Seabed

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Common stingray foraging for invertebrates in seafloor sediment Common stingray tenerife.jpg
Common stingray foraging for invertebrates in seafloor sediment

The seabed (also known as the seafloor, sea floor, ocean floor, and ocean bottom) is the bottom of the ocean. All floors of the ocean are known as 'seabeds'.

Contents

The structure of the seabed of the global ocean is governed by plate tectonics. Most of the ocean is very deep, where the seabed is known as the abyssal plain. Seafloor spreading creates mid-ocean ridges along the center line of major ocean basins, where the seabed is slightly shallower than the surrounding abyssal plain. From the abyssal plain, the seabed slopes upward toward the continents and becomes, in order from deep to shallow, the continental rise, slope, and shelf. The depth within the seabed itself, such as the depth down through a sediment core, is known as the "depth below seafloor". The ecological environment of the seabed and the deepest waters are collectively known, as a habitat for creatures, as the "benthos".

Most of the seabed throughout the world's oceans is covered in layers of marine sediments. Categorized by where the materials come from or composition, these sediments are classified as either: from land (terrigenous), from biological organisms (biogenous), from chemical reactions (hydrogenous), and from space (cosmogenous). Categorized by size, these sediments range from very small particles called clays and silts, known as mud, to larger particles from sand to boulders.

Features of the seabed are governed by the physics of sediment transport and by the biology of the creatures living in the seabed and in the ocean waters above. Physically, seabed sediments often come from the erosion of material on land and from other rarer sources, such as volcanic ash. Sea currents transport sediments, especially in shallow waters where tidal energy and wave energy cause resuspension of seabed sediments. Biologically, microorganisms living within the seabed sediments change seabed chemistry. Marine organisms create sediments, both within the seabed and in the water above. For example, phytoplankton with silicate or calcium carbonate shells grow in abundance in the upper ocean, and when they die, their shells sink to the seafloor to become seabed sediments.

Human impacts on the seabed are diverse. Examples of human effects on the seabed include exploration, plastic pollution, and exploitation by mining and dredging operations. To map the seabed, ships use acoustic technology to map water depths throughout the world. Submersible vehicles help researchers study unique seabed ecosystems such as hydrothermal vents. Plastic pollution is a global phenomenon, and because the ocean is the ultimate destination for global waterways, much of the world's plastic ends up in the ocean and some sinks to the seabed. Exploitation of the seabed involves extracting valuable minerals from sulfide deposits via deep sea mining, as well as dredging sand from shallow environments for construction and beach nourishment.

Structure

Bathymetry of the ocean floor showing the continental shelves and oceanic plateaus (red), the mid-ocean ridges (yellow-green) and the abyssal plains (blue to purple). Like land terrain, the ocean floor has mountains including volcanoes, ridges, valleys, and plains. Mid-ocean ridge system.gif
Bathymetry of the ocean floor showing the continental shelves and oceanic plateaus (red), the mid-ocean ridges (yellow-green) and the abyssal plains (blue to purple). Like land terrain, the ocean floor has mountains including volcanoes, ridges, valleys, and plains.
The major oceanic divisions Oceanic divisions.svg
The major oceanic divisions

Most of the oceans have a common structure, created by common physical phenomena, mainly from tectonic movement, and sediment from various sources. The structure of the oceans, starting with the continents, begins usually with a continental shelf, continues to the continental slope – which is a steep descent into the ocean, until reaching the abyssal plain – a topographic plain, the beginning of the seabed, and its main area. The border between the continental slope and the abyssal plain usually has a more gradual descent, and is called the continental rise, which is caused by sediment cascading down the continental slope.[ citation needed ]

The mid-ocean ridge, as its name implies, is a mountainous rise through the middle of all the oceans, between the continents. Typically a rift runs along the edge of this ridge. Along tectonic plate edges there are typically oceanic trenches – deep valleys, created by the mantle circulation movement from the mid-ocean mountain ridge to the oceanic trench. [1]

Hotspot volcanic island ridges are created by volcanic activity, erupting periodically, as the tectonic plates pass over a hotspot. In areas with volcanic activity and in the oceanic trenches there are hydrothermal vents – releasing high pressure and extremely hot water and chemicals into the typically freezing water around it.

Deep ocean water is divided into layers or zones, each with typical features of salinity, pressure, temperature and marine life, according to their depth. Lying along the top of the abyssal plain is the abyssal zone, whose lower boundary lies at about 6,000 m (20,000 ft). The hadal zone – which includes the oceanic trenches, lies between 6,000 and 11,000 metres (20,000–36,000 ft) and is the deepest oceanic zone. [2] [3]

Depth below seafloor

Depth below seafloor is a vertical coordinate used in geology, paleontology, oceanography, and petrology (see ocean drilling). The acronym "mbsf" (meaning "meters below the seafloor") is a common convention used for depths below the seafloor. [4] [5]

Sediments

Total sediment thickness of the world's oceans and continental margins in meters. Marine sediment thickness (cropped).jpg
Total sediment thickness of the world's oceans and continental margins in meters.

