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94-466: Brines are produced in multiple ways in nature. Modification of seawater via evaporation results in the concentration of salts in the residual fluid, a characteristic geologic deposit called an evaporite is formed as different dissolved ions reach the saturation states of minerals, typically gypsum and halite . Dissolution of such salt deposits into water can produce brines as well. As seawater freezes, dissolved ions tend to remain in solution resulting in

188-412: A platinum plate which was used as the anode, the cathode being a platinum wire partially submerged into mercury. Electrolysis then gave calcium–mercury and magnesium–mercury amalgams, and distilling off the mercury gave the metal. However, pure calcium cannot be prepared in bulk by this method and a workable commercial process for its production was not found until over a century later. At 3%, calcium

282-434: A "steady state" with respect to calcium input and output. This has important climatological implications, as the marine calcium cycle is closely tied to the carbon cycle . Many calcium compounds are used in food, as pharmaceuticals, and in medicine, among others. For example, calcium and phosphorus are supplemented in foods through the addition of calcium lactate , calcium diphosphate , and tricalcium phosphate . The last

376-562: A calcium–lead alloy, in making automotive batteries. Calcium is the most abundant metal and the fifth-most abundant element in the human body . As electrolytes , calcium ions (Ca ) play a vital role in the physiological and biochemical processes of organisms and cells : in signal transduction pathways where they act as a second messenger ; in neurotransmitter release from neurons ; in contraction of all muscle cell types; as cofactors in many enzymes ; and in fertilization . Calcium ions outside cells are important for maintaining

470-468: A concentrated solution of replacement ions, and rinsing the flushing solution from the resin. After treatment, ion-exchange resin beads saturated with calcium and magnesium ions from the treated water, are regenerated by soaking in brine containing 6–12% NaCl. The sodium ions from brine replace the calcium and magnesium ions on the beads. In lower temperatures, a brine solution can be used to de-ice or reduce freezing temperatures on roads. Quenching

564-421: A discharge is generated, commonly called brine. The characteristics of the discharge depend on different factors, such as the desalination technology used, salinity and quality of the water used, environmental and oceanographic characteristics, desalination process carried out, among others. The discharge of desalination plants by seawater reverse osmosis (SWRO), are mainly characterized by presenting

658-661: A few percent of evaporite minerals, the remainder being composed of the more typical detrital clastic rocks and carbonates . Examples of evaporite formations include occurrences of evaporite sulfur in Eastern Europe and West Asia. For a formation to be recognised as evaporitic it may simply require recognition of halite pseudomorphs , sequences composed of some proportion of evaporite minerals, and recognition of mud crack textures or other textures . Evaporites are important economically because of their mineralogy, their physical properties in-situ, and their behaviour within

752-618: A fluid termed a cryogenic brine. At the time of formation, these cryogenic brines are by definition cooler than the freezing temperature of seawater and can produce a feature called a brinicle where cool brines descend, freezing the surrounding seawater. The brine cropping out at the surface as saltwater springs are known as "licks" or "salines". The contents of dissolved solids in groundwater vary highly from one location to another on Earth, both in terms of specific constituents (e.g. halite , anhydrite , carbonates , gypsum , fluoride -salts, organic halides , and sulfate -salts) and regarding

846-642: A gas had not been recognised by the ancient Romans. In 1789, Antoine Lavoisier suspected that lime might be an oxide of a fundamental chemical element . In his table of the elements, Lavoisier listed five "salifiable earths" (i.e., ores that could be made to react with acids to produce salts ( salis = salt, in Latin): chaux (calcium oxide), magnésie (magnesia, magnesium oxide), baryte (barium sulfate), alumine (alumina, aluminium oxide), and silice (silica, silicon dioxide)). About these "elements", Lavoisier reasoned: We are probably only acquainted as yet with

940-412: A high pressure of oxygen, and there is some evidence for a yellow superoxide Ca(O 2 ) 2 . Calcium hydroxide, Ca(OH) 2 , is a strong base, though not as strong as the hydroxides of strontium, barium or the alkali metals. All four dihalides of calcium are known. Calcium carbonate (CaCO 3 ) and calcium sulfate (CaSO 4 ) are particularly abundant minerals. Like strontium and barium, as well as

1034-508: A part of the metallic substances existing in nature, as all those which have a stronger affinity to oxygen than carbon possesses, are incapable, hitherto, of being reduced to a metallic state, and consequently, being only presented to our observation under the form of oxyds, are confounded with earths. It is extremely probable that barytes, which we have just now arranged with earths, is in this situation; for in many experiments it exhibits properties nearly approaching to those of metallic bodies. It

