ozone layer is a layer of oxygen in the form of O3 where oxygen
atoms hang around in groups of three rather than the usual two as in the
O2 version that we all breathe and need to live. The ozone layer
is found in the lower stratosphere about 20 to 30 kilometers (12-19 miles)
above the earth's surface. While at ground level it is a pollutant, up there
it fulfills the incredibly useful function of stopping too much harmful
ultra violet light getting through, soaking up about 97-99%. The
is a thinning of this layer that allows too much harmful ultra violet light
to get through the earth's atmosphere over the south pole during the
Austral spring. This is caused by the pumping into the atmosphere of chlorofluorocarbons
(CFCs) by the industrialized world over a long time period. It has been
recognized since the 1980's.
The ozone hole is probably the best example
of pollutants that are produced in one place, having their effects in another.
As Antarctica is one of the cleanest, least polluted places on earth it
is an ideal location for measuring the spread of global pollutants. Minute
traces of man-made chemicals used in other parts of the world can be detected
in the snow that falls over the region. They become concentrated in the
bodies of local wildlife such as fish and then seals and penguins.
More mundane, but equally great threats to Antarctica are the effects of
casual pollution that goes along with every day life and activities. In
a cold and slowly changing environment the effects of simple events can
be there for years. Organic material for instance can take decades to decay
where it would be gone in months even in the temperate parts of the world.
The outline of footprints on a moss-bank can still be seen years later for
Sewage and food waste are allowed to be disposed of at sea in Antarctica
by ships and bases on land, though more and more land bases have biological
treatment plants that reduce the impact of the raw sewage before it is discherged.
All other waste is shipped out of Antarctica to be dealt with when the ship
spills are an increasing form of pollution in Antarctica as a result of
increasing shipping activity in the region. While ships often have facilities
to contain waste oil and separate oil from water which is then taken out
of Antarctica for disposal, an ever greater presence is bound to lead to
more accidents which do happen. In recent years there have been a number
of groundings of tourist ships in shallow, poorly chartered waters and also
accidents involving fishing boats in pursuit of the Patagonian toothfish.
November 2007, holing and subsequent sinking by an iceberg of the M/V Explorer
in the Bransfield Strait (picture left).
The ship was carrying approximately 178m3 of diesel, 24m3
of lube oil and 1,200 L of gasoline some of which was seen to start leaking
out over the following days creating an oil slick. Fortunately for the environment
the ship sank in deep water away from land and the typically rough nature
of the Southern Ocean meant that the oil was dispersed by wind and wave
before it could cause any significant damage.
With the Southern Ocean being so rich in animal life and any clean-up operation
being far from land, oil spills are potentially disastrous in Antarctica.
seals entangled in discarded rubbish
Use of pictures by permission
Rodrigo Hucke-Gaete, Instituto de Ecologie y Evolucion,
Universidad Austral de Chile
An increasing problem in Antarctic waters (and in the
rest of the world too) is flotsam and debris lost overboard from ships,
particularly fishing ships. Bits of fishing net, fishing line, boxes, strapping
bands etc. might sound harmless if unsightly, but they can have a deadly
effect on wildlife.
Birds and seals get tangled up up lines and net. Fur seals can suffer the
most as the youngsters in particular are very playful and what starts off
as a game with a plastic band can soon turn nasty as it gets stuck over
the seals head. Unable to remove the band it begins to cut into the flesh
causing physical injury, infection and ultimately a long and slow death.