mercury (element)
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Mercury is a
chemical element A chemical element is a species of atoms that have a given number of protons in their atomic nucleus, nuclei, including the pure Chemical substance, substance consisting only of that species. Unlike chemical compounds, chemical elements canno ...
with the
symbol A symbol is a mark, sign, or word that indicates, signifies, or is understood as representing an idea, object, or relationship. Symbols allow people to go beyond what is known or seen by creating linkages between otherwise very different ...
Hg and
atomic number The atomic number or nuclear charge number (symbol ''Z'') of a chemical element is the charge number of an atomic nucleus. For ordinary nuclei, this is equal to the proton number (''n''p) or the number of protons found in the nucleus of every ...
80. It is also known as quicksilver and was formerly named hydrargyrum ( ) from the Greek words, ''hydor'' (water) and ''argyros'' (silver). A
heavy Heavy may refer to: Measures * Heavy (aeronautics), a term used by pilots and air traffic controllers to refer to aircraft capable of 300,000 lbs or more takeoff weight * Heavy, a characterization of objects with substantial weight * Heavy, ...
, silvery
d-block A block of the periodic table is a set of elements unified by the atomic orbitals their valence electrons or vacancies lie in. The term appears to have been first used by Charles Janet. Each block is named after its characteristic orbital: s-bloc ...
element, mercury is the only metallic element that is known to be liquid at
standard temperature and pressure Standard temperature and pressure (STP) are Technical standard, standard sets of conditions for experimental measurements to be established to allow comparisons to be made between different sets of data. The most used standards are those of the I ...
; the only other element that is liquid under these conditions is the
halogen The halogens () are a group in the periodic table The periodic table, also known as the periodic table of the (chemical) elements, is a rows and columns arrangement of the chemical elements. It is widely used in chemistry, physics, and ...
bromine Bromine is a chemical element A chemical element is a species of atoms that have a given number of protons in their atomic nucleus, nuclei, including the pure Chemical substance, substance consisting only of that species. Unlike chemical ...
, though metals such as
caesium Caesium (IUPAC spelling) (or cesium in American English) is a chemical element with the Symbol (chemistry), symbol Cs and atomic number 55. It is a soft, silvery-golden alkali metal with a melting point of , which makes it one of only five elem ...
,
gallium Gallium is a chemical element with the Symbol (chemistry), symbol Ga and atomic number 31. Discovered by France, French chemist Paul-Émile Lecoq de Boisbaudran in 1875, Gallium is in boron group, group 13 of the periodic table and is similar to ...
, and
rubidium Rubidium is the chemical element with the Symbol (chemistry), symbol Rb and atomic number 37. It is a very soft, whitish-grey solid in the alkali metal group, similar to potassium and caesium. Rubidium is the first alkali metal in the group to ha ...
melt just above
room temperature Colloquially, "room temperature" is a range of air temperatures that most people prefer for indoor settings. It feels comfortable to a person when they are wearing typical indoor clothing. Human comfort can extend beyond this range depending on ...
. Mercury occurs in deposits throughout the world mostly as
cinnabar Cinnabar (), or cinnabarite (), from the grc, κιννάβαρι (), is the bright scarlet to brick-red form of Mercury sulfide, mercury(II) sulfide (HgS). It is the most common source ore for refining mercury (element), elemental mercury and ...
( mercuric sulfide). The red pigment
vermilion Vermilion (sometimes vermillion) is a color, color family, and pigment most often made, since ancient history, antiquity until the 19th century, from the powdered mineral cinnabar (a form of mercury sulfide, which is toxic) and its correspondi ...
is obtained by grinding natural cinnabar or synthetic mercuric sulfide. Mercury is used in
thermometer A thermometer is a device that temperature measurement, measures temperature or a temperature gradient (the degree of hotness or coldness of an object). A thermometer has two important elements: (1) a temperature sensor (e.g. the bulb of a merc ...
s,
barometer A barometer is a scientific instrument that is used to measure air pressure in a certain environment. Pressure tendency can forecast short term changes in the weather. Many measurements of air pressure are used within surface weather analysis ...
s,
manometer Pressure measurement is the measurement of an applied force by a fluid (liquid or gas) on a surface. Pressure is typically measured in unit of measurement, units of force per unit of surface area. Many techniques have been developed for the me ...
s,
sphygmomanometer A sphygmomanometer ( ), a blood pressure monitor, or blood pressure gauge, is a device used to measure blood pressure, composed of an inflatable cuff to collapse and then release the artery under the cuff in a controlled manner, and a mercury (e ...
s,
float valve A ballcock (also balltap or float valve) is a mechanism or machine for filling water tanks, such as those found in flush toilets, while avoiding overflow and (in the event of low water pressure) backflow. The modern ballcock was invented by J ...
s,
mercury switch A mercury switch is an electrical switch that opens and closes a electrical circuit, circuit when a small amount of the liquid metal mercury (element), mercury connects metal electrodes to close the circuit. There are several different basic des ...
es,
mercury relay A mercury relay (mercury displacement relay, mercury contactor) is a relay that uses mercury (element), mercury as the switching element. They are used as high-current switches or contactors, where contact erosion from constant cycling would be a ...
s,
fluorescent lamp A fluorescent lamp, or fluorescent tube, is a low-pressure mercury-vapor gas-discharge lamp that uses fluorescence to produce visible light. An electric current in the gas excites mercury vapor, which produces short-wave ultraviolet, ult ...
s and other devices, though concerns about the element's toxicity have led to mercury thermometers and sphygmomanometers being largely phased out in clinical environments in favor of alternatives such as
alcohol Alcohol most commonly refers to: * Alcohol (chemistry) In chemistry, an alcohol is a type of organic compound that carries at least one hydroxyl () functional group bound to a Saturated and unsaturated compounds, saturated carbon atom. The ...
- or
galinstan Galinstan (R) is a brand name for a alloy composed of gallium, indium, and tin which melts at and is thus liquid at room temperature. However, it is not a eutectic alloy but a near eutectic alloy. In scientific literature, galinstan is also used ...
-filled glass thermometers and
thermistor A thermistor is a type of resistor whose resistance is strongly dependent on temperature, more so than in standard resistors. The word thermistor is a portmanteau of ''thermal'' and ''resistor''. Thermistors are divided based on their conductio ...
- or
infrared Infrared (IR), sometimes called infrared light, is electromagnetic radiation (EMR) with wavelengths longer than those of Light, visible light. It is therefore invisible to the human eye. IR is generally understood to encompass wavelengths from ...
-based electronic instruments. Likewise, mechanical pressure gauges and electronic strain gauge sensors have replaced mercury sphygmomanometers. Mercury remains in use in scientific research applications and in amalgam for
dental restoration Dental restoration, dental fillings, or simply fillings are treatments used to restore the function, integrity, and morphology of missing tooth A tooth (plural, : teeth) is a hard, calcification, calcified structure found in the jaws (or mou ...
in some locales. It is also used in
fluorescent lighting A fluorescent lamp, or fluorescent tube, is a low-pressure mercury-vapor gas-discharge lamp that uses fluorescence to produce visible light. An electric current in the gas excites mercury vapor, which produces short-wave ultraviolet lig ...
. Electricity passed through mercury vapor in a fluorescent lamp produces short-wave
ultraviolet light Ultraviolet (UV) is a form of electromagnetic radiation with wavelength from 10 nanometer, nm (with a corresponding frequency around 30 Hertz, PHz) to 400 nm (750 Hertz, THz), shorter than that of visible light, but longer than ...
, which then causes the phosphor in the tube to
fluoresce Fluorescence is the emission of light by a substance that has absorbed light or other electromagnetic radiation. It is a form of luminescence. In most cases, the emitted light has a longer wavelength, and therefore a lower photon energy, tha ...
, making visible light.
Mercury poisoning Mercury poisoning is a type of metal poisoning due to exposure to mercury. Symptoms depend upon the type, dose, method, and duration of exposure. They may include muscle weakness, poor coordination, numbness in the hands and feet, skin rash ...
can result from exposure to water-soluble forms of mercury (such as mercuric chloride or
methylmercury Methylmercury (sometimes methyl mercury) is an organometallic cation with the formula . It is the simplest organomercury compound. Methylmercury is extremely toxic, and its derivatives are the major source of organic mercury for humans. It is a ...
), by inhalation of mercury vapor, or by ingesting any form of mercury.


Properties


Physical properties

Mercury is a heavy, silvery-white metal that is liquid at room temperature. Compared to other metals, it is a poor conductor of heat, but a fair conductor of electricity. in It has a
freezing point The melting point (or, rarely, liquefaction point) of a substance is the temperature at which it changes state of matter, state from solid to liquid. At the melting point the solid and liquid phase_(matter), phase exist in Thermodynamic equilibr ...
of −38.83 °C and a
boiling point The boiling point of a substance is the temperature at which the vapor pressure of a liquid equals the pressure surrounding the liquid and the liquid changes into a vapor. The boiling point of a liquid varies depending upon the surrounding en ...
of 356.73 °C, both the lowest of any stable metal, although preliminary experiments on
copernicium Copernicium is a synthetic chemical element A chemical element is a species of atoms that have a given number of protons in their atomic nucleus, nuclei, including the pure Chemical substance, substance consisting only of that species. U ...
and
flerovium Flerovium is a superheavy chemical element A chemical element is a species of atoms that have a given number of protons in their atomic nucleus, nuclei, including the pure Chemical substance, substance consisting only of that species. Un ...
have indicated that they have even lower boiling points. This effect is due to
lanthanide contraction The lanthanide contraction is the greater-than-expected decrease in Atomic radius, atomic radii/ionic radius, ionic radii of the chemical element, elements in the lanthanide series from atomic number 57, lanthanum, to 71, lutetium, which results in ...
and relativistic contraction reducing the radius of the outermost electrons, and thus weakening the metallic bonding in mercury. Upon freezing, the volume of mercury decreases by 3.59% and its density changes from 13.69 g/cm3 when liquid to 14.184 g/cm3 when solid. The coefficient of volume expansion is 181.59 × 10−6 at 0 °C, 181.71 × 10−6 at 20 °C and 182.50 × 10−6 at 100 °C (per °C). Solid mercury is malleable and ductile and can be cut with a knife. Table of thermal and physical properties of liquid mercury:


Chemical properties

Mercury does not react with most acids, such as dilute
sulfuric acid Sulfuric acid (American spelling and the preferred IUPAC name) or sulphuric acid (English in the Commonwealth of Nations, Commonwealth spelling), known in antiquity as oil of vitriol, is a mineral acid composed of the elements sulfur, oxygen ...
, although oxidizing acids such as concentrated sulfuric acid and
nitric acid Nitric acid is the inorganic compound with the formula . It is a highly corrosive mineral acid. The compound is colorless, but older samples tend to be yellow cast due to decomposition into oxides of nitrogen. Most commercially available ni ...
or aqua regia dissolve it to give
sulfate The sulfate or sulphate ion is a polyatomic ion, polyatomic anion with the empirical formula . Salts, acid derivatives, and peroxides of sulfate are widely used in industry. Sulfates occur widely in everyday life. Sulfates are salt (chemistry), ...
,
nitrate Nitrate is a polyatomic ion with the chemical formula . salt (chemistry), Salts containing this ion are called nitrates. Nitrates are common components of fertilizers and explosives. Almost all inorganic nitrates are solubility, soluble in wat ...
, and
chloride The chloride ion is the anion (negatively charged ion) Cl−. It is formed when the chemical element, element chlorine (a halogen) gains an electron or when a chemical compound, compound such as hydrogen chloride is dissolved in water or o ...
. Like silver, mercury reacts with atmospheric
hydrogen sulfide Hydrogen sulfide is a chemical compound with the chemical formula, formula . It is a colorless Chalcogen hydride, chalcogen-hydride gas, and is poisonous, corrosive, and flammable, with trace amounts in ambient atmosphere having a characteristic ...
. Mercury reacts with solid sulfur flakes, which are used in mercury spill kits to absorb mercury (spill kits also use
activated carbon Activated carbon, also called activated charcoal, is a form of carbon commonly used to filter contaminants from water and air, among many other uses. It is processed (activated) to have small, low-volume pores that increase the surface area availa ...
and powdered zinc).


Amalgams

Mercury dissolves many metals such as
gold Gold is a chemical element with the Symbol (chemistry), symbol Au (from la, aurum) and atomic number 79. This makes it one of the higher atomic number elements that occur naturally. It is a Brightness, bright, slightly orange-yellow, dense, s ...
and
silver Silver is a chemical element with the Symbol (chemistry), symbol Ag (from the Latin ', derived from the Proto-Indo-European wikt:Reconstruction:Proto-Indo-European/h₂erǵ-, ''h₂erǵ'': "shiny" or "white") and atomic number 47. A soft, whi ...
to form amalgams.
Iron Iron () is a chemical element with Symbol (chemistry), symbol Fe (from la, Wikt:ferrum, ferrum) and atomic number 26. It is a metal that belongs to the first transition series and group 8 element, group 8 of the periodic table. It is, Abundance ...
is an exception, and iron flasks have traditionally been used to trade mercury. Several other first row transition metals with the exception of
manganese Manganese is a chemical element with the Symbol (chemistry), symbol Mn and atomic number 25. It is a hard, brittle, silvery metal, often found in minerals in combination with iron. Manganese is a transition metal with a multifaceted array of ...
,
copper Copper is a chemical element with the Symbol (chemistry), symbol Cu (from la, cuprum) and atomic number 29. It is a soft, malleable, and ductility, ductile metal with very high thermal conductivity, thermal and electrical conductivity. A fre ...
and
zinc Zinc is a chemical element with the Symbol (chemistry), symbol Zn and atomic number 30. Zinc is a slightly brittle metal at room temperature and has a shiny-greyish appearance when oxidation is removed. It is the first element in group 12 eleme ...
are also resistant in forming amalgams. Other elements that do not readily form amalgams with mercury include
platinum Platinum is a chemical element with the Symbol (chemistry), symbol Pt and atomic number 78. It is a density, dense, malleable, ductility, ductile, highly unreactive, precious metal, precious, silverish-white transition metal. Its name origina ...
.
Sodium amalgam Sodium amalgam, commonly denoted Na(Hg), is an alloy of mercury and sodium. The term amalgam is used for alloys, intermetallic compounds, and solutions (both solid solutions and liquid solutions) involving mercury as a major component. Sodium ...
is a common reducing agent in
organic synthesis Organic synthesis is a special branch of chemical synthesis and is concerned with the intentional construction of organic compounds. Organic chemistry, Organic molecules are often more complex than Inorganic chemistry, inorganic compounds, and t ...
, and is also used in
high-pressure sodium A sodium-vapor lamp is a gas-discharge lamp that uses sodium in an excited state to produce light at a characteristic wavelength near 589  nm. Two varieties of such lamps exist: low pressure and high pressure. Low-pressure sodium lamps ar ...
lamps. Mercury readily combines with
aluminium Aluminium (aluminum in American and Canadian English) is a chemical element A chemical element is a species of atoms that have a given number of protons in their atomic nucleus, nuclei, including the pure Chemical substance, substan ...
to form a mercury-aluminium amalgam when the two pure metals come into contact. Since the amalgam destroys the aluminium oxide layer which protects metallic aluminium from oxidizing in-depth (as in iron
rust Rust is an iron oxide, a usually reddish-brown oxide formed by the reaction of iron and oxygen in the catalytic presence of water or air moisture. Rust consists of hydrous ferric oxides, hydrous iron(III) oxides (Fe2O3·nH2O) and iron(III) oxi ...
ing), even small amounts of mercury can seriously corrode aluminium. For this reason, mercury is not allowed aboard an aircraft under most circumstances because of the risk of it forming an amalgam with exposed aluminium parts in the aircraft. Mercury embrittlement is the most common type of liquid metal embrittlement.


