Sudden arrival of marine litter on the northeastern coast of Brazil: Physical forcings and associated transport

Abstract

This study made use of four asynchronously coupled numerical simulations (four Eulerian and four Lagrangian) to investigate an event of a sudden arrival of more than 50 tons of marine litter on the northeastern Brazilian coast. This material mysteriously landed on several beaches, compromising water quality and impacting tourism, therefore raising serious concerns about its origin from local authorities. A total of 87,030 virtual particles were released and had their trajectories investigated, as well as their relationship with major physical forcings, including tides, winds and the North Brazil Under Current (NBUC). The virtual particles followed predominantly towards the north/northwest, mainly due to the presence of the NBUC and southeast trade winds. This pattern indicated that the flow of marine surface litter followed the continental shelf northwards, and the role of winds was key in providing the conditions for oceanic originated material to being deposit along the coastline. This study provided important insights about the regional circulation and main forcings that act in the transport and deposition of floating materials that reach the shallow shelf of the Brazilian northeast. Further investigation on the variability of these forcings along the seasonal cycle seems to be extremely important and should be undertaken soon.