They might look calm and peaceful as they gently lap against Germany’s shores. But hidden in the depths of the North Sea and Baltic Sea is an unfathomable danger.
Around 1.6 million tonnes of explosives and 220,000 tons of chemical weapons from two world wars lie at the bottom of these two seas.
And as if those weren’t enough, experts say there are also huge numbers of unexploded bombs from military tests and exercises conducted during times of peace.
“By now it has become recognised that something must be done,” says Edmund Maser of Kiel University’s Institute for Toxicology and Pharmacology. Thanks to research by his team it is clear that toxic materials leaking from the munitions can be taken on by marine animals.
For a long time it was assumed that it was simply enough to cover up the munitions and leave things to themselves. But the shells are rusting, setting free their contents.
What happens next with these materials is one of the central issues to be taken up next week at a symposium of the Leibniz Institute for Baltic Sea Research Warnemuende (IOW).
Most of the materials come from German munitions left over after the war that fell into the Allies’ hands.
“The Allies were afraid that the Germans could use them to lead a partisan resistance, so they simply dumped everything in the sea,” explains Jens Greinert of the Helmholtz Centre for Marine Research in Kiel and head of a project called Environmental Monitoring for the Delaberation of Munitions in the Sea (UDEMM).
The “out of sight, out of mind” approach has not worked, Greinert says. Even after more than 70 years the explosives are still hazardous.
The TNT can still explode, while the TNT degradation product ADNT is highly poisonous. “But there is a lack of basic knowledge because of the decades of inaction,” he says.
Politicians have in the meantime grasped the issue. The task now is to find out “what’s going on down there.”
IOW researcher Maser notes that marine animals can help in the studies. There are also plans to deploy remote-controlled robots to cut open the shells and deactivate the explosives inside. But first researchers need to determine whether this would set free substances and affect the marine environment.
In this regard, clams serving as “bio-monitors” are highly-effective water filtration machines that pump several litres of water through their bodies every hour.
The Kiel researchers have been setting small baskets full of the animals on top the shells. “Before-and-after measurements” show that the TNT toxants can be found inside the clams’ tissue.
“We already have a problem of leaking hazardous materials,” the toxicologist says. There’s even the prospect of these materials “landing on our plates” at some point. But so far there’s no reliable data on the acceptable limits for humans. In addition, there are many different contaminants.
The IOW has developed a simulation model using currents and temperatures in the Baltic Sea that could provide answers as to how the explosive materials spread.
This model can then show when it makes sense to recover the materials, even with a risk of leakage, says IOW researcher Anja Eggert.
The model also helps researchers search for locations where explosives have not yet been discovered. If substances suddenly crop up in high concentrations at a certain location, then calculations can be made to possibly identify where they originated.
Researchers estimate the removal of these explosives will cost billions. All the while, the dangers posed by them are constantly increasing.
Shipping channels are being dredged, pipelines laid down and new offshore windparks require electrical cable connections to the mainland. All this is taking place where dangerous munitions lie in wait to release their deadly contents. – DPA


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