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1128-437: A picture into past Earth climates. Some particular deposits even show important tectonic and climatic changes. These deposits also may contain important minerals that help in today's economy. Thick non-marine deposits that accumulate tend to form where evaporation rates will exceed the inflow rate, and where there is sufficient soluble supplies. The inflow also has to occur in a closed basin, or one with restricted outflow, so that

1222-418: A process known as pickling . Meat and fish are typically steeped in brine for shorter periods of time, as a form of marination , enhancing its tenderness and flavor , or to enhance shelf period. Elemental chlorine can be produced by electrolysis of brine ( NaCl solution). This process also produces sodium hydroxide (NaOH) and hydrogen gas (H 2 ). The reaction equations are as follows: Brine

1316-423: A rather high neutron flux to allow short-lived Ca to capture a neutron. Ca is produced by electron capture in the r-process in type Ia supernovae , where high neutron excess and low enough entropy ensures its survival. Ca and Ca are the first "classically stable" nuclides with a 6-neutron or 8-neutron excess respectively. Although extremely neutron-rich for such a light element, Ca is very stable because it

1410-401: A result, when Ca does decay, it does so by double beta decay to Ti instead, being the lightest nuclide known to undergo double beta decay. Ca can also theoretically undergo double beta decay to Ti, but this has never been observed. The most common isotope Ca is also doubly magic and could undergo double electron capture to Ar , but this has likewise never been observed. Calcium is

1504-413: A salinity concentration that can, in the worst case, double the salinity of the seawater used, and unlike of thermal desalination plants, have practically the same temperature and dissolved oxygen as the seawater used. The discharge could contain trace chemical products used during the industrial treatments applies,such as antiscalants , coagulants , flocculants which are discarded together with

1598-463: A series of mandatory requirements that are mainly related to the monitoring of discharge, using a series of measurements and characterizations based on physical-chemical and biological information. In addition, the PVAs could also include different requirements related to monitoring the effects of seawater intake and those that may potentially be related to effects on the terrestrial environment . Brine

1692-449: A significant environmental hazard, both due to corrosive and sediment-forming effects of salts and toxicity of other chemicals diluted in it. Unpolluted brine from desalination plants and cooling towers can be returned to the ocean. From the desalination process, reject brine is produced, which proposes potential damages to the marine life and habitats. To limit the environmental impact, it can be diluted with another stream of water, such as

1786-473: Is calcium carbonate , found in limestone and the fossilised remnants of early sea life; gypsum , anhydrite , fluorite , and apatite are also sources of calcium. The name derives from Latin calx " lime ", which was obtained from heating limestone. Some calcium compounds were known to the ancients, though their chemistry was unknown until the seventeenth century. Pure calcium was isolated in 1808 via electrolysis of its oxide by Humphry Davy , who named

1880-507: Is a chemical element ; it has symbol Ca and atomic number 20. As an alkaline earth metal , calcium is a reactive metal that forms a dark oxide-nitride layer when exposed to air. Its physical and chemical properties are most similar to its heavier homologues strontium and barium . It is the fifth most abundant element in Earth's crust, and the third most abundant metal, after iron and aluminium . The most common calcium compound on Earth

1974-472: Is a cosmogenic nuclide , continuously produced through neutron activation of natural Ca. Many other calcium radioisotopes are known, ranging from Ca to Ca. They are all much shorter-lived than Ca, the most stable being Ca (half-life 163 days) and Ca (half-life 4.54 days). Isotopes lighter than Ca usually undergo beta plus decay to isotopes of potassium, and those heavier than Ca usually undergo beta minus decay to isotopes of scandium , though near

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2068-438: Is a doubly magic nucleus , having 20 protons and 28 neutrons arranged in closed shells. Its beta decay to Sc is very hindered because of the gross mismatch of nuclear spin : Ca has zero nuclear spin, being even–even , while Sc has spin 6+, so the decay is forbidden by the conservation of angular momentum . While two excited states of Sc are available for decay as well, they are also forbidden due to their high spins. As

2162-497: Is a better conductor by mass than both due to its very low density. While calcium is infeasible as a conductor for most terrestrial applications as it reacts quickly with atmospheric oxygen, its use as such in space has been considered. The chemistry of calcium is that of a typical heavy alkaline earth metal. For example, calcium spontaneously reacts with water more quickly than magnesium and less quickly than strontium to produce calcium hydroxide and hydrogen gas. It also reacts with

2256-514: Is a byproduct of many industrial processes, such as desalination , power plant cooling towers , produced water from oil and natural gas extraction, acid mine or acid rock drainage , reverse osmosis reject, chlor-alkali wastewater treatment, pulp and paper mill effluent, and waste streams from food and beverage processing. Along with diluted salts, it can contain residues of pretreatment and cleaning chemicals, their reaction byproducts and heavy metals due to corrosion. Wastewater brine can pose

