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| A simple cycle model |
According to the law of conservation, matter in a closed system can be neither created nor destroyed in
any chemical reaction. It can take different forms.
A cycle is a thing that runs over
and over again- a cycle model is shown above. A typical working Ghanaian urban dweller may have a cycle as I
am about to describe. Their day start with waking up from sleep in the morning.
After waking up from sleep one says one’s prayers. After that one does one’s
aerobics. Thereafter one does ones morning chores in the house, and then get
showered ready for work. After closing from work in the evening one comes back
to the house, take dinner and watch some television programs, and then
eventually go to sleep to wake up the next day to start the day all over again
as such.
The natural environment has its
cycles. They are variously called environmental cycles, biogeochemical cycles and
nutrient cycles. Specifically, the cycles are nitrogen cycle, carbon cycle,
phosphorous cycle, oxygen cycle (these are the nutrient cycles) and water
cycle. In the environmental cycle elements flow through the structure of the
environment in various forms. Elements flow through the air, soil, water and
organisms (including humans), making the natural environment a medium for
constant flow of elements i.e. nitrogen, oxygen, carbon etc. You may have an
Albert Einstein atom throbbing in your body, recycled!
Cycles are important features of
the natural environment. Without cycles the natural environment may get into a
state of inertia- cycles keep the natural environment running. Cycles are a
cine quo non for the functionality of the natural environment, and indeed life.
NITROGEN
CYCLE
Nitrogen is a colorless, odorless
chemical element making up 78% of air by volume. Nitrogen is essential component
in the tissues of living things. It is present in all proteins and some
minerals. Its atomic number is 7 and symbol N. Proteins are big molecules
containing amino acid residues. They are in every cell of a living thing. Some
of the things proteins do in a living thing are copying of DNA, moving molecules
from one place to another and responding to stimuli within a cell. They are in
every one of the 100 million or so cells in your body applying themselves to
keep your body running.
The path of the nitrogen cycle is
as follows:
Start: As indicated nitrogen takes up 78% of the air. That nitrogen
in its raw stage cannot be absorbed by plants. One way to make it absorbable
for plants is through lightning. When lightning strikes through the air
nitrogen becomes absorbable. Also, there are bacteria that help to convert
nitrogen into a usable form for plants to use. Technically that process is
called fixation.
Next: Plants absorb nitrogen through their roots in the form of
amino acid, ammonium ions, nitrate ions etc. Animals get their nitrogen through
the eating of plants. The absorption of nitrogen by plants is termed
assimilation.
Next: The nitrogen in a dead plant, a dead animal or feces of
animal is initially organic. The organic nitrogen is changed into ammonium by
bacteria or fungi. The conversion process is termed ammonification.
Next: Bacteria in the soil convert ammonium into nitrates and
nitrites. This process is termed nitrification.
Completion: Some bacteria reduce nitrates back to raw nitrogen to
complete the cycle. The reduction process is termed denitrification.
OTHER CYCLES
Other nutrient cycles follow
similar paths. I have used the nitrogen cycle as an example. In each case,
matter is neither created nor destroyed, no matter the number of forms it
takes.
WATER CYCLE
Water cycle starts with
evaporation of water from the oceans. When evaporation occurs due to heat from
the sun, liquid water is turn into a gaseous form called water vapor. In the
atmosphere the gaseous water turns into droplets of water in clouds. Under
gravity the droplets fall back on Earth into the oceans or other water bodies
for a restart of the process through evaporation. In the case of snow, the
evaporated liquid water forms ice in the clouds in the atmosphere which later
fall as snow.
SUMMARY
- There are cycles in the natural environment to keep it dynamic, intact and balanced, sustainably.
- Through the cycles nutrients needed to sustain the life of living things flow through the environment for their benefit.
- The nutrients as matter, as they go through changes in the cycle, are preserved, because they can neither be destroyed nor created though they change form.
- Nitrogen in the form of protein is needed for the cells in living things (including humans) to function properly.
PARTING SHOT
The dynamics of the natural
environment keep it intact, all things being equal. Earthlings could learn a
lot more from the dynamics of nature to help preserve the natural environment
even as we secure our sustenance from it.
Reference:
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