Seabed mining

DEFINITION: Extraction of minerals from the ocean floor and beneath it

Seabed mining has the potential to yield an abundant supply of valuable minerals, but the processes involved in such mining also have the potential to destroy unique marine life-forms, change the composition of the ocean waters, and seriously disturb marine ecosystems.

Until the discovery of hydrothermal vents with rich deposits of minerals in the deep seabed in 1977, seabed mining operations were relatively simple, done close to seacoasts and with the permission of coastal states, which exercised their rights to explore and exploit the oceans within 200 nautical miles of their coasts—that is, within their exclusive economic zones. (A nation’s exclusive economic zone, or EEZ, is the area of the sea and the seabed to which that nation claims exclusive rights.) Because of technological limitations of the processes used for seabed mining, such mining was possible only up to depths of 70 meters (230 feet). The first seabed mining operations involved dragging buckets along the seafloor to collect mineral-rich sand and then hauling the buckets up to boats, where iron ore was separated out through the use of magnets and other minerals were separated out through repeated sieving of the slurry. The remaining after the minerals were extracted was returned to the sea. Improved technology eventually replaced the buckets with suction pumps.

During the 1960s, scientists found excessively warm deepwater temperatures in the Red Sea and a sediment sample that resembled hot tar. In 1966, the National Science Foundation funded a research voyage by the Woods Hole Oceanographic Institution to obtain sediment samples from the Red Sea, and the resulting samples were found to be filled with various metals, including iron, copper, and manganese. Given the fact that the Red Sea has a mid-ocean ridge where the seafloor is separating, the scientists concluded that the mineral-rich sediment and warm temperatures were most likely not a phenomenon unique to the Red Sea but might exist in other oceans where the seafloor was separating. As a result, research was carried out in the Atlantic, Pacific, and Indian oceans, as well as others, and researchers found sediment containing large amounts of minerals. Further research led to discovery of a link between volcanic action on the seafloor and the formation of mineral-rich sediment and the possible existence of hydrothermal vents.

In February 1977, scientists on the Galápagos Hydrothermal Expedition discovered the first hydrothermal vent. They also made an unexpected discovery: An abundance of unusual marine life-forms were living in the water gushing from the vent. More exploration led to the discovery of more hydrothermal vents wherever the seafloor was separating. The discovery of these mineral-rich deposits of sediment in the deep sea revolutionized the concept of seabed mining and simultaneously raised myriad complex issues. Questions such as the following arose: Who would have the legal right to exploit these deposits in the open ocean? What types of technologies would need to be developed? Could the deposits be mined commercially on a cost-effective basis? What impacts would mining have on the environment?

Environmental Concerns

Conventional coastal seabed mining at depths of 25–70 meters (82–230 feet) has always created environmental concerns, especially in regard to waste disposal in the ocean. Deep-seabed mining raises much greater and more complex problems of environmental damage. The marine life discovered at the hydrothermal vents is composed of species and populations about which scientists have little knowledge; therefore they are unable to assess the effects of disturbances to the on these life-forms. Most scientists agree that if the environments of these newly discovered species are disturbed or destroyed before the species can be studied adequately, a vast amount of knowledge about how the planet formed will be lost. The species living in or near the hydrothermal vents are existing in darkness and in an atmosphere of extremely high temperature permeated with toxic fluids—an environment totally opposite to that which is necessary to the life-forms with which scientists are familiar. Not all of the hydrothermal vents are active, and some proponents of seabed mining have suggested that only inactive vents be mined; however, inactive vents are also surrounded by many unusual life-forms, so any mining activity will inevitably have impacts on the biodiversity of the seabed.

Another major concern is the disposal of the waste from the mining, or tailings. Minerals compose a small percentage of the deposits, and when the minerals are brought up to the surface, as much nonmineral waste as possible is separated from the minerals to reduce the bulk. One way in which this is done is by grinding the rock, or nodules, into on the seabed floor. Depending on the method used, the are discarded into the ocean at various depths, introducing foreign matter into the environments of the marine life at these various levels.