2350-491: Is a chart that shows minerals that form the marine evaporite rocks. They are usually the most common minerals that appear in this kind of deposit. Evaporite minerals start to precipitate when their concentration in water reaches such a level that they can no longer exist as solutes . The minerals precipitate out of solution in the reverse order of their solubilities, such that the order of precipitation from sea water is: The abundance of rocks formed by seawater precipitation

2444-425: Is a heat-treatment process when forging metals such as steel. A brine solution, along with oil and other substances, is commonly used to harden steel. When brine is used, there is an enhanced uniformity of the cooling process and heat transfer. The desalination process consists of the separation of salts from an aqueous solution to obtain fresh water from a source of seawater or brackish water ; and in turn,

2538-643: Is achieved by fractional crystallization . The resulting purified salt is called evaporated salt or vacuum salt . Evaporite An evaporite ( / ɪ ˈ v æ p ə ˌ r aɪ t / ) is a water- soluble sedimentary mineral deposit that results from concentration and crystallization by evaporation from an aqueous solution . There are two types of evaporite deposits: marine, which can also be described as ocean deposits, and non-marine, which are found in standing bodies of water such as lakes. Evaporites are considered sedimentary rocks and are formed by chemical sediments . Although all water bodies on

2632-424: Is also used as a polishing agent in toothpaste and in antacids . Calcium lactobionate is a white powder that is used as a suspending agent for pharmaceuticals. In baking, calcium phosphate is used as a leavening agent . Calcium sulfite is used as a bleach in papermaking and as a disinfectant, calcium silicate is used as a reinforcing agent in rubber, and calcium acetate is a component of liming rosin and

2726-421: Is also used to strengthen aluminium alloys used for bearings, for the control of graphitic carbon in cast iron , and to remove bismuth impurities from lead. Calcium metal is found in some drain cleaners, where it functions to generate heat and calcium hydroxide that saponifies the fats and liquefies the proteins (for example, those in hair) that block drains. Besides metallurgy, the reactivity of calcium

2820-452: Is even possible that all the substances we call earths may be only metallic oxyds, irreducible by any hitherto known process. Calcium, along with its congeners magnesium, strontium, and barium, was first isolated by Humphry Davy in 1808. Following the work of Jöns Jakob Berzelius and Magnus Martin af Pontin on electrolysis , Davy isolated calcium and magnesium by putting a mixture of the respective metal oxides with mercury(II) oxide on

2914-505: Is exploited to remove nitrogen from high-purity argon gas and as a getter for oxygen and nitrogen. It is also used as a reducing agent in the production of chromium , zirconium , thorium , vanadium and uranium . It can also be used to store hydrogen gas, as it reacts with hydrogen to form solid calcium hydride , from which the hydrogen can easily be re-extracted. Calcium isotope fractionation during mineral formation has led to several applications of calcium isotopes. In particular,

Brine - Misplaced Pages Continue

3008-513: Is fully ionized. Other cations found in various brines include K, Mg, Ca, and Sr. The latter three are problematic because they form scale and they react with soaps. Aside from chloride, brines sometimes contain Br and I and, most problematically, SO 4 . Purification steps often include the addition of calcium oxide to precipitate solid magnesium hydroxide together with gypsum (CaSO 4 ), which can be removed by filtration. Further purification

3102-466: Is in the same order as the precipitation given above. Thus, limestone (dolomite are more common than gypsum , which is more common than halite, which is more common than potassium and magnesium salts. Evaporites can also be easily recrystallized in laboratories in order to investigate the conditions and characteristics of their formation. Recent evidence from satellite observations and laboratory experiments suggest evaporites are likely present on

3196-465: Is less reactive than strontium or barium, the oxide–nitride coating that results in air is stable and lathe machining and other standard metallurgical techniques are suitable for calcium. In the United States and Canada, calcium is instead produced by reducing lime with aluminium at high temperatures. Calcium cycling provides a link between tectonics , climate , and the carbon cycle . In

3290-453: Is more complicated and involves the bicarbonate ion (HCO 3 ) that forms when CO 2 reacts with water at seawater pH : At seawater pH, most of the dissolved CO 2 is immediately converted back into HCO 3 . The reaction results in a net transport of one molecule of CO 2 from the ocean/atmosphere into the lithosphere . The result is that each Ca ion released by chemical weathering ultimately removes one CO 2 molecule from

