WWII shipwreck still contaminating the North Sea: study

An 80-year-old World War II shipwreck is still leaking hazardous pollutants — such as explosives and heavy metals — into the sediment of the North Sea, a new study has found.

This ongoing contamination is influencing the marine microbiology and the geochemistry of the ocean floor where the ship rests, according to the study, published in Frontiers in Marine Science on Tuesday.

Yet this vessel is just one of thousands of ship and aircraft wrecks, warfare agents and millions of tons of conventional munition lingering in the depths of the North Sea, the study authors warned. 

And while these wrecks contain dangerous substances, like petroleum and explosives, there is a lack of information as to their exact locations and how they might affect the environment, the researchers observed. 

“The general public is often quite interested in shipwrecks because of their historical value, but the potential environmental impact of these wrecks is often overlooked,” lead author Josefien Van Landuyt, a PhD candidate at Belgium’s Ghent University, said in a statement. 

As part of the North Sea Wrecks Project, Van Landuyt and her colleagues explored how the V-1302 John Mahn shipwreck in the Belgian part of the North Sea is affecting the surrounding microbiome and seabed. 

The V-1302 John Mahn was a German fishing trawler that was repurposed during World War II to work as a patrol boat, the researchers noted. In 1942, however, the ship was attacked by the British Royal Air Force and quickly sank.

“While wrecks can function as artificial reefs and have tremendous human story-telling value, we should not forget that they can be dangerous,” Van Landuyt said, stressing that these are “human-made objects” that ended up in a natural environment. 

“Today, new shipwrecks are removed for this exact reason,” she continued.

The Ghent University researchers took steel hull and sediment samples from in and around the ship, at various distances and directions, according to the study. 

They found that the concentrations of toxic pollutants depended on the distance from the shipwreck. 

Among the toxins they identified were heavy metals — such as nickel and copper — as well as arsenic, explosive compounds and polycyclic aromatic hydrocarbons, chemicals that occur naturally in coal, crude oil and gasoline. 

The highest metal concentrations were in samples closest to the ship’s coal bunker, although the freshly deposited sediment near the wreck also had a high metal content, according to the study.

The biggest polycyclic aromatic hydrocarbon concentrations were closest to the ship as well, the researchers found. 

Certain bacteria — such as Rhodobacteraceae and Chromatiaceae — that are known to degrade polycyclic aromatic hydrocarbons were present in samples that had the highest pollutant content. 

In addition, the researchers found sulfate-reducing bacteria — such as one type called Desulfobulbia — in the hull samples. These bacteria likely led to the corrosion of the hull, according to the study.

Van Landuyt acknowledged that she and her team investigated only one ship, located at one depth and in one area of the sea. 

Although she stressed the need for further research into other shipwrecks, she surmised that their findings are only the tip of the iceberg. 

“People often forget that below the sea surface, we, humans, have already made quite an impact on the local animals, microbes, and plants living there and are still making an impact, Van Landuyt said. 

These artificial vessels, she added, are “leaching chemicals, fossil fuels, heavy metals from — sometimes century old — wrecks we don’t even remember are there.”