Sediments in the seabed vary in origin, from eroded land materials carried into the ocean by rivers or wind flow, waste and decompositions of sea creatures, and precipitation of chemicals within the sea water itself, including some from outer space. [6] There are four basic types of sediment of the sea floor:

  1. Terrigenous (also lithogenous) describes the sediment from continents eroded by rain, rivers, and glaciers, as well as sediment blown into the ocean by the wind, such as dust and volcanic ash.
  2. Biogenous material is the sediment made up of the hard parts of sea creatures, mainly phytoplankton, that accumulate on the bottom of the ocean.
  3. Hydrogenous sediment is material that precipitates in the ocean when oceanic conditions change, or material created in hydrothermal vent systems.
  4. Cosmogenous sediment comes from extraterrestrial sources. [7]

Terrigenous and biogenous

Satellite image of wind-blown mineral dust over the Atlantic. Dust may become terrigenous sediment on the seabed. Saharan dust - Jun 18, 2020.jpg
Satellite image of wind-blown mineral dust over the Atlantic. Dust may become terrigenous sediment on the seabed.
Phytoplankton grow shells which later sink to the seabed to become biogenous sediments. For example, diatoms make silicate shells, which become siliceous ooze. Diatom algae (Bacillariophyta).jpg
Phytoplankton grow shells which later sink to the seabed to become biogenous sediments. For example, diatoms make silicate shells, which become siliceous ooze.

Terrigenous sediment is the most abundant sediment found on the seafloor. Terrigenous sediments come from the continents. These materials are eroded from continents and transported by wind and water to the ocean. Fluvial sediments are transported from land by rivers and glaciers, such as clay, silt, mud, and glacial flour. Aeolian sediments are transported by wind, such as dust and volcanic ash. [8]

Biogenous sediment is the next most abundant material on the seafloor. Biogenous sediments are biologically produced by living creatures. Sediments made up of at least 30% biogenous material are called "oozes." There are two types of oozes: Calcareous oozes and Siliceous oozes. Plankton grow in ocean waters and create the materials that become oozes on the seabed. Calcareous oozes are predominantly composed of calcium shells found in phytoplankton such as coccolithophores and zooplankton like the foraminiferans. These calcareous oozes are never found deeper than about 4,000 to 5,000 meters because at further depths the calcium dissolves. [9] Similarly, Siliceous oozes are dominated by the siliceous shells of phytoplankton like diatoms and zooplankton such as radiolarians. Depending on the productivity of these planktonic organisms, the shell material that collects when these organisms die may build up at a rate anywhere from 1 mm to 1 cm every 1000 years. [9]

Hydrogenous and cosmogenous

Hydrothermal vent fluids cause chemical reactions that precipitate out minerals that form sediments on the surrounding seafloor. Minerals sediments.jpg
Hydrothermal vent fluids cause chemical reactions that precipitate out minerals that form sediments on the surrounding seafloor.

Hydrogenous sediments are uncommon. They only occur with changes in oceanic conditions such as temperature and pressure. Rarer still are cosmogenous sediments. Hydrogenous sediments are formed from dissolved chemicals that precipitate from the ocean water, or along the mid-ocean ridges, they can form by metallic elements binding onto rocks that have water of more than 300 °C circulating around them. When these elements mix with the cold sea water they precipitate from the cooling water. [9] Known as manganese nodules, they are composed of layers of different metals like manganese, iron, nickel, cobalt, and copper, and they are always found on the surface of the ocean floor. [9]

Cosmogenous sediments are the remains of space debris such as comets and asteroids, made up of silicates and various metals that have impacted the Earth. [10]

Size classification

Sediment types from the Southern Ocean showing many different grain sizes: A) gravel and sand, B) gravel, C) bioturbated mud and sand, and D) laminated clays and silts. Sediment-images hg.jpg
Sediment types from the Southern Ocean showing many different grain sizes: A) gravel and sand, B) gravel, C) bioturbated mud and sand, and D) laminated clays and silts.

Another way that sediments are described is through their descriptive classification. These sediments vary in size, anywhere from 1/4096 of a mm to greater than 256 mm. The different types are: boulder, cobble, pebble, granule, sand, silt, and clay, each type becoming finer in grain. The grain size indicates the type of sediment and the environment in which it was created. Larger grains sink faster and can only be pushed by rapid flowing water (high energy environment) whereas small grains sink very slowly and can be suspended by slight water movement, accumulating in conditions where water is not moving so quickly. [12] This means that larger grains of sediment may come together in higher energy conditions and smaller grains in lower energy conditions.

Benthos

Seaweed and two chitons in a tide pool Tidepools Small.jpg
Seaweed and two chitons in a tide pool

Benthos (from Ancient Greek βένθος (bénthos) 'the depths [of the sea]'), also known as benthon, is the community of organisms that live on, in, or near the bottom of a sea, river, lake, or stream, also known as the benthic zone. [13] This community lives in or near marine or freshwater sedimentary environments, from tidal pools along the foreshore, out to the continental shelf, and then down to the abyssal depths.

