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Impact
of metals and non-metals on living
systems and the environment
Francine
Taylor-Campbell, Contributor
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| Students
from Vauxhall High School perform
at the official launch of the
Kingston Harbour Public Awareness
Campaign, 'Bring back the Life',
at the Jamaica Conference Centre,
downtown Kingston, on November
11, 2004. - Rudolph Brown Photo |
POINTS
TO NOTE
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Water is made available for mankind
through the water cycle in which there
is a continual exchange of water between
the surface of the earth and the atmosphere.
The essential processes in the cycle
are evaporation, condensation, transpiration,
precipitation and runoff.
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Nitrogen is made available to living
systems through the process of fixation.
This can occur in three ways - atmospheric
fixation, industrial fixation and
biological fixation.
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The carbon cycle maintains the concentration
of carbon dioxide in the air. This
gas is taken in by plants and converted
to organic compounds through the process
of photosynthesis and is released
by plants and animals through respiration.
NON-METALS
AND LIVING SYSTEMS
1.
Carbon dioxide and water are important
elements in the process of photosynthesis.
6CO2(g) + 6H2O(l)
===== C6H12O6(aq)
+ 6O2(g) sunlight
/ chlorophyll
2.
Oxygen is important to the process
of respiration in which food is burnt
to produce energy. C6H12O6(aq)
+ 6O2(g) ====
6CO2(g) + 6H2O(l)
+ energy
3.
Nitrogen and sulphur are important
in protein synthesis, which is essential
for growth and development of tissues.
4.
Phosphorus is an important plant nutrient
and helps to build strong bones and
teeth.
5.
Water, containing the elements hydrogen
and oxygen, is a universal solvent,
which is essential for many processes
and reactions in living cells.
NON-METALS
AND THE ENVIRONMENT
1.
Ions of nitrogen, phosphorus and sulphur
(NO3-, PO4
3- and SO4²-)
from untreated sewage, detergents
and fertilizers can affect water bodies
by causing nutrient enrichment which
can lead to oxygen depletion and death
of aquatic organisms.
2.
Organic waste from sewage can affect
aquatic organisms by depleting their
oxygen supply.
3.
Insecticides and herbicides can become
toxic to animals and can become concentrated
up the food chain.
4.
Oxides of nitrogen, sulphur and carbon
from the combustion of fuels can dissolve
in rainwater forming acid rain, which
is harmful to plants and animals and
can corrode buildings.
5.
Chlorofluorocarbons (CFC's) from aerosols
can break down the ozone layer thereby
allowing harmful ultraviolet-radiation
to reach earth, which can lead to
skin cancers.
METALS
AND LIVING SYSTEMS
1.
Magnesium and iron are important constituents
of chlorophyll in green plants. Iron
forms part of the haemoglobin molecule
found in red blood cells.
2.
Calcium is essential for the formation
of healthy teeth and bones.
3.
Ions of sodium and potassium are needed
for the transmission of nerve impulses.
4.
Zinc, copper, manganese and cobalt
are examples of trace elements needed
by plants and animals for their proper
growth and development.
METALS
AND THE ENVIRONMENT
Heavy
metals such as lead and mercury are
toxic to living organisms causing
brain damage and death. These metals
can accumulate in the environment
and concentrate in consumers in the
food chain where they become more
toxic. Other metals such as tin, cadmium,
copper and zinc can affect aquatic
animals and are suspected cancer-causing
agents.
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Francine Taylor-Campbell is
an independent contributor.
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