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93-641: The West Ice Shelf is a prominent ice shelf extending about 350 km (220 mi) in an east–west direction along the Leopold and Astrid Coast in East Antarctica between Barrier Bay and Posadowsky Bay , and up to 120 km northwards from the continental margin. The ice shelf was discovered and named by the First German Antarctica Expedition , 1901–1903, under Dr Erich von Drygalski . The toponym describes

186-415: A "hotspot of global warming". It broke over a period of three weeks or less, with a factor in this fast break-up being the powerful effects of water; ponds of meltwater formed on the surface during the near 24 hours of daylight in the summertime, flowed down into cracks and, acting like a multitude of wedges, levered the shelf apart. Other likely factors in the break-up were the higher ocean temperatures and

279-487: A 2:3 ratio during the 1947 expedition. A few years later, another adventurer, William Willis , claimed to have drunk two cups of seawater and one cup of fresh per day for 70 days without ill effect when he lost part of his water supply. During the 18th century, Richard Russell advocated the medical use of this practice in the UK, and René Quinton expanded the advocation of this practice to other countries, notably France, in

372-467: A balance of minerals within their diet, but it also impacts the amount of iron that is regenerated back into the ocean. The whale's excretions also contain the absorbed iron which would allow iron to be reinserted into the ocean’s ecosystem. Overall, one mineral deficiency such as iron in the Southern Ocean can spark a significant chain of disturbances within the marine ecosystems which demonstrates

465-478: A chemical/ tectonic system which removes as much salt as is deposited; for instance, sodium and chloride sinks include evaporite deposits, pore-water burial, and reactions with seafloor basalts . Climate change , rising levels of carbon dioxide in Earth's atmosphere , excess nutrients, and pollution in many forms are altering global oceanic geochemistry . Rates of change for some aspects greatly exceed those in

558-580: A day, mixed with fresh water in a 2:3 ratio, produces no ill effect. The French physician Alain Bombard survived an ocean crossing in a small Zodiak rubber boat using mainly raw fish meat, which contains about 40% water (like most living tissues), as well as small amounts of seawater and other provisions harvested from the ocean. His findings were challenged, but an alternative explanation could not be given. In his 1948 book The Kon-Tiki Expedition , Thor Heyerdahl reported drinking seawater mixed with fresh in

651-522: A huge ice island in 2017. From 31 January 2002 to March 2002 the Larsen B sector partially collapsed and parts broke up, 3,250 km (1,250 sq mi) of ice 220 m (720 ft) thick, an area comparable to the US state of Rhode Island . In 2015, a study concluded that the remaining Larsen B ice-shelf would disintegrate by 2020, based on observations of faster flow and rapid thinning of glaciers in

744-474: A hunt for undiscovered chemicals in organisms that have evolved in deep sea trenches, hoping to find "the next generation" of antibiotics, anticipating an "antibiotic apocalypse" with a dearth of new infection-fighting drugs. The EU-funded research will start in the Atacama Trench and then move on to search trenches off New Zealand and Antarctica. The ocean has a long history of human waste disposal on

837-615: A large crack in the Ward Hunt shelf had begun to form, and in 2003 it was announced that the ice sheet had split completely in two in 2002, releasing a huge pool of freshwater from the largest epishelf lake in the Northern Hemisphere, located in Disraeli Fjord. In April 2008, scientists discovered that the shelf fractured into dozens of deep, multi-faceted cracks. On August 13, 2005, The Ayles Ice Shelf , which

930-594: A litre of seawater may hold more than 20,000 species. Mitchell Sogin from the Marine Biological Laboratory feels that "the number of different kinds of bacteria in the oceans could eclipse five to 10 million." Bacteria are found at all depths in the water column , as well as in the sediments, some being aerobic, others anaerobic. Most are free-swimming, but some exist as symbionts within other organisms – examples of these being bioluminescent bacteria. Cyanobacteria played an important role in

1023-443: A marked effect on microbial life in the vicinity, as well as harbouring pathogens and toxins affecting all forms of marine life . The protist dinoflagellates may at certain times undergo population explosions called blooms or red tides , often after human-caused pollution. The process may produce metabolites known as biotoxins, which move along the ocean food chain, tainting higher-order animal consumers. Pandoravirus salinus ,

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1116-439: A mass of ice from a glacier , iceberg , ice front , ice shelf, or crevasse ). Snow accumulation on the upper surface and melting from the lower surface are also important to the mass balance of an ice shelf. Ice may also accrete onto the underside of the shelf. The effects of climate change are visible in the changes to the cryosphere , such as reduction in sea ice and ice sheets , and disruption of ice shelves. In