Many organisms adapted to deep-water pressure cannot survive in the upper parts of the water column. The pressure difference can be very significant (approximately one atmosphere for every 10 metres of water depth). [14]

Because light is absorbed before it can reach deep ocean water, the energy source for deep benthic ecosystems is often organic matter from higher up in the water column that drifts down to the depths. This dead and decaying matter sustains the benthic food chain; most organisms in the benthic zone are scavengers or detritivores.

The term benthos, coined by Haeckel in 1891, [15] comes from the Greek noun βένθος 'depth of the sea'. [13] [16] Benthos is used in freshwater biology to refer to organisms at the bottom of freshwater bodies of water, such as lakes, rivers, and streams. [17] There is also a redundant synonym, Benton. [18]

Topography

World map with ocean topography World map of bathymetric data - GEBCO 2014.jpg
World map with ocean topography

Seabed topography (ocean topography or marine topography) refers to the shape of the land (topography) when it interfaces with the ocean. These shapes are obvious along coastlines, but they occur also in significant ways underwater. The effectiveness of marine habitats is partially defined by these shapes, including the way they interact with and shape ocean currents, and the way sunlight diminishes when these landforms occupy increasing depths. Tidal networks depend on the balance between sedimentary processes and hydrodynamics however, anthropogenic influences can impact the natural system more than any physical driver. [19]

Marine topographies include coastal and oceanic landforms ranging from coastal estuaries and shorelines to continental shelves and coral reefs. Further out in the open ocean, they include underwater and deep sea features such as ocean rises and seamounts. The submerged surface has mountainous features, including a globe-spanning mid-ocean ridge system, as well as undersea volcanoes, [20] oceanic trenches, submarine canyons, oceanic plateaus and abyssal plains.

The mass of the oceans is approximately 1.35×1018  metric tons, or about 1/4400 of the total mass of the Earth. The oceans cover an area of 3.618×108 km2 with a mean depth of 3,682 m, resulting in an estimated volume of 1.332×109 km3. [21]

Features

Layers of the pelagic zone Pelagiczone.svg
Layers of the pelagic zone

Each region of the seabed has typical features such as common sediment composition, typical topography, salinity of water layers above it, marine life, magnetic direction of rocks, and sedimentation. Some features of the seabed include flat abyssal plains, mid-ocean ridges, deep trenches, and hydrothermal vents.

Seabed topography is flat where layers of sediments cover the tectonic features. For example, the abyssal plain regions of the ocean are relatively flat and covered in many layers of sediments. [22] Sediments in these flat areas come from various sources, including but not limited to: land erosion sediments from rivers, chemically precipitated sediments from hydrothermal vents, Microorganism activity, sea currents eroding the seabed and transporting sediments to the deeper ocean, and phytoplankton shell materials.

Where the seafloor is actively spreading and sedimentation is relatively light, such as in the northern and eastern Atlantic Ocean, the original tectonic activity can be clearly seen as straight line "cracks" or "vents" thousands of kilometers long. These underwater mountain ranges are known as mid-ocean ridges. [7]

Other seabed environments include hydrothermal vents, cold seeps, and shallow areas. Marine life is abundant in the deep sea around hydrothermal vents. [23] Large deep sea communities of marine life have been discovered around black and white smokers — vents emitting chemicals toxic to humans and most vertebrates. This marine life receives its energy both from the extreme temperature difference (typically a drop of 150 degrees) and from chemosynthesis by bacteria. Brine pools are another seabed feature, [24] usually connected to cold seeps. In shallow areas, the seabed can host sediments created by marine life such as corals, fish, algae, crabs, marine plants and other organisms.

Human impact

Exploration

A video describing the operation and use of an autonomous lander in deep sea research.

The seabed has been explored by submersibles such as Alvin and, to some extent, scuba divers with special equipment. Hydrothermal vents were discovered by an underwater camera platform by researchers in 1977. [23] In recent years satellite measurements of ocean surface topography show very clear maps of the seabed, [25] and these satellite-derived maps are used extensively in the study and exploration of the ocean floor.

Plastic pollution

In 2020 scientists created what may be the first scientific estimate of how much microplastic currently resides in Earth's seafloor, after investigating six areas of ~3 km depth ~300 km off the Australian coast. They found the highly variable microplastic counts to be proportionate to plastic on the surface and the angle of the seafloor slope. By averaging the microplastic mass per cm3, they estimated that Earth's seafloor contains ~14 million tons of microplastic – about double the amount they estimated based on data from earlier studies – despite calling both estimates "conservative" as coastal areas are known to contain much more microplastic pollution. These estimates are about one to two times the amount of plastic thought – per Jambeck et al., 2015 – to currently enter the oceans annually. [26] [27] [28]

Exploitation

Schematic of a polymetallic nodule mining operation. From top to bottom, the three zoom-in panels illustrate the surface operation vessel, the midwater sediment plume, and the nodule collector operating on the seabed. The midwater plume comprises two stages: (i) the dynamic plume, in which the sediment-laden discharge water rapidly descends and dilutes to a neutral buoyancy depth, and (ii) the subsequent ambient plume that is advected by the ocean current and subject to background turbulence and settling. (MIT/2021) Schematic-of-a-polymetallic-nodule-mining-operation-From-top-to-bottom-the-three (2).png
Schematic of a polymetallic nodule mining operation. From top to bottom, the three zoom-in panels illustrate the surface operation vessel, the midwater sediment plume, and the nodule collector operating on the seabed. The midwater plume comprises two stages: (i) the dynamic plume, in which the sediment-laden discharge water rapidly descends and dilutes to a neutral buoyancy depth, and (ii) the subsequent ambient plume that is advected by the ocean current and subject to background turbulence and settling. (MIT/2021)

