What is water pollution?
Water
pollution is any chemical, physical or biological change in the quality
of water that has a harmful effect on any living thing that drinks or
uses or lives (in) it. When humans drink polluted water it often has
serious effects on their health. Water pollution can also make water
unsuited for the desired use.
What are the major water pollutants?
There
are several classes of water pollutants. The first are disease-causing
agents. These are bacteria, viruses, protozoa and parasitic worms that
enter sewage systems and untreated waste.
A second category of
water pollutants is oxygen-demanding wastes; wastes that can be
decomposed by oxygen-requiring bacteria. When large populations of
decomposing bacteria are converting these wastes it can deplete oxygen
levels in the water. This causes other organisms in the water, such as
fish, to die.
A third class of water pollutants is water-soluble
inorganic pollutants, such as acids, salts and toxic metals. Large
quantities of these compounds will make water unfit to drink and will
cause the death of aquatic life.
Another class of water pollutants
are nutrients; they are water-soluble nitrates and phosphates that cause
excessive growth of algae and other water plants, which deplete the
water's oxygen supply. This kills fish and, when found in drinking
water, can kill young children.
Water can also be polluted by a
number of organic compounds such as oil, plastics and pesticides, which
are harmful to humans and all plants and animals in the water.
A
very dangerous category is suspended sediment, because it causes
depletion in the water's light absorption and the particles spread
dangerous compounds such as pesticides through the water.
Finally, water-soluble radioactive compounds can cause cancer, birth defects and genetic damage and are thus very dangerous
water pollutants.
Water
pollution is usually caused by human activities. Different human
sources add to the pollution of water. There are two sorts of sources,
point and nonpoint sources. Point sources discharge pollutants at
specific locations through pipelines or sewers into the surface water.
Nonpoint sources are sources that cannot be traced to a single site of
discharge.
Examples of point sources are: factories, sewage treatment plants, underground mines, oil wells, oil tankers and agriculture.
Examples of nonpoint sources are: acid deposition from the air,
traffic, pollutants that are spread through rivers and pollutants that
enter the water through groundwater.
Nonpoint pollution is hard to control because the perpetrators cannot be traced.
