Environmental Engineering Reference
In-Depth Information
entry into the hydrosphere. Electroplating, leather tanning and textile industries also
release relatively large amounts of chromium in surface waters.
Copper
Copper, along with gold the i rst metal known to mankind, was named from the Greek
word kyprios , that is, the Island of Cyprus, where copper deposits were mined by the
ancients. The chemical symbol for copper is Cu which is derived from the Latin name
for copper, cuprium . Of all the materials mined, copper is the most versatile and dura-
ble - it appears everywhere in our everyday lives. This miraculous metal has a number
of unique properties: besides being nonmagnetic, copper is conductive, ductile, malleable,
resistant and biostatic. Copper is at the heart of all technology, from telecommunications
to transportation.
Copper is a natural element found in abundance in the Earth's crust. As a result, drink-
ing water often contains copper, which is safe to drink, even in instances where the cop-
per level is high enough to add a metallic taste to the water. Like chromium, copper is an
essential nutrient and is required by the body in daily dietary amounts of 1 to 2 milligrams
for adults. Copper dei ciency can lead to illness, as will excessive copper when ingested.
However, the World Health Organization has concluded that copper dei ciency is much
more of a global problem than copper toxicity (TRI 2007). Although those living near cop-
per mines may be fearful of polluted air and water, acute copper poisoning is a rare event,
largely restricted to the accidental drinking of solutions of copper nitrate or copper sul-
phate. These and organic copper salts are powerful emetics and large inadvertent doses
are normally rejected by vomiting. Chronic copper poisoning is also very rare, with a few
reports referring to patients with liver disease. However, the capacity for healthy human
livers to excrete copper is considerable and it is primarily for this reason that no cases of
chronic copper poisoning have been medically coni rmed (TRI 2007). Copper is, however,
much more toxic to plants and is commonly used as an herbicide and fungicide. Even at
very low concentrations of less than 20
Copper appears everywhere in
our everyday lives.
The World Health Organization
has concluded that copper
defi ciency is much more of a
global problem than copper
toxicity.
ยต
g/L, copper is toxic to some freshwater aquatic
phytoplankton species.
Uranium and its Decay Products
Uranium, named after the planet Uranus, was i rst identii ed as an element in 1789 by
Martin Klaproth, a German chemist (NRCC 2006, from which the following text bor-
rows). It is generally not found in concentrated deposits, although it is more abundant
than silver, cadmium or mercury. It remained little more than a curiosity for over a cen-
tury, being used to manufacture vivid green glass but having little other application.
Uranium occurs in nature in two main isotopic forms: U-235 and U-238. Uranium-235
was the i rst element in which nuclear i ssion was observed. An atom of U-235 will cap-
ture a neutron and become U-236. U-236 is not stable and achieves stability by splitting
into two lighter atoms, releasing some energy and two or three fast-moving neutrons.
If those neutrons are slowed down sufi ciently they can be captured by another atom of
U-235 and the process is repeated. A piece of apparatus containing uranium-235, some
material for slowing neutrons down and some means to remove the heat energy produced
is the basis for a nuclear reactor. Today energy from the i ssion of uranium produces one-
sixth of the world's electricity. The same amount of energy is produced from 20 kg of ura-
nium as from 400,000 kg of coal and nuclear power stations produce much less waste than
Today energy from the fi ssion of
uranium produces one-sixth of
the world's electricity.
 
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