Effects of Mercury on the environment

Mercury is a toxic substance which has no known function in human biochemistry or physiology and does not occur naturally in living organisms. Inorganic mercury poisoning is associated with tremors, gingivitis and/or minor psychological changes, together with spontaneous abortion and congenital malformation.

Monomethylmercury causes damage to the brain and the central nervous system, while foetal and postnatal exposure have given rise to abortion, congenital malformation and development changes in young children.

In what form is emitted Mercury?

Mercury is a global pollutant with complex and unusual chemical and physical properties. The major natural source of mercury is the degassing of the Earth’s crust, emissions from volcanoes and evaporation from natural bodies of water.

World-wide mining of the metal leads to indirect discharges into the atmosphere. The usage of mercury is widespread in industrial processes and in various products (e.g. batteries, lamps and thermometers). It is also widely used in dentistry as an amalgam for fillings and by the pharmaceutical industry. Concern over mercury in the environment arises from the extremely toxic forms in which mercury can occur.

Mercury is mostly present in the atmosphere in a relatively unreactive form as a gaseous element. The long atmospheric lifetime (of the order of 1 year) of its gaseous form means the emission, transport and deposition of mercury is a global issue.

Natural biological processes can cause methylated forms of mercury to form which bioaccumulate over a million-fold and concentrate in living organisms, especially fish. These forms of mercury: monomethylmercury and dimethylmercury are highly toxic, causing neurotoxicological disorders. The main pathway for mercury to humans is through the food chain and not by inhalation.

The main sources of mercury emissions in the UK are from the manufacture of chlorine in mercury cells, non-ferrous metal production, coal combustion and crematoria. UK emissions of mercury are uncertain and it is estimated that the range is from 13 to 36 tonnes per year (DERA). Emissions are estimated to have declined by around ¾’s between 1970-1998 (NAEI), mainly due to improved controls on mercury cells and their replacement, and the fall in coal use.

Whilst there has been a decline in the level of European emissions of mercury, emissions from outside of Europe have started to increase – increasing the level of ambient concentrations in the continent.

Read more: http://www.lenntech.com/processes/heavy/heavy-metals/heavy-metals.htm#ixzz212WAPl00

Mercury is a chemical element with the symbol Hg and atomic number 80. It is also known as quicksilver or hydrargyrum ( < Greek "hydr-" water and "argyros" silver). A heavy, silvery d-block element, mercury is the only metal that is liquid at standard conditions for temperature and pressure; the only other element that is liquid under these conditions is bromine, though metals such as caesium, francium, gallium, and rubidium melt just above room temperature. With a freezing point of −38.83 °C and boiling point of 356.73 °C, mercury has one of the narrowest ranges of its liquid state of any metal.^[2]^[3]^[4]

Mercury occurs in deposits throughout the world mostly as cinnabar (mercuric sulfide). The red pigment vermilion is mostly obtained by reduction from cinnabar. Cinnabar is highly toxic by ingestion or inhalation of the dust. Mercury poisoning can also result from exposure to water-soluble forms of mercury (such as mercuric chloride or methylmercury), inhalation of mercury vapor, or eating seafood contaminated with mercury.

Mercury is used in thermometers, barometers, manometers, sphygmomanometers, float valves, mercury switches, 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 alcohol-filled, galinstan-filled, digital, or thermistor-based instruments. It remains in use in scientific research applications and in amalgam material for dental restoration. It is used in lighting: electricity passed through mercury vapor in a phosphor tube produces short-wave ultraviolet light which then causes the phosphor to fluoresce, making visible light.

. What is mercury?

1.1 In what forms does mercury exist?
1.2 How does mercury exist in the environment?
1.3 How can the form of mercury affect living organisms and the environment?

1.1 In what forms does mercury exist?

Mercury occurs naturally in the environment. Sometimes known as quicksilver, it is a heavy metal, like lead or cadmium, that exists in different chemical forms:

Elemental mercury or metallic mercury is the element in its pure, ‘un-combined’ form. It is a shiny, silver-white metal that is liquid at room temperature, but is rarely found in this form in nature. If not sealed off, mercury slowly evaporates into the air, forming a vapour. The quantity of vapour formed increases as temperatures rise. Elemental mercury is traditionally used in thermometers and some electrical switches.
Inorganic mercury compounds or mercury salts, more commonly found in nature, include mercuric sulphide (HgS), mercuric oxide (HgO) and mercuric chloride (HgCl₂). Most of these are white powders or crystals, except for mercuric sulphide which is red and turns black after exposure to light. Some mercury salts, such as mercury chloride, also form vapour, but they stay in the air for a shorter time than elemental mercury because they are more soluble in water and more reactive.
Organic mercury is formed when mercury combines with carbon and other elements. Examples oforganic mercury compounds are dimethylmercury, phenylmercuric acetate and methylmercuric chloride. The form most commonly found in the environment is methylmercury.

