Scientists recently discovered that the wreck of the V-1302 John Mahn, a German fishing trawler requisitioned by the German Navy as a patrol boat during World War II, is still leaking toxic chemicals into the North Sea, according to an article published in Frontiers in Marine Science.
Historical records show the ship was patrolling the Belgian coast on February 12, 1942, when it was sighted by six British Royal Air Force fighter aircrafts. Two aerial bombs struck and sunk the ship, claming the lives of 11 sailors and carrying its cargo to the seabed, where its munitions and coal reserves have been slowly leaching away into the surrounding ecosphere.
“While wrecks can function as artificial reefs and have tremendous human story-telling value, we should not forget that they can be dangerous, human-made objects which were unintentionally introduced into a natural environment,” cautioned Josefien Van Landuyt, a bioengineer and also one of the study’s authors. “Today, new shipwrecks are removed for this exact reason.”
The researchers took samples from around the John Mahn at intervals of increasing distance away from the wreck in various directions to see how far the pollution stretched. In their findings, they noted that the ship was still seeping toxic chemicals called polycyclic aromatic hydrocarbons, or PAHs, which are often associated with the burning of coal, oil, gas and tobacco. Scientists consider several kinds of PAHs to be cancer-causing.
The scientists also noted that the presence of the PAHs meant that the wreck is still influencing the chemical makeup and microbiome ecology of the ocean floor in its radius. The highest concentrations of chemicals, including PAHs and arsenic, were found closest to where the ship’s coal bunker and munitions deck would have been located, indicating the remnants of a “strong historic contamination or a continuous slow leaching.”
However, some of the chemicals that were found on or near the wreck, like naphthalene, which is also toxic in large amounts, have shorter half lives, suggesting that the ship’s contents are still leaching into its environs, even nearly a century later. Part of this can be attributed to the fact that as ships age, their metal corrodes, exposing the contents of spaces that may have been previously enclosed.
The North Sea Wrecks group, which worked with the researchers, is dedicated to investigating these sites and to educating the public about the dangers of hazardous war remnants, which have been shown to cause damage to marine life, impacting growth, reproduction, feeding and tissues of marine organisms.
“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, leaching chemicals, fossil fuels, heavy metals from — sometimes century old — wrecks we don’t even remember are there,” Van Landuyt said in a statement.
Across the world’s oceans, shipwrecks from both world wars contain between 2.5 million and 20.4 million metric tons of petroleum products.
The research will help scientists develop decision-making tools to assess the potential environmental impacts of other wartime shipwrecks, with the goal of creating a safer marine environment.