1209-413: A more sustainable water supply from seawater. Although desalination also comes with environmental concerns, such as costs and resources, researchers are working closely to determine more sustainable practices, such as creating more productive water plants that can deal with larger water supplies in areas where these plans weren't always available. Although seawater extractions can benefit society greatly, it

1302-542: A result of degradation of organic matter in these waters. It can be as high as 8.4 in surface waters in areas of high biological productivity . Measurement of pH is complicated by the chemical properties of seawater, and several distinct pH scales exist in chemical oceanography . There is no universally accepted reference pH-scale for seawater and the difference between measurements based on different reference scales may be up to 0.14 units. Seawater contains more dissolved ions than all types of freshwater. However,

1395-511: A salinity of 35 g/kg. The thermal conductivity decreases with increasing salinity and increases with increasing temperature. The water in the sea was thought to come from the Earth's volcanoes , starting 4 billion years ago, released by degassing from molten rock. More recent work suggests much of the Earth's water may come from comets . Scientific theories behind the origins of sea salt started with Sir Edmond Halley in 1715, who proposed that salt and other minerals were carried into

1488-558: A slow melt rate, in contrast to the undefended western portion. According to the American Geophysical Union in a 2021 study, the Thwaites Eastern Ice Shelf (TEIS) buttresses one-third of Thwaites glacier . Removal of the shelf has the potential to increase the contribution of Thwaites glacier to sea level rise by up to 25%. As of 2021 , the ice shelf appears to be losing its grip on

1581-489: A species of very large virus, with a genome much larger than that of any other virus species, was discovered in 2013. Like the other very large viruses Mimivirus and Megavirus , Pandoravirus infects amoebas, but its genome, containing 1.9 to 2.5 megabases of DNA, is twice as large as that of Megavirus , and it differs greatly from the other large viruses in appearance and in genome structure. In 2013 researchers from Aberdeen University announced that they were starting

1674-439: A stream under an Antarctic glacier : the measured temperature was −2.6 °C (27.3 °F). Seawater pH is typically limited to a range between 7.5 and 8.4. However, there is no universally accepted reference pH-scale for seawater and the difference between measurements based on different reference scales may be up to 0.14 units. Although the vast majority of seawater has a salinity of between 31 and 38 g/kg, that

1767-459: A submarine shoal that acts as a pinning point and the shear margin that separates the Thwaites Eastern Ice Shelf from the Thwaites glacier Tongue has extended, further weakening the ice shelf connection to the pinning point. A sequence of Sentinel-1 radar imagery shows that parallel wing and comb cracks have recently formed rifts at high angles to the main shear margin and are propagating into

1860-412: Is denser than both fresh water and pure water (density 1.0 kg/L at 4 °C (39 °F)) because the dissolved salts increase the mass by a larger proportion than the volume. The freezing point of seawater decreases as salt concentration increases. At typical salinity, it freezes at about −2 °C (28 °F). The coldest seawater still in the liquid state ever recorded was found in 2010, in

1953-417: Is water from a sea or ocean . On average, seawater in the world's oceans has a salinity of about 3.5% (35 g/L, 35 ppt, 600 mM). This means that every kilogram (roughly one liter by volume) of seawater has approximately 35 grams (1.2 oz) of dissolved salts (predominantly sodium ( Na ) and chloride ( Cl ) ions ). The average density at the surface is 1.025 kg/L. Seawater

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2046-434: Is 1088 kg/m . The pH value at the surface of oceans in pre-industrial time (before 1850) was around 8.2. Since then, it has been decreasing due to a human-caused process called ocean acidification that is related to carbon dioxide emissions : Between 1950 and 2020, the average pH of the ocean surface fell from approximately 8.15 to 8.05. The pH value of seawater is naturally as low as 7.8 in deep ocean waters as

2139-597: Is 3.1–3.8%, seawater is not uniformly saline throughout the world. Where mixing occurs with freshwater runoff from river mouths, near melting glaciers or vast amounts of precipitation (e.g. monsoon ), seawater can be substantially less saline. The most saline open sea is the Red Sea , where high rates of evaporation , low precipitation and low river run-off, and confined circulation result in unusually salty water. The salinity in isolated bodies of water can be considerably greater still – about ten times higher in

2232-557: Is about 1000 mOsm/L. Small amounts of other substances are found, including amino acids at concentrations of up to 2 micrograms of nitrogen atoms per liter, which are thought to have played a key role in the origin of life . Research in 1957 by the Scripps Institution of Oceanography sampled water in both pelagic and neritic locations in the Pacific Ocean. Direct microscopic counts and cultures were used,