Isotopes

There are seven stable
isotope Isotopes are two or more types of atoms that have the same atomic number (number of protons in their nuclei) and position in the periodic table (and hence belong to the same chemical element), and that differ in nucleon numbers (mass numbe ...
s of mercury, with being the most abundant (29.86%). The longest-lived
radioisotope A radionuclide (radioactive nuclide, radioisotope or radioactive isotope) is a nuclide that has excess nuclear energy, making it unstable. This excess energy can be used in one of three ways: emitted from the nucleus as gamma radiation; transferr ...
s are with a
half-life Half-life (symbol ) is the time required for a quantity (of substance) to reduce to half of its initial value. The term is commonly used in nuclear physics to describe how quickly unstable atoms undergo radioactive decay or how long stable ato ...
of 444 years, and with a half-life of 46.612 days. Most of the remaining radioisotopes have half-lives that are less than a day. and are the most often studied NMR-active nuclei, having spins of and respectively. For the
synthesis of precious metals The synthesis of precious metals Precious metals are rare, naturally occurring metallic chemical elements of high Value (economics), economic value. Chemically, the precious metals tend to be less reactivity (chemistry), reactive than mo ...
two stable mercury isotopes are of potential interest - the trace isotope and the more abundant . Both are "one neutron removed" from , a radioisotope which decays to , the only known stable isotope of gold. However, the rarity of and the high energy requirements of
nuclear reaction In nuclear physics Nuclear physics is the field of physics that studies atomic nuclei and their constituents and interactions, in addition to the study of other forms of nuclear matter. Nuclear physics should not be confused with atomic phy ...
s "knocking out" a neutron from (either via
photodisintegration Photodisintegration (also called phototransmutation, or a photonuclear reaction) is a nuclear process in which an atomic nucleus absorbs a high-energy gamma ray, enters an excited state, and immediately decays by emitting a subatomic particle. The ...
or via a (n,2n) reaction involving
fast neutron The neutron detection temperature, also called the neutron energy, indicates a free neutron The neutron is a subatomic particle, symbol or , which has a neutral (not positive or negative) charge, and a mass slightly greater than that of ...
s), have thus far ruled out practical application of this "real philosopher's stone".


Etymology

"Hg" is the modern
chemical symbol Chemical symbols are the abbreviations used in chemistry for chemical elements, functional groups and chemical compounds. Element symbols for chemical elements normally consist of one or two letters from the Latin alphabet and are written with th ...
for mercury. It is an abbreviation of , a
romanized Romanization or romanisation, in linguistics, is the conversion of text from a different writing system to the Latin script, Roman (Latin) script, or a system for doing so. Methods of romanization include transliteration, for representing writ ...
form of the
ancient Greek Ancient Greek includes the forms of the Greek language used in ancient Greece and the classical antiquity, ancient world from around 1500 BC to 300 BC. It is often roughly divided into the following periods: Mycenaean Greek (), Greek Dark ...
name for mercury, (). is a Greek compound word meaning "water-silver", from - (-), the root of () "water", and () "silver". Like the English name quicksilver ("living-silver"), this name was due to mercury's liquid and shiny properties. The modern English name "mercury" comes from the planet Mercury. In medieval
alchemy Alchemy (from Arabic: ''al-kīmiyā''; from Ancient Greek: χυμεία, ''khumeía'') is an ancient branch of natural philosophy, a philosophical and protoscience, protoscientific tradition that was historically practiced in Chinese alchemy, C ...
, the seven known metals—quicksilver,
gold Gold is a chemical element with the Symbol (chemistry), symbol Au (from la, aurum) and atomic number 79. This makes it one of the higher atomic number elements that occur naturally. It is a Brightness, bright, slightly orange-yellow, dense, s ...
,
silver Silver is a chemical element with the Symbol (chemistry), symbol Ag (from the Latin ', derived from the Proto-Indo-European wikt:Reconstruction:Proto-Indo-European/h₂erǵ-, ''h₂erǵ'': "shiny" or "white") and atomic number 47. A soft, whi ...
,
copper Copper is a chemical element with the Symbol (chemistry), symbol Cu (from la, cuprum) and atomic number 29. It is a soft, malleable, and ductility, ductile metal with very high thermal conductivity, thermal and electrical conductivity. A fre ...
,
iron Iron () is a chemical element with Symbol (chemistry), symbol Fe (from la, Wikt:ferrum, ferrum) and atomic number 26. It is a metal that belongs to the first transition series and group 8 element, group 8 of the periodic table. It is, Abundance ...
,
lead Lead is a chemical element with the Symbol (chemistry), symbol Pb (from the Latin ) and atomic number 82. It is a heavy metals, heavy metal that is density, denser than most common materials. Lead is Mohs scale of mineral hardness#Intermediate ...
, and
tin Tin is a chemical element with the Chemical symbol, symbol Sn (from la, :la:Stannum, stannum) and atomic number 50. Tin is a silvery-coloured metal. Tin is soft enough to be cut with little force and a bar of tin can be bent by hand wit ...
—were associated with the seven planets. Quicksilver was associated with the fastest planet, which had been named after the Roman god Mercury, who was associated with speed and mobility. The astrological symbol for the planet became one of the
alchemical symbol Alchemical symbols, originally devised as part of alchemy, were used to denote some elements and some compounds until the 18th century. Although notation like this was mostly standardized, style and symbol varied between alchemists, so this pag ...
s for the metal, and "Mercury" became an alternative name for the metal. Mercury is the only metal for which the alchemical planetary name survives, as it was decided it was preferable to "quicksilver" as a chemical name.


History

Mercury was found in Egyptian tombs that date from 1500 BC. In
China China, officially the People's Republic of China (PRC), is a country in East Asia. It is the world's List of countries and dependencies by population, most populous country, with a Population of China, population exceeding 1.4 billion, slig ...
and
Tibet Tibet (; ''Böd''; ) is a region in East Asia, covering much of the Tibetan Plateau and spanning about . It is the traditional homeland of the Tibetan people. Also resident on the plateau are some other ethnic groups such as Monpa people, ...
, mercury use was thought to prolong life, heal fractures, and maintain generally good health, although it is now known that exposure to mercury vapor leads to serious adverse health effects. The first emperor of a unified China, Qín Shǐ Huáng Dì—allegedly buried in a
tomb A tomb ( grc-gre, τύμβος ''tumbos'') is a :wikt:repository, repository for the remains of the dead. It is generally any structurally enclosed interment space or burial chamber, of varying sizes. Placing a corpse into a tomb can be ...
that contained rivers of flowing mercury on a model of the land he ruled, representative of the rivers of China—was reportedly killed by drinking a mercury and powdered
jade Jade is a mineral used as jewellery or for ornament (art), ornaments. It is typically green, although may be yellow or white. Jade can refer to either of two different silicate minerals: nephrite (a silicate of calcium and magnesium in the amp ...
mixture formulated by Qin alchemists intended as an elixir of immortality.
Khumarawayh ibn Ahmad ibn Tulun Abu 'l-Jaysh Khumārawayh ibn Aḥmad ibn Ṭūlūn ( ar, أبو الجيش خمارويه بن أحمد بن طولون; 864 – 18 January 896) was a son of the founder of the Tulunid dynasty, Ahmad ibn Tulun. His father, the autonomous ruler o ...
, the second Tulunid ruler of Egypt (r. 884–896), known for his extravagance and profligacy, reportedly built a basin filled with mercury, on which he would lie on top of air-filled cushions and be rocked to sleep. In November 2014 "large quantities" of mercury were discovered in a chamber 60 feet below the 1800-year-old pyramid known as the " Temple of the Feathered Serpent," "the third largest pyramid of
Teotihuacan Teotihuacan (Spanish language, Spanish: ''Teotihuacán'') (; ) is an ancient Mesoamerican city located in a sub-valley of the Valley of Mexico, which is located in the State of Mexico, northeast of modern-day Mexico City. Teotihuacan is ...
," Mexico along with "jade statues, jaguar remains, a box filled with carved shells and rubber balls".
Aristotle Aristotle (; grc-gre, Ἀριστοτέλης ''Aristotélēs'', ; 384–322 BC) was a Greek philosopher and polymath during the Classical Greece, Classical period in Ancient Greece. Taught by Plato, he was the founder of the Peripatet ...
recounts that
Daedalus In Greek mythology, Daedalus (, ; Greek language, Greek: Δαίδαλος; Latin language, Latin: ''Daedalus''; Etruscan language, Etruscan: ''Taitale'') was a skillful architect and craftsman, seen as a symbol of wisdom, knowledge and power. H ...
made a wooden statue of
Venus Venus is the second planet from the Sun. It is sometimes called Earth's "sister" or "twin" planet as it is almost as large and has a similar composition. As an Inferior and superior planets, interior planet to Earth, Venus (like Mercury (pl ...
move by pouring quicksilver in its interior. In
Greek mythology A major branch of classical mythology, Greek mythology is the body of myths originally told by the Ancient Greece, ancient Greeks, and a genre of Ancient Greek folklore. These stories concern the Cosmogony, origin and Cosmology#Metaphysical co ...
Daedalus gave the appearance of voice in his statues using quicksilver. The
ancient Greeks Ancient Greece ( el, Ἑλλάς, Hellás) was a northeastern Mediterranean Sea, Mediterranean civilization, existing from the Greek Dark Ages of the 12th–9th centuries BC to the end of Classical Antiquity, classical antiquity ( AD 600), th ...
used
cinnabar Cinnabar (), or cinnabarite (), from the grc, κιννάβαρι (), is the bright scarlet to brick-red form of Mercury sulfide, mercury(II) sulfide (HgS). It is the most common source ore for refining mercury (element), elemental mercury and ...
(mercury sulfide) in ointments; the
ancient Egyptians #REDIRECT Ancient Egypt Ancient Egypt was a civilization in Northeast Africa situated in the Nile Valley. Ancient Egyptian civilization followed prehistoric Egypt and coalesced around 3100Anno Domini, BC (according to conventional Egypti ...
and the Romans used it in
cosmetics Cosmetics are constituted mixtures of chemical compounds derived from either Natural product, natural sources, or synthetically created ones. Cosmetics have various purposes. Those designed for personal care and skin care can be used to Clea ...
. In Lamanai, once a major city of the
Maya civilization The Maya civilization () of the Mesoamerican people is known by its ancient temples and Glyph, glyphs. Its Maya script is the most sophisticated and highly developed writing system in the Pre-Columbian era, pre-Columbian Americas. It is also ...
, a pool of mercury was found under a marker in a
Mesoamerican ballcourt A Mesoamerican ballcourt ( nah, tlachtli) is a large masonry Masonry is the building of structures from individual units, which are often laid in and bound together by mortar (masonry), mortar; the term ''masonry'' can also refer to the unit ...
. By 500 BC mercury was used to make amalgams (Medieval Latin ''amalgama'', "alloy of mercury") with other metals. Alchemists thought of mercury as the First Matter from which all metals were formed. They believed that different
metals A metal (from ancient Greek, Greek μέταλλον ''métallon'', "mine, quarry, metal") is a material that, when freshly prepared, polished, or fractured, shows a lustrous appearance, and conducts electrical resistivity and conductivity, e ...
could be produced by varying the quality and quantity of
sulfur Sulfur (or sulphur in British English British English (BrE, en-GB, or BE) is, according to Oxford Dictionaries, " English as used in Great Britain, as distinct from that used elsewhere". More narrowly, it can refer specifically to the ...
contained within the mercury. The purest of these was gold, and mercury was called for in attempts at the transmutation of base (or impure) metals into gold, which was the goal of many alchemists. The mines in
Almadén Almadén () is a town and municipality A municipality is usually a single administrative division Administrative division, administrative unit,Article 3(1). country subdivision, administrative region, subnational entity, constituent sta ...
(Spain),
Monte Amiata Mount Amiata is the largest of the lava dome In volcanology, a lava dome is a circular mound-shaped protrusion resulting from the slow Extrusive rock, extrusion of viscous lava from a volcano. Dome-building eruptions are common, particularly ...
(Italy), and
Idrija Idrija (, in older sources ''Zgornja Idrija''; german: (Ober)idria, it, Idria) is a town in western Slovenia. It is the seat of the Municipality of Idrija. It is located in the traditional region of Inner Carniola and is in the Gorizia Statistic ...
(now Slovenia) dominated mercury production from the opening of the mine in Almadén 2500 years ago, until new deposits were found at the end of the 19th century.


