Bringing the Ocean to Society
2 May 2017
Underwater debris is clouding hopes for sustainable deep-sea mining
Treasure troves of raw materials are resting on the ocean floor and their potential abundance is driving the emergence of deep-sea mining, and throwing up concerns about the environmental impact.

The ocean covers two-thirds of our planet, and offers a lot more potential in finding valuable raw materials than the land. Like any sort of mining, this will leave its mark on the planet and there’s now a race against time to address the environmental risks before the emerging industry takes off.

‘Plumes are the biggest problem,’ said Professor Philip Weaver, managing director at Seascape Consultants, a business that suggests ways to better manage the marine environment. ‘You can destroy the area you mine, that’s bad enough, but you can also destroy huge areas around the mine.’

Plumes are clouds of dust that hang suspended within the water. The particles themselves can cause harm and in some areas they may also contain toxic chemicals. They can spread over large areas of the seabed, which can have devastating effects on ecosystems.

‘The impacts of particle rain falling down on fauna can clog the filter feeding mechanism of some organisms which may then die,’ said Prof. Weaver. ‘This is a challenge for the (deep-sea) mining industry.’

Other environmental risks range from loss of habitat over large areas to noise and light pollution. In light of this, the EU-funded MIDAS research project brought together industry and NGOs to examine how best to manage the environmental impacts of deep-sea mining.

MIDAS, coordinated by Prof. Weaver, carried out plume modelling to evaluate the impacts of deep sea mining. Their research confirmed the importance of constraining plumes to prevent significant damage to ecosystems.

They also explored the three main targets of deep-sea mining. The first was manganese nodules, golf-ball to potato-sized rocks that contain high amounts of valuable metals like copper and nickel. The second was cobalt crusts that cover exposed rocky seabeds and also contain copper and nickel, as well as cobalt and platinum.

According to Prof. Weaver, the most sustainable option is the third; seafloor massive sulphides. These huge three-dimensional deposits of copper, gold and silver are formed from hot fluids coming from the earth’s crust, yet mining them affects a smaller area of the sea floor.

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