2325-521: Is about 1028 kg/m and that of glacial ice from about 850 kg/m to well below 920 kg/m , the limit for very cold ice without bubbles. The height of the shelf above the sea can be even larger, if there is much less dense firn and snow above the glacier ice. A large portion of the Antarctic coastline has ice shelves attached. Their aggregate area is over 1,550,000 square kilometers (600,000 square miles). It has been found that of all

2418-507: Is above the kidney's maximum concentrating ability. Eventually the blood's sodium concentration rises to toxic levels, removing water from cells and interfering with nerve conduction, ultimately producing fatal seizure and cardiac arrhythmia . Survival manuals consistently advise against drinking seawater. A summary of 163 life raft voyages estimated the risk of death at 39% for those who drank seawater, compared to 3% for those who did not. The effect of seawater intake on rats confirmed

2511-448: Is an indicator that krill is in whale diets. Antarctic krill had an average iron level of 174.3mg/kg dry weight, but the iron in the krill varied from 12 to 174 mg/kg dry weight. The average iron concentration of the muscular tissue of blue whales and fin whales was 173 mg/kg dry weight, which demonstrates that the large marine mammals are important to marine ecosystems such as they are to the Southern Ocean. In fact, to have more whales in

2604-476: Is considered a superior taste. A restaurant run by Joaquín Baeza sources as much as 60,000 litres a month from supplier Mediterranea Animals such as fish, whales, sea turtles , and seabirds , such as penguins and albatrosses , have adapted to living in a high-saline habitat. For example, sea turtles and saltwater crocodiles remove excess salt from their bodies through their tear ducts . Minerals have been extracted from seawater since ancient times. Currently

2697-557: Is crucial to consider the environmental impact and to ensure that all extractions are conducted in a way that acknowledges and considers the associated risks to the sustainability of seawater ecosystems. ASTM International has an international standard for artificial seawater : ASTM D1141-98 (Original Standard ASTM D1141-52). It is used in many research testing labs as a reproducible solution for seawater such as tests on corrosion, oil contamination, and detergency evaluation. The minerals found in seawater can also play an important role in

2790-421: Is not easily accessible. Although it is not typical to use salt water as a means to grow plants as the salt gathers and ruins the surrounding soil, it has been proven to be successful in sand and gravel soils. Large-scale desalination of seawater is another factor that would contribute to the success of agriculture farming in dry, desert environments. One of the most successful plants in salt water agriculture

2883-627: Is one of the biggest ice shelves in West Antarctica , though it is highly unstable and disintegrating rapidly. Since the 1980s, the Thwaites Glacier , nicknamed the "Doomsday glacier", has had a net loss of over 600 billion tons of ice, though pinning of the Thwaites Ice Shelf has served to slow the process. The Thwaites Ice Shelf has acted like a dam for the eastern portion of glacier, bracing it and allowing for

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2976-399: Is the halophyte . The halophyte is a salt tolerant plant whose cells are resistant to the typically detrimental effects of salt in soil. The endodermis forces a higher level of salt filtration throughout the plant as it allows for the circulation of more water through the cells. The cultivation of halophytes irrigated with salt water were used to grow animal feed for livestock ; however,

3069-453: The Age of Sail . Larger sailing warships with large crews, such as Nelson 's HMS  Victory , were fitted with distilling apparatus in their galleys . The natural sea salt obtained by evaporating seawater can also be collected and sold as table salt , typically sold separately owing to its unique mineral make-up compared to rock salt or other sources. A number of regional cuisines across

3162-550: The Benguela Current upwelling zone, eventually falling to the seafloor. Bacteria-like Archaea surprised marine microbiologists by their survival and thriving in extreme environments, such as the hydrothermal vents on the ocean floor. Alkalotolerant marine bacteria such as Pseudomonas and Vibrio spp. survive in a pH range of 7.3 to 10.6, while some species will grow only at pH 10 to 10.6. Archaea also exist in pelagic waters and may constitute as much as half

3255-607: The Karpinsky Ice Cap to the south and the Rusanov Ice Cap to the north. In 2012 it ceased to exist. In the last several decades, glaciologists have observed consistent decreases in ice shelf extent through melt, calving , and complete disintegration of some shelves. Well studied examples include disruptions of the Thwaites Ice Shelf , Larsen Ice Shelf , Filchner–Ronne Ice Shelf (all three in