Occurrence

Mercury is an extremely rare element in Earth's crust, having an average crustal abundance by mass of only 0.08 parts per million (ppm). Because it does not blend geochemically with those elements that constitute the majority of the crustal mass, mercury ores can be extraordinarily concentrated considering the element's abundance in ordinary rock. The richest mercury ores contain up to 2.5% mercury by mass, and even the leanest concentrated deposits are at least 0.1% mercury (12,000 times average crustal abundance). It is found either as a
native metal A native metal is any metal that is found pure in its metallic form in nature. Metals that can be found as native element mineral, native deposits singly or in alloys include aluminium, antimony, arsenic, bismuth, cadmium, chromium, cobalt, indiu ...
(rare) or in
cinnabar Cinnabar (), or cinnabarite (), from the grc, κιννάβαρι (), is the bright scarlet to brick-red form of Mercury sulfide, mercury(II) sulfide (HgS). It is the most common source ore for refining mercury (element), elemental mercury and ...
, metacinnabar,
sphalerite Sphalerite (sometimes spelled sphaelerite) is a sulfide mineral The sulfide minerals are a class of minerals containing sulfide (S2−) or disulfide (S22−) as the major anion. Some sulfide minerals are economically important as metal ores ...
,
corderoite Corderoite is an extremely rare mercury (element), mercury sulfide chloride mineral with formula Hg3S2Cl2. It crystallizes in the Cubic (crystal system), isometric crystal system. It is soft, 1.5 to 2 on the Mohs scale, and varies in color from li ...
, livingstonite and other
mineral In geology and mineralogy, a mineral or mineral species is, broadly speaking, a solid chemical compound with a fairly well-defined chemical composition and a specific crystal structure that occurs naturally in pure form.John P. Rafferty, ed. (2 ...
s, with cinnabar (HgS) being the most common ore. Mercury ores often occur in hot springs or other
volcanic A volcano is a rupture in the Crust (geology), crust of a Planet#Planetary-mass objects, planetary-mass object, such as Earth, that allows hot lava, volcanic ash, and volcanic gas, gases to escape from a magma chamber below the surface. On Ear ...
regions. Beginning in 1558, with the invention of the patio process to extract silver from ore using mercury, mercury became an essential resource in the economy of Spain and its American colonies. Mercury was used to extract silver from the lucrative mines in
New Spain New Spain, officially the Viceroyalty of New Spain ( es, Virreinato de Nueva España, ), or Kingdom of New Spain, was an integral territorial entity of the Spanish Empire, established by Habsburg Spain during the Spanish colonization of the Amer ...
and
Peru , image_flag = Flag of Peru.svg , image_coat = Escudo nacional del Perú.svg , other_symbol = Great Seal of the State , other_symbol_type = Seal (emblem), National seal , national_motto = "Fi ...
. Initially, the Spanish Crown's mines in Almadén in Southern Spain supplied all the mercury for the colonies. Mercury deposits were discovered in the New World, and more than 100,000 tons of mercury were mined from the region of
Huancavelica Huancavelica () or Wankawillka in Southern Quechua, Quechua is a city in Peru. It is the Capital (political), capital of the department of Huancavelica and according to the 2017 Peru Census, 2017 census had a population of 49,570 people. Th ...
, Peru, over the course of three centuries following the discovery of deposits there in 1563. The patio process and later pan amalgamation process continued to create great demand for mercury to treat silver ores until the late 19th century. Former mines in Italy, the United States and Mexico, which once produced a large proportion of the world supply, have now been completely mined out or, in the case of Slovenia (
Idrija Idrija (, in older sources ''Zgornja Idrija''; german: (Ober)idria, it, Idria) is a town in western Slovenia. It is the seat of the Municipality of Idrija. It is located in the traditional region of Inner Carniola and is in the Gorizia Statistic ...
) and Spain (
Almadén Almadén () is a town and municipality A municipality is usually a single administrative division Administrative division, administrative unit,Article 3(1). country subdivision, administrative region, subnational entity, constituent sta ...
), shut down due to the fall of the price of mercury.
Nevada Nevada ( ; ) is a U.S. state, state in the Western United States, Western region of the United States. It is bordered by Oregon to the northwest, Idaho to the northeast, California to the west, Arizona to the southeast, and Utah to the east. N ...
's McDermitt Mine, the last mercury mine in the United States, closed in 1992. The price of mercury has been highly volatile over the years and in 2006 was $650 per 76-pound (34.46 kg) flask. Mercury is extracted by heating cinnabar in a current of air and condensing the vapor. The equation for this extraction is :HgS + O2 → Hg + SO2 In 2005, China was the top producer of mercury with almost two-thirds global share followed by
Kyrgyzstan Kyrgyzstan,, pronounced or the Kyrgyz Republic, is a landlocked country in Central Asia. Kyrgyzstan is bordered by Kazakhstan to Kazakhstan-Kyrgyzstan border, the north, Uzbekistan to Kyrgyzstan-Uzbekistan border, the west, Tajikistan to K ...
. Several other countries are believed to have unrecorded production of mercury from copper
electrowinning Electrowinning, also called electroextraction, is the Electrophoretic deposition, electrodeposition of metals from their ores that have been put in solution via a process commonly referred to as leaching. Electrorefining uses a similar process t ...
processes and by recovery from effluents. Because of the high toxicity of mercury, both the mining of cinnabar and refining for mercury are hazardous and historic causes of mercury poisoning. In China, prison labor was used by a private mining company as recently as the 1950s to develop new cinnabar mines. Thousands of prisoners were used by the Luo Xi mining company to establish new tunnels. Worker health in functioning mines is at high risk. A newspaper claimed that an unidentified
European Union The European Union (EU) is a supranational union, supranational political union, political and economic union of Member state of the European Union, member states that are located primarily in Europe, Europe. The union has a total area of ...
directive calling for energy-efficient lightbulbs to be made mandatory by 2012 encouraged China to re-open cinnabar mines to obtain the mercury required for CFL bulb manufacture. Environmental dangers have been a concern, particularly in the southern cities of
Foshan Foshan (, ), postal map romanization, alternately romanization of Chinese, romanized as Fatshan, is a prefecture-level city in central Guangdong province of China, Province, China. The entire prefecture covers and had a population of 9,498,863 ...
and
Guangzhou Guangzhou (, ; ; or ; ), also known as Canton () and alternatively romanized as Kwongchow or Kwangchow, is the capital and largest city of Guangdong province in southern China. Located on the Pearl River about north-northwest of Hong K ...
, and in
Guizhou Guizhou (; formerly Kweichow) is a landlocked province in the southwest region of the People's Republic of China China, officially the People's Republic of China (PRC), is a country in East Asia. It is the world's List of countries ...
province in the southwest. Abandoned mercury mine processing sites often contain very hazardous waste piles of roasted cinnabar calcines. Water run-off from such sites is a recognized source of ecological damage. Former mercury mines may be suited for constructive re-use. For example, in 1976
Santa Clara County, California Santa Clara County, officially the County of Santa Clara, is the sixth-most populous county in the U.S. state of California, with a population of 1,936,259, as of the 2020 United States Census, 2020 census. Santa Clara County and neighboring Sa ...
purchased the historic Almaden Quicksilver Mine and created a county park on the site, after conducting extensive safety and environmental analysis of the property.


Chemistry

All known mercury compounds exhibit one of two positive oxidation states: I and II. Experiments have failed to unequivocally demonstrate any higher oxidation states: both the claimed 1976 electrosynthesis of an unstable Hg(III) species and 2007 cryogenic isolation of HgF4 have disputed interpretations and remain difficult (if not impossible) to reproduce.


Compounds of mercury(I)

Unlike its lighter neighbors, cadmium and zinc, mercury usually forms simple stable compounds with metal-metal bonds. Most mercury(I) compounds are
diamagnetic Diamagnetic materials are repelled by a magnetic field A magnetic field is a vector field that describes the magnetic influence on moving electric charges, electric currents, and magnetic materials. A moving charge in a magnetic field expe ...
and feature the dimeric cation, Hg. Stable derivatives include the chloride and nitrate. Treatment of Hg(I) compounds complexation with strong ligands such as sulfide, cyanide, etc. induces disproportionation to and elemental mercury.
Mercury(I) chloride Mercury(I) chloride is the chemical compound with the formula Hg2Cl2. Also known as the mineral calomel (a rare mineral) or mercurous chloride, this dense white or yellowish-white, odorless solid is the principal example of a mercury (element), me ...
, a colorless solid also known as
calomel Calomel is a Mercury element, mercury chloride mineral with Chemical formula, formula Hg2Cl2 (see mercury(I) chloride). The name derives from Greek ''kalos'' (beautiful) and ''melas'' (black) because it turns black on reaction with ammonia. This ...
, is really the compound with the formula Hg2Cl2, with the connectivity Cl-Hg-Hg-Cl. It is a standard in electrochemistry. It reacts with chlorine to give mercuric chloride, which resists further oxidation. Mercury(I) hydride, a colorless gas, has the formula HgH, containing no Hg-Hg bond. Indicative of its tendency to bond to itself, mercury forms mercury polycations, which consist of linear chains of mercury centers, capped with a positive charge. One example is .


Compounds of mercury(II)

Mercury(II) is the most common oxidation state and is the main one in nature as well. All four mercuric halides are known. They form tetrahedral complexes with other ligands but the halides adopt linear coordination geometry, somewhat like Ag+ does. Best known is
mercury(II) chloride Mercury(II) chloride (or mercury bichloride, mercury dichloride), historically also known as sulema or corrosive sublimate, is the inorganic chemical compound of mercury and chlorine Chlorine is a chemical element with the Symbol (chem ...
, an easily sublimating white solid. HgCl2 forms
coordination complex A coordination complex consists of a central atom Every atom is composed of a atomic nucleus, nucleus and one or more electrons bound to the nucleus. The nucleus is made of one or more protons and a number of neutrons. Only the most common ...
es that are typically tetrahedral, e.g. .
Mercury(II) oxide Mercury(II) oxide, also called mercuric oxide or simply mercury oxide, is the inorganic compound with the formula Hg O. It has a red or orange color. Mercury(II) oxide is a solid at room temperature and pressure. The mineral form montroydite is ...
, the main
oxide An oxide () is a chemical compound that contains at least one oxygen atom and one other chemical element, element in its chemical formula. "Oxide" itself is the dianion of oxygen, an O2– (molecular) ion. with oxygen in the oxidation state of ...
of mercury, arises when the metal is exposed to air for long periods at elevated temperatures. It reverts to the elements upon heating near 400 °C, as was demonstrated by
Joseph Priestley Joseph Priestley (; 24 March 1733 – 6 February 1804) was an English chemist, Natural philosophy, natural philosopher, English Separatist, separatist theologian, Linguist, grammarian, multi-subject educator, and Liberalism, liberal Politi ...
in an early synthesis of pure
oxygen Oxygen is the chemical element with the chemical symbol, symbol O and atomic number 8. It is a member of the chalcogen Group (periodic table), group in the periodic table, a highly Chemical reaction, reactive nonmetal, and an oxidizing a ...
. Hydroxides of mercury are poorly characterized, as they are for its neighbors gold and silver. Being a soft metal, mercury forms very stable derivatives with the heavier
chalcogens The chalcogens (ore forming) ( ) are the chemical element A chemical element is a species of atoms that have a given number of protons in their atomic nucleus, nuclei, including the pure Chemical substance, substance consisting only of tha ...
. Preeminent is mercury(II) sulfide, HgS, which occurs in nature as the ore
cinnabar Cinnabar (), or cinnabarite (), from the grc, κιννάβαρι (), is the bright scarlet to brick-red form of Mercury sulfide, mercury(II) sulfide (HgS). It is the most common source ore for refining mercury (element), elemental mercury and ...
and is the brilliant pigment vermillion. Like ZnS, HgS crystallizes in two
forms Form is the shape, visual appearance, or :wikt:configuration, configuration of an object. In a wider sense, the form is the way something happens. Form also refers to: *Form (document), a document (printed or electronic) with spaces in which to ...
, the reddish cubic form and the black
zinc blende Sphalerite (sometimes spelled sphaelerite) is a sulfide mineral with the chemical formula . It is the most important ore of zinc. Sphalerite is found in a variety of deposit types, but it is primarily in Sedimentary exhalative deposits, sedimen ...
form. The latter sometimes occurs naturally as metacinnabar. Mercury(II) selenide (HgSe) and mercury(II) telluride (HgTe) are also known, these as well as various derivatives, e.g.
mercury cadmium telluride Hg1−xCdxTe or mercury cadmium telluride (also cadmium mercury telluride, MCT, MerCad Telluride, MerCadTel, MerCaT or CMT) is a chemical compound of cadmium telluride (CdTe) and mercury telluride (HgTe) with a tunable bandgap spanning the shortwave ...
and mercury zinc telluride being
semiconductors A semiconductor is a material which has an electrical resistivity and conductivity, electrical conductivity value falling between that of a electrical conductor, conductor, such as copper, and an insulator (electricity), insulator, such as glas ...
useful as
infrared detector An infrared detector is a detector A sensor is a device that produces an output signal for the purpose of sensing a physical phenomenon. In the broadest definition, a sensor is a device, module, machine, or subsystem that detects events or ...
materials. Mercury(II) salts form a variety of complex derivatives with
ammonia Ammonia is an inorganic chemical compound, compound of nitrogen and hydrogen with the chemical formula, formula . A Binary compounds of hydrogen, stable binary hydride, and the simplest pnictogen hydride, ammonia is a colourless gas with a dis ...
. These include Millon's base (Hg2N+), the one-dimensional polymer (salts of )), and "fusible white precipitate" or g(NH3)2l2. Known as Nessler's reagent, potassium tetraiodomercurate(II) () is still occasionally used to test for ammonia owing to its tendency to form the deeply colored iodide salt of Millon's base. Mercury fulminate is a
detonator A detonator, frequently a blasting cap, is a device used to trigger an explosive device. Detonators can be chemically, mechanically, or electrically initiated, the last two being the most common. The commercial use of explosives uses electri ...
widely used in
explosive An explosive (or explosive material) is a reactive substance that contains a great amount of potential energy that can produce an explosion if released suddenly, usually accompanied by the production of light, heat, sound, and pressure. An expl ...
s.


