the dominant type of material in both sites, exposed beach (89.92 %) and bathing area (83.96 %). The litter's possible source was different. In the underwater bathing area was more related to food packages (couscous, rice). On the other hand, litter on the exposed beach was associated with beach use (single-use plastic such as plastic cups). The brand audit identified 21 companies, whereby most brands were Brazilian and food-related. Regarding interactions with the biota, the litter in the bathing area had more bio-fouling (87.73 %) than the litter collected on the exposed beach (10.00 %). Information about bathing area litter can be useful to draw different management strategies. Due to the differences in litter types and behavior between the two sites, the same mitigation strategies might not be equally efficient.

Spatiotemporal variation of sterols in sediment as markers of primary production and ocean sewage dumping in the southwestern East Sea (Japan Sea)

The sedimentation of organic carbon in the Ulleung Basin, in the southwestern East Sea (Japan Sea) was investigated using radiocarbon and sterols. The accumulation rates of organic carbon and the contents of brassicasterol and dinosterol were higher on the slope than in the central basin, reflecting the surface water productivity, whereas cholesterol showed similar or higher contents in the central basin. The coprostanol concentration in surface sediments reflected the dispersion of sewage dumped in this region. The vertical distribution showed that the coprostanol concentration was the highest in the top 5-cm layer near the Korea Strait, close to one of the two dumping sites. A high coprostanol concentration was also found near the coast further north, where the content peaked at ∼10 cm depth. The vertical distribution of coprostanol helped to estimate the sediment accumulation rate at sites where radiocarbon gradient was too small or the values were too variable.

Design and Construction of an Automated Boat that Removes Debris from the Ocean

Water bodies have a huge aquatic ecosystem within them. Any high concentration of suspended solids can cause numerous issues for aquatic life by blocking light from reaching submerged vegetation, hence there is a need for a solution to remove this debris from the water bodies. This project design and construction of an automated boat to remove debris from the ocean is focused on developing a robust and efficient prototype solution for autonomously collecting and managing marine Debris, thereby contributing to environment conservation. The two-channel remote control with receiver will enable the boat to navigate predefined routes, identify and collect debris using specialized mechanism and return to a designated collective point. The Two-Channel remote control system allows for precise maneuverability and control over the boat’s function. Through a combination of engineering principles, propellers, conveyer belt, tread mill arrangement and shafts. this project aims to address the critical issues of ocean pollution while showcasing the potential for remote controlled boat in maritime environmental management. The anticipated outcomes include a functional prototype, comprehensive operational documentation and preliminary performance assessments, setting the stage for potential scalability and deployment in real-world Ocean clean up initiative

Acoustic camera-based super-resolution reconstruction approach for underwater perception in low-visibility marine environments

In low-visibility environments, the underwater perception range of optical cameras is severely restricted, and perception operations in ocean engineering often rely on sonar. Acoustic cameras are a type of forward-looking sonar that have attracted considerable attention because of their ability to produce images similar to those of optical cameras. However, owing to the unique imaging mechanism employed by acoustic cameras, the resulting images suffer from insufficient resolution and a loss of feature details. This issue considerably diminishes the precision of downstream visual tasks, limiting the application of acoustic cameras. In this study, we propose a deep-learning-based super-resolution reconstruction approach for acoustic cameras, where the reconstruction process relies only on images, without prior assumptions regarding the detection scenes. We verified the effectiveness of the proposed method for two practical applications: marine debris detection and marine structure inspection. The experimental results show that our proposed method can robustly reconstruct high-resolution sonar images, and the obtained images have superior feature details, which improved the precision of downstream vision tasks. In this study, we aim to provide better solutions for underwater perception in low-visibility marine environments, while exploring the application of acoustic cameras in marine debris detection and structure inspection.