3348-661: The Markham Ice Shelf broke up in 2008. The remaining ice shelves have also lost a significant amount of their area over time, with the Milne Ice Shelf being the last to be affected, with it breaking off in August 2020. The Matusevich Ice Shelf was a 222 square kilometers (86 square miles) ice shelf located in Severnaya Zemlya being fed by some of the largest ice caps on October Revolution Island ,

3441-614: The Ross Ice Shelf and the Filchner-Ronne Ice Shelf in Antarctica. The movement of ice shelves is principally driven by gravity -induced pressure from the grounded ice. That flow continually moves ice from the grounding line to the seaward front of the shelf. Typically, a shelf front will extend forward for years or decades between major calving events (calving is the sudden release and breaking away of

3534-470: The Southern Ocean around the continent of Antarctica . The term captured ice shelf has been used for the ice over a subglacial lake , such as Lake Vostok . Ice shelves are thick plates of ice, formed continuously by glaciers, that float atop an ocean. The shelves act as "brakes" for the glaciers. These shelves serve another important purpose—"they moderate the amount of melting that occurs on

3627-454: The oil and gas released from the operation of merchant ships decreases the air quality and causes more pollution both in the seawater and surrounding areas. Another human use of seawater that has been considered is the use of seawater for agricultural purposes. In areas with higher regions of sand dunes , such as Israel , the use of seawater for irrigation of plants would eliminate substantial costs associated with fresh water when it

3720-484: The 1960s, but only a few grams of uranium were extracted in Japan in the late 1990s. The main issue is not one of technological feasibility but that current prices on the uranium market for uranium from other sources are about three to five times lower than the lowest price achieved by seawater extraction. Similar issues hamper the use of reprocessed uranium and are often brought forth against nuclear reprocessing and

3813-687: The 20th century. Currently, it is widely practiced in Nicaragua and other countries, supposedly taking advantage of the latest medical discoveries. Like any other type of raw or contaminated water , seawater can be evaporated or filtered to eliminate salt, germs, and other contaminants that would otherwise prevent it from being considered potable . Most oceangoing vessels desalinate potable water from seawater using processes such as vacuum distillation or multi-stage flash distillation in an evaporator , or, more recently, reverse osmosis . These energy-intensive processes were not usually available during

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3906-674: The Antarctic) and the disruption of the Ellesmere Ice Shelf in the Arctic. The effects of climate change are visible in the changes to the cryosphere , such as reduction in sea ice and ice sheets , and disruption of ice shelves. Thwaites Ice Shelf (), is an Antarctic ice shelf in the Amundsen Sea . It was named by ACAN after Fredrik T. Thwaites, a glacial geologist and geomorphologist . The Thwaites Ice Shelf

3999-554: The Ellesmere Ice Shelf had been in place for at least 3,000 years. During the twentieth century, the Ellesmere Ice Shelf broke up into six separate shelves. From west to east, these were the Serson Ice Shelf , Petersen Ice Shelf , Milne Ice Shelf , Ayles Ice Shelf , Ward Hunt Ice Shelf , and Markham Ice Shelf . The smaller pieces continued to disintegrate. In April 2000, satellite images revealed that

4092-585: The Milne Ice Shelf, also ultimately experienced a major breakup at the end of July 2020, losing over 40% of its area. The Ellesmere Ice Shelf was the largest ice shelf in the Arctic, encompassing about 9,100 square kilometres (3,500 square miles) of the north coast of Ellesmere Island , Nunavut , Canada. The ice shelf was first documented by the British Arctic Expedition of 1875–76, in which Lieutenant Pelham Aldrich 's party went from Cape Sheridan to Cape Alert . The continuous mass of

4185-583: The November 2006 sighting of several large icebergs from the coast of the South Island of New Zealand , the first time since 1931 that any icebergs had been observed from the New Zealand mainland. A large group of small icebergs (the largest some 1000 metres in length), were seen off the south-east coast of the island, with one of them drifting close enough to shore to be visible from the hills above

4278-432: The amount of iron that can be recycled and stored in seawater. A positive feedback loop is created, increasing the overall productivity of marine life in the Southern Ocean. Organisms of all sizes play a significant role in the balance of marine ecosystems with both the largest and smallest inhabitants contributing equally to recycling nutrients in seawater. Prioritizing the recovery of whale populations because they boost

4371-415: The animals that were fed these plants consumed more water than those that did not. Although agriculture from use of saltwater is still not recognized and used on a large scale, initial research has shown that there could be an opportunity to provide more crops in regions where agricultural farming is not usually feasible. Accidentally consuming small quantities of clean seawater is not harmful, especially if

