Riverine systems act as converging pathways for discarded litter within drainage basins, becoming key elements in gauging the transfer of mismanaged waste into the ocean. However, riverine litter data are scarce and biased towards microplastics, generally lacking information about larger items. Based on the first ever database of riverine floating macrolitter across Europe, we have estimated that between 307 and 925 million litter items are released annually from Europe into the ocean. The plastic fraction represented 82% of the observed litter, mainly fragments and single-use items (that is, bottles, packaging and bags). Our modelled estimates show that a major portion of the total litter loading is routed through small-sized drainage basins (<100 km2), indicating the relevance of small rivers, streams and coastal run-off. Moreover, the major contribution of high-income countries to the macrolitter inputs suggests that reducing ocean pollution cannot be achieved only by improving waste management, but also requires changing consumption habits and behaviour to curb waste generation at source. The inability of countries with well-developed recovery systems to control the leakage of waste into the environment further supports the need to regulate the production and use of plastic on a global scale.
Research into the scope of litter pollution in freshwater systems has shown similar levels to the marine and coastal environment. Global model estimates of riverine emission rates of anthropogenic litter are largely based on microplastic studies as long-term and holistic observations of riverine macroplastics are still scarce. This study therefore aims to contribute a detailed assessment of macrolitter in the transitional waters of three major North Sea tributaries: Ems, Weser, and Elbe. Litter surveys were carried out in four river compartments: along the embankment, on the river surface, in the water column, and on the river bed. The data revealed spatio-temporal variability and distinct pollution levels for each compartment. Beaches had the highest debris diversity and were significantly more littered than vegetated sites and harbors. Stony embankments were least polluted. Benthic litter levels appeared substantial despite rapid burial of objects being likely due to high suspended sediment loads. Two extrapolation approaches were tested to scale daily and annual litter emission quantities of surface- and subsurface-floating litter. Using the mean (median) litter item mass from water column samples, total annual mass discharges were calculated: ∼0.9 (0.2) t y⁻¹ to ∼2.8 (0.5) t y⁻¹ emitted via the Ems, ∼1.3 (0.2) t y⁻¹ to ∼12.0 (1.9) t y⁻¹ through the Weser, and ∼14.7 (2.4) t y⁻¹ to ∼801 (128) t y⁻¹ carried into the North Sea by the Elbe. These rates deviate considerably from previous model estimates of plastic loads discharged by these three rivers. Future studies should therefore ground-truth model estimates with more river-specific and long-term field observations. Overall, the estimated plastic debris discharge quantities account for <1% of the total mass of mismanaged plastic waste per catchment.
Marine litter is an issue of global concern, as recognised by the Marine Strategy Framework Directive (MSFD). In order to establish programmes of measures that aim to reduce plastics and their possible impacts, sources of litter and their pathways to the marine environment need to be identified and quantified. Riverine litter input is estimated to be a major contributor to marine litter, but there is no comprehensive information about the amount of litter being transported through rivers to the sea. Furthermore, there are no harmonised methodologies for providing quantitative data for comparable assessments of riverine litter. This technical report compiles the options for monitoring riverine litter and quantifying litter fluxes, focusing on anthropogenic litter. It includes the current scientific and technical background regarding litter in river systems, their flow regime and basic properties. The document aims to provide recommendations for monitoring approaches and methodologies. It also provides indications on the issues which need to be further developed in a collaborative approach. An extensive literature review has been performed in order to identify the existing options for the monitoring of litter items in rivers. Different monitoring methods are used in two environmental compartments: river water bodies and riverbanks. For a river water body, the river water surface can be monitored by visual observation and image acquisition, while collection methodologies of the water column include the use of retaining structures and sampling using grids, nets and filtration systems (with different mesh sizes and openings) at different water depths. Riverbank monitoring comprises the observation and eventual collection of litter items and sediment samples from the riverbanks. Methodologies are described and technical details are reported whenever available. As methodologies are further developed and basic research is ongoing, it is currently not possible to provide clear guidance on how to monitor riverine litter, though some initial recommendations can be made. General recommendations highlight the need for additional scientific knowledge, which should be made accessible to facilitate communication and coordination among key players in order to harmonise efforts and provide guidance at international level in a collaborative way. Knowledge gaps should be filled by analysing the outcome of these ongoing activities (the recommendations include a list of identified gaps). As there are no agreed monitoring methodologies at the international level, guidance on the monitoring of riverine litter is needed, including metadata requirements and reporting units. In order to quantify riverine litter input to the marine environment, monitoring methods have to provide data that can be related to river flow in order to be able to calculate litter fluxes (e.g. visual observation of the river water surface and collection method for the river water body).
