Deep dilemma

On Tuesday 18 February 1873, the British naval corvette HMS Challenger hove to some 160 miles southwest of the tiny island of Ferro, part of the Canaries, at a site designated by chief scientist George Wyville Thomson as Station 3 of the Atlantic transect. As always, the dredge took an age to reach the seafloor and another age before it reached the surface again, finally arriving back at 5pm. It was just another routine chore in Challenger’s epic voyage around the world to study the natural history of the world’s oceans.

With the evening sun already dipping toward the western horizon, the dredge finally surfaced, carrying a load of coral fragments that Wyville Thomson identified as members of the Corallium genus. Despite the fact that the corals were dead, they all gleamed with a peculiar blackish metallic lustre, which ship’s chemist John Buchanan’s tests showed was a coating of peroxide of manganese, mixed with some form of phosphate. The scientists aboard HMS Challenger did not know it, but they had just witnessed the birth of a new industry – deep sea mining.

Fast forward 140 years to London March 2014 and the Second Deep Sea Mining summit made the BBC news. Today, deep sea drilling is poised to become a major provider of rare earth elements (REEs) – the essential ingredient of everything from mobile phones to hybrid car batteries – as well as a host of other minerals such as cobalt, copper and sulphides not to mention Challenger’s manganese – or, as they now known to be, polymetallic – nodules.

Jon Copley of the Southampton Oceanography Centre, UK, pointed out at the meeting, for example, that deposits of copper deposits – an essential requirement in modern electronics – are common around deep sea smoker vents. Surprisingly, a hybrid car contains about 80kg of copper while an ordinary car has between 30 and 50kg.

Cobalt crusts on submerged mountains (sea mounts) are an important source of ferrous and manganese minerals and, since there are about 39,000 sea mounts worldwide of which only a few hundred have thus far been tapped, the potential resource is huge. Tracey Shimmield of the Scottish Association for Marine Science in Oban, UK, says that this ferromanganese resource could be particularly profitable because its exploitation can be enhanced by computer modelling. Her own group has been simulating the movements of water currents around promising sea mounts at the 800–2500m depths where cobalt deposits form and they have successfully managed to predict were the deposits will be most accessible because of ocean winnowing. ‘In this way we can save time and money in the location of these deposits and also mitigate the environmental footprint of mining operations,’ she says.

Along with mineral recovery, meanwhile, there is also a growing emphasis on environmental impact minimisation. Remotely Operated Vehicles (ROVs) developed for deep sea mining are fitted with an array of environmental sensors as well as sensors to find ore deposits.

One of the latest innovations is a turbidity sensor that continuously monitors water quality from mining operations to make sure it stays within prescribed limits, Shimmield explains – avoiding contaminating too much of the surrounding area with ejected sediment. Such ROVs are also routinely equipped with temperature, oxygen concentration and salinity sensors, and the latest generation will be equipped with sensors to detect the concentration of toxic heavy metals mobilised by drilling operations.

But it is the rare earth elements that are exciting the world mining community. REEs are key to both the technological and green revolutions. They are essential for manufacturing everything from mobile phones, laptop computers, LCD and plasma TV screens to wind and wave turbines as well as the motors and batteries in hybrid cars. As the US Geological Survey puts it, ‘in that substitutes for the REE are inferior or unknown [they] have acquired a level of technological significance much greater than expected from their relative obscurity’.

Many land based mines have closed as uneconomic, and the largest mine in China controls about 90% of the land-based supply. As Copley says, the burgeoning interest in deep sea mining of rare earth elements is also about security of supply.

The technology to exploit mineral resources in the deep sea is relatively mature, but environmental considerations remain a huge issue.

Deep sea vents first came to prominence in the 1970s because of their exotic fauna  such as giant tube worms and eyeless crabs new to science. Some have even speculated that such vents could be the cradle in which terrestrial life evolved.

Copley has studied five deep sea vents in the Cayman Trough near the Canary Islands and discovered at least 30 new species that depend on their unique ecologies to survive. He points out that we simply do not yet know enough about the cumulative effects and risks of mining in those habitats. The same is true for polymetallic nodules, covering vast swathes of the ocean floor, where new species have also been found living.

But what of mining in areas outside a nation’s exclusive economic zone? At the moment, the deep ocean outside territorial waters is defined as the ‘common heritage of mankind’. What does that mean for mining rights and our responsibility for looking after the environment?

The UN International Seabed authority is an intergovernmental body based in Kingston, Jamaica. Its remit is to organise and control all mineral related mining in the international seabed. Since 2001, it has issued 13 mining licences but in recent months there has been a surge in demand. Nii A Odunton, the authorities’ secretary general, is bullish about the future. ‘Those who are interested and who can put together the resources, the science and technology... will be able to [go out and] get as much of it as they want.’

But all is not necessarily plain sailing. UK Seabed Resources have only recently reached an arbitrated settlement for the exploitation of the waters around Papua New Guinea, and not withstanding international agreements about common heritage, the PNG government is going to do very nicely out of the deal. Expect many more such arguments in the decades ahead as deep sea mining gains traction.

One of the primary objectives of the voyage of HMS Challenger was to discover new forms of life on the ocean floor. It was thought that, since the deep ocean was an unchanging environment, forms of live would be found alive on the sea bed that were only known as fossils on land.

Although Challenger was not successful in this respect, we know now that the sea bed and areas such as the mid-ocean ridges are the likeliest area on Earth to discover new species. Some of these species are chemoautotrophic, that is, they use chemical processes other than photosynthesis to fix energy. Some scientists speculate that these may be the oldest types of organism on Earth still using the original chemistry of life.

If this is the case, then not only do we have a lot to learn from them and their exotic chemistry but also they represent the roots of the tree of life. Whatever exploitation we undertake there, clearly care and respect will be required.

Richard Corfield is a freelance writer based in Oxford, UK