A
Threatening Void
One cannot just look at the sky
to locate the hole in the atmospheric ozone layer.
It is an invisible threat. The problem, produced by
the alteration of the Earth's environmental conditions
as a result of human activity, poses great dangers
for humanity and ecosystems.
The ozone hole is not really
a hole, but a thinning of the ozone layer that surrounds
our planet and serves to filter out harmful ultraviolet
rays. This thinning is concentrated in the Earth's
extreme south.
When this natural filter is reduced,
the Sun's rays reach the Earth's surface with greater
intensity and can cause biological changes that are
not yet fully understood. In the case of human beings,
and of some animal species, the harmful rays can lead
to skin or eye problems.
The ozone hole is oval-shaped
and its center is found some 900 km from the South
Pole. The phenomenon reaches its maximum - meaning
the thinned area is largest - during the Southern
Hemisphere spring, September to December, and affects
the residents of such southern cities as Chile's Punta
Arenas.
Experts on the ozone layer report
that at the hole can cover 24 million square km, but
has even reached 27 million square km.
The existence of the ozone hole
was first suggested by research in the 1970s. By the
mid-1980s, governments around the world signed the
Vienna
Convention to protect the ozone layer, and in
1987 it was proposed that all nations sign the Montreal
Protocol.
This Protocol calls for a ban
on the production of chlorofluorocarbons (CFCs) and
other compounds that are known to cause chemical reactions
that harm the ozone layer. CFCs are present in our
everyday lives, as they are used in the cooling systems
of refrigerators and in manufacturing aerosols.
The magnitude of this problem
is reflected in the proliferation of Internet sites
dedicated to the ozone layer, explaining
the phenomenon occurring up in the sky in simple terms
or in scientific
studies, official
documents or images.
UNEP:
Ozone Secretariat
UNEP:
Montreal Protocol
Document:
Action on Ozone 2000
Secretariat
for Implementation of Montreal Protocol
Vienna
Convention
Frequently
Asked Questions about the Ozone Layer
World
Meteorological Organization: Ozone Bulletin
Yahoo!:
News on the Ozone
NASA: Ozone Mapping
Ozone
Hole Tour
Greenpeace:
Ozone Crisis
FAQs:
Ozone Depletion
Slithering
Creatures
Snakes have slithered across
the surface of the Earth for millions of years. They
are part of the reptile group, primitive beings in
the evolution of life. They have always captivated
the imagination of humans, who give snakes a leading
role in various mythologies.
Snakes are members of the subgroup
''serpents'' and, according to scientific
classification, are divided among some 20 families
for a total of more than 2,900 species.
The most numerous family is the
colubridae, but the most remarkable are cobras, rattlesnakes,
or the enormous constrictors, like the anaconda.
Though serpents appear frequently
in our cultures and legends, they tend to be rejected
by our collective unconscious. Many people fear snakes
because some are truly very dangerous, capable of
biting and injecting their victims with deadly venom.
But there are those of the opposite
opinion, evident in the fact that most Internet
websites about snakes are maintained by people who
keep these creatures as pets. And they assert that
there are plenty of reasons to promote the peaceful
coexistence between snakes and humans.
Thesnake.org
Snakes
Snakebite
Emergency Information
Scientific
Classification
Rattlesnake
Museum
Anacondas:
Biggest Snakes
A
Big Little World
Ants appeared on Earth some 100
million years ago, and even became one of the planet's
most representative inhabitants, with social practices
that continue to amaze children, strategists, engineers,
psychologists and scientists alike.
These small creatures are the
object of study in the scientific discipline known
as myrmecology.
And it is no accident that they are the target of
investigation because the word ''ant'' describes approximately
20,000 species.
According to the scientific
classification, they are members of the family Formicadae,
of the order Hymenopteron. But their best-known trait
is that they belong to a group known as ''social insects.''
Ants build amazing homes
- ant's nests or anthills - where they establish communities
in which each member serves a purpose. Some theorists
say that these insects have thus been able to put
the idea of ''super-organism''
into practice.
Ant
colonies begin with the fertilization of the queen
ant. The fascination produced by the abilities, loyalty,
specificity and perfection of the ants' work has led
some people to develop the hobby of creating artificial
ant colonies in an attempt to get a closer look at
how they function.
On the Internet, there are portals
on ants, educational websites that cover the complex
existence of these tiny
creatures, and some sites that focus on certain
species, such as the fire
ants, considered a plague in the United States.
Portal:
Myrmecology.org
Portal:
Antcolony.org
Ants:
Photo Encyclopedia
Nova:
The Little Creatures Who Run the World
Ant
Information
Fire
Ants in the United States: Pest and Health Hazard
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