Macroplastic Pollution Research Articles

Seasonal hotspots of beach litter in the North-East Atlantic linked to aquaculture and river runoff

Macroplastic pollution is a pervasive global environmental challenge, adversely affecting marine ecosystems, wildlife and human health. Understanding temporal variations is crucial for identifying pollution sources and developing effective mitigation policies. However, in-situ data from beach surveys are often irregular, both spatially and temporally, and highly variable, complicating robust statistical conclusions. Here we employ a Bayesian machine learning framework to investigate seasonal variations, identify regional hotspots and elucidate their anthropogenic drivers. Using data from 3866 surveys across 168 western European beaches, we leverage a spatial log-Gaussian Cox Process to enhance statistical inference by integrating information from nearby beaches. Distinct seasonal patterns emerge, with winter and spring exhibiting the highest pollution levels, while pronounced regional differences highlight seasonal pollution hotspots in the western Iberian Peninsula, French coastline, Irish Sea and Skagerrak region. These peaks are attributed to riverine emissions and aquaculture activities, highlighting the potential impact of these sources on beach pollution. Our findings advocate for enhanced, time-specific monitoring to effectively manage litter hotspots, emphasizing the importance of aquaculture-related plastic emissions.

Riverine macroplastic survey along the segments of Tullahan River in Metro Manila, Philippines

The Philippines is one of the world’s main contributors to global marine plastic pollution. However, field data remains scarce, so model estimates of riverine plastic pollution may be inaccurate. This paper aims to characterize the macrolitter observed along the Tullahan River, with focus on plastics, passing through the barangays of Quezon City and Valenzuela City in Metro Manila. The impact of solid waste management and land use activities on plastic flux were also investigated. For the floating litter, visual counting and float method were used to determine the plastic flux and river velocity, respectively. Riverbank litter was collected manually to characterize it based on plastic product and polymer type. Results show that the macroplastic flux was lowest on the site where residential houses are farthest from the stream. Waste characterization revealed that riverbank litter was primarily plastic – 30%–41% were residuals, and 5%–21% were recyclables. Both methods revealed that wrappers and thin PE plastics are the top contributors to riverine macroplastic pollution. Therefore, the entry of macroplastics into the river may be due to land use activities and weak enforcement of existing solid waste management (SWM) policies. The points discussed in the study can help in improving SWM and land use planning. The results can also increase the accuracy of model estimates.

Low incidence of microplastics in coral reefs of Kāneʻohe Bay, Hawaiʻi, USA

This study investigated microplastic and other micro-debris pollution in sediment, seawater, sea cucumbers, and corals from fringing and patch reefs in Kāneʻohe Bay, Oʻahu, Hawaiʻi, USA. Microplastic pollution in Kāneʻohe Bay Bay was low compared to other tropical coral reefs. Microplastics were detected in sediments (29 %), sea cucumbers (9 %), and coral (0–2 %) samples but were not quantifiable. Seawater had quantifiable microplastic (< 0.5 mm) and macroplastic (> 0.5 mm) pollution, with mean concentrations ranging from 0.0061 to 0.081 particles m−3. Most particles detected in seawater samples were larger, floating plastic debris consisting mostly of polyethylene, polypropylene fragments, and fibers. Across the other matrices, the most detected particles were polyester, polypropylene, and cotton fibers. These results provide baseline data for this important coral reef ecosystem, and further monitoring is recommended to understand the seasonal and long-term trends in microplastic pollution and its potential future impacts.

A local-to-global emissions inventory of macroplastic pollution

Negotiations for a global treaty on plastic pollution1 will shape future policies on plastics production, use and waste management. Its parties will benefit from a high-resolution baseline of waste flows and plastic emission sources to enable identification of pollution hotspots and their causes2. Nationally aggregated waste management data can be distributed to smaller scales to identify generalized points of plastic accumulation and source phenomena3–11. However, it is challenging to use this type of spatial allocation to assess the conditions under which emissions take place12,13. Here we develop a global macroplastic pollution emissions inventory by combining conceptual modelling of emission mechanisms with measurable activity data. We define emissions as materials that have moved from the managed or mismanaged system (controlled or contained state) to the unmanaged system (uncontrolled or uncontained state—the environment). Using machine learning and probabilistic material flow analysis, we identify emission hotspots across 50,702 municipalities worldwide from five land-based plastic waste emission sources. We estimate global plastic waste emissions at 52.1 [48.3–56.3] million metric tonnes (Mt) per year, with approximately 57% wt. and 43% wt. open burned and unburned debris, respectively. Littering is the largest emission source in the Global North, whereas uncollected waste is the dominant emissions source across the Global South. We suggest that our findings can help inform treaty negotiations and develop national and sub-national waste management action plans and source inventories.

