Water is the Solution
If it were not for the movement of water, no
cycles would be possible. Water is the major transportation medium of all elements. It
takes things where they need to go.
The solar energy provided by the sun makes the movement of
to form clouds and falls to the ground.
The high energy exerted by the
sun excites water molecules and enables them to escape into the
atmosphere as vapor.
water recycles, it helps promote other
cycles in several ways:
Water acts as a
for chemical reactions.
Materials contained in water get
to interact with all parts of the ecosystem.
Water is necessary for plants to
turn solar energy into chemical energy.
nothing could survive on earth without water.
stays on the earth because earth's gravity is strong
enough to keep the water from escaping.
In addition, the sun provides enough heat to keep water in its
liquid form, yet is not so hot that all of the water
have discovered canyons on Mars that suggest water once existed there.
Water is gone now because Mar's small amount of gravity allows
water escape into space. If water existed on
Mars, vegetation would begin to grow and life could exist.
A Double-Edged Sword
Recycling of water and carbon take care of our needs for
making carbohydrates and fats, but what about the proteins and nucleic
acids contained in our RNA and DNA? All
of these chemicals contain nitrogen, another chemical that has to be
recycled in the environment. The
air you breathe contains roughly 70% nitrogen gas, but this gas form of
nitrogen provides a small contribution to the total nitrogen exchanged in the
environment. In order for
nitrogen to be used by organisms, it must be converted to a
compound called ammonia (NH3). The
majority of the ammonia available for exchange in an ecosystem is formed from two
different methods, both involving the bacteria:
Molecular nitrogen (N2) is fixed by bacteria to
make ammonia (consumes lots of energy).
Fungi and bacteria decompose the
nitrogen contained in dead organic matter and release
nitrates (NO3) and ammonia (releases energy).
excess nitrogen to these cycles from outside sources disrupts the
balance of the cycle, and the extra nitrogen is released into the
atmosphere in a form called nitrous oxide.
What element does nitrogen combine with to form this compound?
This form of nitrogen is a pollutant because it falls back to
land with rain in the form of nitric acid (HNO3).
Human actions create most of this problem. The sources that contribute the most to the excess nitrogen
Agriculture – deforestation and breaking up
Industry – combustion (burning
Automobile exhaust – combustion