3384-400: Is not involved in the purification process itself, but used for regeneration of ion-exchange resin on cyclical basis. The water being treated flows through the resin container until the resin is considered exhausted and water is purified to a desired level. Resin is then regenerated by sequentially backwashing the resin bed to remove accumulated solids, flushing removed ions from the resin with

3478-452: Is required, both for the construction and operational phases. During its development, the most important legal management tools are established within the local environmental regulation, to prevent and adopt mitigation measures that guarantee the sustainable development of desalination projects. This includes a series of administrative tools and periodic environmental monitoring, to adopt preventive, corrective and further monitoring measures of

3572-458: Is the fifth most abundant element in the Earth's crust , and the third most abundant metal behind aluminium and iron . It is also the fourth most abundant element in the lunar highlands . Sedimentary calcium carbonate deposits pervade the Earth's surface as fossilized remains of past marine life; they occur in two forms, the rhombohedral calcite (more common) and the orthorhombic aragonite (forming in more temperate seas). Minerals of

3666-425: Is the second-most common isotope. The other four natural isotopes, Ca, Ca, Ca, and Ca, are significantly rarer, each comprising less than 1% of all natural calcium. The four lighter isotopes are mainly products of the oxygen-burning and silicon-burning processes, leaving the two heavier ones to be produced via neutron capture processes. Ca is mostly produced in a "hot" s-process , as its formation requires

3760-454: Is used as a secondary fluid in large refrigeration installations for the transport of thermal energy . Most commonly used brines are based on inexpensive calcium chloride and sodium chloride . It is used because the addition of salt to water lowers the freezing temperature of the solution and the heat transport efficiency can be greatly enhanced for the comparatively low cost of the material. The lowest freezing point obtainable for NaCl brine

3854-503: Is used to make metallic soaps and synthetic resins. Calcium is on the World Health Organization's List of Essential Medicines . Foods rich in calcium include dairy products such as milk and yogurt , cheese , sardines , salmon , soy products, kale , and fortified breakfast cereals . Because of concerns for long-term adverse side effects, including calcification of arteries and kidney stones , both

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3948-431: Is very soluble in water, 85% of extracellular calcium is as dicalcium phosphate with a solubility of 2.00  mM , and the hydroxyapatite of bones in an organic matrix is tricalcium phosphate with a solubility of 1000 μM. Calcium is a common constituent of multivitamin dietary supplements , but the composition of calcium complexes in supplements may affect its bioavailability which varies by solubility of

4042-454: Is −21.1 °C (−6.0 °F) at the concentration of 23.3% NaCl by weight. This is called the eutectic point. Because of their corrosive properties salt-based brines have been replaced by organic liquids such as ethylene glycol . Sodium chloride brine spray is used on some fishing vessels to freeze fish. The brine temperature is generally −5 °F (−21 °C). Air blast freezing temperatures are −31 °F (−35 °C) or lower. Given

4136-722: The Great Salt Lake in Utah and the Dead Sea , which lies between Jordan and Israel. Evaporite depositional environments that meet the above conditions include: The most significant known evaporite depositions happened during the Messinian salinity crisis in the basin of the Mediterranean . Evaporite formations need not be composed entirely of halite salt. In fact, most evaporite formations do not contain more than

4230-487: The United States (about 2000 to 4000 tonnes per year). Canada and France are also among the minor producers. In 2005, about 24000 tonnes of calcium were produced; about half of the world's extracted calcium is used by the United States, with about 80% of the output used each year. In Russia and China, Davy's method of electrolysis is still used, but is instead applied to molten calcium chloride . Since calcium

4324-418: The carboxyl groups of glutamic acid or aspartic acid residues; through interacting with phosphorylated serine , tyrosine , or threonine residues; or by being chelated by γ-carboxylated amino acid residues. Trypsin , a digestive enzyme, uses the first method; osteocalcin , a bone matrix protein, uses the third. Some other bone matrix proteins such as osteopontin and bone sialoprotein use both

4418-509: The contraction of muscles , nerve conduction, and the clotting of blood. As a result, intra- and extracellular calcium levels are tightly regulated by the body. Calcium can play this role because the Ca ion forms stable coordination complexes with many organic compounds, especially proteins ; it also forms compounds with a wide range of solubilities, enabling the formation of the skeleton . Calcium ions may be complexed by proteins through binding

4512-496: The nuclear drip lines , proton emission and neutron emission begin to be significant decay modes as well. Like other elements, a variety of processes alter the relative abundance of calcium isotopes. The best studied of these processes is the mass-dependent fractionation of calcium isotopes that accompanies the precipitation of calcium minerals such as calcite , aragonite and apatite from solution. Lighter isotopes are preferentially incorporated into these minerals, leaving

