Ocean depths lure mining companies

“In the depths of the ocean, there are mines of zinc, iron, silver and gold that would be quite easy to exploit,” said Captain Nemo, hero of Jules Verne’s Twenty Thousand Leagues Under the Sea, in 1870. Now 21st-century technology is confirming his statement, as mining companies, spurred by high commodity prices, prepare to extract metal ore from rich deposits more than a kilometre under water.

The Euroscience conference in Munich heard on Tuesday that marine science and mining technology had combined to make it realistic for the first time to exploit minerals deposited on the seabed in volcanic areas known as ocean ridges, which typically lie 1km-2km below the surface. They are rich in zinc, iron, silver and gold, as well as copper and lead.

Steven Scott, a seabed geologist at the University of Toronto, said two marine mining companies were actively exploring deep ocean mining prospects.

Nautilus Minerals – based in Vancouver and quoted on the Toronto Stock Exchange, and which shares its name with Captain Nemo’s submarine – is focusing on the Manus basin near Papua New Guinea, while Neptune Minerals, based in Sydney and quoted on the London market, concentrates on an area off the coast of New Zealand’s North Island.

The prospect has evoked “knee-jerk” opposition from some environmentalists, according to Prof Scott. “There is understandably going to be legitimate concern from many in the public,” he said, though he believes deep ocean mining would be less damaging than terrestrial extraction.

There is no acid mine drainage, since acids are neutralised immediately by alkaline seawater. The operations would not touch the active hydrothermal vents, known as “black smokers”, which boast extraordinary colonies of submarine animals and plants that have evolved to thrive in extreme conditions. And the sulphide mineral deposits lie directly on the sea floor.

Other seabed researchers at the Munich conference agreed cautiously with Prof Scott. Colin Devey, of the Leibnitz Institute of Marine Sciences in Germany, said: “The ocean ridges are active volcanic landscapes . . . that is not a fragile environment. The creatures there have adjusted to life on the edge.” However, Prof Devey, who runs InterRidge, an international organisation of ocean ridge researchers, added: “There is some difference of opinion within the scientific community.”