Mismanaged plastic waste as a predictor for river plastic pollution

Hydrometeorological processes are often assumed to be key drivers of plastic transport. However, the predominant focus on these factors overlooks the impact of anthropogenic factors, such as mismanaged plastic waste (MPW) on plastic transport variability. Here, we investigate the roles of both anthropogenic and hydrometeorological factors on plastic pollution in the Odaw catchment, Ghana. Data on macroplastic transport and density were collected at ten locations between December 2021 and December 2022. We tested for differences between the wet and dry seasons and applied a multiple regression analysis to examine the separate and combined impact of hydrometeorological variables (rainfall, discharge, and windspeed) on macroplastic transport. Additionally, we analyzed the spatial correlation in macroplastic transport/density with MPW and population density. Data collection involved visual counting of floating macroplastics at 10 river locations and counting litter at 9 riverbanks and land locations. Rainfall data was sourced from TAHMO (Trans-African Hydrometeorological Observatory), discharge was measured during field campaigns, and windspeed data sourced from a global climate data provider. We used globally modelled MPW estimates to represent anthropogenic factors. Contrary to previous studies, we found no seasonal differences in macroplastic pollution and only weak correlations were observed between the hydrometeorological variables and macroplastic transport. However, a strong correlation was observed between MPW and macroplastic pollution. We hypothesize that, the influence of hydrometeorological factors on macroplastic transport depend on the relative impact of anthropogenic factors. Our research highlights the limited role of hydrometeorology, showing the significant role of mismanaged plastic waste to field monitored macroplastic pollution variability in the catchment. This insight is essential for future research as it highlights the importance of holistically investigating both anthropogenic and hydrometeorological factors in explaining plastic transport and retention dynamics. This insight is essential for developing interventions that effectively address plastic pollution in catchments.

The largest estuary on the planet is not spared from plastic pollution: Case of the St. Lawrence River Estuary

The St. Lawrence River, one of the world's largest estuaries, drains >25 % of the world's freshwater reserves and is affected by various anthropogenic effluents. Although previous studies reported micro- and nanoplastics contamination in the Estuary and Gulf of St. Lawrence (EGSL), this study provides a first evaluation of macroplastic pollution along the north and south shores of the EGSL. Plastic debris categorization was performed according to the OSPAR protocol completed by polymer identification using Fourier-transform infrared spectroscopy. The EGSL appeared ubiquitously contaminated by plastic debris, dominated by single-use plastics primarily made of polypropylene (28 %), polyethylene (25 %) and polystyrene (17 %). The EGSL shores exhibited a mean contamination level of 0.17 ± 0.11 items/m2 and distance to Montreal significantly influenced the distribution of plastic debris. This study provides an essential baseline for implementing local waste reduction and management actions in the St. Lawrence watershed to reduce plastic pollution.

Disentangling marine plastic impacts in Life Cycle Assessment: Spatially explicit Characterization Factors for ecosystem quality