The potential for seabed mining to pollute the ocean waters, both at lower depths and at the surface, remains a serious concern. The minerals are brought up in a wet sulfide slurry, which is transported on barges. If oxidized, the slurry can quickly become sulfuric acid, which is harmful to the environment. In addition, the chemicals, fuels, and other materials used in the mining process pose the threat of accidental spilling, which could cause further harm to the environment.

Mining Technology

Although some companies are attempting to develop more environmentally friendly equipment and methods for mining the deep seabed, the technologies in use thus far pose significant environmental threats to the life-forms at both active and inactive hydrothermal vents, to other marine life, and to the oceans. The primary technique used in deep-seabed mining is one of scraping, either with a tow sled or a self-powered unit. This process raises clouds of sediment and buries large numbers of life-forms around the hydrothermal vents. Because new populations quickly establish themselves at the vent sites, some mining interests have argued that disturbances on the seabed are not significant. The same species do not reappear at the sites, however; studies of the new populations have revealed that the replacement populations may be of hardier yet less desirable types.

Both mining interests and scientific research groups have conducted experiments aimed at the development of mining technologies that could minimize environmental risks. However, tests and experiments to determine the environmental safety of various mining technologies and the types of damage associated with seabed mining cannot accurately depict what will occur in actual mining operations, as commercial mining activities are of much longer duration than any cost-effective experiment can be, and the physical area of seabed actually mined is much larger than can be devoted to an experiment. Nevertheless, scientists and seabed mining companies have gained some insights from these studies.

Although some deep-seabed mining can actually be done in the EEZs of island nations where hydrothermal vents occur in back-arc basins, most of the world’s hydrothermal vents and seabed mineral deposits are located in open areas of the oceans that are not under the control of individual nations. Because of the possibility for conflict and environmental damage in the mining of the deep seabed, in 1994 the United Nations Convention on the Law of the Sea created the International Seabed Authority to set environmental standards and issue licenses and permits for mining in those areas of the world’s oceans not under jurisdiction of EEZs.

Deep-seabed mining interests have also made efforts to minimize damage to the oceans and marine biodiversity by mining the seabed in ways that avoid severely affecting marine ecosystems. As part of this effort, in 1987 the industry established the International Marine Minerals Society, which worked to develop its Code for Environmental Management of Marine Mining to provide guidance to mining companies. The code was adopted in 2001 and continues to undergo revisions, the most recent of which was in 2010; compliance with the code’s provisions is voluntary.

All of the parties involved in or concerned about deep-seabed mining—individual nations, international bodies, scientific research groups, and mining companies and engineers—are significantly aware of the potential for environmental damage to the oceans associated with the retrieval of seabed mineral deposits. For the most part, these parties have taken into account the marine environment and its biodiversity, as well as the benefits gained from exploitation of the seabeds’ mineral resources, in their decision making and actions.

Bibliography

"Code for Environmental Management." International Marine Minerals Society, 26 Jan. 2022, www.immsoc.org/environmental-management-code. Accessed 22 July 2024.

Cronan, David Spencer, ed. Handbook of Marine Mineral Deposits. Boca Raton, Fla.: CRC Press, 1999.

Friedham, Robert R. Negotiating the New Ocean Regime. Columbia: University of South Carolina Press, 1992.

Nelson, Jason C. “The Contemporary Seabed Mining Regime: A Critical Analysis of the Mining Regulations Promulgated by the International Seabed Authority.” Colorado Journal of International Environmental Law and Policy 16, no. 1 (2005): 27-76.

Sohn, Louis B., et al. The Law of the Sea in a Nutshell. 2d ed. St. Paul, Minn.: West, 2010.

Van Dover, Cindy Lee. The Ecology of Deep-Sea Hydrothermal Vents. Princeton, N.J.: Princeton University Press, 2000.