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Ticking time bombs in the North and Baltic Sea

Harald Franzen
August 23, 2017

Huge amounts of bombs and grenades rest at the bottom of the North Sea and Baltic Sea. But the risk of them exploding should be the least of our worries.

Explosion in the Baltic Sea
Image: picture-alliance/dpa/B. Wüstneck
Diver with mine, under water
Bombs must be recovered, as here in Lake Constance. If they are blown up, their chemical components contaminate the environment.Image: picture-alliance/dpa/Kampfmittelräumdienst Baden-Württemberg
Two unexploded mines are detonated under controlled conditions in waters off Tallinn
Today, bombs are mainly removed by companies that are constructing under water pipelines.Image: Getty Images/AFP/R. Pajula

Amber has been valued for its beauty since antiquity and until this day, pieces of the fossilized tree resin wash up on the shores of the Baltic Sea. Many vacationers wandering along the beaches in places like Hiddensee or Usedom hope to find a piece and many are in luck. A 67-year-old rock collector, strolling along a beach east of the northern German city of Kiel thought he was in luck as well, when he picked up what he thought was a piece of amber three years ago. It almost killed him.

What he had picked up was in fact a piece of white phosphorous. When it washes up on the shore the substance seems harmless but as soon as it dries the compound spontaneously self-ignites –with a fury. Phosphorus burns at around 1300 degrees Celsius. You can't put out the fire with water either, that will only create phosphoric acid, which causes severe skin burns and the phosphorous will just keep burning anyway.

But how did this dangerous compound get into the ocean? It's a relict of war.

"After the Second World War, Germany was to be disarmed and part of that was to dispose of stocks of ammunition as quickly as possible," explains Ingo Ludwichowski, director of the Nature and Biodiversity Conservation Union (NABU) in the German state of Schleswig-Holstein.

The easiest way to do that was to load the ammunition on ships, take it out to sea and throw it overboard, which was done extensively. So extensively that there are now gigantic amounts of ammunition in both the North Sea and the Baltic Sea. In German waters alone, there are about 1.6 million tons, 1.3 million in the North Sea, 300,000 in the Baltic Sea.

For a long time, public officials claimed that ammunition in the oceans wasn't a serious problem. But they should really have known better and one might argue that in fact they did.

A long struggle for the truth

The true extent of the problem was first discovered by Stefan Nehring, a marine biologist who specializes in invasive species. Nehring was tasked with writing an assessment of pollution in the North Sea. "This was about all sorts of things, discharge from water processing plants and God knows what. And during my research, I also came across the scuttling of ammunition," Nehring recalls.

He knew ammunition had been dumped near the Danish island of Bornholm but not that ordnance had been disposed of in coastal waters as well. And he came across inconsistencies. He was told that only small amounts had ended up in the sea but also found indications that the dumping had gone on for years and that entire shiploads had been scuttled.

His curiosity had been piqued so Nehring started digging. He lives in Koblenz, home to Germany's federal archives, which gave him the opportunity to go through mountains of state and federal records to eventually prove conclusively that there are staggering amounts of bombs and grenades in the seas. In fact, the government eventually accepted his calculations. And how couldn't they? They were based on their own figures.

Blowing it up isn't the answer

So what could you do with all those bombs? An obvious idea would be to just blow them up, something that was initially done occasionally. It's not really a bright idea though. "When a 500 kilogram bomb like that explodes, maybe two-thirds or three-quarters of the explosives are actually transformed," says Ingo Ludwichowski. "But the rest initially gets into the water and the explosion even distributes it widely."

Such blasts devastating effects go even further: "It will kill a diver or a harbor porpoise if they are anywhere within a few hundred meters of the explosion and the same goes for fish," says Ludwichowski. "And even if it's several kilometers away, it will affect their hearing." And hearing is key to the survival of harbor porpoises and several fish species, which primarily use sound rather than sight to navigate and hunt or avoid predators in the often murky waters of the North Sea and the Baltic Sea. And then there is the poison.

Even conventional explosives are a highly toxic mix of chemicals. Hexanitrodiphenylamine or HND, for example, was used widely by the German military in bombs during World War 2. "HND initially stains the hands but through that it also enters the body and it is carcinogenic and mutagenic," says Ingo Ludwichowski.

Ticking bomb

"In the coming decades, this is going to become a huge problem," says Stefan Nehring. Bombs are made of metal and metal corrodes, especially in salt water, and eventually the various poisonous contents of the bombs will be set free and enter the ecosystem. And there are indications that this is happening already.

High concentrations of arsenic have repeatedly been found in fish caught in the Baltic Sea. The undisputed source: poison gas ammunition. The situation with conventional ammunition isn't much better. "The explosive crumbles and particles eventually get so small that they can be absorbed by mussels, for example," says Ingo Ludwichowski. "Mussels are either part of the food chain or are consumed directly by humans."

The only real solution would be to recover the ammunition as quickly as possible and dispose of it properly, which would be a daunting and very costly enterprise considering the sheer amounts. "The government is doing pretty much nothing," says Nehring. Unless someone wants to build a wind park or run a pipeline along the sea floor. "Then the companies have to look for ammunition and dispose of it and the authorities sit back," says Nehring.

"This is a huge problem and it is getting worse as time passes, not better," Ludwichowki agrees. Not only will more and more bombs corrode and release their toxic cargo, once the metal casing is gone, it will also be virtually impossible to find the explosives again so it really is a race against time.

Ingo Ludwichowski
After World War II bombs should be out of sight as quickly as possible. Today this is becoming a problem, says Ingo Ludwichowski of the NABU.Image: NABU/V. Gehrmann
Beach in Kiel-Schilksee, Baltic Sea
When phosphorus appears ashore, it can easily be confused with amber.Image: DW/H. Franzen