Inputs of persistent plastic items to marine environments continue to pose a serious and long-term threat to marine fauna and ecosystem health, justifying further interventions on local and global scales. While Life Cycle Assessment (LCA) is frequently used for sustainability evaluations by industries and policymakers, plastic leakage to the environment and its subsequent impacts remains absent from the framework. Incorporating plastic pollution in the assessments requires development of both inventories and impact assessment methods. Here, we propose spatially explicit Characterization Factors (CF) for quantifying the impacts of plastic entanglement on marine megafauna (mammals, birds and reptiles) on a global scale. We utilize Lagrangian particle tracking and a Species Sensitivity Distribution (SSD) model along with species susceptibility records to estimate potential entanglement impacts stemming from lost plastic-based fishing gear. By simulating plastic losses from fishing hotspots within all Exclusive Economic Zones (EEZs) we provide country-specific impact estimates for use in LCA. The impacts were found to be similar across regions, although the median CF associated with Oceania was higher compared to Europe, Africa and Asia. Our findings underscore the presence of susceptible species across the world and the transboundary issue of plastic pollution. We discuss the application of the factors and identify areas of further refinement that can contribute towards a comprehensive assessment of macroplastic pollution in sustainability assessments. Degradation and beaching rates for different types of fishing gear remain a research gap, along with population-level effects on marine taxa beyond surface breathing megafauna. Increasing the coverage of impacts specific to the marine realm in LCA alongside other stressors can facilitate informed decision-making towards more sustainable marine resource management.

Plastics in the deep sea – A global estimate of the ocean floor reservoir

The exponential increase in plastic production coupled with variable global waste management system efficiencies has resulted in large amounts of plastic waste entering the ocean every year. Although we know millions of tonnes of plastic have entered the oceans, we do not yet understand the patterns of its accumulation across space nor the drivers of these patterns. The deep ocean is expected to be a resting place, or reservoir, for most plastic pollution. Here, we conducted a rigorous, systematic review of previously published datasets to synthesize our understanding of macroplastic pollution (>5 mm) on the ocean floor. Using extracted data, we built predictive additive models to estimate the amount and distribution of plastic on the ocean floor. We built two models: one using data from remote operated vehicles (ROVs) and another using data from bottom trawls. Using the model built with ROV data, which was better-constrained, we estimate that 3 to 11 million metric tonnes (MMT) of plastic pollution resides on the ocean floor as of 2020. This is of similar magnitude to annual inputs from land and one to two orders of magnitude greater than what is predicted to be floating on the ocean surface. To improve future estimates and our understanding of global patterns, we provide recommendations for ocean floor monitoring of plastic pollution.

Catchment scale assessment of macroplastic pollution in the Odaw river, Ghana

Catchment-scale plastic pollution assessments provide insights in its sources, sinks, and pathways. We present an approach to quantify macroplastic transport and density across the Odaw catchment, Ghana. We divided the catchment into the non-urban riverine, urban riverine, and urban tidal zones. Macroplastic transport and density on riverbanks and land were monitored at ten locations in December 2021. The urban riverine zone had the highest transport, and the urban tidal zone had the highest riverbank and land macroplastic density. Water sachets, soft fragments, and foam fragments were the most abundant items. Our approach aims to be transferable to other catchments globally.

A macroplastic vulnerability index for marine mammals, seabirds, and sea turtles in Hawai‘i

Plastic pollution is having devastating consequences for marine organisms across the planet. However, the population level effects of macroplastic pollution remain difficult and costly to quantify. As a result, there is a need for alternative approaches to evaluate species risk to plastic pollution and inform management needs. We apply a trait-based framework for macroplastic pollution to develop a relative vulnerability index—informed by three dimensions: likelihood of exposure, species' sensitivity, and population resilience—for marine mammals, seabirds, and sea turtles found in Hawai‘i. This index ranks 63 study species based on their population level vulnerability to macroplastic pollution, with the highest scoring species being the most vulnerable. Our results indicate that ducks, waders, and noddies with large populations were the least vulnerable to macroplastics, while the most vulnerable were the Hawaiian monk seal, sea turtles, baleen whales, and some albatross and petrel species. This index can inform species in need of population monitoring in Hawai'i, and direct other management priorities (e.g., locations for clean-ups or booms). More broadly, this work exemplifies the value of qualitative risk assessment approaches for better understanding the population level effects of macroplastic pollution and showcases how vulnerability indices can be used to inform management priorities.