4464-400: The area. Larsen B was stable for at least 10,000 years, essentially the entire Holocene period since the last glacial period. By contrast, Larsen A was absent for a significant part of that period, reforming about 4,000 years ago. Despite its great age, the Larsen B was clearly in trouble at the time of the collapse. With warm currents eating away the underside of the shelf, it had become

4557-537: The assumption that its vast size makes it capable of absorbing and diluting all noxious material. While this may be true on a small scale, the large amounts of sewage routinely dumped has damaged many coastal ecosystems, and rendered them life-threatening. Pathogenic viruses and bacteria occur in such waters, such as Escherichia coli , Vibrio cholerae the cause of cholera , hepatitis A , hepatitis E and polio , along with protozoans causing giardiasis and cryptosporidiosis . These pathogens are routinely present in

4650-404: The ballast water of large vessels, and are widely spread when the ballast is discharged. The speed of sound in seawater is about 1,500 m/s (whereas the speed of sound is usually around 330 m/s in air at roughly 101.3 kPa pressure, 1 atmosphere), and varies with water temperature, salinity, and pressure. The thermal conductivity of seawater is 0.6 W/mK at 25 °C and

4743-506: The case of the Dead Sea . Historically, several salinity scales were used to approximate the absolute salinity of seawater. A popular scale was the "Practical Salinity Scale" where salinity was measured in "practical salinity units (PSU)". The current standard for salinity is the "Reference Salinity" scale with the salinity expressed in units of "g/kg". The density of surface seawater ranges from about 1020 to 1029 kg/m , depending on

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4836-453: The central part of the ice shelf at rates as high as 2 km per year. Satellite data, ground-penetrating radar, and GPS measurements taken in 2021 indicate that collapse of the ice shelf may be initiated by intersection of rifts with hidden basal crevasse zones as soon as 2026. Two sections of Antarctica's Larsen Ice Shelf broke apart into hundreds of unusually small fragments (hundreds of meters wide or less) in 1995 and 2002, Larsen C calved

4929-714: The city of Dunedin . If these were indeed the remnants of this calving, then over the course of five and a half years they had travelled slowly north and also east around over half the globe, a journey of some 13,500 km. From January 12 and January 13, 2010, an area of sea ice larger than the state of Rhode Island , or one-seventh the size of Wales , broke away from the Ronne–Filchner Ice Shelf and shattered into many smaller pieces. The Moderate-Resolution Imaging Spectroradiometer (MODIS) on NASA's Aqua and Terra satellites captured this event in this series of photo-like images. In May 2021, Iceberg A-76 broke off

5022-463: The coast (usually of great horizontal extent with a very gently sloping surface), resulting from the flow of ice sheets , initially formed by the accumulation of snow, and often filling embayments in the coastline of an ice sheet." In contrast, sea ice is formed on water, is much thinner (typically less than 3 m (9.8 ft)), and forms throughout the Arctic Ocean . It is also found in

5115-424: The condition of the sea post-extraction, and constant monitoring. The use of technology, such as underwater drones , can facilitate sustainable extractions. The use of low-carbon infrastructure would also allow for more sustainable extraction processes while reducing the carbon footprint from mineral extractions. Another practice that is being considered closely is the process of desalination in order to achieve

5208-404: The contrary) is that the gut cannot absorb water at such concentrations, so that there is no benefit in drinking such water. The salinity of Baltic surface water, however, is never 2%. It is 0.9% or less, and thus never higher than that of bodily fluids. Drinking seawater temporarily increases blood's NaCl concentration. This signals the kidney to excrete sodium, but seawater's sodium concentration

5301-515: The decline of the ice of the peninsula. In October 1998, the iceberg A-38 broke off the Filchner–Ronne ice shelf. It had an extent of roughly 150 by 50 km and was thus larger than Delaware . It later broke up again into three parts. A similar-sized calving in May 2000 created an iceberg 167 by 32 km in extent, dubbed A-43 – the disintegration of this is thought to have been responsible for

5394-495: The direct counts in some cases showing up to 10 000 times that obtained from cultures. These differences were attributed to the occurrence of bacteria in aggregates, selective effects of the culture media, and the presence of inactive cells. A marked reduction in bacterial culture numbers was noted below the thermocline , but not by direct microscopic observation. Large numbers of spirilli -like forms were seen by microscope but not under cultivation. The disparity in numbers obtained by

