Second world war shipwreck is leaking toxic chemicals in the North Sea

A second world war shipwreck is leaking hazardous chemicals, including explosives and heavy metals, into the North Sea, suggesting that other wartime wrecks may need to be removed from the seabed.

The V-1302 John Mahn was a fishing trawler requisitioned by the German navy during the second world war and sunk by UK bombers in 1942. It has rested at 30 metres below sea level in the Belgian North Sea ever since.

Now, Josefien Van Landuyt at Ghent University in Belgium and her colleagues have analysed samples taken from the boat’s steel hull and the surrounding ocean floor and found traces of arsenic, explosives and heavy metals such as nickel and copper. The team also found  (PAHs), a group of chemicals that occur naturally in fossil fuels.

“We found that the closer you get to the ship, and especially the closer you get to the coal bunker, you see that the concentration of PAHs goes up,” says Van Landuyt.

These chemicals are reshaping the microbiome in the immediate vicinity of the ship, she says, with known PAH-degrading microbes like Rhodobacteraceae and Chromatiaceae found in the samples with the highest pollution levels.

Van Landuyt says the pollution caused by the V-1302 John Mahn is relatively minor, allowing the wreck to still act as an artificial reef and nursery for fish.

But thousands of other wrecked ships and aircraft from the period could well be leaking larger amounts of toxic materials into the North Sea, she warns. Little is known about where they are on the seabed or what they were carrying on board.

“Some of these ships… were hit while they were still packed full of munitions,” she says.

Van Landuyt’s work is part of the North Sea Wrecks project, which is expected to make a recommendation later this year about whether wartime wrecks need to be removed from the seabed to protect marine life.

Without action, the wrecks could continue polluting for decades, says Andrew Turner at the University of Plymouth, UK. “If it’s anti-fouling paint or electronics or coal PAHs, they are going to last a long time. The PAHs at the bottom of the sea will take decades to degrade.”