Can Knowledge, Responsibility and Environmentalism Explain Preference Heterogeneity? A Latent-Class Probit Model Analysis for Plastic Pollution Abatement

This study explores the impact of prior experiences, environmental concern and awareness levels on pro-environmental behavior in the context of mitigation of plastic pollution. Using survey and geo-location data after a tsunami and a monsoon season, this survey employs a latent class analysis through a Generalized Structural Equation Model (GSEM) to identify similarities between groups’ willingness to pay (WTP) to mitigate macroplastic pollution in riverbeds and beaches in Indonesia. Results show that more environmentally-conscious respondents were also more sensitive to the issue of pollution while having observed more plastic pollution also increases support for pollution mitigation. Proximity to polluted waterways also increased WTP, especially to urban participants. Overall, accounting for prior experiences, environmental concern and awareness levels does lead to statistical differences between classes, with those scoring higher in these categories being also more willing to monetarily contribute to mitigate that issue. The use of such an integrated latent class model (LCM) can help with disentangling drivers of preferences, especially in the context of determining levels of support for pollution abatement in a developing country.

Litter Selfie: A Citizen Science Guide for Photorecording Macroplastic Deposition along Mountain Rivers Using a Smartphone

Macroplastic pollution in mountain rivers can threaten water resources, biodiversity, and the recreational values provided by them. The first step towards evaluating and then mitigating these risks is the systematic collection of reliable and spatially uniform data on the amount and type of macroplastics deposited in different land covers occurring in a mountain river channel. To maximise the opportunity for the large-scale collection of such data using the citizen science approach, we propose in this study an illustrated step-by-step guide to sample the macroplastic deposited along mountain rivers and to record the collected information using a photo taken by smartphone and a simple online form. Our guide includes three steps: (i) the location of sampling plots across 3–4 predefined surface covers occurring in mountain rivers of temperate climate, (ii) the hand collection of macroplastic deposited in them, and (iii) the photorecording and archiving of information on macroplastics collected using a smartphone and an online form. The proposed guide can allow for the low-cost collection of data on macroplastic deposition in mountain rivers on regional and global scales. The collected data can be further analysed by environmental scientists to quantify the amount and types of macroplastic deposited and to evaluate the resulting risks. They can be also used as illustrative materials to increase the awareness of local communities about the plastic pollution problem.

Macroplastic concentrations in the water column of the river Rhine increase with higher discharge

Riverine macroplastic pollution (>0.5 cm) negatively impacts ecosystems and human livelihoods. Monitoring data are crucial for understanding this issue and for the design of effective interventions strategies. Macroplastic pollution floating on the river surface and plastic deposited on riverbanks are studied relatively often. Data on riverine plastics in the water column remain scarce. In this study, we utilized trawl nets at different depths to sample plastic pollution in the water column at the entry point of the river Rhine to the Netherlands. We show that plastic concentrations in the water column increased during higher discharge. Moreover, the results indicate that the vertical distribution of macroplastic pollution changes during different flow conditions. Significantly higher concentrations of macroplastic can be seen near the riverbed during low discharge conditions, while no significant differences in concentration are observed between the bottom, middle, and surface samples during high discharge conditions. Taking into account the recurrence time of low discharge conditions the transport of plastic during low discharge conditions is substantial. These findings provide first insights into the key role of hydrology in explaining macroplastic transport in the water column. These insights can be used to improve future monitoring and intervention strategies.

Sources, pathways, and abatement strategies of macroplastic pollution: an interdisciplinary approach for the southern North Sea

The issue of marine plastic pollution has been extensively studied by various scientific disciplines in recent decades due to its global threat. However, owing to its complexity, it requires an interdisciplinary approach to develop effective management strategies. The multidisciplinary scientific approach presented here focuses on understanding the sources and pathways of macroplastic litter and developing abatement strategies in the southern North Sea region. Over 2.5 years, more than 63,400 biodegradable wooden drifters were deployed with the help of citizen science to study the sources, pathways, and accumulation areas of floating marine litter. Rivers act as sinks of most of the floating marine litter released within their waterways. Short-term field experiments were also conducted to analyse the hydrodynamic and atmospheric processes that govern the transport of floating litter particles at the sea surface. Numerical models were used to examine the transport of virtual litter particles in the entire North Sea and in coastal regions. It was found that there are no permanent accumulation areas in the North Sea, and the Skagerrak and fronts can increase the residence times of floating marine litter and favour sinking. Field surveys revealed that the majority of litter objects originate from fisheries and consumer waste. To develop effective abatement strategies, the key stakeholder landscape was analysed on a regional level. The interdisciplinary approach developed in this study highlights the importance of synergizing scientific resources from multiple disciplines for a better understanding of marine plastic pollution and the development of effective management strategies.

