Contaminants come from major rivers — Elbe, Weser, Rhine, Meuse, Scheldt, Seine, Thames, Humber - and also from dredged material and atmospheric inputs.
Stórárnar Saxelfur, Weser, Rín, Meuse, Scheldt, Signa, Thames og Humber bera með sér milda mengun en einnig kemur mengun frá úrfalli og uppmokstri vegna dýpkunar.