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
Health effects of barium
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 effects
are 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.
Environmental effects of barium
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.