4606-455: The oxygen and nitrogen in air to form a mixture of calcium oxide and calcium nitride . When finely divided, it spontaneously burns in air to produce the nitride. Bulk calcium is less reactive: it quickly forms a hydration coating in moist air, but below 30% relative humidity it may be stored indefinitely at room temperature. Besides the simple oxide CaO, calcium peroxide , CaO 2 , can be made by direct oxidation of calcium metal under

4700-413: The potential difference across excitable cell membranes , protein synthesis, and bone formation. Calcium is a very ductile silvery metal (sometimes described as pale yellow) whose properties are very similar to the heavier elements in its group, strontium , barium , and radium . A calcium atom has twenty electrons, with electron configuration [Ar]4s . Like the other elements placed in group 2 of

4794-424: The 1997 observation by Skulan and DePaolo that calcium minerals are isotopically lighter than the solutions from which the minerals precipitate is the basis of analogous applications in medicine and in paleoceanography. In animals with skeletons mineralized with calcium, the calcium isotopic composition of soft tissues reflects the relative rate of formation and dissolution of skeletal mineral. In humans, changes in

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4888-604: The U.S. Institute of Medicine (IOM) and the European Food Safety Authority (EFSA) set Tolerable Upper Intake Levels (ULs) for combined dietary and supplemental calcium. From the IOM, people of ages 9–18 years are not to exceed 3 g/day combined intake; for ages 19–50, not to exceed 2.5 g/day; for ages 51 and older, not to exceed 2 g/day. EFSA set the UL for all adults at 2.5 g/day, but decided

4982-567: The absence of steric hindrance , smaller group 2 cations tend to form stronger complexes, but when large polydentate macrocycles are involved the trend is reversed. Though calcium is in the same group as magnesium and organomagnesium compounds are very widely used throughout chemistry, organocalcium compounds are not similarly widespread because they are more difficult to make and more reactive, though they have recently been investigated as possible catalysts . Organocalcium compounds tend to be more similar to organoytterbium compounds due to

5076-488: The alkali metals and the divalent lanthanides europium and ytterbium , calcium metal dissolves directly in liquid ammonia to give a dark blue solution. Due to the large size of the calcium ion (Ca ), high coordination numbers are common, up to 24 in some intermetallic compounds such as CaZn 13 . Calcium is readily complexed by oxygen chelates such as EDTA and polyphosphates , which are useful in analytic chemistry and removing calcium ions from hard water . In

5170-519: The calcium isotopic composition of urine have been shown to be related to changes in bone mineral balance. When the rate of bone formation exceeds the rate of bone resorption, the Ca/ Ca ratio in soft tissue rises and vice versa. Because of this relationship, calcium isotopic measurements of urine or blood may be useful in the early detection of metabolic bone diseases like osteoporosis . A similar system exists in seawater, where Ca/ Ca tends to rise when

5264-480: The concentration level. Using one of several classification of groundwater based on total dissolved solids (TDS), brine is water containing more than 100,000 mg/L TDS. Brine is commonly produced during well completion operations, particularly after the hydraulic fracturing of a well. Brine is a common agent in food processing and cooking. Brining is used to preserve or season the food. Brining can be applied to vegetables , cheeses , fruit and some fish in

5358-492: The construction of desalination plants with more corrosion-resistant coatings . Therefore, the concentration values of heavy metals in the discharge of SWRO plants are much lower than the acute toxicity levels to generate environmental impacts on marine ecosystems. The discharge is generally dumped back into the sea, through an underwater outfall or coastal release, due to its lower energy and economic cost compared to other discharge methods. Due to its increase in salinity,

5452-433: The discharge has a greater density compared to the surrounding seawater. Therefore, when the discharge reaches the sea, it can form a saline plume that can tends to follow the bathymetric line of the bottom until it is completely diluted. The distribution of the salt plume may depend on different factors, such as the production capacity of the plant, the discharge method, the oceanographic and environmental conditions of

5546-545: The discharge point, among others. Brine discharge might lead to an increase in salinity above certain threshold levels that has the potential to affect benthic communities , especially those more sensitive to osmotic pressure, finally having an effect on their abundance and diversity. However, if appropriate mitigation measures are applied, the potential environmental impacts of discharges from SWRO plants can be correctly minimized. Some examples can be found in countries such as Spain , Israel , Chile or Australia , in which

5640-491: The discharge, and which could affect the physical-chemical quality of the effluent . However, these are practically consumed during the process and the concentrations in the discharge are very low, which are practically diluted during the discharge, without affecting marine ecosystems . The materials used in SWRO plants are dominated by non-metallic components and stainless steels , since lower operating temperatures allow

