The wreck of the Second World War that continues to pollute

It rests on the bottom of the sea, witness of a shipwreck eighty years ago. And it is part of the ecosystem, hosting – in its thousand ravines – fish and molluscs. But the wreck of the historic fishing boat “V-1302 John Mahn”, which sank in 1942 in the North Sea during the “Cerberus” operation, continues to pollute. And like him the thousands of boats that rest on the seabed of the whole world, including the Mediterranean. This is what emerges from the research of a group of Belgian researchers, just published in the scientific journal Frontiers in Marine Science with the title “80 years later: Marine sediments still influenced by an old war ship”.

The study, carried out as part of the “North Sea Wrecks” project (literally, North Sea wrecks) showed how the wreck is still dispersing into the sea dangerous pollutantsin particular heavy metals, on the sediments of the ocean floor. With potentially harmful effects on ecosystems. Above all, it suggests urgently assessing the opportunity of a remediation, where possible, of the hundreds of ship and plane wrecksas well as of bullets and bombs still deposited on the seabed of the North Sea, investigated by the research team, and of seas around the world. Whose effects on the biodiversity and ecosystem health they are often underestimated.

“That’s right. – confirms Maarten De Rijckeamong the authors of the article, researcher at the Flanders Marine Institute in Oostende, Belgium – Even if the concentrations of pollutants that we have detected around this wreck are not particularly relevant, at least a hundred times below the levels considered toxic, our results are particularly significant for the North Sea because they are able to suggest to policy makers that these wrecks are not only objects of enormous cultural and historical value, but also source of potential long-term environmental risks“.

To demonstrate this, the researchers detected heavy metals (nickel and copper above all), traces of explosives, arsenic and polycyclic aromatic hydrocarbons (PAH or PAH from English), compounds naturally present in oil or coal, sampling sediments and water in directions and different from the wreck, a German fishing boat requisitioned during the Second World War to be used as a patrol boat and sank off the Belgian coast following an attack by the British air force.

The Po dry: the wreck sunk during the Second World War re-emerges

Inexorable confirmation of the starting hypothesis: “We have confirmation that the wrecks abandoned on the seabed, net of their artificial barrier function and their narrative value as historical witnesses, can be considered dangerous, which is why we proceed today their immediate removal “, he explains Josefien Van Landuyt of the University of Ghent, among the authors of the research.

But the removal of the historical ones is certainly more complex. “We estimate that WWI and WWII wrecks around the world collectively contain between 2.5 and 20.4 million tonnes of petroleum products,” the researchers note. Many of them are invisible. But this does not mean that their effects on the environment are less significant. “Their advanced age amplifies the environmental risk due to corrosion: in many cases, fractures are generated and spaces that were previously closed open up. We can therefore speak of an ever-changing environmental impact”. How much do you need to worry about? Another study, conducted by a series of partners of the North Sea Wrecks project with a detailed focus on explosives abandoned in the seas, highlighted – underlines Maarten De Rijcke – that “fish fauna absorbs traces of TNT in the tissues, with concentrations still reassuring, because 300 times lower than those harmful to humans. It would therefore be safe to eat fish “.

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And what happens in the Mediterranean? “Turning the light on the potential impact of wrecks and abandoned weapons on our seabed would be more than appropriate to develop a mapping of the risk of biomass contamination and understand, for example, the long-term costs of a war – he stresses. Roberto Danovaroformer president of the Anton Dohrn Zoological Station, which teaches Marine Ecology at the Polytechnic University of Marche – That said, it is essential to distinguish between accidental sinking and sinking apparently accidental, which in reality they are not, and on which we have not infrequently tried to turn the spotlight on. In the first case, the danger of the wreck tends to be linked to the content of what it carries. If they are toxic or even radioactive substances, as has also happened, it is the health of our ecosystems and of ourselves that is at risk and that is why the scientific community can only hope for the funding of studies such as the one carried out in Belgium. On the other hand, there is no lack of wrecks that do not pollute and around which it has also developed over time, thanks to biomass that lives there, a relevant underwater tourism. Also for this there is no other solution than to deepen. As soon as possible”.