KIEL, Germany – Beneath the popular tourist beaches of northern Germany lies a dangerous environmental threat: vast quantities of World War II munitions slowly corroding on the Baltic Sea floor and releasing toxic chemicals into the marine ecosystem.

Scientists are warning that as saltwater eats away at the metal casings of rockets, artillery shells and bombs, they are leaking contaminants such as the explosive TNT into the surrounding waters.

Research expedition maps underwater dangers

A research vessel departed from the port city of Kiel this month to better map these underwater hazards. The bay around Kiel is amongst the most heavily contaminated areas with unexploded ordnance.

Twelve scientists from Germany, Poland and Lithuania, supported by an 11-strong crew, are spending three weeks aboard the Alkor, operated by the Kiel-based GEOMAR oceanographic research centre.

During their voyage, they will pass a sunken torpedo boat, destroyer, minesweeper and submarine, all identified from naval logbooks and other records held in German military archives.

“One of the goals of the project is to develop some new tools for cleaning it up,” said Aaron Beck, a scientist leading the expedition. “The idea is, what can we do to prevent this before the pollution comes out?”

Massive scale of contamination

Along the German coast, approximately 1.6 million tonnes of munitions litter the seafloor, particularly near the ports of Kiel and Luebeck, making it one of the world’s most contaminated areas.

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Most of this ordnance was hastily dumped by the victorious Allied powers after Germany’s 1945 surrender, as they sought to quickly eliminate what remained of the Nazi war machine.

Toxic traces detected in marine life

Nearly 80 years later, traces of carcinogenic explosives have been detected in shellfish and other sea life throughout the region.

The Baltic Sea’s shallow waters and narrow passage between Sweden and Denmark to the open ocean mean pollution tends to linger rather than disperse.

A modern boom in undersea construction of pipelines, telecommunications cables and offshore wind farms has brought renewed attention to this environmental issue.

The research team is using an underwater robot to film the seabed and deploying probes to collect sediment and water samples. They are also placing packets of mussels, which will later be retrieved to study contamination levels.

However, Beck reassured that the pollution does not pose an immediate danger to humans. “For a human being to ingest, at current concentrations, a concerning amount of explosive compounds, they would have to consume seven kilos of fish a day for more than a year,” he said.

Fuel poses greater threat than ammunition

Ammunition on sunken warships is not the only environmental danger. “On some of these ships, you have 10 tonnes of ammunition, but 200 tonnes of fuel. That’s undoubtedly the biggest problem,” Beck explained.

One wreck still holding fuel is the Franken, a German navy tanker torpedoed by Soviet forces on 8 April 1945. It sank off what is now the Polish city of Gdansk, at the time still the German city of Danzig.

Uwe Wiechert, 70, a former German naval officer and part of the research team, called it a “time bomb”.

The Franken also poses a legal puzzle: who will pay to pump fuel from a German ship, sunk by the Soviets, that now rests in Polish waters?

Global problem requires international solution

Seafloor munitions dumps are a worldwide problem, with other major sites located along the coasts of the United States, Britain, Japan and Australia, and even in Swiss lakes.

Germany has been at the forefront of European efforts to deal with unexploded underwater ordnance, according to the European Commission.

Beyond mapping the problem, Germany has taken initial steps towards munitions disposal. In Luebeck Bay, a pilot project to destroy WWII munitions on a specially built floating disposal platform has begun.

Some contractors working on the project have experience clearing munitions for large offshore wind farms along the Baltic and North Sea coasts.

Divers and underwater robots have sorted through tonnes of dumped munitions at four sites in the bay as part of the project, funded with an initial 100 million euros.

Funding challenges remain

However, it remains unclear whether the pilot project could become a model for cleanups elsewhere. So far, no government has committed the long-term funding needed to tackle the problem comprehensively.

When a similar project might start in waters off Kiel, said Beck, “is anybody’s guess”.

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