5734-434: The divalent salts and calcium metal, because the enthalpy of formation of MX 2 is much higher than those of the hypothetical MX. This occurs because of the much greater lattice energy afforded by the more highly charged Ca cation compared to the hypothetical Ca cation. Calcium, strontium, barium, and radium are always considered to be alkaline earth metals ; the lighter beryllium and magnesium , also in group 2 of

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5828-439: The element. Calcium compounds are widely used in many industries: in foods and pharmaceuticals for calcium supplementation , in the paper industry as bleaches, as components in cement and electrical insulators, and in the manufacture of soaps. On the other hand, the metal in pure form has few applications due to its high reactivity; still, in small quantities it is often used as an alloying component in steelmaking, and sometimes, as

5922-399: The first and the second. Direct activation of enzymes by binding calcium is common; some other enzymes are activated by noncovalent association with direct calcium-binding enzymes. Calcium also binds to the phospholipid layer of the cell membrane , anchoring proteins associated with the cell surface. As an example of the wide range of solubility of calcium compounds, monocalcium phosphate

6016-747: The first type include limestone , dolomite , marble , chalk , and iceland spar ; aragonite beds make up the Bahamas , the Florida Keys , and the Red Sea basins. Corals , sea shells , and pearls are mostly made up of calcium carbonate. Among the other important minerals of calcium are gypsum (CaSO 4 ·2H 2 O), anhydrite (CaSO 4 ), fluorite (CaF 2 ), and apatite ([Ca 5 (PO 4 ) 3 X], X = OH, Cl, or F).gre The major producers of calcium are China (about 10000 to 12000 tonnes per year), Russia (about 6000 to 8000 tonnes per year), and

6110-415: The formation of bone by allowing and enhancing the deposition of calcium ions there, allowing rapid bone turnover without affecting bone mass or mineral content. When plasma calcium levels fall, cell surface receptors are activated and the secretion of parathyroid hormone occurs; it then proceeds to stimulate the entry of calcium into the plasma pool by taking it from targeted kidney, gut, and bone cells, with

6204-441: The higher temperature of brine, the system efficiency over air blast freezing can be higher. High-value fish usually are frozen at much lower temperatures, below the practical temperature limit for brine. Brine is an auxiliary agent in water softening and water purification systems involving ion exchange technology. The most common example are household dishwashers , utilizing sodium chloride in form of dishwasher salt . Brine

6298-417: The information for children and adolescents was not sufficient to determine ULs. Calcium is an essential element needed in large quantities. The Ca ion acts as an electrolyte and is vital to the health of the muscular, circulatory, and digestive systems; is indispensable to the building of bone in the form of hydroxyapatite ; and supports synthesis and function of blood cells. For example, it regulates

6392-461: The marine environments. Common minerals that are found in these deposits include blödite , borax , epsomite , gaylussite , glauberite , mirabilite , thenardite and trona . Non-marine deposits may also contain halite, gypsum, and anhydrite, and may in some cases even be dominated by these minerals, although they did not come from ocean deposits. This, however, does not make non-marine deposits any less important; these deposits often help to paint

6486-598: The mitigation measures adopted reduce the area affected by the discharge, guaranteeing a sustainable development of the desalination process without significant impacts on marine ecosystems. When noticeable effects have been detected on the environment surrounding discharge areas, it generally corresponds to old desalination plants in which the correct mitigation measures were not implemented. Some examples can be found in Spain, Australia or Chile, where it has been shown that saline plumes do not exceed values of 5% with respect to

6580-501: The most common isotope of calcium in nature is Ca, which makes up 96.941% of all natural calcium. It is produced in the silicon-burning process from fusion of alpha particles and is the heaviest stable nuclide with equal proton and neutron numbers; its occurrence is also supplemented slowly by the decay of primordial K . Adding another alpha particle leads to unstable Ti, which decays via two successive electron captures to stable Ca; this makes up 2.806% of all natural calcium and

6674-409: The natural salinity of the sea in a radius less than 100 m from the point of discharge when proper measures are adopted. The mitigation measures that are typically employed to prevent negatively impact sensitive marine environment are listed below: Currently, in many countries, such as Spain , Israel , Chile and Australia , the development of a rigorous environmental impact assessment process

6768-434: The neighbouring group 2 metals. It crystallises in the face-centered cubic arrangement like strontium and barium; above 443 °C (716 K), it changes to a body-centered cubic . Its density of 1.526 g/cm (at 20 °C) is the lowest in its group. Calcium is harder than lead but can be cut with a knife with effort. While calcium is a poorer conductor of electricity than copper or aluminium by volume, it