1.2 How does mercury exist in the environment?

Several forms of mercury exist naturally in the environment, the most common being metallic mercury, mercuric sulphide, mercuric chloride, and methylmercury.

Natural processes can change the mercury from one form to another. For instance, chemical reactions in the atmosphere can transform elemental mercury into inorganic mercury.

Some micro-organisms can produce organic mercury, particularly methylmercury, from other mercury forms. Methylmercury can accumulate in living organisms and reach high levels in fish and marine mammals via a process called biomagnification (i.e. concentrations increase in the food chain).

Because mercury is one of the basic chemical elements, of which all things are made, it cannot be broken down or degraded into something else. Once released into the biosphere through natural events or human activities (see Question 4), mercury readily moves and cycles through the environment. Soil, water bodies and the sediments underneath them are believed to be the places where mercury comes to rest until it is ultimately removed from the biosphere again. More...

Mercury Poisoning

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Mercury introduction

Mercury is contained in some of the fish we eat, whether caught in local lakes and streams or bought in a grocery store. Mercury is also contained in some of the products we use, which may be found in your home, at the dentist, and at schools. This article provides links to information about sources of mercury exposure, potential health effects, fish that may contain mercury, consumer products that contain mercury, and ways to reduce your exposure to mercury.

General information about mercury and mercury exposure

Forms of mercury. Mercury is a naturally occurring element that is found in air, water and soil. It exists in several forms:

elemental or metallic mercury,
inorganic mercury compounds, and
organic mercury compounds.

Sources of mercury. Mercury is an element in the earth's crust. Humans cannot create or destroy mercury. Pure mercury is a liquid metal, sometimes referred to as quicksilver that volatizes readily. It has traditionally been used to make products like thermometers, switches, and some light bulbs.

Mercury is found in many rocks including coal. When coal is burned, mercury is released into the environment. Coal-burning power plants are the largest human-caused source of mercury emissions to the air in the United States, accounting for over 40 percent of all domestic human-caused mercury emissions. EPA has estimated that about one quarter of U.S. emissions from coal-burning power plants are deposited within the contiguous U.S. and the remainder enters the global cycle. Burning hazardous wastes, producing chlorine, breaking mercury products, and spilling mercury, as well as the improper treatment and disposal of products or wastes containing mercury, can also release it into the environment. Current estimates are that less than half of all mercury deposition within the U.S. comes from U.S. sources.

Exposure to mercury. Mercury in the air eventually settles into water or onto land where it can be washed into water. Once deposited, certain microorganisms can change it into methylmercury, a highly toxic form that builds up in fish, shellfish and animals that eat fish. Fish and shellfish are the main sources of methylmercury exposure to humans. Methylmercury builds up more in some types of fish and shellfish than others. The levels of methylmercury in fish and shellfish depend on what they eat, how long they live and how high they are in the food chain.

EPA works with the U.S. Food and Drug Administration (FDA) and with states and tribes to issue advice to women who may become pregnant,pregnant women, nursing mothers, and parents of young children about how often they should eat certain types of commercially-caught fish and shellfish. Fish advisories are also issued for men, women, and children of all ages when appropriate. In addition, EPA releases an annual summary of information on locally-issued fish advisories and safe-eating guidelines to the public. Fish is a beneficial part of the diet, so EPA & FDA encourage people to continue to eat fish that are low in methylmercury.

Another less common exposure to mercury that can be a concern isbreathing mercury vapor. These exposures can occur when elemental mercury or products that contain elemental mercury break and release mercury to the air, particularly in warm or poorly-ventilated indoor spaces.

Health effects of mercury. Mercury exposure at high levels can harm thebrain, heart, kidneys, lungs, and immune system of people of all ages. Research shows that most people's fish consumption does not cause a health concern. However, it has been demonstrated that high levels of methylmercury in the bloodstream of unborn babies and young children may harm the developing nervous system, making the child less able to think and learn. More information

Ecological effects of mercury. Birds and mammals that eat fish are more exposed to mercury than other animals in water ecosystems. Similarly, predators that eat fish-eating animals may be highly exposed. At high levels of exposure, methylmercury's harmful effects on these animals include death, reduced reproduction, slower growth and development, andabnormal behavior.

Reducing mercury releases. EPA issues regulations that require industry to reduce mercury releases to air and water and to properly treat and dispose of mercury wastes. EPA also works with industry to promote voluntary reductions in mercury use and releases, and with partners in state, local and tribal governments to improve their mercury reduction programs. EPA works with international organizations to prevent the release of mercury in other countries. The public can contribute to mercury reduction efforts by purchasing mercury-free products and correctly disposing of products that contain mercury by reducing demand for products whose production leads to the release of mercury into the environment.

Stop Mercury Pollution

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All Comments (1)

Wow the commentator spoke waaaay too fast! This is an important message I'm sure, but it is equally important to understand the message!

whaler3232 4 years ago