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Nitrogen is a common normally colourless,
odourless, tasteless and
mostly diatomic non-metal gas. It has five electrons in its outer shell,
so it is trivalent in most compounds.
Applications
The greatest single commercial use of nitrogen is as a component in
the manufacture of ammonia, subsequently used as fertilizer and to
produce nitric acid.
Liquid nitrogen (often referred to as LN2) is used as a
refrigerant for freezing and transporting food products,
for the preservation of bodies and reproductive cells (sperm and eggs),
and for stable storage of biological samples.
Nitric acid salts include some important compounds, for example
potassium nitrate, nitric acid, and ammonium
nitrate. Nitrated organic compounds, such as nitro-glycerine and trinitrotoluene, are often explosives.
Nitrogen in the environment
Nitrogen constitutes 78 percent of Earth's atmosphere and is a
constituent of all living tissues. Nitrogen is an essential element for
life, because it is a constituent of DNA and, as such, is part of the
genetic code.
Nitrogen molecules occur mainly in air. In water and soils nitrogen
can be found in nitrates and nitrites. All of these substances are a
part of the nitrogen cycle, and
there are all interconnected.
Humans have changed natural nitrate and nitrite proportions
radically, mainly due to the application of nitrate-containing manures.
Nitrogen is emitted extensively by industrial companies, increasing the
nitrate and nitrite supplies in soil and
water as a consequence of reactions that take place in the nitrogen
cycle. Nitrate concentrations in
drinking water will greatly increase due to this.
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Nitrates and nitrites are known to cause several health effects.
These are the
most common effects:
- Reactions with haemoglobin in blood, causing the oxygen carrying
capacity of the blood to decrease (nitrite)
- Decreased functioning of the thyroid gland (nitrate)
- Vitamin A shortages (nitrate)
- Fashioning of nitro amines, which are known as one of the most
common causes of cancer (nitrates and nitrites)
But from a metabolic point of view, nitric oxide (NO) is much more
important than nitrogen alone. In 1987, Salvador Moncada
discovered that this was a vital body messenger for relaxing
muscles, and today we know that it is involved in the
cardiovascular system, the immune system, the central nervous
system and the peripheral nervous system. The enzyme that produces
nitric oxide, called nitric oxide synthesis, is abundant in the
brain.
Although nitric oxide is relatively short-lived, it
can diffuse through membranes to carry out its functions. In
1991, a team headed by K.E. Anderson of Lund University Hospital, Sweden,
showed that nitric oxide activates an erection by relaxing the
muscle that controls the bloodflow into the penis. The drug Viagra works by releasing nitric oxide to produce the same effect.
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Humans have radically changed natural
supplies of nitrates and nitrites. The main cause of the addition
of nitrates and nitrites is the extensive use of fertilizers.
Combustion processes can also enhance the nitrate and nitrite
supplies, due to the emission of nitrogen oxides that can be
converted to nitrates and nitrites in the environment.
Nitrates and nitrites also form during chemical production and
they are used as food conservers. This causes groundwater and surface water
nitrogen concentration, and nitrogen in
food to increase greatly.
The addition of nitrogen bonds in the environment has various
effects. Firstly, it can change the composition of species due to
susceptibility of certain organisms to the consequences of
nitrogen compounds. Secondly, mainly nitrite may cause various
health effects in humans and animals. Food that is rich in
nitrogen compounds can cause the oxygen transport of the blood to
decrease, which can have serious consequences for cattle.
High nitrogen uptake can cause problems
in the thyroid gland and it can lead to vitamin A shortages. In
the animal stomach and intestines nitrates can form
nitroamines; dangerously carcinogenic compounds.
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Back to the periodic
chart
Find our
nitrogen in water
page
For more information on nitrogen in the environment, move to
the nitrogen
cycle |
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