Copper
Copper is a reddish metal with a face-centered cubic crystalline
structure. It reflects red
and orange light and absorbs other frequencies in the visible spectrum,
due to its band structure, so it as a nice reddish colour. It is malleable, ductile, and an extremely
good conductor of both heat and electricity. It is softer than
iron but
harder than zinc and can be polished to a bright finish. It is found in
group Ib of the
periodic table, together with silver and
gold. Copper has low
chemical reactivity. In moist air it slowly forms a greenish surface
film called patina; this coating protects the metal from further attack.
Applications
Most copper is used for electrical equipment (60%); construction,
such as roofing and plumbing (20%); industrial machineri, such as heat
exchangers (15%) and alloys (5%). The main long established copper
alloys are bronze, brass (a copper-zinc alloy),
copper-tin-zinc, which was strong enough to make
guns and cannons, and was known as gun metal, copper and
nichel, known as cupronickel, which was the
preferred metal for low-denomination coins.
Copper is ideal for electrical wiring because it is easily worked, can
be drawn into fine wire and has a high electrical conductivity.
Copper in the environment
Copper is a very common substance that occurs
naturally in the environment and spreads through the environment
through natural phenomena. Humans widely use copper. For instance
it is applied in the industries and in agriculture. The production
of copper has lifted over the last decades and due to this copper
quantities in the environment have expanded.
The world's copper production is still
rising. This basically means that more and more copper ends up in
the environment. Rivers are depositing sludge on their banks that
is contaminated with copper, due to the disposal of
copper-containing wastewater. Copper enters the air, mainly
through release during the combustion of fossil fuels. Copper in
air will remain there for an eminent period of time, before it
settles when it starts to rain. It will than end up mainly in
soils. As a result soils may also contain large quantities of
copper after copper from the air has settled.
Copper can be released into the environment by both natural
sources and human activities. Examples of natural sources are
wind-blown dust, decaying vegetation, forest fires and sea spray.
A few examples of human activities that contribute to copper
release have already been named. Other examples are mining, metal
production, wood production and phosphate fertilizer production.
Because copper is released both naturally and through human
activity it is very widespread in the environment. Copper is often
found near mines, industrial settings, landfills and waste
disposals.
Most copper compounds will settle and be bound to either water
sediment or soil particles. Soluble copper compounds form the
largest threat to human health. Usually water-soluble copper
compounds occur in the environment after release through
application in agriculture.
World production of copper amounts to 12 million tonnes a year and
exploitable reserves are aroun 300 million tonnes, which are expected to
last for only another 25 years. About 2 million tonnes a year are
reclaimed by recycling. Today copper is mined as major deposists in
Chile, Indonesia, USA, Australia and Canada, which together account for
around 80% of the world's copper. The main ore is a yellow copper-iron
sulfide called chalcopyrite (CuFeS2).
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Routes of exposition
Copper can be found in many kinds of food, in drinking water and
in air. Because of that we absorb eminent quantities of copper
each day by eating, drinking and breathing. The absorption of
copper is necessary, because copper is a trace element that is
essential for human health. Although humans can handle
proportionally large concentrations of copper, too much copper can
still cause eminent health problems.
Copper concentrations in air are usually quite low, so that
exposure to copper through breathing is negligible. But people
that live near smelters that process copper ore into metal do
experience this kind of exposure.
People that live in houses that still have copper plumbing are
exposed to higher levels of copper than most people, because
copper is released into their drinking water through corrosion of
pipes.
Occupational exposure to copper often occurs. In the work place
environment copper contagion can lead to a flu-like condition
known as metal fever. This condition will pass after two days and
is caused by over sensitivity.
Effects
Long-term exposure to copper can cause irritation of the nose,
mouth and eyes and it causes headaches, stomachaches, dizziness,
vomiting and diarrhoea. Intentionally high uptakes of copper may
cause liver and kidney damage and even death. Whether copper is
carcinogenic has not been determined yet.
There are scientific articles that indicate a link between
long-term exposure to high concentrations of copper and a decline
in intelligence with young adolescents. Whether this should be of
concern is a topic for further investigation.
Industrial exposure to copper fumes,
dusts, or mists may result in metal fume
fever with atrophic changes in nasal mucous membranes. Chronic
copper poisoning results in Wilson’s Disease,
characterized by a hepatic cirrhosis, brain
damage, demyelination, renal disease, and copper deposition in the cornea.
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When copper ends up in soil it strongly attaches to organic matter
and minerals. As a result it does not travel very far after
release and it hardly ever enters groundwater. In surface water
copper can travel great distances, either suspended on sludge
particles or as free ions.
Copper does not break down in the environment and because of
that it can accumulate in plants and animals when it is found in
soils. On copper-rich soils only a limited number of plants has a
chance of survival. That is why there is not much plant diversity
near copper-disposing factories. Due to the effects upon plants
copper is a serious threat to the productions of farmlands. Copper
can seriously influence the proceedings of certain farmlands,
depending upon the acidity of the soil and the presence of organic
matter. Despite of this, copper-containing manures are still
applied.
Copper can interrupt the activity in soils, as it negatively
influences the activity of microrganisms and earthworms. The
decomposition of organic matter may seriously slow down because of
this.
When the soils of farmland are polluted with copper, animals
will absorb concentrations that are damaging to their health.
Mainly sheep suffer a great deal from copper poisoning, because
the effects of copper are manifesting at fairly low
concentrations.
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Back to periodic
chart Recommended
daily intake of copper |
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