Organomercury compounds

Organic mercury compounds are historically important but are of little industrial value in the western world. Mercury(II) salts are a rare example of simple metal complexes that react directly with aromatic rings. Organomercury compounds are always divalent and usually two-coordinate and linear geometry. Unlike organocadmium and
organozinc Organozinc compounds in organic chemistry contain carbon (C) to zinc (Zn) chemical bonds. Organozinc chemistry is the science of organozinc compounds describing their physical properties, synthesis and reactions.The Chemistry of Organozinc Compoun ...
compounds, organomercury compounds do not react with water. They usually have the formula HgR2, which are often volatile, or HgRX, which are often solids, where R is
aryl In organic chemistry, an aryl is any functional group or substituent derived from an aromaticity, aromatic ring, usually an aromatic hydrocarbon, such as phenyl and naphthyl. "Aryl" is used for the sake of abbreviation or generalization, and "Ar ...
or
alkyl In organic chemistry Organic chemistry is a subdiscipline within chemistry involving the science, scientific study of the structure, properties, and reactions of organic compounds and organic materials, i.e., matter in its various forms that ...
and X is usually halide or acetate.
Methylmercury Methylmercury (sometimes methyl mercury) is an organometallic cation with the formula . It is the simplest organomercury compound. Methylmercury is extremely toxic, and its derivatives are the major source of organic mercury for humans. It is a ...
, a generic term for compounds with the formula CH3HgX, is a dangerous family of compounds that are often found in polluted water. They arise by a process known as
biomethylation In the chemical sciences, methylation denotes the addition of a methyl, methyl group on a Substrate (chemistry), substrate, or the substitution of an atom (or group) by a methyl group. Methylation is a form of alkylation, with a methyl group repla ...
.


Applications

Mercury is used primarily for the manufacture of industrial chemicals or for electrical and electronic applications. It is used in some
liquid-in-glass thermometer A thermometer is a device that temperature measurement, measures temperature or a temperature gradient (the degree of hotness or coldness of an object). A thermometer has two important elements: (1) a temperature sensor (e.g. the bulb of a merc ...
s, especially those used to measure high temperatures. A still increasing amount is used as gaseous mercury in fluorescent lamps, while most of the other applications are slowly being phased out due to health and safety regulations. In some applications, mercury is replaced with less toxic but considerably more expensive
Galinstan Galinstan (R) is a brand name for a alloy composed of gallium, indium, and tin which melts at and is thus liquid at room temperature. However, it is not a eutectic alloy but a near eutectic alloy. In scientific literature, galinstan is also used ...
alloy An alloy is a mixture of chemical elements of which at least one is a metal. Unlike chemical compounds with metallic bases, an alloy will retain all the properties of a metal in the resulting material, such as electrical conductivity, ductility, ...
.


Medicine

Mercury and its compounds have been used in medicine, although they are much less common today than they once were, now that the toxic effects of mercury and its compounds are more widely understood. An example of the early therapeutic application of mercury of was published in 1787 by
James Lind James Lind (4 October 1716 – 13 July 1794) was a Scottish doctor. He was a pioneer of naval hygiene Hygiene is a series of practices performed to preserve health. According to the World Health Organization (WHO), "Hygiene refers to co ...
. The first edition of the Merck's Manual (1899) featured many mercuric compounds such as: * Mercauro * Mercuro-iodo-hemol. * Mercury-ammonium chloride * Mercury Benzoate * Mercuric * Mercury Bichloride (Corrosive Mercuric Chloride, U.S.P.) * Mercury Chloride * Mild Mercury Cyanide * Mercury Succinimide * Mercury Iodide * Red Mercury Biniodide * Mercury Iodide * Yellow Mercury Proto-iodide * Black (Hahnemann), Soluble Mercury Oxide * Red Mercury Oxide * Yellow Mercury Oxide * Mercury Salicylate * Mercury Succinimide * Mercury Imido-succinate * Mercury Sulphate * Basic Mercury Subsulphate; Turpeth Mineral * Mercury Tannate * Mercury-Ammonium Chloride Mercury is an ingredient in dental amalgams.
Thiomersal Thiomersal (International Nonproprietary Name, INN), or thimerosal (United States Adopted Name, USAN, Japanese Accepted Name, JAN), is an organomercury compound. It is a well-established antiseptic and antifungal agent. The pharmaceutical corpor ...
(called ''Thimerosal'' in the United States) is an
organic compound In chemistry, organic compounds are generally any chemical compounds that contain carbon-hydrogen or carbon-carbon chemical bond, bonds. Due to carbon's ability to Catenation, catenate (form chains with other carbon atoms), millions of organic c ...
used as a
preservative A preservative is a substance or a chemical that is added to products such as food products, beverages, pharmaceutical drugs, paints, biological samples, cosmetics, wood, and many other products to prevent decomposition by microbial growth or by ...
in
vaccine A vaccine is a biological Dosage form, preparation that provides active acquired immunity to a particular infectious disease, infectious or cancer, malignant disease. The safety and effectiveness of vaccines has been widely studied and verifie ...
s, though this use is in decline. Thiomersal is metabolized to ethyl mercury. Although it was widely speculated that this mercury-based preservative could cause or trigger
autism The autism spectrum, often referred to as just autism or in the context of a professional diagnosis autism spectrum disorder (ASD) or autism spectrum condition (ASC), is a neurodevelopmental disorder, neurodevelopmental condition (or conditions) ...
in children, scientific studies showed no evidence supporting any such link. Nevertheless, thiomersal has been removed from, or reduced to trace amounts in all U.S. vaccines recommended for children 6 years of age and under, with the exception of inactivated influenza vaccine. Another mercury compound, merbromin (Mercurochrome), is a topical antiseptic used for minor cuts and scrapes that is still in use in some countries. Mercury in the form of one of its common ores, cinnabar, is used in various traditional medicines, especially in
traditional Chinese medicine Traditional Chinese medicine (TCM) is an alternative medicine, alternative medical practice drawn from traditional medicine in China. It has been described as "fraught with pseudoscience", with the majority of its treatments having no logica ...
. Review of its safety has found that cinnabar can lead to significant mercury intoxication when heated, consumed in
overdose A drug overdose (overdose or OD) is the ingestion Ingestion is the consumption of a substance by an organism. In animals, it normally is accomplished by taking in a substance through the mouth into the gastrointestinal tract, such as through e ...
, or taken long term, and can have adverse effects at therapeutic doses, though effects from therapeutic doses are typically reversible. Although this form of mercury appears to be less toxic than other forms, its use in traditional Chinese medicine has not yet been justified, as the therapeutic basis for the use of cinnabar is not clear. Today, the use of mercury in medicine has greatly declined in all respects, especially in developed countries. Thermometers and
sphygmomanometer A sphygmomanometer ( ), a blood pressure monitor, or blood pressure gauge, is a device used to measure blood pressure, composed of an inflatable cuff to collapse and then release the artery under the cuff in a controlled manner, and a mercury (e ...
s containing mercury were invented in the early 18th and late 19th centuries, respectively. In the early 21st century, their use is declining and has been banned in some countries, states and medical institutions. In 2002, the U.S. Senate passed legislation to phase out the sale of non-prescription mercury thermometers. In 2003, Washington and
Maine Maine () is a U.S. state, state in the New England and Northeastern United States, Northeastern regions of the United States. It borders New Hampshire to the west, the Gulf of Maine to the southeast, and the Provinces and territories of Canad ...
became the first states to ban mercury blood pressure devices. Mercury compounds are found in some
over-the-counter drug Over-the-counter (OTC) drugs are medication, medicines sold directly to a consumer without a requirement for a medical prescription, prescription from a healthcare professional, as opposed to prescription drugs, which may be supplied only to co ...
s, including topical
antiseptics An antiseptic (from Greek ἀντί ''anti'', "against" and σηπτικός ''sēptikos'', "putrefactive") is an antimicrobial substance or compound that is applied to living biological tissue, tissue/skin to reduce the possibility of infection ...
, stimulant laxatives, diaper-rash
ointment A topical medication is a medication that is applied to a particular place on or in the body. Most often topical medication means application to body surface area, body surfaces such as the human skin, skin or mucous membranes to treat ailments ...
,
eye drops Eye drops or eyedrops are liquid drops applied directly to the surface of the eye usually in small amounts such as a single drop or a few drops. Eye drops usually contain saline (medicine), saline to match the salinity of the eye. Drops contai ...
, and
nasal spray Nasal sprays are used to deliver medications locally in the nasal cavities or systemically. They are used locally for conditions such as nasal congestion and allergic rhinitis. In some situations, the nasal delivery route is preferred for s ...
s. The
FDA The United States Food and Drug Administration (FDA or US FDA) is a List of United States federal agencies, federal agency of the United States Department of Health and Human Services, Department of Health and Human Services. The FDA is respon ...
has "inadequate data to establish general recognition of the safety and effectiveness" of the mercury ingredients in these products. Mercury is still used in some diuretics although substitutes now exist for most therapeutic uses.


Production of chlorine and caustic soda

Chlorine Chlorine is a chemical element with the Symbol (chemistry), symbol Cl and atomic number 17. The second-lightest of the halogens, it appears between fluorine and bromine in the periodic table and its properties are mostly intermediate betwee ...
is produced from
sodium chloride Sodium chloride , commonly known as salt (although sea salt also contains other chemical salt (chemistry), salts), is an ionic compound with the chemical formula NaCl, representing a 1:1 ratio of sodium and chloride ions. With molar masses of ...
(common salt, NaCl) using
electrolysis In chemistry Chemistry is the scientific study of the properties and behavior of matter. It is a natural science that covers the elements that make up matter to the compounds made of atoms, molecules and ions: their composition, str ...
to separate the metallic
sodium Sodium is a chemical element with the Symbol (chemistry), symbol Na (from Latin ''natrium'') and atomic number 11. It is a soft, silvery-white, highly reactive metal. Sodium is an alkali metal, being in group 1 element, group 1 of the ...
from the chlorine gas. Usually the salt is dissolved in water to produce a brine. By-products of any such
chloralkali process The chloralkali process (also chlor-alkali and chlor Alkali#Alkali salts, alkali) is an industrial process for the electrolysis of NaCl, sodium chloride (NaCl) solutions. It is the technology used to Chlorine production, produce chlorine and sodi ...
are hydrogen (H2) and
sodium hydroxide Sodium hydroxide, also known as lye and caustic soda, is an inorganic compound with the formula NaOH. It is a white solid ionic compound consisting of sodium cations and hydroxide anions . Sodium hydroxide is a highly corrosive, caustic base (c ...
(NaOH), which is commonly called caustic soda or
lye A lye is a metal hydroxide traditionally obtained by leaching wood ashes, or a strong alkali In chemistry Chemistry is the scientific study of the properties and behavior of matter. It is a natural science that covers the el ...
. By far the largest use of mercury in the late 20th century was in the mercury cell process (also called the Castner-Kellner process) where metallic sodium is formed as an amalgam at a
cathode A cathode is the electrode from which a conventional current leaves a polarized electrical device. This definition can be recalled by using the mnemonic ''CCD'' for ''Cathode Current Departs''. A conventional current describes the direction in ...
made from mercury; this sodium is then reacted with water to produce sodium hydroxide. Many of the industrial mercury releases of the 20th century came from this process, although modern plants claimed to be safe in this regard. After about 1985, all new chloralkali production facilities that were built in the United States used membrane cell or diaphragm cell technologies to produce chlorine.


Laboratory uses

Some medical thermometers, especially those for high temperatures, are filled with mercury; they are gradually disappearing. In the United States, non-prescription sale of mercury fever thermometers has been banned since 2003. Some transit telescopes use a basin of mercury to form a flat and absolutely horizontal mirror, useful in determining an absolute vertical or perpendicular reference. Concave horizontal parabolic mirrors may be formed by rotating liquid mercury on a disk, the parabolic form of the liquid thus formed reflecting and focusing incident light. Such
liquid-mirror telescope Liquid-mirror telescopes are telescopes with mirrors made with a reflective liquid. The most common liquid used is Mercury (element), mercury, but other liquids will work as well (for example, Fusible alloy, low-melting alloys of gallium). The liq ...
s are cheaper than conventional large mirror telescopes by up to a factor of 100, but the mirror cannot be tilted and always points straight up. Liquid mercury is a part of popular secondary reference
electrode An electrode is an electrical conductor used to make contact with a nonmetallic part of a Electronic circuit, circuit (e.g. a semiconductor, an electrolyte, a vacuum or air). Electrodes are essential parts of Electric battery, batteries that can ...
(called the calomel electrode) in
electrochemistry Electrochemistry is the branch of physical chemistry concerned with the relationship between Electric potential, electrical potential difference, as a measurable and quantitative phenomenon, and identifiable chemical change, with the potential dif ...
as an alternative to the
standard hydrogen electrode The standard hydrogen electrode (abbreviated SHE), is a redox electrode which forms the basis of the Table of standard electrode potentials, thermodynamic scale of oxidation-reduction potentials. Its absolute electrode potential is estimated to be ...
. The calomel electrode is used to work out the
electrode potential In electrochemistry Electrochemistry is the branch of physical chemistry concerned with the relationship between Electric potential, electrical potential difference, as a measurable and quantitative phenomenon, and identifiable chemical change, w ...
of half cells. Last, but not least, the
triple point In thermodynamics, the triple point of a substance is the temperature and pressure at which the three Phase (matter), phases (gas, liquid, and solid) of that substance coexist in thermodynamic equilibrium.. It is that temperature and pressure at w ...
of mercury, −38.8344 °C, is a fixed point used as a temperature standard for the International Temperature Scale (
ITS-90 The International Temperature Scale of 1990 (ITS-90) is an equipment calibration standard specified by the CIPM, International Committee of Weights and Measures (CIPM) for making measurements on the Kelvin and Degree Celsius, Celsius temperature sc ...
). In polarography both the
dropping mercury electrode A liquid metal electrode is an electrode that uses a liquid metal, such as mercury (element), mercury, Galinstan, and NaK. They can be used in electrocapillarity, voltammetry, and Electrical impedance, impedance measurements. Dropping mercury elec ...
and the
hanging mercury drop electrode A liquid metal electrode is an electrode that uses a liquid metal, such as mercury (element), mercury, Galinstan, and NaK. They can be used in electrocapillarity, voltammetry, and Electrical impedance, impedance measurements. Dropping mercury elec ...
use elemental mercury. This use allows a new uncontaminated electrode to be available for each measurement or each new experiment. Mercury-containing compounds are also of use in the field of
structural biology Structural biology is a field that is many centuries old which, and as defined by the Journal of Structural Biology, deals with structural analysis of living material (formed, composed of, and/or maintained and refined by living cells) at every le ...
. Mercuric compounds such as
mercury(II) chloride Mercury(II) chloride (or mercury bichloride, mercury dichloride), historically also known as sulema or corrosive sublimate, is the inorganic chemical compound of mercury and chlorine Chlorine is a chemical element with the Symbol (chem ...
or potassium tetraiodomercurate(II) can be added to protein crystals in an effort to create heavy atom derivatives that can be used to solve the
phase problem In physics, the phase problem is the problem of loss of information concerning the phase that can occur when making a physical measurement. The name comes from the field of X-ray crystallography X-ray crystallography is the experimental science ...
in
X-ray crystallography X-ray crystallography is the experimental science determining the atomic and molecular structure of a crystal, in which the crystalline structure causes a beam of incident X-rays to Diffraction, diffract into many specific directions. By measurin ...
via
isomorphous replacement Multiple isomorphous replacement (MIR) is historically the most common approach to solving the phase problem in X-ray crystallography studies of proteins. For protein crystals this method is conducted by soaking the crystal of a sample to be analyze ...
or
anomalous scattering Anomalous X-ray scattering (AXRS or XRAS) is a non-destructive determination technique within X-ray diffraction X-ray crystallography is the experimental science determining the atomic and molecular structure of a crystal, in which the crystallin ...
methods.


