Abstract
Oil platforms on the Norwegian shelf discharge large volumes of produced water which is highly enriched in radioactive nuclides like 226Ra. In the recipient water, 226Ra may spread in both dissolved and solid form. Here, we investigate the fate of discharged 226Ra from production on 44 platforms on the Norwegian continental shelf for two scenarios; one where all 226Ra is released as dissolved matter, and one where 226Ra is released as solid matter bound in the lattice of BaSO4. Our approach is to follow the fate of discharged particles over four years to allow for long-time effects to take place, such as solid matter settling on the seabed and subsequent resuspension from sediments. We find that when 226Ra is released as dissolved matter radioactive concentrations drop rapidly around discharge areas for most platforms, although for some platforms concentration levels about 1mBq/L persist for kilometres around discharge locations. When 226Ra is released in solid form, concentrations in sediments reaching up to 15 Bq/kg is predicted over a time period of 30 years for the most impacted areas.