Barium
Barium is a silvery-white metal that can be
found in the environment, where it exists naturally. It occurs
combined with other chemicals, such as Sulfur,
Carbon or Oxygen.
Ii is very light and its density is half that of Iron. Barium oxidizes
in air, reacts vigoroulsy with water to form the hydroxide, liberating
Hydrogen. Barium reacts with almost all the non-metals, forming often
poisouning compounds.
Applications
Barium is often used in Barium-Nickel alloys for spark-plug
electrodes an in vacuum tubes as drying and Oxygen-removing agent. It is
also used in fluorescent lamps: impure Barium sulfide phosphoresces
after exposure to the light.
Barium compounds are used by the oil and gas industries to make
drilling mud. Drilling mud simplifies drilling through rocks by
lubricating the drill.
Barium compounds are also used to make paint, bricks, tiles,
glass, and rubber. Barium nitrate and clorate give fireworks a
green colour.
Barium in the environment
Barium is surprisingly abundant in the Earth's crust, being the 14th
most abundant element. High amounts of Barium may only be found in
soils and in food, such as nuts, seaweed, fish and certain plants.
Because of the extensive use of Barium in the industries human
activities add greatly to the release of Barium in the
envIronment. As a result Barium concentrations in air, water and
soil may be higher than naturally occurring concentrations on many
locations.
Barium enters the air during mining processes, refining processes,
and during the production of Barium compounds. It can also enter
the air during coal and oil combustion.
The chief mined ores are barite, which is also the most common and
witserite. The main mining areas are UK, Italy, Czech Republic, USA and
Germany. Each year about 6 million tonnes are produced and reserves are
expected to exceed 400 million tonnes.
The amount of Barium that is detected in food and
water usually is not high enough to become a health concern.
People with the greatest risk to Barium exposure with additional
Health effectsare those that work in the Barium industry. Most of
the health risks that they can undergo are caused by breathing in
air that contains Barium sulphate or Barium Carbonate.
Many hazardous waste sites contain certain amounts of Barium.
People that live near them may be exposed to harmful levels. The
exposure will than be caused by breathing dust, eating soil or
plants, or drinking water that is polluted with Barium. Skin
contact may also occur.
The Health effects of Barium depend upon the water-solubility of
the compounds. Barium compounds that dissolve in water can be
harmful to human health. The uptake of very large amounts of
Barium that are water-soluble may cause paralyses and in some
cases even death.
Small amounts of water-soluble Barium may cause a person to
experience breathing difficulties, increased blood pressures,
heart rhythm changes, stomach irritation, muscle weakness, changes
in nerve reflexes, swelling of brains and liver, kidney and heart
damage.
Barium has not shown to cause cancer with humans. There is no
proof that Barium can cause infertility or birth defects.
Some Barium compounds that are released during industrial
processes dissolve easily in water and are found in lakes, rivers,
and streams. Because of their water-solubility these Barium
compounds can spread over great distances. When fish and other
aquatic organisms absorb the Barium compounds, Barium will
accumulate in their bodies.
Because it forms insoluble salts with other common components of
the environment, such as Carbonate and sulphate, Barium is not
mobile and poses little risk. Barium compounds that are persistent
usually remain in soil surfaces, or in the sediment of water
soils. Barium is found in most land soils at low levels. These
levels may be higher at hazardous waste sites. |