Niche uses

Gaseous mercury is used in
mercury-vapor lamp A mercury-vapor lamp is a gas-discharge lamp that uses an electric arc through vaporized Mercury (element), mercury to produce light. The arc discharge is generally confined to a small fused quartz arc tube mounted within a larger Soda–lime g ...
s and some "
neon sign In the signage industry, neon signs are electric signs lighted by long luminous gas-discharge tubes that contain rarefied neon or other gases. They are the most common use for neon lighting, which was first demonstrated in a modern form in Decem ...
" type advertising signs and
fluorescent lamp A fluorescent lamp, or fluorescent tube, is a low-pressure mercury-vapor gas-discharge lamp that uses fluorescence to produce visible light. An electric current in the gas excites mercury vapor, which produces short-wave ultraviolet, ult ...
s. Those low-pressure lamps emit very spectrally narrow lines, which are traditionally used in
optical spectroscopy Spectroscopy is the field of study that measures and interprets the electromagnetic spectra that result from the interaction Interaction is action that occurs between two or more objects, with broad use in philosophy and the sciences. It may ...
for calibration of spectral position. Commercial calibration lamps are sold for this purpose; reflecting a fluorescent ceiling light into a spectrometer is a common calibration practice. Gaseous mercury is also found in some electron tubes, including
ignitron An ignitron is a type of gas-filled tube A gas-filled tube, also commonly known as a discharge tube or formerly as a Plücker tube, is an arrangement of electrodes in a gas within an insulating, temperature-resistant envelope. Gas-filled tub ...
s,
thyratron A thyratron is a type of gas-filled tube used as a high-power electrical switch and controlled rectifier. Thyratrons can handle much greater currents than similar hard-vacuum tubes. Electron multiplication occurs when the gas becomes ionized, pro ...
s, and
mercury arc rectifier Mercury commonly refers to: * Mercury (planet), the nearest planet to the Sun * Mercury (element), a metallic chemical element with the symbol Hg * Mercury (mythology), a Roman god Mercury or The Mercury may also refer to: Companies * Mercury ...
s. It is also used in specialist medical care lamps for skin tanning and disinfection. Gaseous mercury is added to
cold cathode A cold cathode is a cathode that is not electrically heated by a filament.A negatively charged electrode emits electron The electron ( or ) is a subatomic particle with a negative one elementary charge, elementary electric charge. Elect ...
argon Argon is a chemical element with the Symbol (chemistry), symbol Ar and atomic number 18. It is in group 18 of the periodic table and is a noble gas. Argon is the third-most abundant gas in Earth's atmosphere, at 0.934% (9340 Parts-per notatio ...
-filled lamps to increase the
ionization Ionization, or Ionisation is the process by which an atom Every atom is composed of a atomic nucleus, nucleus and one or more electrons bound to the nucleus. The nucleus is made of one or more protons and a number of neutrons. Only the mos ...
and
electrical conductivity Electrical resistivity (also called specific electrical resistance or volume resistivity) is a fundamental property of a material that measures how strongly it resists electric current. A low resistivity indicates a material that readily allows ...
. An argon-filled lamp without mercury will have dull spots and will fail to light correctly. Lighting containing mercury can be bombarded/oven pumped only once. When added to
neon Neon is a chemical element A chemical element is a species of atoms that have a given number of protons in their atomic nucleus, nuclei, including the pure Chemical substance, substance consisting only of that species. Unlike chemical com ...
filled tubes the light produced will be inconsistent red/blue spots until the initial burning-in process is completed; eventually it will light a consistent dull off-blue color. File:Germicidal UV discharge tube glow rotate.jpg, The deep violet glow of a mercury vapor discharge in a
germicidal lamp A germicidal lamp (also known as disinfection lamp or sterilizer lamp) is an electric light that produces ultraviolet C (UVC) light. This short-wave ultraviolet light disrupts DNA base pairing, causing formation of pyrimidine dimers, and leads ...
, whose spectrum is rich in invisible ultraviolet radiation. File:Mercuryvaporlamp.jpg, Skin tanner containing a low-pressure mercury vapor lamp and two infrared lamps, which act both as light source and
electrical ballast An electrical ballast is a device placed in series with a load to limit the amount of electric current, current in an electrical network, electrical circuit. A familiar and widely used example is the inductive ballast used in fluorescent lamp ...
File:Leuchtstofflampen-chtaube050409.jpg, Assorted types of fluorescent lamps. File:Deep Space Atomic Clock-DSAC.jpg, The miniaturized Deep Space Atomic Clock is a linear ion-trap-based mercury ion clock, designed for precise and real-time radio navigation in deep space.
The Deep Space Atomic Clock (DSAC) under development by the
Jet Propulsion Laboratory The Jet Propulsion Laboratory (JPL) is a Federally funded research and development centers, federally funded research and development center and NASA field center in the City of La Cañada Flintridge, California, La Cañada Flintridge, California ...
utilises mercury in a linear ion-trap-based clock. The novel use of mercury allows very compact atomic clocks, with low energy requirements, and is therefore ideal for space probes and Mars missions.


Cosmetics

Mercury, as
thiomersal Thiomersal (International Nonproprietary Name, INN), or thimerosal (United States Adopted Name, USAN, Japanese Accepted Name, JAN), is an organomercury compound. It is a well-established antiseptic and antifungal agent. The pharmaceutical corpor ...
, is widely used in the manufacture of
mascara Mascara is a Cosmetics, cosmetic commonly used to enhance the upper and lower eyelashes. It is used to darken, thicken, lengthen, and/or define the eyelashes. Normally in one of three forms—liquid, powder, or cream—the modern mascara produc ...
. In 2008, Minnesota became the first state in the United States to ban intentionally added mercury in cosmetics, giving it a tougher standard than the federal government. A study in geometric mean urine mercury concentration identified a previously unrecognized source of exposure (skin care products) to inorganic mercury among
New York City New York, often called New York City or NYC, is the List of United States cities by population, most populous city in the United States. With a 2020 population of 8,804,190 distributed over , New York City is also the L ...
residents. Population-based biomonitoring also showed that mercury concentration levels are higher in consumers of seafood and fish meals.


Skin whitening

Mercury is effective as an active ingredient in
skin whitening Skin whitening, also known as skin lightening and skin bleaching, is the practice of using chemical substances in an attempt to lighten the skin or provide an even skin color by reducing the melanin Melanin (; from el, μέλας, melas, ...
compounds used to depigment skin. The Minamata Convention on Mercury limits the concentration of mercury in such whiteners to 1 part per million. However, as of 2022, many commercially sold whitener products continue to exceed that limit, and are considered toxic.


Firearms

Mercury(II) fulminate Mercury(II) fulminate, or Hg(CNO)2, is a primary explosive. It is highly sensitive to friction, heat and shock (mechanics), shock and is mainly used as a trigger for other explosives in percussion caps and detonators. Mercury(II) cyanate, though i ...
is a
primary explosive An explosive (or explosive material) is a reactive substance that contains a great amount of potential energy that can produce an explosion if released suddenly, usually accompanied by the production of light, heat, sound, and pressure. An expl ...
which is mainly used as a primer of a cartridge in firearms.


