Riverine anthropogenic litter load to the Mediterranean Sea near the metropolitan area of Barcelona, Spain

Every year more than 4 million tons of plastic are estimated to enter in the oceans and much of it comes from the land by rivers or estuaries. Plastic residues persist and accumulate in the environment and they can easily interact with marine organisms. An important step to understand and alleviate the severe problem of marine litter is to fill the lack of information related to plastic inputs from rivers. In this frame, the RIMMEL project proposed a harmonised approach based on a visual observation for monitoring the floating macro litter transported from different European rivers into the marine environment. Quantifying mismanaged waste in freshwater inputs requires a complex previous study of the riverine area considering hotspots and possible sources. Herein, we provide the results of one year of monitoring (October 2016 - September 2017) in the Llobregat and El Besòs rivers, which are flowing through an industrialised and populated area nearby the city of Barcelona (Catalonia, NE Spain). Results highlighted that discharged items categories were influenced by urban centres located along the rivers. Overall, more than 50% of the identified floating litter items were plastics, mainly related to the food or beverage sectors. Approximately 0.4 tons of plastic per year were estimated to be loaded into the sea by these two Catalan rivers. Finally, 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.JRC.D.2-Water and Marine Resource