5487-456: The direction in which the German expedition first viewed the ice shelf. Their limited westward view became a prolonged one; on February 21, 1902, the ship became stuck in the pack ice , remaining imprisoned there until February 8, 1903. A 416 ha (1,030 acres) site 68°36′29″S 77°53′37″E  /  68.60806°S 77.89361°E  / -68.60806; 77.89361 on sea ice near

5580-505: The evolution of ocean processes, enabling the development of stromatolites and oxygen in the atmosphere. Some bacteria interact with diatoms , and form a critical link in the cycling of silicon in the ocean. One anaerobic species, Thiomargarita namibiensis , plays an important part in the breakdown of hydrogen sulfide eruptions from diatomaceous sediments off the Namibian coast, and generated by high rates of phytoplankton growth in

5673-509: The floating ice is above the ocean surface, depending on how much pressurized air is contained in the bubbles within the glacial ice, stemming from compressed snow. The formula for the denominators above is 1 / [ ( ρ seawater − ρ glacial ice ) / ρ seawater ] {\textstyle 1/[(\rho _{\text{seawater}}-\rho _{\text{glacial ice}})/\rho _{\text{seawater}}]} , density of cold seawater

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5766-530: The four most concentrated metals – Na , Mg , Ca and K – are commercially extracted from seawater. During 2015 in the US 63% of magnesium production came from seawater and brines. Bromine is also produced from seawater in China and Japan. Lithium extraction from seawater was tried in the 1970s, but the tests were soon abandoned. The idea of extracting uranium from seawater has been considered at least from

5859-540: The glaciers' surfaces. Once their ice shelves are removed, the glaciers increase in speed due to meltwater percolation and/or a reduction of braking forces, and they may begin to dump more ice into the ocean than they gather as snow in their catchments. Glacier ice speed increases are already observed in Peninsula areas where ice shelves disintegrated in prior years." The density contrast between glacial ice and liquid water means that at least ⁠ 1 / 9 ⁠ of

5952-528: The historical and recent geological record. Major trends include an increasing acidity , reduced subsurface oxygen in both near-shore and pelagic waters, rising coastal nitrogen levels, and widespread increases in mercury and persistent organic pollutants. Most of these perturbations are tied either directly or indirectly to human fossil fuel combustion, fertilizer, and industrial activity. Concentrations are projected to grow in coming decades, with negative impacts on ocean biota and other marine resources. One of

6045-477: The ice shelf. The Ellesmere ice shelf was reduced by 90% in the twentieth century, leaving the separate Alfred Ernest , Ayles , Milne , Ward Hunt , and Markham ice shelves. A 1986 survey of Canadian ice shelves found that 48 km (3.3 cubic kilometres) of ice calved from the Milne and Ayles ice shelves between 1959 and 1974. The Ayles Ice Shelf calved entirely on August 13, 2005. The Ward Hunt Ice Shelf,

6138-422: The ice shelves on Earth, nearly all of them are in Antarctica. In steady state, about half of Antarctica's ice shelf mass is lost to basal melt and half is lost to calving , but the relative importance of each process varies significantly between ice shelves. In recent decades, Antarctica's ice shelves have been out of balance, as they have lost more mass to basal melt and calving than has been replenished by

6231-401: The important role that seawater plays in the food chain . Upon further analysis of the dynamic relationship between diatoms, krill, and baleen whales, fecal samples of baleen whales were examined in Antarctic seawater. The findings included that iron concentrations were 10 million times higher than those found in Antarctic seawater, and krill was found consistently throughout their feces which

6324-448: The influx of new ice and snow. The Ross Ice Shelf is the largest ice shelf of Antarctica (as of 2013 , an area of roughly 500,809 square kilometres (193,363 sq mi) and about 800 kilometres (500 mi) across: about the size of France). It is several hundred metres thick. The nearly vertical ice front to the open sea is more than 600 kilometres (370 mi) long, and between 15 and 50 metres (50 and 160 ft) high above

6417-557: The largest remaining section of thick (>10 meters (33 feet)) landfast sea ice along the northern coastline of Ellesmere Island, lost 600 square kilometers (230 square miles) of ice in a massive calving in 1961–1962. It further decreased by 27% in thickness (13 meters (43 feet)) between 1967 and 1999. In the summer of 2002, the Ward Ice Shelf experienced another major breakup, and other instances of note happened in 2008 and 2010 as well. The last remnant to remain mostly intact,

6510-479: The last several decades, glaciologists have observed consistent decreases in ice shelf extent through melt, calving , and complete disintegration of some shelves. Well studied examples include disruptions of the Thwaites Ice Shelf , Larsen Ice Shelf , Filchner–Ronne Ice Shelf (all three in the Antarctic) and the disruption of the Ellesmere Ice Shelf in the Arctic. An ice shelf is "a floating slab of ice originating from land of considerable thickness extending from