Historic uses

Many historic applications made use of the peculiar physical properties of mercury, especially as a dense liquid and a liquid metal: * Quantities of liquid mercury ranging from have been recovered from elite
Maya Maya may refer to: Civilizations * Maya peoples, of southern Mexico and northern Central America ** Maya civilization, the historical civilization of the Maya peoples ** Maya language (disambiguation), Maya language, the languages of the Maya peop ...
tombs (100–700 AD) or ritual caches at six sites. This mercury may have been used in bowls as
mirrors A mirror or looking glass is an object that Reflection (physics), reflects an image. Light that bounces off a mirror will show an image of whatever is in front of it, when focused through the lens of the eye or a camera. Mirrors reverse the ...
for
divinatory Divination (from Latin ''divinare'', 'to foresee, to foretell, to predict, to prophesy') is the attempt to gain insight into a question or situation by way of an occultic, standardized process or ritual. Used in various forms throughout history ...
purposes. Five of these date to the Classic Period of Maya civilization (c. 250–900) but one example predated this. * In
Islamic Spain Al-Andalus DIN 31635, translit. ; an, al-Andalus; ast, al-Ándalus; eu, al-Andalus; ber, ⴰⵏⴷⴰⵍⵓⵙ, label=Berber languages, Berber, translit=Andalus; ca, al-Àndalus; gl, al-Andalus; oc, Al Andalús; pt, al-Ândalus; es, ...
, it was used for filling decorative pools. Later, the American artist
Alexander Calder Alexander Calder (; July 22, 1898 – November 11, 1976) was an American Sculpture, sculptor known both for his innovative mobile (sculpture), mobiles (kinetic sculptures powered by motors or air currents) that embrace chance in their aesthetic, ...
built a mercury fountain for the Spanish Pavilion at the 1937 World Exhibition in Paris. The fountain is now on display at the Fundació Joan Miró in
Barcelona Barcelona ( , , ) is a city on the coast of northeastern Spain. It is the capital and largest city of the autonomous community of Catalonia, as well as the second most populous municipality of Spain. With a population of 1.6 million within ci ...
. * Mercury was used inside wobbler lures. Its heavy, liquid form made it useful since the lures made an attractive irregular movement when the mercury moved inside the plug. Such use was stopped due to environmental concerns, but illegal preparation of modern fishing plugs has occurred. * The
Fresnel lens A Fresnel lens ( ; ; or ) is a type of composite compact lens (optics), lens developed by the French physicist Augustin-Jean Fresnel (1788–1827) for use in lighthouses. It has been called "the invention that saved a million ships." The desi ...
es of old lighthouses used to float and rotate in a bath of mercury which acted like a bearing. * Mercury
sphygmomanometer A sphygmomanometer ( ), a blood pressure monitor, or blood pressure gauge, is a device used to measure blood pressure, composed of an inflatable cuff to collapse and then release the artery under the cuff in a controlled manner, and a mercury (e ...
s (blood pressure meter),
barometer A barometer is a scientific instrument that is used to measure air pressure in a certain environment. Pressure tendency can forecast short term changes in the weather. Many measurements of air pressure are used within surface weather analysis ...
s,
diffusion pump Diffusion pumps use a high speed jet of vapor to direct gas molecules in the pump throat down into the bottom of the pump and out the exhaust. They were the first type of high vacuum pumps operating in the regime of free molecular flow, where the ...
s, coulometers, and many other laboratory instruments took advantage of mercury's properties as a very dense, opaque liquid with a nearly linear thermal expansion. * As an electrically conductive liquid, it was used in
mercury switch A mercury switch is an electrical switch that opens and closes a electrical circuit, circuit when a small amount of the liquid metal mercury (element), mercury connects metal electrodes to close the circuit. There are several different basic des ...
es (including home mercury light switches installed prior to 1970), tilt switches used in old fire detectors, and tilt switches in some home thermostats. * Owing to its acoustic properties, mercury was used as the propagation medium in
delay-line memory Delay-line memory is a form of computer memory, now obsolete, that was used on some of the earliest Digital data, digital computers. Like many modern forms of electronic computer memory, delay-line memory was a memory refresh, refreshable memory, ...
devices used in early digital computers of the mid-20th century. * Experimental mercury vapor turbines were installed to increase the efficiency of fossil-fuel electrical power plants. The South Meadow power plant in Hartford, CT employed mercury as its
working fluid For fluid power, a working fluid is a gas or liquid that primarily transfers force, motion, or mechanical energy. In hydraulics, water or hydraulic fluid transfers force between hydraulic components such as hydraulic pumps, hydraulic cylinders, a ...
, in a
binary Binary may refer to: Science and technology Mathematics * Binary number A binary number is a number expressed in the base-2 numeral system or binary numeral system, a method of mathematical expression which uses only two symbols: typical ...
configuration with a secondary water circuit, for a number of years starting in the late 1920s in a drive to improve plant efficiency. Several other plants were built, including the Schiller Station in Portsmouth, NH, which went online in 1950. The idea did not catch on industry-wide due to the weight and toxicity of mercury, as well as the advent of supercritical steam plants in later years. * Similarly, liquid mercury was used as a
coolant A coolant is a substance, typically liquid, that is used to reduce or regulate the temperature of a system. An ideal coolant has high thermal capacity, low viscosity, is low-cost, non-toxic, chemically inert and neither causes nor promotes corrosio ...
for some
nuclear reactor A nuclear reactor is a device used to initiate and control a fission nuclear chain reaction or nuclear fusion reactions. Nuclear reactors are used at nuclear power plants for electricity generation and in nuclear marine propulsion. Heat from nu ...
s; however,
sodium Sodium is a chemical element with the Symbol (chemistry), symbol Na (from Latin ''natrium'') and atomic number 11. It is a soft, silvery-white, highly reactive metal. Sodium is an alkali metal, being in group 1 element, group 1 of the ...
is proposed for reactors cooled with liquid metal, because the high density of mercury requires much more energy to circulate as coolant. * Mercury was a propellant for early ion engines in electric space propulsion systems. Advantages were mercury's high molecular weight, low ionization energy, low dual-ionization energy, high liquid density and liquid storability at
room temperature Colloquially, "room temperature" is a range of air temperatures that most people prefer for indoor settings. It feels comfortable to a person when they are wearing typical indoor clothing. Human comfort can extend beyond this range depending on ...
. Disadvantages were concerns regarding environmental impact associated with ground testing and concerns about eventual cooling and condensation of some of the propellant on the spacecraft in long-duration operations. The first spaceflight to use electric propulsion was a mercury-fueled ion thruster developed at NASA Glenn Research Center and flown on the Space Electric Rocket Test " SERT-1" spacecraft launched by
NASA The National Aeronautics and Space Administration (NASA ) is an independent agencies of the United States government, independent agency of the US federal government responsible for the civil List of government space agencies, space program ...
at its
Wallops Flight Facility Wallops Flight Facility (WFF) is a rocket launch site on Wallops Island on the Eastern Shore of Virginia, United States, just east of the Delmarva Peninsula and approximately north-northeast of Norfolk, VA, Norfolk. The facility is operated by ...
in 1964. The SERT-1 flight was followed up by the SERT-2 flight in 1970. Mercury and
caesium Caesium (IUPAC spelling) (or cesium in American English) is a chemical element with the Symbol (chemistry), symbol Cs and atomic number 55. It is a soft, silvery-golden alkali metal with a melting point of , which makes it one of only five elem ...
were preferred propellants for ion engines until
Hughes Research Laboratory HRL Laboratories (formerly Hughes Research Laboratories) is a research center in Malibu, California California is a U.S. state, state in the Western United States, located along the West Coast of the United States, Pacific Coast. With ne ...
performed studies finding
xenon Xenon is a chemical element A chemical element is a species of atoms that have a given number of protons in their atomic nucleus, nuclei, including the pure Chemical substance, substance consisting only of that species. Unlike chemical c ...
gas to be a suitable replacement. Xenon is now the preferred propellant for ion engines as it has a high molecular weight, little or no reactivity due to its
noble gas The noble gases (historically also the inert gases; sometimes referred to as aerogens) make up a class of chemical elements with similar properties; under Standard conditions for temperature and pressure, standard conditions, they are all odorle ...
nature, and has a high liquid density under mild cryogenic storage. Other applications made use of the chemical properties of mercury: * The
mercury battery A mercury battery (also called mercuric oxide battery, mercury cell, button cell, or Ruben-Mallory) is a non-rechargeable electrochemical battery, a primary cell. Mercury batteries use a reaction between mercuric oxide and zinc electrodes in an ...
is a non-rechargeable electrochemical battery, a
primary cell A primary battery or primary cell is a battery (electricity), battery (a galvanic cell) that is designed to be used once and discarded, and not recharged with electricity and reused like a secondary cell (rechargeable battery). In general, the el ...
, that was common in the middle of the 20th century. It was used in a wide variety of applications and was available in various sizes, particularly button sizes. Its constant voltage output and long shelf life gave it a niche use for camera light meters and hearing aids. The mercury cell was effectively banned in most countries in the 1990s due to concerns about the mercury contaminating landfills. * Mercury was used for preserving wood, developing
daguerreotype Daguerreotype (; french: daguerréotype) was the first publicly available photography, photographic process; it was widely used during the 1840s and 1850s. "Daguerreotype" also refers to an image created through this process. Invented by Loui ...
s,
silvering Silvering is the chemistry, chemical process of coating a non-conductive substrate such as glass with a reflectivity, reflective substance, to produce a mirror. While the metal is often silver, the term is used for the application of any reflect ...
mirror A mirror or looking glass is an object that Reflection (physics), reflects an image. Light that bounces off a mirror will show an image of whatever is in front of it, when focused through the lens of the eye or a camera. Mirrors reverse the ...
s,
anti-fouling paint Anti-fouling paint is a specialized category of coatings applied as the outer (outboard) layer to the hull (ship), hull of a ship or boat, to slow the growth of and facilitate detachment of subaquatic organisms that biofouling, attach to the hu ...
s (discontinued in 1990),
herbicide Herbicides (, ), also commonly known as weedkillers, are substances used to control undesired plants, also known as weeds.EPA. February 201Pesticides Industry. Sales and Usage 2006 and 2007: Market Estimates. Summary in press releasMain page fo ...
s (discontinued in 1995), interior latex paint, handheld maze games, cleaning, and road leveling devices in cars. Mercury compounds have been used in
antiseptic An antiseptic (from Greek ἀντί ''anti'', "against" and σηπτικός ''sēptikos'', "putrefactive") is an antimicrobial substance or compound that is applied to living biological tissue, tissue/skin to reduce the possibility of infection ...
s, laxatives,
antidepressant Antidepressants are a class of medication used to treat major depressive disorder, anxiety disorders, chronic pain conditions, and to help manage addictions. Common Side effect, side-effects of antidepressants include Xerostomia, dry mouth, weig ...
s, and in antisyphilitics. * It was allegedly used by allied spies to sabotage Luftwaffe planes: a mercury paste was applied to bare
aluminium Aluminium (aluminum in American and Canadian English) is a chemical element A chemical element is a species of atoms that have a given number of protons in their atomic nucleus, nuclei, including the pure Chemical substance, substan ...
, causing the metal to rapidly
corrode Corrosion is a Erosion, natural process that converts a refined metal into a more chemically stable oxide. It is the gradual deterioration of materials (usually a metal) by chemical or electrochemical reaction with their environment. Corrosio ...
; this would cause structural failures. *
Chloralkali process The chloralkali process (also chlor-alkali and chlor Alkali#Alkali salts, alkali) is an industrial process for the electrolysis of NaCl, sodium chloride (NaCl) solutions. It is the technology used to Chlorine production, produce chlorine and sodi ...
: The largest industrial use of mercury during the 20th century was in electrolysis for separating chlorine and sodium from brine; mercury being the
anode An anode is an electrode of a polarized electrical device through which conventional current enters the device. This contrasts with a cathode, an electrode of the device through which conventional current leaves the device. A common mnemonic is ...
of the Castner-Kellner process. The chlorine was used for bleaching paper (hence the location of many of these plants near paper mills) while the sodium was used to make sodium hydroxide for soaps and other cleaning products. This usage has largely been discontinued, replaced with other technologies that utilize membrane cells. * As
electrode An electrode is an electrical conductor used to make contact with a nonmetallic part of a Electronic circuit, circuit (e.g. a semiconductor, an electrolyte, a vacuum or air). Electrodes are essential parts of Electric battery, batteries that can ...
s in some types of
electrolysis In chemistry Chemistry is the scientific study of the properties and behavior of matter. It is a natural science that covers the elements that make up matter to the compounds made of atoms, molecules and ions: their composition, str ...
, batteries ( mercury cells),
sodium hydroxide Sodium hydroxide, also known as lye and caustic soda, is an inorganic compound with the formula NaOH. It is a white solid ionic compound consisting of sodium cations and hydroxide anions . Sodium hydroxide is a highly corrosive, caustic base (c ...
and
chlorine Chlorine is a chemical element with the Symbol (chemistry), symbol Cl and atomic number 17. The second-lightest of the halogens, it appears between fluorine and bromine in the periodic table and its properties are mostly intermediate betwee ...
production, handheld games,
catalyst Catalysis () is the process of increasing the reaction rate, rate of a chemical reaction by adding a substance known as a catalyst (). Catalysts are not consumed in the reaction and remain unchanged after it. If the reaction is rapid and the ...
s,
insecticide Insecticides are substances used to kill insect Insects (from Latin ') are pancrustacean Hexapoda, hexapod invertebrates of the class (biology), class Insecta. They are the largest group within the arthropod phylum. Insects have a chit ...
s. * Mercury was once used as a gun barrel bore cleaner. * From the mid-18th to the mid-19th centuries, a process called " carroting" was used in the making of
felt Felt is a textile material that is produced by matting, condensing and pressing fibers together. Felt can be made of natural fibers such as wool or animal fur, or from synthetic fibers such as petroleum-based acrylic fiber, acrylic or acrylonit ...
hats. Animal skins were rinsed in an orange solution (the term "carroting" arose from this color) of the mercury compound mercuric nitrate, Hg(NO3)2·2H2O. This process separated the fur from the pelt and matted it together. This solution and the vapors it produced were highly toxic. The
United States Public Health Service The United States Public Health Service (USPHS or PHS) is a collection of agencies of the Department of Health and Human Services concerned with public health, containing nine out of the department's twelve operating divisions. The Assistant S ...
banned the use of mercury in the felt industry in December 1941. The psychological symptoms associated with mercury poisoning inspired the phrase " mad as a hatter".
Lewis Carroll Charles Lutwidge Dodgson (; 27 January 1832 – 14 January 1898), better known by his pen name Lewis Carroll, was an English author, poet and mathematician. His most notable works are ''Alice's Adventures in Wonderland'' (1865) and its sequel ...
's " Mad Hatter" in his book ''
Alice's Adventures in Wonderland ''Alice's Adventures in Wonderland'' (commonly ''Alice in Wonderland'') is an 1865 English novel by Lewis Carroll. It details the story of a young girl named Alice (Alice's Adventures in Wonderland), Alice who falls through a rabbit hole into a ...
'' was a play on words based on the older phrase, but the character himself does not exhibit symptoms of mercury poisoning. * Gold and silver mining. Historically, mercury was used extensively in hydraulic gold mining in order to help the gold to sink through the flowing water-gravel mixture. Thin gold particles may form mercury-gold amalgam and therefore increase the gold recovery rates. Large-scale use of mercury stopped in the 1960s. However, mercury is still used in small scale, often clandestine, gold prospecting. It is estimated that 45,000 metric tons of mercury used in California for
placer mining Placer mining () is the mining of stream bed (Alluvium, alluvial) deposits for minerals. This may be done by open-pit mining, open-pit (also called open-cast mining) or by various surface excavating equipment or tunneling equipment. Placer minin ...
have not been recovered. Mercury was also used in silver mining.


Historic medicinal uses

Mercury(I) chloride Mercury(I) chloride is the chemical compound with the formula Hg2Cl2. Also known as the mineral calomel (a rare mineral) or mercurous chloride, this dense white or yellowish-white, odorless solid is the principal example of a mercury (element), me ...
(also known as calomel or mercurous chloride) has been used in
traditional medicine Traditional medicine (also known as indigenous medicine or folk medicine) comprises medical aspects of traditional knowledge that developed over generations within the folk beliefs of various societies, including indigenous peoples, before t ...
as a
diuretic A diuretic () is any substance that promotes diuresis, the increased production of urine. This includes forced diuresis. A diuretic tablet is sometimes colloquially called a water tablet. There are several categories of diuretics. All diuretics in ...
, topical
disinfectant A disinfectant is a chemical substance or compound used to inactivate or destroy microorganisms on inert surfaces. Disinfection does not necessarily kill all microorganisms, especially resistant endospore, bacterial spores; it is less effecti ...
, and
laxative Laxatives, purgatives, or aperients are substances that loosen stools and increase bowel movements. They are used to treat and prevent constipation. Laxatives vary as to how they work and the side effects they may have. Certain stimulant, l ...
.
Mercury(II) chloride Mercury(II) chloride (or mercury bichloride, mercury dichloride), historically also known as sulema or corrosive sublimate, is the inorganic chemical compound of mercury and chlorine Chlorine is a chemical element with the Symbol (chem ...
(also known as mercuric chloride or corrosive sublimate) was once used to treat
syphilis Syphilis () is a sexually transmitted infection caused by the bacterium ''Treponema pallidum'' subspecies ''pallidum''. The signs and symptoms of syphilis vary depending in which of the four stages it presents (primary, secondary, latent, and ...
(along with other mercury compounds), although it is so toxic that sometimes the symptoms of its toxicity were confused with those of the syphilis it was believed to treat. It is also used as a disinfectant. Blue mass, a pill or syrup in which mercury is the main ingredient, was prescribed throughout the 19th century for numerous conditions including constipation, depression, child-bearing and toothaches. In the early 20th century, mercury was administered to children yearly as a laxative and dewormer, and it was used in teething powders for infants. The mercury-containing organohalide merbromin (sometimes sold as Mercurochrome) is still widely used but has been banned in some countries such as the U.S.


Toxicity and safety

Mercury and most of its compounds are extremely toxic and must be handled with care; in cases of spills involving mercury (such as from certain thermometers or fluorescent light bulbs), specific cleaning procedures are used to avoid exposure and contain the spill. Protocols call for physically merging smaller droplets on hard surfaces, combining them into a single larger pool for easier removal with an eyedropper, or for gently pushing the spill into a disposable container. Vacuum cleaners and brooms cause greater dispersal of the mercury and should not be used. Afterwards, fine
sulfur Sulfur (or sulphur in British English British English (BrE, en-GB, or BE) is, according to Oxford Dictionaries, " English as used in Great Britain, as distinct from that used elsewhere". More narrowly, it can refer specifically to the ...
,
zinc Zinc is a chemical element with the Symbol (chemistry), symbol Zn and atomic number 30. Zinc is a slightly brittle metal at room temperature and has a shiny-greyish appearance when oxidation is removed. It is the first element in group 12 eleme ...
, or some other powder that readily forms an amalgam (alloy) with mercury at ordinary temperatures is sprinkled over the area before itself being collected and properly disposed of. Cleaning porous surfaces and clothing is not effective at removing all traces of mercury and it is therefore advised to discard these kinds of items should they be exposed to a mercury spill. Mercury can be absorbed through the skin and mucous membranes and mercury vapors can be inhaled, so containers of mercury are securely sealed to avoid spills and evaporation. Heating of mercury, or of compounds of mercury that may decompose when heated, should be carried out with adequate ventilation in order to minimize exposure to mercury vapor. The most toxic forms of mercury are its
organic compounds In chemistry, organic compounds are generally any chemical compounds that contain carbon-hydrogen or carbon-carbon chemical bond, bonds. Due to carbon's ability to Catenation, catenate (form chains with other carbon atoms), millions of organic c ...
, such as
dimethylmercury Dimethylmercury ((CH3)2Hg) is an extremely toxic organomercury compound. A highly volatile, reactive, flammable, and colorless liquid, dimethylmercury is one of the strongest known neurotoxin Neurotoxins are toxins that are destructive to n ...
and
methylmercury Methylmercury (sometimes methyl mercury) is an organometallic cation with the formula . It is the simplest organomercury compound. Methylmercury is extremely toxic, and its derivatives are the major source of organic mercury for humans. It is a ...
. Mercury can cause both chronic and acute poisoning.


