North and Baltic Sea: Ammunition Remnants as a Danger from the Deep – Auto & Mobil

If you stand on the beach and look at the North Sea, you hardly suspect the danger that lies at its bottom. “These are depth charges,” says Sven van Haelst. He shows a photo he took of a shipwreck on the ocean floor. Isn’t it dangerous to dive there? “Usually the depth charges don’t explode as quickly,” says the research diver and underwater archaeologist. Normally? Well, he puts it down, of course you shouldn’t touch them. But something else is much more dangerous.

The research diver shows more photos that he took near the island of Helgoland. In the murky North Sea water, plate mines with a diameter of 42 centimeters can be seen, no algae grow on their surfaces, only dark brown discoloration can be seen. “This is TNT,” says van Haelst, who works at the scientific Vlaams Instituut voor de Zee in Belgium. Trinitrotoluene (TNT) is the most commonly used explosive and is considered to be carcinogenic.

In the end, the stuff can end up in the food chain too

There are tons of war scrap lying on the bottom of the North and Baltic Seas. Shipwrecks, cartridges, bombs, grenades, bazookas and mines from the First and Second World Wars. For more than 75 years, these legacies have been rusting largely unnoticed. Experts estimate that 1.3 million tons of war ammunition were sunk in German waters in the North and Baltic Seas alone. The biggest problem is that the metallic shells are increasingly rusting through and the explosives get into the water. The chemical substances can pose a threat to the ecosystem and reach humans via the food chain, via plants, fish and mussels.

Where exactly is how much ammunition is located? What are the risks of the rusting war wrecks? And how can the ammunition be defused or recovered? The interdisciplinary research project “North Sea Wrecks”, in which institutes and universities from five countries are involved, has been dealing with these questions for three years. In the Baltic Sea war ammunition has been investigated on the seabed for a long time, in the North Sea it is the first major analysis of its kind. The scientists are now showing their results so far in a Special exhibition of the German Maritime Museum (DSM) in Bremerhaventhat opened last week. The show “Toxic Legacies of War – North Sea Wrecks” (translated: “The toxic legacy of war – North Sea wrecks”) will now tour for one year as a traveling exhibition through Germany and the countries bordering the North Sea.

“We examine the wrecks and their cargoes and assess the risks,” says Sunhild Kleingärtner, director of the DSM, director of the exhibition and professor at the University of Bremen. On a large screen you can see film recordings made by van Haelst and the other divers of the wrecks on the ocean floor. At interactive stations, visitors can see how the scientists find the wrecks in the sea, how they take samples there, examine them in laboratories and evaluate the results.

The remains of ammunition do not only come from ships sunk in sea battles

More than 680 ammunition-laden wrecks are still suspected in the Belgian, Dutch, German, Danish and Norwegian waters of the North Sea. They come not only from ships that were sunk in sea battles during the two world wars. In 1945 there were still huge amounts of ammunition stored all over Germany and since destruction on land was time-consuming and dangerous, the material was simply dumped into the sea. “One thought: ‘Out of sight, out of mind'”, says DSM director allotment gardener. “And used the sea as a garbage dump.”

In order to determine the extent, the locations of the wrecks and the ammunition must first be identified and mapped, an often small-scale and arduous task. In the archives there are numerous files with military records and historical nautical charts, on which the dumping areas were entered after the war, but they do not always match the actual locations, says Cornelia Riml, who works at the Maritime Museum. The tides and the strong currents in the North Sea have carried away a lot and many wrecks have been washed over by sediment and sand. In addition, not all skippers stuck to the agreed dump sites and sometimes dumped ammunition overboard on the way there.

Research divers and diving robots are now looking for the wrecks. Van Haelst has dived more than 30 times for the project in the North Sea in the past three years and has taken photos and films of the shipwrecks, which are at a depth of around 30 to 40 meters. The divers scraped plankton from the sides of the ship, collected plants, fish, crabs as well as water and sand samples and attached nets with mussels to the wrecks. After a few months, the mussels were recovered and analyzed by toxicologists, because they filter large amounts of water and are good indicators for measuring levels of pollution.

The fry die in close proximity to the wrecks

“We found that the more rusty the ammunition, the more chemical substances get into the environment,” says Edmund Maser, professor at the Institute for Toxicology at the University Medical Center Schleswig-Holstein (UKSH). The mussels that were sunk there have increased TNT levels. And 25 percent of the fish in such areas have liver tumors. Fish also use the rusted mines as caves and lay their eggs in them. “The TNT concentration there, at three milligrams per liter, is so high that the fry die,” says Maser. It is to be feared that this will also reduce fish stocks.

The aftermath of the war is not only a threat to the ecosystem. The white phosphorus contained in incendiary bombs remains flammable in the long term and is often mistaken for amber when collecting on the beach. Sea mines can also become a dangerous obstacle when laying submarine cables, building offshore wind farms, fishing and shipping. In 2005, three Dutch fishermen pulled a war bomb out of the water and died in the process. Last year, the crew of an English fishing trawler barely survived and was seriously injured in some cases when ammunition exploded.

Open detailed view

In order to collect an overall picture of the pollution and to evaluate it, the data of historians, divers and toxicologists are digitally recorded, merged and evaluated. “We are developing an international ammunition register in which we record everything that is available worldwide in terms of ammunition pollution,” says Jann Wendt, who is also responsible for the North Sea Wrecks project with his company Egeos developed a software model. The risk assessment should show where the problem is most pressing – and where action must be taken first. “They are huge areas and we try to generate as precise a picture as possible that tells us where the biggest hotspots are,” says Wendt. In the Baltic Sea, for example, there is such a hotspot in the Kolberger Heide, a sandbank just a few kilometers off the coast of Kiel, where 18,000 large explosive devices are said to have been sunk.

“These are ticking time bombs”

Thanks to remote-controlled and autonomously driving robots, it is now technically possible to recover and defuse ammunition. But that is expensive and so far there has been a lack of political will to provide the money. Where salvage is not possible, the remains of the war must be blown up. But that is dangerous and controversial. Because the explosives can spread even further and the bang of the explosion can seriously damage the hearing of marine animals such as whales. Complex legal issues also complicate the subject, national responsibilities are not always easy to clarify. And many of the wrecks are also sea graves.

“We still have room for maneuver,” says Claus Böttcher from the Ministry of the Environment in Schleswig-Holstein, who also chairs the advisory board of the North Sea Wrecks project. But time is of the essence. “These are ticking time bombs,” says Böttcher. The ammunition cases not only rust through, the sediment also acts like sandpaper on them. And once the toxic explosives have escaped there is no chance of catching them again.

The special exhibition “Toxic Legacies of War – North Sea Wrecks” is touring through Germany, Denmark, the Netherlands, Norway and Belgium until September 2022. The next stop is from November 23rd to 25th in Bruges, Belgium.