Deep sea mining is the extraction of minerals from the ocean floor found at depths of 200 metres (660 ft) [29] [30] to 6,500 metres (21,300 ft). [31] [32] [33] As of 2021, the majority of marine mining efforts were limited to shallow coastal waters, where sand, tin and diamonds are more readily accessible. [34] It is a growing subfield of experimental seabed mining. Three types of deep sea mining have generated interest: polymetallic nodule mining, polymetallic sulfide mining, and cobalt-rich ferromanganese crusts. [35] The majority of proposed deep sea mining sites are near polymetallic nodules or active and extinct hydrothermal vents at 1,400 to 3,700 metres (4,600 to 12,100 ft) depth. [36] The vents create globular or "massive" sulfide deposits that contain valuable metals such as silver, gold, copper, manganese, cobalt, and zinc. [37] [38] The deposits are mined using hydraulic pumps or bucket systems that carry ore to the surface for processing.

Marine minerals include sea-dredged and seabed minerals. Sea-dredged minerals are normally extracted by dredging operations within coastal zones, at depths of about 200 m. Minerals normally extracted from these depths include sand, silt and mud for construction purposes, mineral rich sands such as ilmenite and diamonds. [39]

The environmental impact of deep sea mining is disputed. [40] [41] Environmental advocacy groups such as Greenpeace and the Deep Sea Mining Campaign [42] have argued against seabed mining because of the potential for damage to deep sea ecosystems and pollution by heavy metal-laden plumes. [37] Environmental activists and state leaders have called for moratoriums [43] [44] or permanent bans. [45] Anti-seabed mining campaigns have won the support of industry, including some increasingly reliant on the metals such mining can provide. Individual countries[ which? ] with significant deposits of seabed minerals within their large exclusive economic zones (EEZ's) are making their own decisions pertaining to deep sea mining, exploring how to minimize environmental damage, [46] or deciding not to proceed. [47] Some companies are attempting to build deep sea mining equipment that preserves marine habitats. [48]

As of 2022, no commercial deep sea mining was underway. However, the International Seabed Authority granted 19 exploration licenses for polymetallic nodules within the Clarion Clipperton Zone. [49] In 2022 the Cook Islands Seabed Minerals Authority (SBMA) granted 3 exploration licenses for polymetallic nodules within their EEZ. [50]

At some point, mining could proceed at a range of scales within the oceans. Related technologies could involve robotic mining machines, as well as surface ships, and onshore metal refineries. [51] [52]

Wind farms, solar energy, electric cars, and improved battery technologies use a high volume and wide range of metals including "green" or "critical" metals, many of which are in relatively short supply. Seabed mining could provide many of these metals. [51]

In art and culture

Some children's play songs include elements such as "There's a hole at the bottom of the sea", or "A sailor went to sea... but all that he could see was the bottom of the deep blue sea".

On and under the seabed are archaeological sites of historic interest, such as shipwrecks and sunken towns. This underwater cultural heritage is protected by the UNESCO Convention on the Protection of the Underwater Cultural Heritage. The convention aims at preventing looting and the destruction or loss of historic and cultural information by providing an international legal framework. [53]

See also

Related Research Articles

<span class="mw-page-title-main">Benthos</span> Community of organisms that live in the benthic zone

Benthos, also known as benthon, is the community of organisms that live on, in, or near the bottom of a sea, river, lake, or stream, also known as the benthic zone. This community lives in or near marine or freshwater sedimentary environments, from tidal pools along the foreshore, out to the continental shelf, and then down to the abyssal depths.

<span class="mw-page-title-main">Manganese nodule</span> Mineral concretion on the sea bottom made of concentric layers of iron/manganese hydroxides

Polymetallic nodules, also called manganese nodules, are mineral concretions on the sea bottom formed of concentric layers of iron and manganese hydroxides around a core. As nodules can be found in vast quantities, and contain valuable metals, deposits have been identified as a potential economic interest. Depending on their composition and autorial choice, they may also be called ferromanganese nodules. Ferromanganese nodules are mineral concretions composed of silicates and insoluble iron and manganese oxides that form on the ocean seafloor and terrestrial soils. The formation mechanism involves a series of redox oscillations driven by both abiotic and biotic processes. As a byproduct of pedogenesis, the specific composition of a ferromanganese nodule depends on the composition of the surrounding soil. The formation mechanisms and composition of the nodules allow for couplings with biogeochemical cycles beyond iron and manganese. The high relative abundance of nickel, copper, manganese, and other rare metals in nodules has increased interest in their use as a mining resource.

<span class="mw-page-title-main">Hydrothermal vent</span> Fissure in a planets surface from which heated water emits

Hydrothermal vents are fissures on the seabed from which geothermally heated water discharges. They are commonly found near volcanically active places, areas where tectonic plates are moving apart at mid-ocean ridges, ocean basins, and hotspots. Hydrothermal deposits are rocks and mineral ore deposits formed by the action of hydrothermal vents.