Releases in the environment

Preindustrial deposition rates of mercury from the atmosphere may be about 4 ng /(1 L of ice deposit). Although that can be considered a natural level of exposure, regional or global sources have significant effects. Volcanic eruptions can increase the atmospheric source by 4–6 times. Natural sources, such as
volcano A volcano is a rupture in the Crust (geology), crust of a Planet#Planetary-mass objects, planetary-mass object, such as Earth, that allows hot lava, volcanic ash, and volcanic gas, gases to escape from a magma chamber below the surface. On Ear ...
es, are responsible for approximately half of atmospheric mercury emissions. The human-generated half can be divided into the following estimated percentages: * 65% from stationary combustion, of which
coal-fired power plant A coal-fired power station or coal power plant is a thermal power station which burns coal to generate electricity. Worldwide, there are about 8,500 coal-fired power stations totaling over 2,000 gigawatts Nameplate capacity, capacity. They ...
s are the largest aggregate source (40% of U.S. mercury emissions in 1999). This includes power plants fueled with gas where the mercury has not been removed. Emissions from coal combustion are between one and two orders of magnitude higher than emissions from oil combustion, depending on the country. * 11% from gold production. The three largest point sources for mercury emissions in the U.S. are the three largest gold mines. Hydrogeochemical release of mercury from gold-mine tailings has been accounted as a significant source of atmospheric mercury in eastern Canada. * 6.8% from
non-ferrous metal In metallurgy, non-ferrous metals are metals or alloy An alloy is a mixture of chemical elements of which at least one is a metal. Unlike chemical compounds with metallic bases, an alloy will retain all the properties of a metal in the resul ...
production, typically
smelter Smelting is a process of applying heat to ore, to extract a base metal. It is a form of extractive metallurgy. It is used to extract many metals from their ores, including Silver mining#Ore processing, silver, iron-making, iron, copper extracti ...
s. * 6.4% from
cement A cement is a binder (material), binder, a chemical substance used for construction that solidification, sets, hardens, and adheres to other materials to bind them together. Cement is seldom used on its own, but rather to bind sand and gravel ...
production. * 3.0% from
waste disposal Waste management or waste disposal includes the processes and actions required to manage waste from its inception to its final disposal. This includes the Waste collection, collection, transport, treatment and disposal of waste, togeth ...
, including
municipal A municipality is usually a single administrative division Administrative division, administrative unit,Article 3(1). country subdivision, administrative region, subnational entity, constituent state, as well as many similar terms, are ge ...
and
hazardous waste Hazardous waste is waste that has substantial or potential threats to public health or the natural environment, environment. Hazardous waste is a type of dangerous goods. They usually have one or more of the following hazardous traits:Flammabili ...
,
crematoria Cremation is a method of Disposal of human corpses, final disposition of a Cadaver, dead body through Combustion, burning. Cremation may serve as a funeral or post-funeral rite and as an alternative to burial. In some countries, including India ...
, and
sewage sludge Sewage sludge is the residual, quasi-solid, semi-solid material that is produced as a by-product during sewage treatment of industrial or municipal wastewater. The term "septage" also refers to sludge from simple wastewater treatment but is con ...
incineration. * 3.0% from
caustic soda Sodium hydroxide, also known as lye and caustic soda, is an inorganic compound with the formula NaOH. It is a white solid ionic compound consisting of sodium cations and hydroxide anions . Sodium hydroxide is a highly corrosive, caustic base (c ...
production. * 1.4% from
pig iron Pig iron, also known as crude iron, is an intermediate product of the Ferrous metallurgy, iron industry in the production of steel which is obtained by smelting iron ore in a blast furnace. Pig iron has a high carbon content, typically 3.8–4.7 ...
and
steel Steel is an alloy made up of iron with added carbon to improve its strength of materials, strength and fracture toughness, fracture resistance compared to other forms of iron. Many other elements may be present or added. Stainless steels that ...
production. * 1.1% from mercury production, mainly for batteries. * 2.0% from other sources. The above percentages are estimates of the global human-caused mercury emissions in 2000, excluding biomass burning, an important source in some regions. Recent atmospheric mercury contamination in outdoor urban air was measured at 0.01–0.02 μg/m3. A 2001 study measured mercury levels in 12 indoor sites chosen to represent a cross-section of building types, locations and ages in the New York area. This study found mercury concentrations significantly elevated over outdoor concentrations, at a range of 0.0065 – 0.523 μg/m3. The average was 0.069 μg/m3. Artificial lakes, or
reservoir A reservoir (; from French language, French ''réservoir'' ) is an enlarged lake behind a dam. Such a dam may be either artificial, built to water storage, store fresh water or it may be a natural formation. Reservoirs can be created in a num ...
s, may be contaminated with mercury due to the absorption by the water of mercury from submerged trees and soil. For example,
Williston Lake Williston Lake is a reservoir created by the W. A. C. Bennett Dam and is located in the British Columbia Interior, Northern Interior of British Columbia, Canada. Geography The lake fills the basin of the upper Peace River, backing into the Rocky M ...
in northern British Columbia, created by the damming of the
Peace River The Peace River (french: links=no, rivière de la Paix) is a river in Canada that originates in the Rocky Mountains of northern British Columbia and flows to the northeast through northern Alberta. The Peace River joins the Athabasca River in th ...
in 1968, is still sufficiently contaminated with mercury that it is inadvisable to consume fish from the lake.
Permafrost Permafrost is ground that continuously remains below 0 °C (32 °F) for two or more years, located on land or under the ocean. Most common in the Northern Hemisphere, around 15% of the Northern Hemisphere or 11% of the global surface ...
soils have accumulated mercury through atmospheric deposition, and permafrost thaw in cryospheric regions is also a mechanism of mercury release into lakes, rivers, and
wetland A wetland is a distinct ecosystem that is flooded or saturated by water, either permanently (for years or decades) or seasonally (for weeks or months). Flooding results in oxygen-free (Anoxic waters, anoxic) processes prevailing, especially in t ...
s. Mercury also enters into the environment through the improper disposal (e.g., land filling, incineration) of certain products. Products containing mercury include: auto parts, batteries, fluorescent bulbs, medical products, thermometers, and thermostats. Due to health concerns (see below), toxics use reduction efforts are cutting back or eliminating mercury in such products. For example, the amount of mercury sold in thermostats in the United States decreased from 14.5 tons in 2004 to 3.9 tons in 2007. Most thermometers now use pigmented
alcohol Alcohol most commonly refers to: * Alcohol (chemistry) In chemistry, an alcohol is a type of organic compound that carries at least one hydroxyl () functional group bound to a Saturated and unsaturated compounds, saturated carbon atom. The ...
instead of mercury. Mercury thermometers are still occasionally used in the medical field because they are more accurate than alcohol thermometers, though both are commonly being replaced by electronic thermometers and less commonly by galinstan thermometers. Mercury thermometers are still widely used for certain scientific applications because of their greater accuracy and working range. Historically, one of the largest releases was from the Colex plant, a lithium isotope separation plant at Oak Ridge, Tennessee. The plant operated in the 1950s and 1960s. Records are incomplete and unclear, but government commissions have estimated that some two million pounds of mercury are unaccounted for. A serious
industrial disaster This article lists notable industrial disasters, which are disasters caused by industrial companies, either by accident, negligence Negligence (Lat. ''negligentia'') is a failure to exercise appropriate and/or ethical ruled care expected ...
was the dumping of waste mercury compounds into
Minamata is a Cities of Japan, city located in Kumamoto Prefecture, Japan. It is on the west coast of Kyūshū and faces Amakusa islands. Minamata was established as a village in 1889, re-designated as a town in 1912 and grew into a city in 1949. As of M ...
Bay, Japan, between 1932 and 1968. It is estimated that over 3,000 people suffered various deformities, severe mercury poisoning symptoms or death from what became known as
Minamata disease Minamata disease is a neurological disease caused by severe mercury poisoning Mercury poisoning is a type of metal poisoning due to exposure to mercury. Symptoms depend upon the type, dose, method, and duration of exposure. They may includ ...
. The tobacco plant readily absorbs and accumulates
heavy metals file:Osmium crystals.jpg, upright=1.2, Crystals of osmium, a heavy metal nearly twice as dense as lead Heavy metals are generally defined as metals with relatively high density, densities, atomic weights, or atomic numbers. The criteria used, ...
such as mercury from the surrounding soil into its leaves. These are subsequently inhaled during
tobacco smoking Tobacco smoking is the practice of burning tobacco and ingesting the resulting tobacco smoke, smoke. The smoke may be inhaled, as is done with cigarettes, or simply released from the mouth, as is generally done with tobacco pipes, pipes and cig ...
. While mercury is a constituent of
tobacco smoke Tobacco smoke is a sooty aerosol produced by the incomplete combustion of tobacco during the tobacco smoking, smoking of cigarettes and other tobacco products. Temperatures in burning cigarettes range from about 400 °C between puffs to abo ...
, studies have largely failed to discover a significant correlation between smoking and Hg uptake by humans compared to sources such as occupational exposure, fish consumption, and amalgam tooth fillings.


Sediment contamination

Sediments within large urban-industrial
estuaries An estuary is a partially enclosed coastal body of brackish water with one or more rivers or streams flowing into it, and with a free connection to the open sea. Estuaries form a transition zone between river environments and maritime environment ...
act as an important sink for point source and diffuse mercury pollution within catchments. A 2015 study of foreshore sediments from the
Thames estuary The Thames Estuary is where the River Thames meets the waters of the North Sea, in the south-east of Great Britain. Limits An estuary can be defined according to different criteria (e.g. tidal, geographical, navigational or in terms of salini ...
measured total mercury at 0.01 to 12.07 mg/kg with mean of 2.10 mg/kg and median of 0.85 mg/kg (n=351). The highest mercury concentrations were shown to occur in and around the city of
London London is the capital and List of urban areas in the United Kingdom, largest city of England and the United Kingdom, with a population of just under 9 million. It stands on the River Thames in south-east England at the head of a estuary dow ...
in association with fine grain muds and high total organic carbon content. The strong affinity of mercury for carbon rich sediments has also been observed in salt marsh sediments of the
River Mersey The River Mersey () is in North West England. Its name derives from Old English and means "boundary river", possibly referring to its having been a border between the ancient kingdoms of Mercia and Northumbria. For centuries it has formed part ...
mean of 2 mg/kg up to 5 mg/kg. These concentrations are far higher than those shown in salt marsh river creek sediments of New Jersey and
mangrove A mangrove is a shrub or tree that grows in coastal saline water, saline or brackish water. The term is also used for tropical coastal vegetation consisting of such species. Mangroves are taxonomically diverse, as a result of convergent evoluti ...
s of Southern China which exhibit low mercury concentrations of about 0.2 mg/kg.


Occupational exposure

Due to the health effects of mercury exposure, industrial and commercial uses are regulated in many countries. The
World Health Organization The World Health Organization (WHO) is a list of specialized agencies of the United Nations, specialized agency of the United Nations responsible for international public health. The WHO Constitution states its main objective as "the attainme ...
, OSHA, and
NIOSH The National Institute for Occupational Safety and Health (NIOSH, ) is the United States federal agency responsible for conducting research and making recommendations for the prevention of work-related injury An injury is any physiological ...
all treat mercury as an occupational hazard, and have established specific occupational exposure limits. Environmental releases and disposal of mercury are regulated in the U.S. primarily by the
United States Environmental Protection Agency The Environmental Protection Agency (EPA) is an Independent agencies of the United States government, independent executive agency of the United States federal government tasked with environmental protection matters. President Richard Nixon pro ...
.


Fish

Fish Fish are Aquatic animal, aquatic, craniate, gill-bearing animals that lack Limb (anatomy), limbs with Digit (anatomy), digits. Included in this definition are the living hagfish, lampreys, and Chondrichthyes, cartilaginous and bony fish as we ...
and
shellfish Shellfish is a colloquial and fisheries term for exoskeleton-bearing Aquatic animal, aquatic invertebrates used as food, including various species of Mollusca, molluscs, crustaceans, and echinoderms. Although most kinds of shellfish are harveste ...
have a natural tendency to concentrate mercury in their bodies, often in the form of
methylmercury Methylmercury (sometimes methyl mercury) is an organometallic cation with the formula . It is the simplest organomercury compound. Methylmercury is extremely toxic, and its derivatives are the major source of organic mercury for humans. It is a ...
, a highly toxic organic compound of mercury. Species of fish that are high on the
food chain A food chain is a linear network of links in a food web starting from producer organisms (such as grass or algae which produce their own food via photosynthesis) and ending at an apex predator species (like grizzly bears or killer whales), detr ...
, such as
shark Sharks are a group of elasmobranch fish characterized by a Chondrichthyes#Skeleton, cartilaginous skeleton, five to seven gill slits on the sides of the head, and pectoral fins that are not fused to the head. Modern sharks are classified with ...
,
swordfish Swordfish (''Xiphias gladius''), also known as broadbills in some countries, are large, highly migratory predatory fish characterized by a long, flat, pointed bill. They are a popular sport fish of the billfish category, though elusive. Swordfis ...
,
king mackerel The king mackerel (''Scomberomorus cavalla'') or kingfish, is a migratory species of mackerel of the western Atlantic Ocean and Gulf of Mexico. It is an important species to both the commercial and recreational fishing industries. Description Th ...
,
bluefin tuna Bluefin tuna is a common name used to refer to several species of tuna of the genus ''Thunnus''. {{Animal common name Commercial fish Thunnus Fish common names ...
, albacore tuna, and tilefish contain higher concentrations of mercury than others. Because mercury and methylmercury are fat soluble, they primarily accumulate in the
viscera In biology, an organ is a collection of Tissue (biology), tissues joined in a structural unit to serve a common function. In the biological organization, hierarchy of life, an organ lies between Tissue (biology), tissue and an organ system. Tiss ...
, although they are also found throughout the muscle tissue. Mercury presence in fish muscles can be studied using non-lethal muscle
biopsies A biopsy is a medical test commonly performed by a surgeon, interventional radiologist, or an interventional cardiology, interventional cardiologist. The process involves extraction of sampling (medicine), sample Cell (biology), cells or Biologica ...
. Mercury present in prey fish accumulates in the predator that consumes them. Since fish are less efficient at depurating than accumulating methylmercury, methylmercury concentrations in the fish tissue increase over time. Thus species that are high on the
food chain A food chain is a linear network of links in a food web starting from producer organisms (such as grass or algae which produce their own food via photosynthesis) and ending at an apex predator species (like grizzly bears or killer whales), detr ...
amass body burdens of mercury that can be ten times higher than the species they consume. This process is called
biomagnification Biomagnification, also known as bioamplification or biological magnification, is any concentration of a toxin, such as pesticides, in the tissue (biology), tissues of tolerant organisms at successively higher levels in a food chain. This increas ...
.
Mercury poisoning Mercury poisoning is a type of metal poisoning due to exposure to mercury. Symptoms depend upon the type, dose, method, and duration of exposure. They may include muscle weakness, poor coordination, numbness in the hands and feet, skin rash ...
happened this way in
Minamata is a Cities of Japan, city located in Kumamoto Prefecture, Japan. It is on the west coast of Kyūshū and faces Amakusa islands. Minamata was established as a village in 1889, re-designated as a town in 1912 and grew into a city in 1949. As of M ...
,
Japan Japan ( ja, 日本, or , and formally , ''Nihonkoku'') is an island country in East Asia. It is situated in the northwest Pacific Ocean, and is bordered on the west by the Sea of Japan, while extending from the Sea of Okhotsk in the north ...
, now called
Minamata disease Minamata disease is a neurological disease caused by severe mercury poisoning Mercury poisoning is a type of metal poisoning due to exposure to mercury. Symptoms depend upon the type, dose, method, and duration of exposure. They may includ ...
.