6862-525: The only element with two primordial doubly magic isotopes. The experimental lower limits for the half-lives of Ca and Ca are 5.9 × 10 years and 2.8 × 10 years respectively. Apart from the practically stable Ca, the longest lived radioisotope of calcium is Ca. It decays by electron capture to stable K with a half-life of about 10 years. Its existence in the early Solar System as an extinct radionuclide has been inferred from excesses of K: traces of Ca also still exist today, as it

6956-591: The original water depth remains. At this point, minor carbonates begin to form. The next phase in the sequence comes when the experiment is left with about 20% of its original level. At this point, the mineral gypsum begins to form, which is then followed by halite at 10%, excluding carbonate minerals that tend not to be evaporites. The most common marine evaporites are calcite , gypsum and anhydrite , halite, sylvite , carnallite , langbeinite , polyhalite , and kainite . Kieserite (MgSO 4 ) may also be included, which often will make up less than four percent of

7050-419: The other hand increases the compound's solubility, volatility, and kinetic stability. Natural calcium is a mixture of five stable isotopes ( Ca, Ca, Ca, Ca, and Ca) and one isotope with a half-life so long that it is for all practical purposes stable ( Ca , with a half-life of about 4.3 × 10  years). Calcium is the first (lightest) element to have six naturally occurring isotopes. By far

7144-1067: The outfall of a wastewater treatment or power plant. Since brine is heavier than seawater and would accumulate on the ocean bottom, it requires methods to ensure proper diffusion, such as installing underwater diffusers in the sewerage . Other methods include drying in evaporation ponds , injecting to deep wells, and storing and reusing the brine for irrigation, de-icing or dust control purposes. Technologies for treatment of polluted brine include: membrane filtration processes, such as reverse osmosis and forward osmosis ; ion exchange processes such as electrodialysis or weak acid cation exchange ; or evaporation processes, such as thermal brine concentrators and crystallizers employing mechanical vapour recompression and steam. New methods for membrane brine concentration, employing osmotically assisted reverse osmosis and related processes, are beginning to gain ground as part of zero liquid discharge systems (ZLD). Brine consists of concentrated solution of Na and Cl ions. Sodium chloride per se does not exist in water: it

7238-458: The overall content. However, there are approximately 80 different minerals that have been reported found in evaporite deposits, though only about a dozen are common enough to be considered important rock formers. Non-marine evaporites are usually composed of minerals that are not common in marine environments because in general the water from which non-marine evaporite precipitates has proportions of chemical elements different from those found in

7332-540: The periodic table, are often included as well. Nevertheless, beryllium and magnesium differ significantly from the other members of the group in their physical and chemical behavior: they behave more like aluminium and zinc respectively and have some of the weaker metallic character of the post-transition metals , which is why the traditional definition of the term "alkaline earth metal" excludes them. Calcium metal melts at 842 °C and boils at 1494 °C; these values are higher than those for magnesium and strontium,

7426-450: The periodic table, calcium has two valence electrons in the outermost s-orbital, which are very easily lost in chemical reactions to form a dipositive ion with the stable electron configuration of a noble gas , in this case argon . Hence, calcium is almost always divalent in its compounds, which are usually ionic . Hypothetical univalent salts of calcium would be stable with respect to their elements, but not to disproportionation to

7520-477: The plaster in the tomb of Tutankhamun . The ancient Romans instead used lime mortars made by heating limestone (CaCO 3 ). The name "calcium" itself derives from the Latin word calx "lime". Vitruvius noted that the lime that resulted was lighter than the original limestone, attributing this to the boiling of the water. In 1755, Joseph Black proved that this was due to the loss of carbon dioxide , which as

7614-408: The rate of removal of Ca by mineral precipitation exceeds the input of new calcium into the ocean. In 1997, Skulan and DePaolo presented the first evidence of change in seawater Ca/ Ca over geologic time, along with a theoretical explanation of these changes. More recent papers have confirmed this observation, demonstrating that seawater Ca concentration is not constant, and that the ocean is never in

7708-414: The remaining water is enriched in salts, and they precipitate when the water becomes supersaturated. Marine evaporites tend to have thicker deposits and are usually the focus of more extensive research. When scientists evaporate ocean water in a laboratory, the minerals are deposited in a defined order that was first demonstrated by Usiglio in 1884. The first phase of precipitation begins when about 50% of

7802-407: The salt involved: calcium citrate , malate , and lactate are highly bioavailable, while the oxalate is less. Other calcium preparations include calcium carbonate , calcium citrate malate , and calcium gluconate . The intestine absorbs about one-third of calcium eaten as the free ion , and plasma calcium level is then regulated by the kidneys . Parathyroid hormone and vitamin D promote