<span class="mw-page-title-main">Benthic zone</span> Ecological region at the lowest level of a body of water

The benthic zone is the ecological region at the lowest level of a body of water such as an ocean, lake, or stream, including the sediment surface and some sub-surface layers. The name comes from ancient Greek, βένθος (bénthos), meaning "the depths." Organisms living in this zone are called benthos and include microorganisms as well as larger invertebrates, such as crustaceans and polychaetes. Organisms here generally live in close relationship with the substrate and many are permanently attached to the bottom. The benthic boundary layer, which includes the bottom layer of water and the uppermost layer of sediment directly influenced by the overlying water, is an integral part of the benthic zone, as it greatly influences the biological activity that takes place there. Examples of contact soil layers include sand bottoms, rocky outcrops, coral, and bay mud.

<span class="mw-page-title-main">Bathymetry</span> Study of underwater depth of lake or ocean floors

Bathymetry is the study of underwater depth of ocean floors, lake floors, or river floors. In other words, bathymetry is the underwater equivalent to hypsometry or topography. The first recorded evidence of water depth measurements are from Ancient Egypt over 3000 years ago. Bathymetric charts, are typically produced to support safety of surface or sub-surface navigation, and usually show seafloor relief or terrain as contour lines and selected depths (soundings), and typically also provide surface navigational information. Bathymetric maps may also use a Digital Terrain Model and artificial illumination techniques to illustrate the depths being portrayed. The global bathymetry is sometimes combined with topography data to yield a global relief model. Paleobathymetry is the study of past underwater depths.

<span class="mw-page-title-main">Abyssal plain</span> Flat area on the deep ocean floor

An abyssal plain is an underwater plain on the deep ocean floor, usually found at depths between 3,000 and 6,000 metres. Lying generally between the foot of a continental rise and a mid-ocean ridge, abyssal plains cover more than 50% of the Earth's surface. They are among the flattest, smoothest, and least explored regions on Earth. Abyssal plains are key geologic elements of oceanic basins.

The abyssal zone or abyssopelagic zone is a layer of the pelagic zone of the ocean. The word abyss comes from the Greek word ἄβυσσος (ábussos), meaning "bottomless". At depths of 4,000–6,000 m (13,000–20,000 ft), this zone remains in perpetual darkness. It covers 83% of the total area of the ocean and 60% of Earth's surface. The abyssal zone has temperatures around 2–3 °C (36–37 °F) through the large majority of its mass. The water pressure can reach up to 76 MPa.

<span class="mw-page-title-main">Deep sea</span> Lowest layer in the ocean

The deep sea is broadly defined as the ocean depth where light begins to fade, at an approximate depth of 200 m (660 ft) or the point of transition from continental shelves to continental slopes. Conditions within the deep sea are a combination of low temperatures, darkness, and high pressure. The deep sea is considered the least explored Earth biome as the extreme conditions make the environment difficult to access and explore.

<span class="mw-page-title-main">Pelagic sediment</span> Fine-grained sediment that accumulates on the floor of the open ocean

Pelagic sediment or pelagite is a fine-grained sediment that accumulates as the result of the settling of particles to the floor of the open ocean, far from land. These particles consist primarily of either the microscopic, calcareous or siliceous shells of phytoplankton or zooplankton; clay-size siliciclastic sediment; or some mixture of these. Trace amounts of meteoric dust and variable amounts of volcanic ash also occur within pelagic sediments. Based upon the composition of the ooze, there are three main types of pelagic sediments: siliceous oozes, calcareous oozes, and red clays.

<span class="mw-page-title-main">Seafloor massive sulfide deposits</span> Mineral deposits from seafloor hydrothermal vents

Seafloor massive sulfide deposits or SMS deposits, are modern equivalents of ancient volcanogenic massive sulfide ore deposits or VMS deposits. The term has been coined by mineral explorers to differentiate the modern deposit from the ancient.

Subsea technology involves fully submerged ocean equipment, operations, or applications, especially when some distance offshore, in deep ocean waters, or on the seabed. The term subsea is frequently used in connection with oceanography, marine or ocean engineering, ocean exploration, remotely operated vehicle (ROVs) autonomous underwater vehicles (AUVs), submarine communications or power cables, seafloor mineral mining, oil and gas, and offshore wind power.

<span class="mw-page-title-main">Deep sea mining</span> Mineral extraction from the ocean floor

Deep sea mining is the extraction of minerals from the ocean floor found at depths of 200 metres (660 ft) to 6,500 metres (21,300 ft). As of 2021, the majority of marine mining efforts were limited to shallow coastal waters, where sand, tin and diamonds are more readily accessible. It is a growing subfield of experimental seabed mining. Three types of deep sea mining have generated interest: polymetallic nodule mining, polymetallic sulfide mining, and cobalt-rich ferromanganese crusts. The majority of proposed deep sea mining sites are near polymetallic nodules or active and extinct hydrothermal vents at 1,400 to 3,700 metres depth. The vents create globular or "massive" sulfide deposits that contain valuable metals such as silver, gold, copper, manganese, cobalt, and zinc. The deposits are mined using hydraulic pumps or bucket systems that carry ore to the surface for processing.