Cosmetics

Some facial creams contain dangerous levels of mercury. Most contain comparatively non-toxic inorganic mercury, but products containing highly toxic organic mercury have been encountered.


Effects and symptoms of mercury poisoning

Toxic effects include damage to the brain, kidneys and lungs. Mercury poisoning can result in several diseases, including acrodynia (pink disease), Hunter-Russell syndrome, and
Minamata disease Minamata disease is a neurological disease caused by severe mercury poisoning Mercury poisoning is a type of metal poisoning due to exposure to mercury. Symptoms depend upon the type, dose, method, and duration of exposure. They may includ ...
. Symptoms typically include sensory impairment (vision, hearing, speech), disturbed sensation and a lack of coordination. The type and degree of symptoms exhibited depend upon the individual toxin, the dose, and the method and duration of exposure. Case–control studies have shown effects such as tremors, impaired
cognitive Cognition refers to "the mental action or process of acquiring knowledge and understanding through thought, experience, and the senses". It encompasses all aspects of intellectual functions and processes such as: perception Perceptio ...
skills, and sleep disturbance in workers with chronic exposure to mercury vapor even at low concentrations in the range 0.7–42 μg/m3. A study has shown that acute exposure (4–8 hours) to calculated elemental mercury levels of 1.1 to 44 mg/m3 resulted in chest pain,
dyspnea Shortness of breath (SOB), also medically known as dyspnea (in AmE) or dyspnoea (in BrE), is an uncomfortable feeling of not being able to breathe well enough. The American Thoracic Society defines it as "a subjective experience of breathing d ...
, cough,
hemoptysis Hemoptysis is the coughing up of blood or blood-stained sputum, mucus from the bronchi, larynx, vertebrate trachea, trachea, or lungs. In other words, it is the airway bleeding. This can occur with lung cancer, infections such as tuberculosis, b ...
, impairment of pulmonary function, and evidence of interstitial pneumonitis. Acute exposure to mercury vapor has been shown to result in profound central nervous system effects, including psychotic reactions characterized by delirium, hallucinations, and suicidal tendency. Occupational exposure has resulted in broad-ranging functional disturbance, including erethism, irritability, excitability, excessive shyness, and insomnia. With continuing exposure, a fine tremor develops and may escalate to violent muscular spasms. Tremor initially involves the hands and later spreads to the eyelids, lips, and tongue. Long-term, low-level exposure has been associated with more subtle symptoms of erethism, including fatigue, irritability, loss of memory, vivid dreams and depression.


Treatment

Research on the treatment of mercury poisoning is limited. Currently available drugs for acute mercurial poisoning include chelators N-acetyl-D, L-
penicillamine Penicillamine, sold under the brand name of Cuprimine among others, is a medication primarily used for the treatment of Wilson's disease. It is also used for people with kidney stones who have cystinuria, high urine cystine levels, rheumatoid ar ...
(NAP), British Anti-Lewisite (BAL),
2,3-dimercapto-1-propanesulfonic acid 2,3-Dimercapto-1-propanesulfonic acid (abbreviated DMPS) and its sodium salt (known as Unithiol) are chelating agents that form complexes with various heavy metals. They are related to dimercaprol, which is another chelating agent. The synthesis ...
(DMPS), and
dimercaptosuccinic acid Succimer, sold under the brand name Chemet among others, is a medication used to treat lead poisoning, lead, mercury poisoning, mercury, and arsenic poisoning. When radioactive tracer, radiolabeled with technetium-99m, it is used in a number of ...
(DMSA). In one small study including 11 construction workers exposed to elemental mercury, patients were treated with DMSA and NAP.
Chelation therapy Chelation therapy is a medical procedure that involves the administration of Chelation, chelating agents to remove heavy metals from the body. Chelation therapy has a long history of use in clinical toxicology and remains in use for some very sp ...
with both drugs resulted in the mobilization of a small fraction of the total estimated body mercury. DMSA was able to increase the excretion of mercury to a greater extent than NAP.


Regulations


International

140 countries agreed in the Minamata Convention on Mercury by the
United Nations Environment Programme The United Nations Environment Programme (UNEP) is responsible for coordinating responses to environmental issues within the United Nations system. It was established by Maurice Strong, its first director, after the Declaration of the United Natio ...
(UNEP) to prevent emissions. The convention was signed on 10 October 2013.


United States

In the United States, the
Environmental Protection Agency A biophysical environment is a life, biotic and Abiotic component, abiotic surrounding of an organism or population, and consequently includes the factors that have an influence in their survival, development, and evolution. A biophysical environ ...
is charged with regulating and managing mercury contamination. Several laws give the EPA this authority, including the Clean Air Act, the
Clean Water Act The Clean Water Act (CWA) is the primary federal law in the United States governing water pollution. Its objective is to restore and maintain the chemical, physical, and biological integrity of the nation's waters; recognizing the responsibiliti ...
, the
Resource Conservation and Recovery Act The Resource Conservation and Recovery Act (RCRA), enacted in 1976, is the principal federal law in the United States governing the disposal of solid waste and hazardous waste.United States. Resource Conservation and Recovery Act. , , ''et seq., ...
, and the
Safe Drinking Water Act The Safe Drinking Water Act (SDWA) is the principal federal law Federal law is the body of law created by the federal government of a country. A federal government is formed when a group of political units, such as state (subnational), states o ...
. Additionally, the
Mercury-Containing and Rechargeable Battery Management Act #REDIRECT Mercury-Containing and Rechargeable Battery Management Act {{R from other capitalisation ...
, passed in 1996, phases out the use of mercury in batteries, and provides for the efficient and cost-effective disposal of many types of used batteries. North America contributed approximately 11% of the total global anthropogenic mercury emissions in 1995. The United States Clean Air Act, passed in 1990, put mercury on a list of toxic pollutants that need to be controlled to the greatest possible extent. Thus, industries that release high concentrations of mercury into the environment agreed to install maximum achievable control technologies (MACT). In March 2005, the EPA promulgated a regulation that added power plants to the list of sources that should be controlled and instituted a national
cap and trade Emissions trading is a market-based approach to controlling pollution Pollution is the introduction of contaminants into the natural environment that cause adverse change. Pollution can take the form of any substance (solid, liquid, or gas) o ...
system. States were given until November 2006 to impose stricter controls, but after a legal challenge from several states, the regulations were struck down by a federal appeals court on 8 February 2008. The rule was deemed not sufficient to protect the health of persons living near coal-fired power plants, given the negative effects documented in the EPA Study Report to Congress of 1998. However newer data published in 2015 showed that after introduction of the stricter controls mercury declined sharply, indicating that the Clean Air Act had its intended impact. The EPA announced new rules for
coal-fired power plant A coal-fired power station or coal power plant is a thermal power station which burns coal to generate electricity. Worldwide, there are about 8,500 coal-fired power stations totaling over 2,000 gigawatts Nameplate capacity, capacity. They ...
s on 22 December 2011.
Cement kiln Cement kilns are used for the pyroprocessing stage of manufacture of Portland cement, portland and other types of hydraulic cement, in which calcium carbonate reacts with silicon dioxide, silica-bearing minerals to form a mixture of calcium silic ...
s that burn hazardous waste are held to a looser standard than are standard
hazardous waste Hazardous waste is waste that has substantial or potential threats to public health or the natural environment, environment. Hazardous waste is a type of dangerous goods. They usually have one or more of the following hazardous traits:Flammabili ...
incinerator Incineration is a list of solid waste treatment technologies, waste treatment process that involves the combustion of substances contained in waste materials. Industrial plants for waste incineration are commonly referred to as waste-to-ene ...
s in the United States, and as a result are a disproportionate source of mercury pollution.


European Union

In the
European Union The European Union (EU) is a supranational union, supranational political union, political and economic union of Member state of the European Union, member states that are located primarily in Europe, Europe. The union has a total area of ...
, the directive on the Restriction of the Use of Certain Hazardous Substances in Electrical and Electronic Equipment (see
RoHS The Restriction of Hazardous Substances Directive 2002/95/EC (RoHS 1), short for Directive on the restriction of the use of certain hazardous substances in electrical and electronic equipment, was adopted in February 2003 by the European Unio ...
) bans mercury from certain electrical and electronic products, and limits the amount of mercury in other products to less than 1000 ppm. Article 4 Paragraph 1. e.g. "Member States shall ensure that, from July 1, 2006, new electrical and electronic equipment put on the market does not contain lead, mercury, cadmium, hexavalent chromium, polybrominated biphenyls (PBB) or polybrominated diphenyl ethers (PBDE)." There are restrictions for mercury concentration in packaging (the limit is 100 ppm for sum of mercury,
lead Lead is a chemical element with the Symbol (chemistry), symbol Pb (from the Latin ) and atomic number 82. It is a heavy metals, heavy metal that is density, denser than most common materials. Lead is Mohs scale of mineral hardness#Intermediate ...
,
hexavalent chromium Hexavalent chromium (chromium(VI), Cr(VI), chromium 6) is chromium Chromium is a chemical element with the Symbol (chemistry), symbol Cr and atomic number 24. It is the first element in Group 6 element, group 6. It is a steely-grey, Luster (m ...
and
cadmium Cadmium is a chemical element with the Symbol (chemistry), symbol Cd and atomic number 48. This soft, silvery-white metal is chemically similar to the two other stable metals in group 12 element, group 12, zinc and mercury (element), mercury. Li ...
) and batteries (the limit is 5 ppm). In July 2007, the European Union also banned mercury in non-electrical measuring devices, such as
thermometer A thermometer is a device that temperature measurement, measures temperature or a temperature gradient (the degree of hotness or coldness of an object). A thermometer has two important elements: (1) a temperature sensor (e.g. the bulb of a merc ...
s and
barometer A barometer is a scientific instrument that is used to measure air pressure in a certain environment. Pressure tendency can forecast short term changes in the weather. Many measurements of air pressure are used within surface weather analysis ...
s. The ban applies to new devices only, and contains exemptions for the health care sector and a two-year grace period for manufacturers of barometers.


Norway

Norway Norway, officially the Kingdom of Norway, is a Nordic countries, Nordic country in Northern Europe, the mainland territory of which comprises the western and northernmost portion of the Scandinavian Peninsula. The remote Arctic island of ...
enacted a total ban on the use of mercury in the manufacturing and import/export of mercury products, effective 1 January 2008. In 2002, several lakes in Norway were found to have a poor state of mercury pollution, with an excess of 1 μg/g of mercury in their sediment. In 2008, Norway's Minister of Environment Development Erik Solheim said: "Mercury is among the most dangerous environmental toxins. Satisfactory alternatives to Hg in products are available, and it is therefore fitting to induce a ban."


Sweden

Products containing mercury were banned in Sweden in 2009.


Denmark

In 2008, Denmark also banned dental mercury amalgam, except for molar masticating surface fillings in permanent (adult) teeth.


See also

* Mercury pollution in the ocean *
Red mercury Red mercury is purportedly a substance of uncertain composition used in the creation of nuclear weapons, as well as other weapons systems. Because of the great secrecy surrounding the development and manufacturing of nuclear weapons, there is no ...
* COLEX process (isotopic separation)


References


Further reading

*


External links


Chemistry in its element podcast
(MP3) from the
Royal Society of Chemistry The Royal Society of Chemistry (RSC) is a learned society (professional association) in the United Kingdom with the goal of "advancing the chemistry, chemical sciences". It was formed in 1980 from the amalgamation of the Chemical Society, the Ro ...
's
Chemistry World ''Chemistry World'' is a monthly chemistry Chemistry is the scientific study of the properties and behavior of matter. It is a natural science that covers the elements that make up matter to the compounds made of atoms, molecules and ...

Mercury


at ''
The Periodic Table of Videos ''Periodic Videos'' (also known as ''The Periodic Table of Videos'') is a video project and YouTube channel on chemistry. It consists of a series of videos about chemical elements and the periodic table, with additional videos on other topics i ...
'' (University of Nottingham)
Centers for Disease Control and Prevention – Mercury Topic







Stopping Pollution: Mercury
– Oceana
Natural Resources Defense Council (NRDC): Mercury Contamination in Fish guide
NRDC
NLM Hazardous Substances Databank – Mercury

BBC – Earth News – Mercury "turns" wetland birds such as ibises homosexual

Changing Patterns in the Use, Recycling, and Material Substitution of Mercury in the United States
United States Geological Survey The United States Geological Survey (USGS), formerly simply known as the Geological Survey, is a scientific government agency, agency of the Federal government of the United States, United States government. The scientists of the USGS study th ...

Thermodynamical data on liquid mercury.
* {{DEFAULTSORT:Mercury Chemical elements Coolants Endocrine disruptors Native element minerals Neurotoxins Nuclear reactor coolants Occupational safety and health Transition metals