Heavy rains control the floating macroplastic inputs into the sea from coastal Mediterranean rivers: A case study on the Têt River (NW Mediterranean Sea)

This study focuses on the relevance of small watersheds in the macroplastic pollution of coastal environments. It aims to identify and quantify in terms of composition, number and mass, current riverine flows of floating macroplastics (>2.5 cm). Estimates are based on 66 visual monitoring of total litter over a 4-year-period (2016–2019) in a small coastal Mediterranean river, the Têt River (NW Mediterranean Sea). The plastic fraction represented 97 % of the observed litter, mainly cigarette butts (20.5 %), polystyrene fragments (18.8 %) and light packaging (16.3 %). The Tet River is characterized by frequent flash-flood events caused by heavy rain, that can induce a sudden rise of the water discharge. Such hydroclimatic forcing greatly influence macroplastic flows, both in terms of their average compositions and loads. We have estimated that 354,000 macroplastic items, corresponding to 0.65 tons, are discharged annually from the Tet River into the sea, and that 73 % of them are released during rain events (∼6 % of the year). The short observation distance from the water surface allowed to exhibit the great abundance of small litter (80 % of them were < 10 cm) and to evaluate to 1.8 g the average mass of floating plastics. Our results suggest that remediation actions must be taken on rainy days and target small litter in order to significantly limit macroplastic inputs from rivers to the sea. Moreover, the large share of cigarette butts in macrolitter inputs demonstrates that reducing ocean pollution cannot be achieved solely by improving waste management, but that changes in social behavior are also needed to stem waste production at the source.

The challenge of reducing macroplastic pollution: Testing the effectiveness of a river boom under real environmental conditions

Improving collection technologies is crucial to develop effective and economically feasible solutions for catching plastic from riverine environments. However, floating booms are being constructed and deployed in river around the world without rigorously testing its effectiveness. In this study, we tested the effectiveness of a boom under realistic conditions for several configurations and treatments (including “C-shape” and “Slash-shape” configurations). For this, we used the same macroplastics that leak out of waste management channels in order to be as realistic as possible. In total we used 52 plastic articles of 13 different polymers. The global effectiveness of the tested C-shape boom was lower than expected under such conditions (around 37 % of retention). The effectiveness of the Slash-shape boom was considerably worst (<10 %). However, the effectiveness varies greatly according to the particular characteristics of the plastic articles (i.e., shape and polymer composition), ranged from 0 to 100 %. For example, the boom could be 100 % effective retaining plastics such as Stylofoam trays and cups, 40–20 % for food-wrappers but 0 % for disposable plates and spoons, straws, monofilament fishing lines, packaging straps, hoses, pipes, elastic bands, etc.It seems that to have a reasonable catch-effectiveness and be cost-efficient, boom designs need to be improved and tested under different environmental conditions before to reach the market. In addition, it is unrealistic to select only high buoyancy plastics for testing them.

Macroplastics in Lakes: An Underrepresented Ecological Problem?

Lakes are the greatest reserve of available superficial inland fresh water and concurrently one of the most threatened ecosystems. Among the many pollutants, plastics contaminate lakes worldwide; notwithstanding that, little is known on the impacts of macroplastics. The aim of this work is to provide the first global overview of scientific articles researching macroplastic pollution in lakes. Articles were selected from Web of Science and Scopus databases. We performed a bibliometric analysis of the results on the publication trend, geographical distribution of study areas, investigated matrix (i.e., water, sediment, biota), as well as abundance and type (i.e., shape, litter category, polymer) of lacustrine macroplastics. We also compared the articles’ methodologies. Fourteen articles were collected (the publication trend is increasing in recent years), showing a diffuse contamination by macroplastics. Research efforts are mostly focused on shoreline assessments. There is a lack of information and methodological standardisation (i.e., macroplastic size definition, sampling protocol, shape, litter categories), which limits the comparison of article outputs. We propose the definition of lacustrine macroplastics as plastics &gt;5 mm and the adoption of the UNEP/IOC protocol to sample lake shoreline. We suggest focusing future investigations on (1) testing the methodological standardisation, (2) understanding the factors influencing macroplastic dispersal, and (3) assessing the impacts on biota.