<span class="mw-page-title-main">Marine sediment</span>

Marine sediment, or ocean sediment, or seafloor sediment, are deposits of insoluble particles that have accumulated on the seafloor. These particles either have their origins in soil and rocks and have been transported from the land to the sea, mainly by rivers but also by dust carried by wind and by the flow of glaciers into the sea, or they are biogenic deposits from marine organisms or from chemical precipitation in seawater, as well as from underwater volcanoes and meteorite debris.

<span class="mw-page-title-main">Siliceous ooze</span> Biogenic pelagic sediment located on the deep ocean floor

Siliceous ooze is a type of biogenic pelagic sediment located on the deep ocean floor. Siliceous oozes are the least common of the deep sea sediments, and make up approximately 15% of the ocean floor. Oozes are defined as sediments which contain at least 30% skeletal remains of pelagic microorganisms. Siliceous oozes are largely composed of the silica based skeletons of microscopic marine organisms such as diatoms and radiolarians. Other components of siliceous oozes near continental margins may include terrestrially derived silica particles and sponge spicules. Siliceous oozes are composed of skeletons made from opal silica SiO2·nH2O, as opposed to calcareous oozes, which are made from skeletons of calcium carbonate (CaCO3·nH2O) organisms (i.e. coccolithophores). Silica (Si) is a bioessential element and is efficiently recycled in the marine environment through the silica cycle. Distance from land masses, water depth and ocean fertility are all factors that affect the opal silica content in seawater and the presence of siliceous oozes.

<span class="mw-page-title-main">Deep-sea community</span> Groups of organisms living deep below the sea surface, sharing a habitat

A deep-sea community is any community of organisms associated by a shared habitat in the deep sea. Deep sea communities remain largely unexplored, due to the technological and logistical challenges and expense involved in visiting this remote biome. Because of the unique challenges, it was long believed that little life existed in this hostile environment. Since the 19th century however, research has demonstrated that significant biodiversity exists in the deep sea.

<span class="mw-page-title-main">Marine habitat</span> Habitat that supports marine life

A marine habitat is a habitat that supports marine life. Marine life depends in some way on the saltwater that is in the sea. A habitat is an ecological or environmental area inhabited by one or more living species. The marine environment supports many kinds of these habitats.

<span class="mw-page-title-main">Clarion-Clipperton Zone</span> Fracture zone of the Pacific Ocean seabed

The Clarion-Clipperton Zone (CCZ) or Clarion-Clipperton Fracture Zone is an environmental management area of the Pacific Ocean, administered by the International Seabed Authority (ISA). It includes the Clarion Fracture Zone and the Clipperton Fracture Zone, geological submarine fracture zones. Clarion and Clipperton are two of the five major lineations of the northern Pacific floor, and were discovered by the Scripps Institution of Oceanography in 1954. The CCZ is regularly considered for deep-sea mining due to the abundant presence of manganese nodules.

Ocean Networks Canada is a world-leading research and ocean observing facility hosted and owned by the University of Victoria, and managed by the not-for profit ONC Society. ONC operates unparalleled observatories in the deep ocean and coastal waters of Canada’s three coasts–the Arctic, the Pacific and the Atlantic–gathering biological, chemical, geological and physical data to drive solutions for science, industry and society. ONC operates the NEPTUNE and VENUS cabled ocean observatories in the northeast Pacific Ocean and the Salish Sea. Additionally, Ocean Networks Canada operates smaller community-based observatories offshore from Cambridge Bay, Nunavut., Campbell River, Kitamaat Village and Digby Island. These observatories collect data on physical, chemical, biological, and geological aspects of the ocean over long time periods. As with other ocean observatories such as ESONET, Ocean Observatories Initiative, MACHO and DONET, scientific instruments connected to Ocean Networks Canada are operated remotely and provide continuous streams of freely available data to researchers and the public. Over 200 gigabytes of data are collected every day.

<span class="mw-page-title-main">Seabed mining</span> Mineral recovery from the bottom of the sea

Seabed mining, also known as Seafloor mining is the recovery of minerals from the seabed by techniques of underwater mining. The concept includes mining at shallow depths on the continental shelf and deep-sea mining at greater depths associated with tectonic activity, hydrothermal vents and the abyssal plains. The increased requirement for minerals and metals used in the technology sector has led to a renewed interest in the mining of seabed mineral resources, including massive polymetallic sulfide deposits around hydrothermal vents, cobalt-rich crusts on the sides of seamounts and fields of manganese nodules on the abyssal plains. While the seabed provides a high concentration of valuable minerals, there is an unknown risk of ecological damage on marine species because of a lack of data.

Biogenous ooze is marine sediment that accumulates on the seafloor and is a byproduct of the death and sink of the skeletal remains of marine organisms.

