We measured floating plastic in the Rhine (Netherlands to Switzerland), Odaw (Ghana) and Mekong (Cambodia) rivers using visual counting from bridges. We also measured riverbank and terrestrial plastic density in the Odaw river through physical sampling and classification.
We measured river plastic pollution in three rivers across relevant gradients, including geography, hydrology, and plastic pollution levels. In the Rhine basin (Switzerland, France, Germany, the Netherlands) we showed that urban areas and tributaries may act as entry points of plastic pollution. For the Odaw basin (Ghana) we compared floating, terrestrial and riverbank plastics, identifying source and accumulation zones. Finally, in the Mekong river (Cambodia) we quantified the contribution of the city of Phnom Penh to plastic pollution through quantifying the plastic mass balance in the Mekong-Tonle Sap-Bassac region.