Fate of river-borne floating litter during the flooding event in the northeastern part of the Black Sea in October 2018

Abstract

This study is focused on delivery and fate of floating marine litter (FML) carried by rivers to coastal sea. We examine a large flooding event which happened in the northeastern part of the Black Sea in October 2018. A high resolution circulation model coupled with a Lagrangian particle model is applied to simulate transport of riverine FML in the coastal sea. During this flood multiple river plumes in the study area coalesced into one stripe of freshened water which occupied large segment of coastal sea along the shoreline. Riverine FML was transported within this stripe far off its sources in river mouths and remained arrested near the shore. As a result, approximately half of the discharged FML was washed ashore by the Stokes drift. FML, which remained in the sea, accumulated at convergence lines associated with large salinity gradients at the fronts between the river plumes and the ambient sea.

Keywords: Black Sea; Coastal water quality; Convergence zone; Floating marine litter; Rain-induced flood; River plume.