2. Plan
1. Water.
2. Uses of water.
3. What water is made of.
4. On Earth.
5. Water pollution.
3. Water
Water is the most common liquid on
Earth. It covers about 71.4% of the
Earth. Pure water has no smell, taste, or
color. Lakes, oceans, and rivers are
made of water. Rain is water that falls
from clouds in the sky. If water gets very
cold, it freezes and becomes ice. Frozen
rain can be ice or snow if conditions
permit. If water gets very hot (above
100 degrees Celsius), it boils and
becomes steam. Water is very
important for life.
4. Uses of water
Plants and animals (including
people) are mostly water inside, and
must drink water to live. It gives a
medium for chemical reactions to take
place, and it is the main part of blood.
It keeps the body temperature the
same by sweating from the skin.
Water helps blood carry nutrients
from the stomach to all parts of the
body to keep the body alive. Water
also helps the blood carry oxygen from
the lungs to the body. The human
body is between 60% and 70% water.
5. What water is made of
Water is a molecule made of 2
hydrogen atoms and 1 oxygen atom. Its
chemical formula is H2O. Water has a
surface tension, so a little water makes
drops on a surface, rather than spreading
out to wet the surface. Water can also be
called 'aqua', which is the Roman word
for water. Water is also used for
recreational purposes. Though a human
being can survive for up to a three weeks
without food, they can only survive for a
day or two without water. A few desert
animals can get enough water from their
food, but the others must drink.
6. On Earth
Hydrology is the study of the
movement, distribution, and quality
of water throughout the Earth. The
study of the distribution of water is
hydrography. The study of the
distribution and movement of
groundwater is hydrogeology, of
glaciers is glaciology, of inland waters
is limnology and distribution of
oceans is oceanography. Ecological
processes with hydrology are in
focus of ecohydrology.
7. Water pollution
Water pollution is the pollution of bodies
of water, such as lakes, rivers, the oceans,
as well as groundwater. It occurs when
pollutants reach these bodies of water,
without treatment. Waste from homes,
factories and other buildings get into the
water bodies.
Water pollution is a problem for the
species and ecosystems there. It affects
plants and organisms living in the water.
In almost all cases the effect is damaging
not only to individual species and
populations, but also to the wider
biological communities. The color is
usually green or brown but normal water
can be blue.
