Investigation and risk assessment of ships loaded with chemical ammunition scuttled in Skagerrak

The Norwegian authorities gave in 1945 permission to scuttle ships loaded with captured chemical ammunition on board in an area approximately 14 km X 4 km in size, 25 nautical miles south-east of Arendal. The total amount (gross weight) of chemical ammunition dumped in Skagerrak by the Allies is 168 000 tonnes. A project was carried out by Forsvarets forskningsinstitutt (FFI) in 2002 on behalf of the Norwegian Pollution Control Authority (SFT) to investigate some of the ships scuttled in Skagerrak. This report describes an investigation carried out in two parts in June and September 2002 using the ship KNM Tyr. The aim was to investigate the same wrecks selected in 1989 by using a remote-operated vehicle (ROV) with video cameras. The investigation showed that some of the ammunition was pierced through by corrosion. The content have therefore probably leaked out, which indicate that the release of chemical ammunition to the sea will go on for a long time. The ammunition seen on the seabed has quite thin walls, and many of the shells were pierced through by corrosion. Trying to bring the shells to the surface would most likely not be successful because they will fall into pieces by the movement and the content will leak out. A lot of shrimps and some species of fish were observed close to the bombs. This indicate that no acute toxic effects from the chemical warfare agents in Skagerrak is present, but investigation of the content of chemical warfare agents or degradation products in marine organisms is needed to assess long-term effects.