6603-453: The levels of sodium and chloride in the blood within a very narrow range around 9 g/L (0.9% by mass). In most open waters concentrations vary somewhat around typical values of about 3.5%, far higher than the body can tolerate and most beyond what the kidney can process. A point frequently overlooked in claims that the kidney can excrete NaCl in Baltic concentrations of 2% (in arguments to

6696-539: The main types of phytoplankton are diatoms which is the primary food source of Antarctic krill . As the cycle continues, various larger sea animals feed off of Antarctic krill, but since there is a shortage of iron from the initial phytoplankton/diatoms, then these larger species also lack iron. The larger sea animals include Baleen Whales such as the Blue Whale and Fin Whale . These whales not only rely on iron for

6789-431: The manufacturing of MOX fuel as economically unviable. In order for seawater mineral and element extractions to take place while taking close consideration of sustainable practices, it is necessary for monitored management systems to be put in place. This requires management of ocean areas and their conditions, environmental planning , structured guidelines to ensure that extractions are controlled, regular assessments of

6882-401: The most striking features of this is ocean acidification , resulting from increased CO 2 uptake of the oceans related to higher atmospheric concentration of CO 2 and higher temperatures, because it severely affects coral reefs , mollusks , echinoderms and crustaceans (see coral bleaching ). Seawater is a means of transportation throughout the world. Every day plenty of ships cross

6975-639: The negative effects of drinking seawater when dehydrated. The temptation to drink seawater was greatest for sailors who had expended their supply of fresh water and were unable to capture enough rainwater for drinking. This frustration was described famously by a line from Samuel Taylor Coleridge 's The Rime of the Ancient Mariner : Water, water, everywhere, And all the boards did shrink; Water, water, everywhere, Nor any drop to drink. Although humans cannot survive on seawater in place of normal drinking water, some people claim that up to two cups

7068-587: The north-western margin of the shelf has been designated an Important Bird Area (IBA) by BirdLife International because it supports an emperor penguin colony. Ice shelf Ice shelves are found in Antarctica and the Arctic ( Greenland , Northern Canada , and the Russian Arctic ), and can range in thickness from about 100–1,000 m (330–3,280 ft). The world's largest ice shelves are

7161-424: The northwest corner of the shelf. At 4320 km , it is larger than Majorca , several times larger than Iceberg A-74 which calved in the same year, or approximately 14% the size of Belgium . The ice of the Filchner–Ronne ice shelf can be as thick as 600 m; the water below is about 1400 m deep at the deepest point. The international Filchner–Ronne Ice Shelf Programme (FRISP) was initiated in 1973 to study

7254-399: The ocean and its ecosystem's food cycle. For example, the Southern Ocean contributes greatly to the environmental carbon cycle . Given that this body of water does not contain high levels of iron , the deficiency impacts the marine life living in its waters. As a result, this ocean is not able to produce as much phytoplankton which hinders the first source of the marine food chain. One of

7347-496: The ocean could heighten the amount of iron in seawater through their excretions which would promote a better ecosystem. Krill and baleen whales act as large iron reservoirs in seawater in the Southern Ocean. Krill can retain up to 24% of iron found on surface waters within its range. The process of krill feeding on diatoms releases iron into seawater, highlighting them as an important part of the ocean's iron cycle . The advantageous relationship between krill and baleen whales increases

7440-415: The ocean floor when the ocean formed. The presence of salt's other dominant ion, chloride, results from outgassing of chloride (as hydrochloric acid ) with other gases from Earth's interior via volcanos and hydrothermal vents . The sodium and chloride ions subsequently became the most abundant constituents of sea salt. Ocean salinity has been stable for billions of years, most likely as a consequence of

7533-459: The ocean to deliver goods to various locations around the world. Seawater is a tool for countries to efficiently participate in international commercial trade and transportation, but each ship exhausts emissions that can harm marine life, air quality of coastal areas. Seawater transportation is one of the fastest growing human generated greenhouse gas emissions. The emissions released from ships pose significant risks to human health in nearing areas as

7626-416: The ocean's biomass , clearly playing an important part in oceanic processes. In 2000 sediments from the ocean floor revealed a species of Archaea that breaks down methane , an important greenhouse gas and a major contributor to atmospheric warming. Some bacteria break down the rocks of the sea floor, influencing seawater chemistry. Oil spills, and runoff containing human sewage and chemical pollutants have

