Evolution and fluxes of 137Cs in the Black Sea/Turkish Straits System/North Aegean Sea

► Cleaning of Black Sea surface water from dissolved pollutants is relatively fast. ► Black Sea surface layer loses every year ~ 4% (22 TBq y− 1) of its 137Cs inventory. ► 12 TBq y− 1 are exported to the Marmara Sea through Bosphorus. ► 10 TBq y− 1 are entrained into the inflowing Mediterranean water on the SW shelf. ► This water is then advected at intermediate depth to the Black Sea interior.