UNCLOS – The United Nations Convention on the Law of the Sea

UNCLOS is a major international treaty that was adopted and signed in 1982. It provides rules, principles and guidelines for virtually every ocean use. UNCLOS was created after years of increased concern and debate on how to manage the resources in the ocean floor beyond national jurisdiction. UNCLOS addressed these concerns by dividing the ocean into different jurisdictional zones, three of which are relevant to mineral development: the EEZ (see definition of EEZ), the Continental Shelf, and the International Seabed Area (or simply, the Area) which is under ISA jurisdiction (see definition for ISA). The treaty remains the backbone of international law to this day.

Topographic features

Topography (in relation to the deep-sea) refers to the shape of the ocean basin. Along the seafloor, there are a variety of topographic features like rift valleys, abyssal plains and seamounts. Within the different features, different marine minerals are usually present. For example, polymetallic sulfides are found on rift valleys, manganese nodules are found on abyssal plains and cobalt crusts on seamounts (see the definitions polymetallic sulfides, manganese nodules and cobalt crusts).

Sediment plumes (near bottom and near surface plumes)

A significant environmental concern with deep-sea mining comes in the form of a ‘plume’ at the seafloor. A sediment plume, or simply plume, occurs with the combination of bottom sediments and turbidity in the water column. In the mining process, sediment plumes are created by the action of the mining device and during transport of mined materials. Plumes created by the mining device at the ocean floor are called near bottom plumes, and those created through transportation at the surface are called near surface plumes.With every ton of manganese nodule mined, 2.5-5.5 tonnes of sediment will be brought up into the water column. These suspended loads of sediment persist for long periods and travel laterally, potentially causing devastating effects to marine ecosystems. Near bottom plumes could bury and suffocate benthic flora and fauna (the organisms inhabiting the ocean floor – see definition), as well as clog their filter feeding mechanisms. Near surface plumes might cause even more damage, affecting extensive areas because they spread over greater distances with currents. These could affect the pelagic community (see definition of pelagic zone) by, for example, clogging the filter feeding mechanisms of zooplankton (see definition of zooplankton) and blocking sunlight for a range of photosynthetic organisms, preventing photosynthesis and decreasing biological activity long-term.

MPA – Marine Protected Areas

Marine protected areas, or MPAs, are areas off-limits to economic exploitation (mining included). They are protected to preserve portions of diverse habitats with high levels of biodiversity and ecosystem productivity. MPAs help to protect areas of the ocean where data is limited (seabeds, for example), to avoid exploitation causing unpredictable or irreversible damage.

Polymetallic nodules (or manganese nodules)

Of all the mineral resources considered as potential targets for deep-sea mining, polymetallic nodules (also commonly called manganese nodules) are probably the most likely commodity to be developed into a commercial operation. As well as containing commercially attractive (though variable) levels of metals such as nickel, copper and cobalt, their occurrence on the seafloor surface presents a relatively straightforward engineering challenge in terms of their extraction when compared to some other metal deposits in the deep-sea. Polymetallic nodules are rounded lumps of manganese and iron hydroxides that cover vast areas of the seafloor, but are most abundant on abyssal plains at water depths of 4000-6500 metres (see the definition of topographic features for abyssal plains).The nodules of greatest commercial interest occur in the Clarion-Clipperton Zone in the equatorial Pacific Ocean (CCZ) and in the Central Indian Ocean Basin (see definition for CCZ).” (MIDAS, n/d) As with all other benthic ecosystems (see definition for benthic flora and fauna and benthic layer), it is difficult to assess exactly to what extent mining these nodules will impact the local deep-sea ecosystems, because very few scientific investigations have taken place so far. Many endemic (native) species have already been discovered, who depend on the nodules to survive. It is also known that recovery and recolonization rates are extremely slow.

Lost City Hydrothermal Field (or Lost City)

The Lost City contains by far the largest and oldest deep-sea vent structures found anywhere on Earth. They were discovered in 2000 close to the Mid-Atlantic ridge spreading centre. Despite the Lost City’s scientific importance, the ISA (see definition) approved an exploration contract with the Polish government very close to the site.

Key deep-sea metals

Cobalt: Cobalt is used in batteries, magnets and pigments and colouring. There are estimated to be about 6.6 million tons in reserves around the world (land and sea), 52 % in Congo. Copper: Copper has many electronic applications, such as generators, transformers, PCs, TVs, mobile phones (65 % of copper is used for this) and automobile (7 %). There are estimated to be about 140 million tons in reserves around the world. Iron: Iron is primarily used for steel production (>90 % is used for this), also for automobiles, ships and trains. There are estimated to be about 230 billion tones in reserves around the world. Manganese: Manganese is used primarily in steel production (>85 % is used for this). There are estimated to be about 540 million tons in reserves around the world. Nickel: Nickel is primarily used for making steel (>46 % is used for this) and nonferrous allows and super alloys (>34 %). There are estimated to be about 71 million tons in reserves around the world.