In the first of a two-part report, Kerry MacKay looks at the rise of deep-sea mining, and its implications for a little-understood habitat
ENVIRONMENT
Under pressure
In the first of a two-part report, Kerry MacKay looks at the rise of deep-sea mining, and its implications for a little-understood habitat
Deep-sea mining is a controversial topic. In this two-part piece, we will learn more about the importance of nodules and consider the impacts of deep-sea mining and what we can all do.
Many of us like to think of ourselves as explorers of the deep. While scuba diving anything over 20m is pretty deep, the ocean is so much deeper than most of us comprehend. We’ ve still only explored about 20 % of the deep sea.
The average depth of the ocean is 3,688 metres, the deepest point being Challenger Deep in the Mariana Trench, at 10,984m deep. Mount Everest is only 8,848m high.
Deep-sea exploration technology has rapidly progressed. There are now many deep-sea submersibles and unmanned drones roaming the depths. Even satellites are helping boost our understanding of our incredible oceans.
One discovery that has gained interest from industry is nodules. These are small metallic rocks found in vast areas of the deep sea. Their proper name is polymetallic nodules,
Deep sea footage of a carnivorous sponge growing in a field of nodules
‘ poly-metallic’ meaning‘ composed of many metals’. Manganese and iron are the most common, but they often also contain other trace metals, such as nickel, cobalt, and copper.
These lumps of metal are usually 2-8cm in size and can be all sorts of shapes and textures. They are very porous, full of little holes, a bit like a dish sponge. Most nodules studied so far are thought to be between 8 and 32 million years old. It can take a million years for a nodule to grow just 1mm.
Nodules require very specific conditions to form. They‘ precipitate’ out of the seawater. Precipitation is when something separates out of the liquid it was dissolved in. They form on the seabed or are partially buried in the mud.
Despite first discovering nodules in 1868, we still know very little about them. Nodules seem to be found about
“ Despite first discovering nodules in 1868, we still know very little about them”
3,000-6,000m deep on the abyssal plains of most oceans on earth. They can cover thousands of square miles of the sea floor. The highest known concentration( so far) is in the Clarion- Clipperton Zone in the Pacific Ocean.
The ocean floor is generally very soft mud, much like the fine mud at the bottom of a quarry or sea loch. Many small creatures living on the bottom are actually attached to a shell or stone in the mud. Similarly, deep-sea creatures attach themselves to the nodules, making them an important habitat for deep-sea life.
In the Clarion- Clipperton Zone, more than 600 different types of animals have been found living on the nodules. Two to three times more than the nearby seabed with no nodules. You can find amazing deep-sea glass sponges, corals, crabs, shrimps, brittle stars, bryozoans and fish. It’ s suggested that 90 % of species in these areas are as yet unknown to science.
There are certainly many more discoveries to be made about these nodules and the places they are found. Recent explorations have revealed fascinating chemical processes and could even be a previously unknown source of oxygen on Earth, now called‘ Dark Oxygen’. Nodules are being touted as an easy way to meet future mineral demands. You just gotta scoop‘ em up off the sea floor. But what consequences could this have, and would it be any less damaging than current mining methods? We’ ll find out in part two next month. �
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