References

  1. Kump, Lee R.; Kasting, James F.; Crane, Robert G. (2010). "Chapter 7. Circulation of the Solid Earth". The Earth System (3rd ed.). New Jersey: Pearson Education, Inc. pp. 122–148. ISBN   978-0-321-59779-3.
  2. "Open Ocean – Oceans, Coasts, and Seashores". National Park Service. U.S. Department of the Interior. Retrieved 13 October 2021.
  3. NOAA. "Ocean floor features". National Oceanic and Atmospheric Administration. Retrieved 13 October 2021.
  4. Flood, Roger D.; Piper, D.J.W. (1997). "Preface: Depth Below Seafloor Conventions". In Flood; Piper; Klaus, A.; Peterson, L.C. (eds.). Proceedings of the Ocean Drilling Program, Scientific Results. Vol. 155. p. 3. doi:10.2973/odp.proc.sr.155.200.1997. we follow Ocean Drilling Program (ODP) meters below seafloor (mbsf) convention
  5. Parkes, R. John; Henrik Sass (2007). Sulphate-reducing bacteria environmental and engineered systems. Edited by Larry L. Barton University of New Mexico. Cambridge University Press. pp. 329–358. doi:10.1017/CBO9780511541490.012. ISBN   978-0-521-85485-6 . Retrieved 11 June 2010. metres below the seafloor (mbsf){{cite book}}: |work= ignored (help)
  6. Murray, Richard W. "Ocean-Floor Sediments," Water Encyclopedia
  7. 1 2 Chester, Roy; Jickells, Tim (2012). "Chapter 15. The components of marine sediments". Marine Geochemistry (3rd ed.). Blackwell Publishing Ltd. pp. 321–351. ISBN   978-1-4051-8734-3.
  8. Chester, Roy; Jickells, Tim (2012). "Chapter 13. Marine sediments". Marine Geochemistry (3rd ed.). Blackwell Publishing Ltd. pp. 273–289. ISBN   978-1-4051-8734-3.
  9. 1 2 3 4 "The Bottom of the Ocean," Marine Science
  10. "Types of Marine Sediments", Article Myriad
  11. Grobe, Hannes; Kiekmann, Bernhard; Hillenbrand, Claus-Dieter. "The memory of polar oceans" (PDF): 37–45.{{cite journal}}: Cite journal requires |journal= (help)
  12. Tripati, Aradhna, Lab 6-Marine Sediments, Marine Sediments Reading, E&SSCI15-1, UCLA, 2012
  13. 1 2 Benthos from the Census of Antarctic Marine Life website
  14. US Department of Commerce, National Oceanic and Atmospheric Administration. "How does pressure change with ocean depth?". oceanservice.NOAA.gov.
  15. Haeckel, E. 1891. Plankton-Studien. Jenaische Zeitschrift für Naturwissenschaft 25 / (Neue Folge) 18: 232-336. BHL.
  16. βένθος. Liddell, Henry George; Scott, Robert; A Greek–English Lexicon at the Perseus Project.
  17. "North American Benthological Society website". Archived from the original on 2008-07-05. Retrieved 2008-08-16.
  18. Nehring, S. & Albrecht, U. (1997). Benthos und das redundant Benton: Neologismen in der deutschsprachigen Limnologie. Lauterbornia 31: 17-30, .
  19. Giovanni Coco, Z. Zhou, B. van Maanen, M. Olabarrieta, R. Tinoco, I. Townend. Morphodynamics of tidal networks: Advances and challenges. Marine Geology Journal. 1 December 2013.
  20. Sandwell, D. T.; Smith, W. H. F. (2006-07-07). "Exploring the Ocean Basins with Satellite Altimeter Data". NOAA/NGDC. Retrieved 2007-04-21.
  21. Charette, Matthew A.; Smith, Walter H. F. (June 2010). "The Volume of Earth's Ocean". Oceanography. 23 (2): 112–114. doi: 10.5670/oceanog.2010.51 . hdl: 1912/3862 .
  22. Braathen, Alvar; Brekke, Harald (7 January 2020). Chapter 1 Characterizing the Seabed: a Geoscience Perspective. Brill Nijhoff. pp. 21–35. doi:10.1163/9789004391567_003. ISBN   9789004391567. S2CID   210979539 . Retrieved 13 October 2021.{{cite book}}: |website= ignored (help)
  23. 1 2 "The Discovery of Hydrothermal Vents". Woods Hole Oceanographic Institution. 11 June 2018. Retrieved 13 October 2021.
  24. Wefer, Gerold; Billet, David; Hebbeln, Dierk; Jorgensen, Bo Barker; Schlüter, Michael; Weering, Tjeerd C. E. Van (2013-11-11). Ocean Margin Systems. Springer Science & Business Media. ISBN   978-3-662-05127-6.
  25. "Ocean Surface Topography". Science Mission Directorate. 31 March 2010. Retrieved 13 October 2021.
  26. May, Tiffany (7 October 2020). "Hidden Beneath the Ocean's Surface, Nearly 16 Million Tons of Microplastic". The New York Times. Retrieved 30 November 2020.
  27. "14 million tonnes of microplastics on sea floor: Australian study". phys.org. Retrieved 9 November 2020.
