Plastic waste in surface waters of an urban estuary

Context. Plastic pollution is a threat to ecosystems and is a global problem. Aims. We evaluated the spatio-temporal degradation stage of plastic waste found in surface waters (< 1 m) of the Capibaribe River estuary. Methods. The analysed waste items were sampled in three distinct areas within the estuary, namely, upper, middle and lower regions. Key results. In total, 381 items of debris were classified as macroplastics (< 25 mm), with soft fragments (83.9%) and hard fragments (4.9%) being predominant. Advanced degradation stage occurred throughout the estuary (90.5%). A concentration of 1757 microplastics (< 2.2 mm) was found predominant in the upper and middle regions. Soft fragments corresponded to the most abundant type (69%). Conclusion. In the middle estuary, a plastic hotspot was observed, caused by the flood tide flow, river flow and the flow of a tributary, forming a convergence cell that helps retain plastic debris for long periods. Implications. Identifying the origin, sources and how the hydrodynamic characteristics influence the distribution of plastic debris along the estuary is relevant because it will help decision-makers to develop municipal and state action plans for the recovery of this ecosystem.