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ddt
killing penguins - but why? ddt is now mostly banned
“The use of DDT peaked several decades ago at more than 36,000
metric tons per year (t/yr). Today, less than 1000 t of the organochlorine
pesticide—banned in most countries since the 1980s—is applied
annually for mosquito control and farming, mainly in the Southern Hemisphere.
Despite this drop, Adélie penguins in the Antarctic continue
to have the same levels of total DDT in their bodies as they did 30
years ago. New research [...] identifies Antarctic meltwater as the
continued source of total DDT, and possibly other pollutants, in the
southern continent's ecosystems.”
“In 1958, Olga Owens Hucking, the owner of a private bird sanctuary
in Duxbury, Massachusetts sent a letter to Carson. Ms. Hucking was alarmed
at the dead and dying birds at her sanctuary. That letter may have been
the deciding factor prompting Carson's next book. It was clear to Carson
that the issue of pesticides had to be addressed in a book with a tone
different than her earlier writings. Her book, Silent Spring, was published
in 1962. In it, Carson addressed the dangers posed by DDT and the dangers
of a society blinded by technological progress.
“The evidence was undisputedly conclusive that DDT interfered
with calcium metabolism in birds at the top of the food chain. With
no mechanism to excrete or breakdown DDT, birds at the top of the food
chain accumulated DDT as they ate smaller birds, which, in turn, ate
insects exposed to DDT. The interference with calcium metabolism caused
thinning eggshells that broke easily.” [Quoted from dep.state.pa.us]
The negative response to using DDT, and its widespread
ban, led to the re-emergence of malaria. DDT had kept malaria mosquito
populations under control. It is now understood that selective spraying
of houses with DDT can control mosquito infestation without damaging bird
and plantlife.
related material
malaria
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Silent Spring
by Rachel Carson
first published in 1962
Penguin Classics, 2000
ISBN-10: 0141184949
ISBN-13: 978-0141184944
£6.99
[amazon.co.uk]
Mariner Books, 2002
ISBN-10: 0618249060
ISBN-13: 978-0618249060
$10.17
[amazon.com] |
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the web address for the article above is
http://www.abelard.org/news/lite0805.php#ddt_penguins_100508
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the
potential of tethered windmills
The Magenn company have got the tethered rotor windmill
to work in a hanger.
A
list of claims
- Magenn Air Rotor System is less expensive per unit of actual electrical
energy output than competing wind power systems.
- Magenn Power Air Rotor System will deliver time-averaged output much
closer to its rated capacity than the capacity factor typical with conventional
designs. Magenn efficiency will be 40 to 50 percent. This is hugely
important, since doubling capacity factor cuts the cost of each delivered
watt by half.
- Wind farms can be placed closer to demand centers, reducing transmission
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- Conventional wind generators are only operable in wind speeds between
3 meters/sec and 28 meters/sec. Magenn Air Rotors are operable between
1 meter/sec and in excess of 28 meters/sec.
- Magenn Air Rotors can be raised to higher altitudes, thus capitalizing
on higher winds aloft. Altitudes from 400-ft to 1,000-ft above ground
level are possible, without having to build an expensive tower, or use
a crane to perform maintenance.
- Magenn Air Rotors are mobile and can be easily moved to different
locations to correspond to changing wind patterns. Mobility is also
useful in emergency deployment and disaster relief situations.
related material
Wind power
the web address for the article above is
http://www.abelard.org/news/lite0805.php#tethered_windmills_060508
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