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Under
the broad heading of plant forms we can classify the
following:
Algae
These
organisms are found throughout the world. They
constitute the chief group of aquatic plants both in sea
and fresh water.
Algae
range in size from microscopic organisms to giant
seaweeds several hundred feet in length. They contain
chlorophyll and other pigments which give them a variety
of colors. They manufacture their food by
photosynthesis.
Algae
thrive well in stagnant waters, especially during the
warm weather.
Algae
give water fishy, grassy and other even more
objectionable odors.
While
algae-laden waters are repulsive to man, animals will
drink them, and the presence of blue-green algae has
been known to cause death of cattle drinking this water.
Diatoms
Diatoms
belong to the alga family. Some exist as single cells,
others are found as groups or colonies, more than 15,000
forms of diatoms are known to exist.
Diatoms
have silica-impregnated cell watts. At times they
release essential oils which give water a fishy taste.
Fungi
Fungi
are another large group of plant forms. Like the algae,
fungi have many varieties. Included among these are
molds and bacteria.
Fungi
are not able to manufacture their own food. They exist
by feeding on living things or on dead organic matter.
Depending on their individual characteristics. They are
usually colorless but may vary in this respect.
Molds
One
important category of fungi is molds. This group of
fungi feeds entirely on organic matter. They decompose
carbohydrates such as sugars, starches, and fats as well
as proteins and other substances. They thrive ideally in
water that has a temperature range of approximately 27
to 38 degree Centigrade
The
presence of molds is generally a strong indicator of
heavy pollution of water.
Bacteria
Bacteria
are another important class of fungi. Again numerous
smaller groupings are possible. Among the high organisms
in this group are the iron, manganese, and sulfur
bacteria. These higher bacteria gain their energy from
the oxidation of simple inorganic substances.
Lower
forms of bacteria can be grouped as those that are
helpful and those that are harmful to man. Those harmful
to man are mainly the disease-producing organisms.
Helpful
organisms hasten the process of decomposing organic
waster matter. By feeding on waste material they aid in
the purifying of water.
All
bacteria are sensitive to the temperature and ph of
water. Some bacteria can tolerate acid water. But for
the most part they thrive best in waters that have a ph
between 6.5 to 7.5, that is, essentially neutral waters.
As
to temperature, most pathogenic or disease bacteria
thrive best in water of body temperature. Beyond this no
hard and fast statements can be made.
Some
bacteria are more resistant to heat than others. Some
are more sensitive to cold. At low temperatures, for
example, some bacteria may become dormant for long
periods of time but will still continue to exist.
Interestingly
enough, the waste products of their own growth can
hamper bacteria and may even prove toxic to them.
Coliform
bacteria can be expected to be present in contaminated
water in greater number than are the contaminating
organisms.
They
are readily identifiable as a result of relatively
simple analytical tests.
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