Geometric relationship between the projected surface area and mass of a plastic particle

The quantification of the mass of meso/microplastic (MMP) particles is crucial for assessing the global inventory of ocean plastics and assessing environmental and human health risks. Herein, linear regression models between mass and projected surface area on a log scale were established by directly measuring the masses of 4390 MMP particles collected at 35 sites in 17 Japanese rivers with an ultramicrobalance. The linear regression models estimated mass concentrations more accurately than any previous method based on geometric volume assuming several three-dimensional shapes. Additionally, linear regression models were quite reasonable for determining the geometric relationships of idealized cuboid particles. The slope of the linear regression models was dependent on the three-dimensional shapes of the particles, and their intercept was determined according to their third dimension. Moreover, the third dimension led to uncertainty in the mass estimation of particles; thus, the accuracies of the previous methods were relatively poor. Nevertheless, two limitations for mass measurement by linear regression models were identified, which determined the size range of the MMP particles on the projected surface area (ranging from 10−4 mm2 to 102 mm2) that is applicable for mass estimation of the particles collected from riverine and marine environments. Our results could be used to accurately estimate the mass concentrations in aquatic environments and provide insights into the geometric relationships between the mass and size of MMP particles.

Network power and exclusion of informal waste pickers when plastic flows change: A case study of community waste banks in Klaten Municipality in Indonesia

Countries, like Indonesia, without advanced waste management systems and with higher levels of population and consumption growth, face particular challenges in addressing plastic waste and marine pollution. To address and prevent plastic marine pollution, Indonesia introduced mitigation initiatives, such as Extended Producer Responsibility, waste banks, and take back schemes. While recent research shows such approaches are able to prevent marine litter, research into their social and equity effects is scarce. This is problematic, because mitigation initiatives can have in- and exclusion effects in terms of access to valuable waste for vulnerable, informal waste actors. This article combines the sociology of network and flows with a network power typology to study how the implementation of waste banks in Klaten Municipality, Indonesia not only led to reduction in plastic pollution, but also the exclusion of cartmen, waste pickers and mobile intermediates from waste networks and thus from accessing these valuable waste flows. A waste bank is a community based business that provides households with additional income and turns household waste into economically valuable materials by trading them with recyclers. In doing so they outcompete a vulnerable group like waste pickers. Instead of waste pickers, households become part of the plastic waste networks. In addition to assessing environmental effects of (marine) plastic pollution mitigation initiatives, more scholarly attention should go towards assessing the in- and exclusion dynamics around different plastic mitigation initiatives. The sociology of network and flows is a useful lens through which to examine these in- an exclusion effects.

Marine debris characteristics in various coastal typologies in the Gunungkidul coastal area of Yogyakarta—Indonesia

Marine debris is one of the environmental issues that can be brought on by rapid human development and activity, including marine tourism, like what happened in the coastal area of Gunungkidul, Indonesia. The issue of marine debris might decrease the environmental quality and impact tourism in Gunungkidul. This study aims to identify the characteristics of coastal typologies in Gunungkidul and analyze their influence on the characteristics of marine debris. Google Earth images and the Digital Elevation Model were used to interpret and classify the typology across the study area based on their physical characteristics. Marine debris samples, either macro or meso-sized, were collected using the transect method for each beach. Based on the imagery interpretation combined with elevation data from DEMNAS, there are three typologies in the Gunungkidul coastal area, i.e., pocket, non-pocket, and cliff beaches. Cliff typology was eliminated and only pocket and non-pocket beaches were used as marine debris sample collection locations. Hence, four beaches were chosen as study areas, i.e., Seruni, Drini, Sepanjang, and Sedahan; each represents each coastal typology. About 193 macro-sized and 217 meso-sized debris were found in our research area, totaling 1380.31 g. Compared to non-pocket beaches, pocket beaches contain more marine debris. The higher slopes of the pocket beach typology will trap marine debris and make it challenging to reenter the water. On pocket beaches, oceanographic processes concentrate marine debris in one location. Still, on non-pocket beaches, marine debris can disperse and return to the sea more readily due to the cycling of currents near the coast.

Understanding marine litter origin in a coastal area: Can Gio beaches, Ho Chi Minh City, Vietnam, as the case study

To decrease the leakage of waste and harmful compounds into marine ecosystems, it is imperative to identify the source of marine litter and implement appropriate mitigation strategies. In this study, bottles and single-use containers presented at four beaches in Can Thanh Town, Can Gio District, Ho Chi Minh City were recorded the abundance, country of production, and lifetime from the manufacturing stamp date on the bottles and containers. Instead of collecting items and bringing them to the laboratory like most studies on marine litter, this study used the Mergin Maps application to record data. A total of 522 items were recorded during two surveys. The identification of litter sources has been made considerably more accessible by using trademarks and logos. Among the 60.5 % of items with recorded brands, items with domestic production addresses (Vietnam) accounted for the most significant proportion (78.2 % of items with brands). In addition, Thailand accounted for the most significant proportion of items originating from foreign countries. Lids and caps are essential for long-distance transportation. Epibionts and bite marks indicated that most bottles and containers drifted along the ocean currents in the area. Marine litter from beaches in Can Gio District originated mainly from waste drifting from rivers and oceans. This study not only illustrated where the waste came from but also provided insightful data that would support managers' decisions to illustrate where the waste came from and provided insightful data that would support managers' decisions to regulate and lessen marine litter in the area effectively.

