Monitoring chemical and biological recovery at a confined aquatic disposal site, Oslofjord, Norway.

The recovery of the confined aquatic disposal (CAD) facility located at Malmøykalven in Oslofjord, Norway, has been assessed using an array of field measurement techniques. These methods were used prior to the disposal of dredged sediments as well as during 3 annual postdisposal monitoring campaigns. Traditional sampling to assess chemical recovery indicates that an immediate reduction in total sediment concentrations and surface sediments can be characterized as having good quality. Deposition of new material indicates that the quality of depositing material at the CAD is stabile and representative of the natural background quality in the area. Continued deposition of this material will improve the long-term chemical recovery of the CAD. A positive biological recovery of the benthic community has been observed and is expected to continue along a typical benthic succession pattern. To supplement traditional sampling, passive samplers were deployed at the CAD. Results suggest that the flux and concentrations of polycyclic aromatic hydrocarbon 16 and polychlorinated biphenyl 7 released from the CAD will continue to decrease over time. The combined results from these multiple lines of evidence indicate that the CAD and capping layer function as predicted 3 yr after the construction was completed. There is not only an improvement in the efficacy of the CAD itself but also a general improvement of the area, compared with the situation prior to disposal. Environ Toxicol Chem 2017;36:2552-2559. © 2017 SETAC.