The Environmental Impact of Sunken Shipwrecks
Underwater wrecks get damaged fast
Our ocean is full of wrecks, thousands of shipwrecks sunk during the Second World War and today many many boat are still sinking by accident or intentionnaly to make great dive spots. All the divers love diving in wreck nevertheless the shipwrecks are a potential pollution source. Beneath the effect of water, the metal inevitably corrode itself, and loose a tenth of millimeters of thickness per year. Some super tanker boats, which contain around fifteen millions tons of oil, risk therefore, in short or long term, to liberate their contents. But for Michel l’Hour, pioneer of underwater archeologic, the oil isn’t the most dangerous components which it enclose. Some chemicals products such as yperite, mustard gas, are a lot more concerning through his eyes. In the water, this gas change itself into a sort of yellowish paste that the fish eat, and then finish in our stomach.
A submarine wreck concerning
A very concerning case is the one of the German underwater submarine wreck U-864 and its worrying cargo of mercury. This German submarine, torpedoed by the British the 9 of February 1945, at a few kilometers from the coast of a little Norwegian island, Fedje Island, was transporting 67 tons of mercury contained in steel bottle.
It’s just in February 2003 that we found it, cut in half and laying at 150 meters of deep. In 2005, we discover the steel leaked from one of the 1857 steel bottle, which opened beneath the effect of corrosion. The wreck is therefore examined, and we observe that the cylinders’ thickness have become thicker, in some places it measures no more than one millimeter and not the initial five millimeters.
Two solutions are explored to avoid a disaster :
- – Rescue the submarine and take it out of the water
- – To bury it under a sand sarcophagus, gravel and concrete, of 12 meters of thickness
In May 2014, the Norwegian government choose the second solution, but we will have to wait until 2016 for the works to begin. The wreck was covered by a 30,000 tons of sand, then by 160.000 tons of rocks. We just have to cross our fingers, and hoping that the sarcophagus will do his job.