Capping of TBT-contaminated sediment at Fiskerstrand shipyard – faunal status five years later

Summary

Capping with clean sediment on top of the contaminated sediments is a method that makes it possible to reduce the environmental risk of contaminated sediments in situ. The research project Opticap has aimed at increasing the knowledge about the effects of thin layer capping of contaminated sediments. A key part of the project is to conduct field studies of thin layers with or without active materials that can bind contaminants and thereby reduce bioavailability for sediment-living organisms. Such field testing has been conducted three areas, including Fiskerstrand shipyard in Sula municipality in Møre og Romsdal, where capping was performed on sediments contaminated with tributyltin (TBT). Thin layer capping may be applicable where it is not possible to use full thicknesses. Further, such capping is expected to have less effect on the soft bottom communities, although some work has shown that the use of activated coal may cause long-term changes in benthic fauna.