Every year >4 million tonnes of plastic are estimated to enter the oceans and much of it comes from land-based sources through rivers and estuaries. To fill the lack of information related to plastic inputs from rivers, a harmonized approach based on visual observations for monitoring floating macro litter was followed in this work. We provide the results of one-year monitoring (October 2016–September 2017) in the Llobregat and El Besòs rivers, which are flowing through an industrialized and populated area nearby the city of Barcelona (Catalonia, NE Spain). Floating litter items categories were influenced by urban centres located along the rivers. Overall, similar litter composition was observed in both rivers with a prevalence of plastics, mainly related to the food and beverage sectors. Seasonal variability showed significant correlations with natural factors such as wind and rainfall. Approximately 0.4–0.6 tonnes of plastic per year were estimated to be loaded into the sea by these two Catalan rivers. This study contributes to enlarge our knowledge on anthropogenic riverine litter entering the NW Mediterranean Sea, providing a starting point for the development of further mitigation strategies.
Rivers are the major input pathways for litter entering into the sea. For this reason, the Joint Research Centre is coordinating a network of 36 research bodies that monitors, with the same protocol, floating litter (>2.5 cm) from fixed observation points located nearby the rivers’ mouths (RIMMEL project). In Italy, one of the surveyed rivers is the Tiber, being third longest river in Italy. The Tiber, after running through the city of Rome, divides into two branches before getting into the Tyrrhenian Sea
We present here the first estimates of floating macro-litter in surface waters from the Rhone River, based on monthly visual observations during 1-year period (2016–2017). Plastic represented 77% of the identified items, confirming its predominance in riverine floating litter. Fragments (2.5–50cm) and Single Use Plastics (i.e. bags, bottles and cover/packaging) were among the most abundant items. Frequent non-plastic floating litter were paper items such as packaging material and newspapers, and metal items (mostly cans), representing 14% and 5% of total litter, respectively. A lower-end estimate resulted in ∼223,000 plastic items (∼0.7t of plastic) transported annually by the Rhone surface waters to the Gulf of Lion (NW Mediterranean Sea). Floating macro-plastics are only a fraction of the total plastic export by the Rhone. Our study highlights the current discrepancy between field observations and theoretical estimations. Improvements are needed to harmonize data collection methodologies for field studies and model validation.
