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Earth
is the “watery planet”. With over
70% of the earth’s surface covered with
water; it makes water the most common substance
on earth. Oceans contain 97% of the earth’s
water while the remaining 3% is classified as
freshwater. Seventy-seven percent of this surface
fresh water is stored as ice, and 22% as ground
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and
soil moisture. The remaining fresh water, making
up less than 1% of the world total, is contained
in lakes, rivers and wetlands.
Water is often thought of in terms of a particular
purpose: Is the quality of the water good enough
for the use we want to make of it ? Water fit
for a certain use may be unfit for another.
The quality of lake water, for instance, may
be trusted enough to swim in it, but not enough
to drink it.
Along the same lines, drinking water can be
used for irrigation, but water used for irrigation
may not meet drinking water standards. It is
the quality of the water that determines its
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Drinking water,
for example, is regulated by guidelines
stringent enough to protect human health.
Lack of such guidelines can lead to a
variety of health problems. It has been
estimated, for example, that contaminated
water and poor sanitation cause 30000
deaths around the world daily –
the
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equivalent
of 100 jumbo jets crashing every day!
Industries,
on the other hand, are interested in other aspects
of water quality. For certain applications,
quality is determined by the kinds and amounts
of substances dissolved and suspended in the
water and how those substances affect the process
and the ecosystem. It is the concentrations
of these substances that determine the water
quality and its suitability for particular purposes.
The
world’s demand for water is constantly
increasing, with no end in sight. And
since only 3 percent of the water on
earth is fresh water, and 97 percent
of the water is trapped in glaciers,
most of the water on earth is not easily
available. Yet, this now scarce resource
is being abused by pollution.There are
many causes for water pollution but
two general categories exist: direct
and indirect contaminant sources.
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Direct sources include effluent outfalls from
factories, refineries, waste treatment plants
etc. that emit fluids of varying quality directly
into urban water supplies.
Indirect
sources include contaminants that enter the
water supply from soils / ground water systems
and from the atmosphere via rain water. Soils
and ground waters contain residues of human
agricultural practices (fertilizers, pesticides
etc..) and improperly disposed of industrial
wastes. Atmospheric contaminates are also
derived from human practices (such as gaseous
emissions from automobiles, factories and
even bakeries).
Water
is the lifeblood of the environment, essential
to the survival of all living things- plant,
animal and human- and we must do everything
possible to maintain its quality for today
and the future.
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