7896-489: The sediment has time to pool and form in a lake or other standing body of water. Primary examples of this are called "saline lake deposits". Saline lakes includes things such as perennial lakes, which are lakes that are there year-round, playa lakes, which are lakes that appear only during certain seasons, or any other terms that are used to define places that hold standing bodies of water intermittently or year-round. Examples of modern non-marine depositional environments include

7990-421: The similar ionic radii of Yb (102 pm) and Ca (100 pm). Most of these compounds can only be prepared at low temperatures; bulky ligands tend to favor stability. For example, calcium di cyclopentadienyl , Ca(C 5 H 5 ) 2 , must be made by directly reacting calcium metal with mercurocene or cyclopentadiene itself; replacing the C 5 H 5 ligand with the bulkier C 5 (CH 3 ) 5 ligand on

8084-500: The simplest terms, mountain-building exposes calcium-bearing rocks such as basalt and granodiorite to chemical weathering and releases Ca into surface water. These ions are transported to the ocean where they react with dissolved CO 2 to form limestone ( CaCO 3 ), which in turn settles to the sea floor where it is incorporated into new rocks. Dissolved CO 2 , along with carbonate and bicarbonate ions, are termed " dissolved inorganic carbon " (DIC). The actual reaction

8178-466: The state of the surrounding marine environment. Under the context of this environmental assessment process, numerous countries require compliance with an Environmental Monitoring Program (PVA), in order to evaluate the effectiveness of the preventive and corrective measures established during the environmental assessment process, and thus guarantee the operation of desalination plants without producing significant environmental impacts. The PVAs establishes

8272-522: The steel and become small and spherical, improving castability, cleanliness and general mechanical properties. Calcium is also used in maintenance-free automotive batteries , in which the use of 0.1% calcium– lead alloys instead of the usual antimony –lead alloys leads to lower water loss and lower self-discharging. Due to the risk of expansion and cracking, aluminium is sometimes also incorporated into these alloys. These lead–calcium alloys are also used in casting, replacing lead–antimony alloys. Calcium

8366-674: The subsurface. Evaporite minerals, especially nitrate minerals, are economically important in Peru and Chile. Nitrate minerals are often mined for use in the production on fertilizer and explosives . Thick halite deposits are expected to become an important location for the disposal of nuclear waste because of their geologic stability, predictable engineering and physical behaviour, and imperviousness to groundwater. Halite formations are famous for their ability to form diapirs , which produce ideal locations for trapping petroleum deposits. Halite deposits are often mined for use as salt . This

8460-399: The surface and in aquifers contain dissolved salts, the water must evaporate into the atmosphere for the minerals to precipitate. For this to happen, the water body must enter a restricted environment where water input into this environment remains below the net rate of evaporation. This is usually an arid environment with a small basin fed by a limited input of water. When evaporation occurs,

8554-440: The surface of Titan , Saturn's largest moon. Instead of water oceans, Titan hosts lakes and seas of liquid hydrocarbons (mainly methane) with many soluble hydrocarbons, such as acetylene , that can evaporate out of solution. Evaporite deposits cover large regions of Titan's surface, mainly along the coastlines of lakes or in isolated basins ( Lacunae ) that are equivalent to salt pans on Earth. Calcium Calcium

8648-587: The surficial system (atmosphere, ocean, soils and living organisms), storing it in carbonate rocks where it is likely to stay for hundreds of millions of years. The weathering of calcium from rocks thus scrubs CO 2 from the ocean and atmosphere, exerting a strong long-term effect on climate. The largest use of metallic calcium is in steelmaking , due to its strong chemical affinity for oxygen and sulfur . Its oxides and sulfides, once formed, give liquid lime aluminate and sulfide inclusions in steel which float out; on treatment, these inclusions disperse throughout

8742-473: The surrounding solution enriched in heavier isotopes at a magnitude of roughly 0.025% per atomic mass unit (amu) at room temperature. Mass-dependent differences in calcium isotope composition are conventionally expressed by the ratio of two isotopes (usually Ca/ Ca) in a sample compared to the same ratio in a standard reference material. Ca/ Ca varies by about 1- 2‰ among organisms on Earth. Calcium compounds were known for millennia, though their chemical makeup

8836-516: Was not understood until the 17th century. Lime as a building material and as plaster for statues was used as far back as around 7000 BC. The first dated lime kiln dates back to 2500 BC and was found in Khafajah , Mesopotamia . About the same time, dehydrated gypsum (CaSO 4 ·2H 2 O) was being used in the Great Pyramid of Giza . This material would later be used for

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