Land-based activities are, undoubtedly, the main source of marine litter, particularly in a highly populated closed sea basin, such as the Mediterranean Sea. Rivers, consequently, act as a pathway of mismanaged waste to the sea. While quantification of inputs is a difficult task, the assessment of abundance, composition trends and baselines, and the identification of sources and main sectors producing marine litter are of crucial importance to support the ability of policy makers to improve waste reduction measures. For this reason, the Joint Research Centre (JRC/RIMMEL) coordinated a network of several research bodies that monitored floating litter (> 2.5cm) from fixed observation points located on rivers near the sea using the same systematic research protocol. In Italy, one of the surveyed rivers was the Tiber, the third longest river on the peninsula, which after running through the city of Rome divides into two branches before flowing into the Tyrrhenian Sea. Results of 1year of monitoring, September 2016–August 2017, highlight that 82% of the floating items were plastic and belong to the food and cosmetic sector, and it was estimated that 85.4% (± 9.4) of litter items get into the sea each hour from the Tiber river canal in Fiumicino, of which approximately 30% were already fragmented. Paper at :https://rdcu.be/9RXT
The Mediterranean Sea has been documented to be largely impacted by plastic, being nowadays one of the major hot spots in the world. Rivers are considered important input pathways of plastics to coastal areas. However, the occurrence of plastic fragments in rivers and derived fluxes are poorly understood. In order to shed light on this key issue, the Joint Research Centre (European Commission) launched in 2016 a riverine litter observation network within the RIMMEL project. The main objective of this project was to quantify the floating macro litter loads through rivers to marine waters, combining the experimental observation of macro litter and the modeling of their loading. Floating macro litter (including macro-plastics) was monitored in more than 50 European rivers during 2016-2017. We present here results from the Rhône river (Switzerland / France), one of the major European rivers. Monthly observations were performed in Arles (Southern France), around 40 km NW from the river mouth in the Gulf of Lion (NW Mediterranean Sea). Results showed a mean flux of ~50 litter items/hour (belonging to 22 macro-litter categories) floating down the Rhône to the Mediterranean coast, with plastic items representing the 77 % of macro-litter, supporting the hypothesis of rivers as key pathways for plastic litter to the marine environment. The most abundant plastics were: pieces, bags, sheets and bottles. Considering the median value as a constant flux rate, a rough estimation of the annual input of floating macro-plastics from the Rhône to the NW Mediterranean would be about 220 000 items (with an important uncertainty associated due to the high temporal variability). This is a lower-end estimation since only floating items were counted. These macro-plastics are expected to eventually become micro-plastics due to environmental aging as well as release plastic additives, with yet unknown implications for the aquatic ecosystem.
The JRC exploratory project RIMMEL provides information about litter, mainly plastic waste, entering the European Seas through river systems. RIMMEL has collected data on riverine floating macro litter inputs to the sea. Data acquisition was based on the Riverine Litter Observation Network (RiLON) activities, which collected data from rivers in the European marine basins over a period of one year (September 2016 – September 2017). Data was collected by visual observations and documented with the JRC Floating Litter Monitoring Application for mobile devices, allowing a harmonized reporting, compatible with the MSFD Master List of Categories for Litter Items. This report includes the Top Items lists of riverine floating macro litter, based on the total amount of litter items identified during RiLON activities and ranked by abundance. Top Items lists have been elaborated considering the whole database for the European Seas and further detailed for each individual European regional sea: Baltic Sea, Black Sea, Mediterranean Sea and North-East Atlantic. The North-East Atlantic and the Mediterranean Sea regions showed similar litter categories in their Top 20 Items. These two regions provided most of the available data, influencing the general Top Items list. In the Black Sea and Baltic Sea regions, where data availability was limited, the Top Items lists showed more differences among the different regions. Overall, the general Top Items list for the European Seas showed a predominance of plastic item categories (artificial polymer materials). As a whole, plastic items made up to 80.8% of all objects, with plastic and polystyrene fragments comprising 45% of the identified items in the database. Additionally, Single Use Plastics such as bottles, cover/packaging and bags were also ranked among the most frequently found floating litter. The similarities in the Top 10 and Top 20 items for the different regions, and the appearance of Single Use Plastics scoring high in the ranking, support the need for common actions against plastic pollution at EU level.
A high percentage of the litter entering the marine environment is assumed to come from land-based sources, but freshwater litter inputs have not been quantified. The lack of data and knowledge on fluxes of riverine litter to the sea, i.e., quantities and sources, hinders implementation of appropriate environmental regulations and mitigation measures. Estimations of riverine litter inputs require a consistent and harmonized approach to gather comparable data. The visual observation of floating litter on rivers has been selected as a simple and robust methodology for litter monitoring. A collaborative network of 36 institutions has been setup for large spatial coverage. Currently 58 rivers are being observed regularly. A tablet computer application has been developed for the monitoring of floating macro litter (>2.5 cm) to harmonize the visual observations. The application allows recording of the observed items, their size and geo-position data during monitoring sessions. A common agreed list of litter items and size ranges is used, providing a common harmonized approach for data collection and reporting.