  28. Barrett, Justine; Chase, Zanna; Zhang, Jing; Holl, Mark M. Banaszak; Willis, Kathryn; Williams, Alan; Hardesty, Britta D.; Wilcox, Chris (2020). "Microplastic Pollution in Deep-Sea Sediments From the Great Australian Bight". Frontiers in Marine Science. 7. doi: 10.3389/fmars.2020.576170 . ISSN   2296-7745. S2CID   222125532. CC-BY icon.svg Available under CC BY 4.0.
  29. "Seabed Mining". The Ocean Foundation. 2010-08-07. Archived from the original on 2021-02-28. Retrieved 2021-04-02.
  30. "SPC-EU Deep Sea Minerals Project - Publications and Reports". dsm.gsd.spc.int. Archived from the original on 2021-09-06. Retrieved 2021-09-06.
  31. SITNFlash (2019-09-26). "The Next Gold Rush: Mining in the deep sea". Science in the News. Archived from the original on 2022-10-04. Retrieved 2023-02-17.
  32. Poston, Jonathan. "Deeperminers". site name. Archived from the original on 2023-01-19. Retrieved 2023-02-17.
  33. Nascimento, Decio. "Council Post: Could Deep-Sea Mining Rescue The Future Of The Renewable Transition?". Forbes. Archived from the original on 2022-12-06. Retrieved 2023-02-17.
  34. "Seabed Mining". The Ocean Foundation. 2010-08-07. Archived from the original on 2021-09-08. Retrieved 2021-09-06.
  35. "Exploration Contracts | International Seabed Authority". www.isa.org.jm. Archived from the original on 2021-04-13. Retrieved 2021-04-02.
  36. Ahnert, A.; Borowski, C. (2000). "Environmental risk assessment of anthropogenic activity in the deep-sea". Journal of Aquatic Ecosystem Stress and Recovery. 7 (4): 299–315. doi:10.1023/A:1009963912171. S2CID   82100930.
  37. 1 2 Halfar, Jochen; Fujita, Rodney M. (18 May 2007). "Danger of Deep-Sea Mining". Science. 316 (5827): 987. doi:10.1126/science.1138289. S2CID   128645876.
  38. Glasby, G. P. (28 July 2000). "Lessons Learned from Deep-Sea Mining". Science. 289 (5479): 551–553. doi:10.1126/science.289.5479.551. PMID   17832066. S2CID   129268215.
  39. John J. Gurney, Alfred A. Levinson, and H. Stuart Smith (1991) Marine mining of diamonds off the West Coast of Southern Africa, Gems & Gemology, p. 206
  40. Kim, Rakhyun E. (August 2017). "Should deep seabed mining be allowed?". Marine Policy. 82: 134–137. doi:10.1016/j.marpol.2017.05.010.
  41. Costa, Corrado; Fanelli, Emanuela; Marini, Simone; Danovaro, Roberto; Aguzzi, Jacopo (2020). "Global Deep-Sea Biodiversity Research Trends Highlighted by Science Mapping Approach". Frontiers in Marine Science. 7: 384. doi: 10.3389/fmars.2020.00384 . hdl: 10261/216646 .
  42. Rosenbaum, Dr. Helen (November 2011). "Out of Our Depth: Mining the Ocean Floor in Papua New Guinea". Deep Sea Mining Campaign. MiningWatch Canada, CELCoR, Packard Foundation. Archived from the original on 13 December 2019. Retrieved 2 May 2020.
  43. "Collapse of PNG deep-sea mining venture sparks calls for moratorium". the Guardian. 2019-09-15. Archived from the original on 2021-04-11. Retrieved 2021-04-02.
  44. "David Attenborough calls for ban on 'devastating' deep sea mining". the Guardian. 2020-03-12. Archived from the original on 2021-09-06. Retrieved 2021-09-06.
  45. "Google, BMW, Volvo, and Samsung SDI sign up to WWF call for temporary ban on deep-sea mining". Reuters. 2021-03-31. Archived from the original on 2021-09-06. Retrieved 2021-09-06.
  46. "SPC-EU Deep Sea Minerals Project - Home". dsm.gsd.spc.int. Archived from the original on 2021-09-06. Retrieved 2021-09-06.
  47. "The Environmental Protection Authority (EPA) has refused an application by Chatham Rock Phosphate Limited (CRP)". Deepwater group. 2015. Archived from the original on 2016-01-24. Retrieved 6 September 2021.
  48. "Impossible Mining". Archived from the original on 2022-06-08. Retrieved 2022-06-13.
  49. "Exploration Contracts | International Seabed Authority". isa.org.jm. Archived from the original on 2021-02-05. Retrieved 2021-09-06.
  50. "Cook Islands Seabed Minerals Authority - Map". Archived from the original on 2022-06-30. Retrieved 2022-07-06.
  51. 1 2 SPC (2013). Deep Sea Minerals: Deep Sea Minerals and the Green Economy Archived 2021-11-04 at the Wayback Machine . Baker, E., and Beaudoin, Y. (Eds.) Vol. 2, Secretariat of the Pacific Community
  52. "Breaking Free From Mining" (PDF). Archived from the original (PDF) on 2021-12-23.
  53. Safeguarding the Underwater Cultural Heritage UNESCO. Retrieved 12 September 2012.

Further reading