Unraveling Macroplastic Pollution in Rural and Urban Beaches in Sarangani Bay Protected Seascape, Mindanao, Philippines

Plastic pollution in the ocean is an emerging environmental concern in the Philippines. This study was conducted to investigate the prevalence of macroplastics, composition of plastic litter, and the clean-coast index (CCI) of urban and rural beaches in Sarangani Bay. Plastic litter was collected by delineating a 100-m transecting line with three 4 m × 4 m quadrats. The density of macroplastic litter in urban areas (0.66 items m−2) was significantly higher than in rural areas (0.29 items m−2). The plastics sampled were predominantly food packaging, such as polyethylene bags, which are locally known as sando bags. The accumulation rate of macroplastic litter ranged from 0.07 items d−1 m−2 to 0.40 items d−1 m−2, in which urban beaches (0.25 items d−1 m−2) have a significantly higher accumulation rate than rural beaches (0.11 items d−1 m−2). Overall, the calculated CCI of the beaches of Sarangani Bay was categorized as clean to moderately clean for rural beaches and moderately clean to extremely dirty for urban beaches.

Assessment of Macroplastic Pollution on Selected Tourism Beaches of Barobo, Surigao Del Sur, Philippines

Plastics have proven useful in contemporary society. But accumulation of plastics in form of litter in the marine environment has become prevalent pollution affecting all of the worlds’ oceans. The Philippines being an archipelagic country heavily depends on the marine environment and the ecosystem services that it provides. However, it is also ranked as the third-largest producer of marine plastic pollution and the number one plastic riverine emitter. Tourism is an important economic activity for coastal populations throughout the Philippine archipelago. But there are limited studies that investigate plastic pollution in the tourism sector of the Philippines. This study assessed the macroplastic prevalence in the tourism environment of Barobo, Surigao del Sur. Plastic litters were sampled from four growing tourism sites (Cabgan Island, Turtle Island, Dapdap Beach, Panaraga Beach) of Barobo by establishing transect lines with quadrats. Results reveal that all four sites are contaminated with plastic litters. In terms of mainland and island beaches, beaches located on the island have thrice as many plastics with 0.41 items/m2, compared to 0.15 items/m2 on the mainland beaches. Plastic collected were predominantly food packaging, plastic bags, and fragments. Clean coast index calculations reveal that the tourist beaches of Barobo are moderately clean and clean beaches by international standards.

Occurrence of macroplastic debris in the long-term plastic film-mulched agricultural soil: A case study of Northwest China

Widespread presence of plastic mulch has led to macroplastic (MaP) pollution. While this issue is widely explored in aquatic ecosystems, MaP pollution on land has been neglected. In 2019, we conducted a large-scale survey of MaPs in Northwest China in 0–30 cm soil with long-term mulching. Samples of MaP debris were collected from 67 sites across Gansu, east Qinghai, and north Shannxi Provinces. All visible MaP pieces for each site were separated and weighed. The mass of each MaP piece was calibrated by size measured in digital images. The MaP mass averaged 47.2 kg ha−1, and the number of MaPs averaged 266.2 pieces ha−1. The mass and number of MaPs varied from site to site. The mean size of MaPs was 19.5 cm2 piece−1 or 28.0 mg piece−1. More importantly, the number of small MaP pieces (<5 and 5–20 cm2 piece−1) accounted for 76.7% of the total number of MaPs detected, and small-sized plastic debris (<10 and 10–25 mg piece−1) were detected in 70.1% of the sampling sites. The percentage of small fragments increased before 15-year of mulching and then declined. However, the amount of medium-large debris (20–50 and >50 cm2 piece−1) showed a trend opposite to that of small fragments. The percentage of MaPs was greater in the small size group than in the medium-large size group. The arid to semi-arid area exhibited higher MaP contamination compared with the semi-arid to the semi-humid area. These observations indicate that plastic debris residing in soil tend to be fragmented, making plastic film recovery more challenging and causing severe soil pollution. Further studies are required to regulate plastic mulch methods and explore the degradation process.