Elevated levels of radium-226 and radium-228 in marine sediments of the Norwegian Trench ("Norskrenna") and Skagerrak.

Oil and gas extraction activities discharge waters bearing radium isotopes which may potentially be transported to locations distant from the discharge point. Sediment cores from the Norwegian Trench and Skagerrak, potential sinks for North Sea discharges, were analyzed for the contents of these isotopes. All cores were such that data could be obtained from periods prior to and during extensive operations in the North Sea. Results indicate elevated levels of radium isotopes in upper sedimentary layers when compared to data for the Baltic Sea and Kattegat. Although diagenetic processes involving manganese cycling may be responsible for these enrichments, the data support previous work indicating a possible influence of North Sea discharges on sediments of the area. The results highlight the need for further work on elaborating background levels of these isotopes in the North Sea and related areas such that possible impacts of these discharges can be properly evaluated.