The Baltic Sea is a burial ground for 50,000 tons of chemical weapons. They were already taken into account during the construction phase of Nord Stream, says University of Helsinki professor Paula Vanninen.
Near the leakage points of the Nord Stream gas pipelines, in the Bornholm Deep, there is a place where 50,000 tons of chemical weapons have been sunk since the Second World War.
The Bornholm Trench is one of the key dumping grounds for chemical weapons. In addition, for example, up to 170,000 tons of chemical weapons have been dumped in the Skagerrak area between Denmark and Norway.
After the Second World War, the Allies took possession of war material from Germany, most of which were aircraft bombs and artillery shells loaded with the most toxic chemicals. It was decided to dispose of them in the sea because it was considered a quick and easy way to get rid of them.
Chemical weapons are destroyed today in designated destruction facilities, but at the time of World War II, the technology had not yet been developed.
The gun barrels sunk in the Baltic Sea contained, among other things, mustard gas, adamsite, arsenic oil and clark. They were used in bombs and grenades because of the skin and respiratory irritation they cause.
The submerged barrels have gradually begun to leak due to wear and tear. Leaked chemicals have been found in the seabed soil and water.
The weapons have not been lifted from the seabed, as the lifting operation has been considered too expensive.
The effect of gas leaks on weapons is small
However, the currently known dumping sites are several kilometers away from the explosion sites of the Nord Stream pipelines, so the impact of the leaks on chemical weapons is estimated to be small.
Vanninen points out that the route of Nord Stream’s gas pipelines was already planned during the construction phase so that it goes around the weapon emplacement areas.
– In my opinion, the seabed was cleared pretty well when those pipes were put there. I don’t think there is any real danger from this at the moment, Vanninen says.
However, there is uncertainty about it. Not all weapons were sunk where they were supposed to be: for example, the fishermen who sunk them already sunk them along the way, so that the work could be done faster. So the location of each barrel or box is not known.
According to Vanninen, no one knows for sure how combat gases and methane would react if they came into contact with each other. However, experts estimate that the reaction would not cause a significant danger.
Marine nature suffers from gases
In any case, chemical weapons harm the life of fish and other small organisms in the sea. No traces of combat gases have been found in the fish themselves, but their stock may weaken due to the gases.
Methane leaking from the Nord Stream gas pipelines, on the other hand, does not dissolve in water, so its effect on water quality is minimal, says the Finnish Environment Agency. Fish, marine mammals and birds may die or escape from the area, but the effect is limited to a very small area. Aquatic life may also return to the area once the leaks stop.
The Nord Stream leak, on the other hand, can be very harmful to the climate: the leak has released more methane than Finland’s annual methane emissions. Methane is a greenhouse gas almost 30 times more powerful than carbon dioxide, and it significantly intensifies climate change.