An estimated 300,000 tons of German munitions were dumped at sea after the Second World War. These munitions included quantities of nerve gases such as Sarin, Tabun, tear gas and mustard gas. Part of this, some 50,000 tons, was dumped in the deep waters of the Gotland and Bornholm basins, important spawning grounds for fish species including cod. This, however, is probably not as bad as it sounds. Nerve gas and tear gas are unstable and, as far as is known, dissolve to give concentration levels that are harmless.
“That is true for pure water. But we do not know whether the toxic substances can attach themselves to plankton or particles that act as food for life forms such as small crustaceans and mussels,” says Rune Berglind, a research scientist at FOI.
Mustard gas forms lumps
Mustard gas degenerates to form hard encrusted lumps which are harmless provided that they are not touched. But these lumps can become caught up in fishermen’s nets or may occasionally be washed ashore. Remaining on the seabed are also mines and bombs that constitute a danger now that an increasing amount of infrastructure equipment, such as gas pipelines, wind turbine cables and telephone cables, are being laid on the Baltic seabed.
Research agencies in Sweden, Poland, Germany and Finland have therefore initiated a project with two main aims:
• To chart what is lying on the seabed, using towed array sonars and wire-guided underwater vehicles.
• To study whether marine life or vegetation are being damaged by the chemical agents, using sediment sampling and by catching fish and allowing mussels to grow in baskets located at the dumping sites.
The project is led by the Institute of Oceanology Polish Academy of Science (IOPAS) with FOI contributing with its expert knowledge of chemical agents and the analysis of sediment samples. Also participating are the Swedish Maritime Administration and Umeå University.
Emergency call centre
The project participants will also be proposing guidelines for the action to be taken by anyone bringing up a munition or mustard gas in a fishing net.
“We would suggest a variant of calling 112, a call centre that one can call in the event of bringing up hazardous material in order to find out what one should do,” says Rune Berglind at FOI.
For FOI this task is one that will benefit the agency’s overall competence in a number of ways. It brings new research contacts in other countries as well as affording opportunities to develop methods of chemical analysis to show not only what substances have been found but also where they have come from.