North Sea Plastics II: Fate and impact of river-borne microplastics and their chemical additives in the North Sea Cruise No. AL596, 26 June – 02 July 2023, Kiel, DE – Kiel, DE

The river source of plastic debris to the southern North Sea region appears to be increasing over the past several decades, with a strong seasonal control on riverine MP transport and discharge. The current cruise, AL596, links plastic pollution in the North Sea to seasonal studies in the Elbe and Thames rivers as part of the H2020 LABPLAS project, with the objective to understand the transport and fate of river-derived small micro- and nanoplastics (SMNPs) in the North Sea. The specific objectives of the North Sea Plastics I & II cruises (the current cruise AL596 and previous cruise AL586) form a framework for mapping the distribution of microplastics and their associated chemical contaminants in the coastal southern North Sea and assessing spatial and temporal variation in the delivery and fate of these land-derived pollutants. Cruise AL596 sampled five primary and five intermediate stations between the Elbe and Thames river estuaries. Primary stations included CTD casts to collect discrete water samples between surface and seafloor, “snow catcher” sampling to collect settling aggregates, sediment sampling with Van Veen grab, suspended particle and plankton sampling using a vertical WP2 net, surface neuston sampling using a catamaran trawl, and sea surface microlayer sampling by Garrett screen. Intermediate stations were sampled only by catamaran net. Additional sampling along the cruise track included surface water sample collection from the ship’s underway seawater supply, and during calm weather, floating litter surveys to count the abundance of floating debris. (Alkor-Berichte AL596)