Mercury

“For then she bare a son, of many shifts, blandly cunning, a robber, a cattle driver, a bringer of dreams, a watcher by night, a thief at the gates, one who was soon to show forth wonderful deeds among the deathless gods...” Birth of Greek God Mercury

As Be Cd Cr Co Cu F Pb Hg Ni Tl

For millennia, mercury (Hg) has been considered a valuable natural resource with a wide range of applications. Mercury and the other noble metals were the first elements to be discovered and utilized by humans because they exist in nature either in the free state or as easily decomposable compounds. In the 4th century B.C., Aristotle discussed the use of 'fluid silver' for religious ceremonies. Hippocrates was said to have used mercury for medicinal purposes. And the Romans used vermillion (the red-colored sulfur salt of mercury) extracted from the Almadén cinnabar mines as a cosmetic and decorative. (reference)

Although the toxicity of elemental Hg had been reported already by Pliny the Elder orCaius Plinius Secundus (23-79) it became known as a serious health hazard only in the recent modern industrial age. The toxicity of Hg salts was for example demonstrated by the "mad hatters" making felt hats from furs treated with Hg (as nitrate). Health concern was until a few decades ago focused on occupational exposure, e.g. in mines. Meanwhile, Hg was used in a wide range of fields such as medicine and technology with few or no restrictions until the last decades of the 20^th century. By this time, severe intoxications of people by organic Hg compounds in Iraq, Japan (see Minamata), and the USA was observed, and the public in several industrialized countries forced industry and authorities to recognize the toxicity of Hg and Hg compounds. (reference)

Mercury is ubiquitous in the environment. Spewing from volcanoes, evaporating off bodies of water, and rising as gas from the Earth's crust, the poisonous, metallic element floats in the air as vapor or binds to particles. Eventually it falls to the Earth to settle in sediment, oceans, and lakes, or reenters the atmosphere by evaporation.

The "hand of man" has contributed to this outpouring as well. Since the late 18th century and the dawn of the Industrial Revolution, mercury has been used in products such as light bulbs, batteries, thermometers and barometers, pesticides, and paint. It is released from the burning of fossil fuels in municipal and hospital incinerators, coal combusting power plants, lead smelters, and chlorine producers. Because it can dissolve metals, and particularly because it can separate gold from impurities, it has long been used heavily in mining, and is found in tailings around the world. Even crematoria contribute mercury to the environment as mercury is released when dental amalgams melt.

According to UNEP (United Nations Environment Programme), Hg is still widely used In many countries in industry and society, often unregulated e.g. as an amalgamating agent for gold extraction. The World Health Organization (WHO) estimates that approximately 10,000 tons of mercury are released worldwide from both natural and manmade sources each year. Mercury used has originally been extracted from mines. This Hg has caused anthropogenic emissions for more than two millennia, and has contributed significantly to elevated atmospheric Hg deposition rates, together with the more recent combustion of fossil fuels.

Atmospheric Hg deposition rates have increased by 1.5-3 times globally and up to 10 times in Europe, North America, and Southeastern China since onset of industrialization. Even larger increases since pre-industrial times in deposition rates over mires have been observed in Denmark, Greenland, and Switzerland. It is estimated that the global anthropogenic contribution is presently twice as large as natural Hg emissions. (reference)

Major Consumption Sectors

Chlor-alkali Industry
Dentistry
Explosives, electrical and measuring appliances
Medical uses
Mercury amalgamation
Pigment and organic fungicide production

Toxic Elements: Arsenic, Beryllium, Cadmium, Chromium, Cobalt, Copper, Fluorine, Lead, Mercury, Nickel, Thallium