7719-876: The overall productivity in marine ecosystems as well as increasing iron levels in seawater would allow for a balanced and productive system for the ocean. However, a more in depth study is required to understand the benefits of whale feces as a fertilizer and to provide further insight in iron recycling in the Southern Ocean. Projects on the management of ecosystems and conservation are vital for advancing knowledge of marine ecology. Like any mineral extraction practices, there are environmental advantages and disadvantages. Cobalt and Lithium are two key metals that can be used for aiding with more environmentally friendly technologies above ground, such as powering batteries that energize electric vehicles or creating wind power . An environmentally friendly approach to mining that allows for more sustainability would be to extract these metals from

7812-689: The ratios of solutes differ dramatically. For instance, although seawater contains about 2.8 times more bicarbonate than river water, the percentage of bicarbonate in seawater as a ratio of all dissolved ions is far lower than in river water. Bicarbonate ions constitute 48% of river water solutes but only 0.14% for seawater. Differences like these are due to the varying residence times of seawater solutes; sodium and chloride have very long residence times, while calcium (vital for carbonate formation) tends to precipitate much more quickly. The most abundant dissolved ions in seawater are sodium, chloride, magnesium , sulfate and calcium. Its osmolarity

7905-508: The sea by rivers after rainfall washed it out of the ground. Upon reaching the ocean, these salts concentrated as more salt arrived over time (see Hydrologic cycle ). Halley noted that most lakes that do not have ocean outlets (such as the Dead Sea and the Caspian Sea , see endorheic basin ), have high salt content. Halley termed this process "continental weathering". Halley's theory was partly correct. In addition, sodium leached out of

7998-421: The seafloor. Lithium mining from the seafloor at mass quantities could provide a substantial amount of renewable metals to promote more environmentally friendly practices in society to reduce humans' carbon footprint . Lithium mining from the seafloor could be successful, but its success would be dependent on more productive recycling practices above ground. There are also risks that come with extracting from

8091-409: The seafloor. Many biodiverse species have long lifespans on the seafloor, which means that their reproduction takes more time. Similarly to fish harvesting from the seafloor, the extraction of minerals in large amounts, too quickly, without proper protocols, can result in a disruption of the underwater ecosystems. Contrarily, this would have the opposite effect and prevent mineral extractions from being

8184-411: The seawater is taken along with a larger quantity of fresh water. However, drinking seawater to maintain hydration is counterproductive; more water must be excreted to eliminate the salt (via urine ) than the amount of water obtained from the seawater itself. In normal circumstances, it would be considered ill-advised to consume large amounts of unfiltered seawater. The renal system actively regulates

8277-507: The temperature and salinity. At a temperature of 25 °C, the salinity of 35 g/kg and 1 atm pressure, the density of seawater is 1023.6 kg/m . Deep in the ocean, under high pressure, seawater can reach a density of 1050 kg/m or higher. The density of seawater also changes with salinity. Brines generated by seawater desalination plants can have salinities up to 120 g/kg. The density of typical seawater brine of 120 g/kg salinity at 25 °C and atmospheric pressure

8370-455: The two methods is well known in this and other fields. In the 1990s, improved techniques of detection and identification of microbes by probing just small snippets of DNA , enabled researchers taking part in the Census of Marine Life to identify thousands of previously unknown microbes usually present only in small numbers. This revealed a far greater diversity than previously suspected, so that

8463-554: The water surface. Ninety percent of the floating ice, however, is below the water surface. All Canadian ice shelves are attached to Ellesmere Island and lie north of 82°N. Ice shelves that are still in existence are the Alfred Ernest Ice Shelf , Ward Hunt Ice Shelf , Milne Ice Shelf and Smith Ice Shelf . The M'Clintock Ice Shelf broke up from 1963 to 1966; the Ayles Ice Shelf broke up in 2005; and

8556-470: The world traditionally incorporate seawater directly as an ingredient, cooking other ingredients in a diluted solution of filtered seawater as a substitute for conventional dry seasonings . Proponents include world-renowned chefs Ferran Adrià and Quique Dacosta , whose home country of Spain has six different companies sourcing filtered seawater for culinary use. The water is marketed as la sal perfecta , "the perfect salt", containing less sodium with what

8649-466: Was located approximately 800 km (500 mi) south of the North Pole , broke away from the coast forming the giant Ayles Ice Island 37 metres (121 ft) thick and measuring around 14 by 5 km (8.7 by 3.1 mi) in size with an area of approximately 66 km (25 sq mi) or 2.6 km (0.62 cu mi) in volume. Seawater Seawater , or sea water ,

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