The effects of plastisphere on the physicochemical properties of microplastics.

The plastisphere is the microbial communities that grow on the surface of plastic debris, often used interchangeably with plastic biofilm or biofouled plastics. It can affect the properties of the plastic debris in multiple ways. This review aims to present the effects of the plastisphere on the physicochemical properties of microplastics systematically. It highlights that the plastisphere modifies the buoyancy and movement of microplastics by increasing their density, causing them to sink and settle out. Smaller and film microplastics are likely to settle sooner because of larger surface areas and higher rates of biofouling. Biofouled microplastics may show an oscillating movement in waterbodies when settling due to diurnal and seasonal changes in the growth of the plastisphere until they come close to the bottom of the waterbodies and are entrapped by sediments. The plastisphere enhances the adsorption of microplastics for metals and organic pollutants and shifts the adsorption mechanism from intraparticle diffusion to film diffusion. The plastisphere also increases surface roughness, reduces the pore size, and alters the overall charge of microplastics. Charge alteration is primarily attributed to changes in the functional groups on microplastic surfaces. The plastisphere introduces carbonyl, amine, amide, hydroxyl, and phosphoryl groups to microplastics, causing an increase in their surface hydrophilicity, which could alter their adsorption behaviors for heavy metals. The plastisphere may act as a reactive barrier that enhances the leaching of polar additives. It may anchor bacteria that can break down plastic additives, resulting in decreased crystallinity of microplastics. This review contributes to a better understanding of how the plastisphere alters the fate, transport, and environmental impacts of microplastics. It points to the possibility of engineering the plastisphere to improve microplastic biodegradation.

Temporal changes in microalgal biomass and species composition on different plastic polymers in nutrient-enriched microcosm experiments

Marine plastic debris (MPD) is a potential threat to marine ecosystems, but its function as a vector for the transportation of harmful microalgae and its impact on the habitats of other marine organisms are uncertain. To address this gap in knowledge, we performed month-long experiments in 30 L microcosms that contained plates made of six different plastic polymers (polypropylene [PP], low-density polyethylene [LDPE], high-density polyethylene [HDPE], polyvinyl chloride [PVC], polyethylene terephthalate [PET], and polystyrene [PS]), and examined the time course of changes in planktonic and periphytic microalgae. There were no significant differences in the composition of periphytic microalgae or biomass among the different plastic polymers (p > 0.05). Nutrient depletion decreased the abundance of planktonic microalgae, but increased the biomass of attached periphytic microalgae (p < 0.05). In particular, analysis of the plastic plates showed that the abundance of benthic species that are responsible for harmful algal blooms (HABs), such as Amphidinium operculatum and Coolia monotis, significantly increased over time (days 21–28; p < 0.05). Our findings demonstrated that periphyton species, including benthic microalgae that cause HABs, can easily attach to different types of plastic and potentially spread to different regions and negatively impact these ecosystems. These observations have important implications for understanding the potential role of MPD in the spread of microalgae, including HABs, which pose a significant threat to marine ecosystems.

Biofilms on Plastic Debris and the Microbiome.

Plastic pollution has become a global environmental problem, and the large number of microorganisms attached to plastic debris in the environment has become a hot topic due to their rapid response to pollutants and environmental changes. In this study, we used high-throughput sequencing to investigate the microbial community structure of and explore the metagenome in the biofilm of two types of plastic debris, polystyrene (PS) and polyethylene terephthalate (PET), and compared them with a water sample collected at the sampling site. The phylum Proteobacteria dominated both the PET and PS samples, at 93.43% and 65.95%, respectively. The metagenome data indicated that the biofilm is enriched with a number of hydrocarbon (petroleum, microplastics, etc.) degrading genes. Our results show that the type of plastic determined the bacterial community structure of the biofilm, while the environment had relatively little effect.