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5 December 2013 11:26 am ,
Vol. 342 ,
An animal rights group known as the Nonhuman Rights Project filed lawsuits in three New York courts this week in an...
Researchers have been hot on the trail of the elusive Denisovans, a type of ancient human known only by their DNA and...
Thousands of scientists in the Russian Academy of Sciences (RAS) are about to lose their jobs as a result of the...
Dyslexia, a learning disability that hinders reading, hasn't been associated with deficits in vision, hearing, or...
Exotic, elusive, and dangerous, snakes have fascinated humankind for millennia. They can be hard to find, yet their...
Researchers have sequenced and analyzed the first two snake genomes, which represent two evolutionary extremes. The...
Snake venoms are remarkably complex mixtures that can stun or kill prey within minutes. But more and more researchers...
At age 30, Dutch biologist Freek Vonk has built up a respectable career as a snake scientist. But in his home country,...
- 5 December 2013 11:26 am , Vol. 342 , #6163
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Stratospheric 'Rocks' May Bode Ill for Ozone
8 February 2001 7:00 pm
Bizarre particles in stratospheric clouds could make arctic ozone more vulnerable to the climate change expected this century, researchers report in the 9 February issue of Science. The unexpectedly large particles could help destroy enough ozone during the spring to create a bona fide ozone hole over the Arctic, much like the one above Antarctica.
The discovery came during a January 2000 research flight nearly to the North Pole, report atmospheric chemist David Fahey of the National Oceanic and Atmospheric Administration (NOAA) in Boulder, Colorado, and colleagues. An instrument on NASA's highflying ER-2 plane designed to measure nitrogen-rich gases instead detected humongous particles containing nitric acid. The polar stratospheric cloud (PSC) particles that form in the extreme cold of polar winter generally run a few tenths of a micrometer to a micrometer in diameter. But these oversized particles, more than 3000 times the usual mass, ranged up to 20 micrometers. "These things are rocks compared to" the usual PSC particles, Fahey says.
The discovery is catching researchers' attention because the particles can play an indirect role in ozone destruction. Ozone is protected by the nitrogen atoms in nitric acid, because they can chemically tie up ozone-destroying chlorine and bromine in inactive, harmless forms. So when nitrogen is locked up in PSCs, more chlorine and bromine can remain active to destroy ozone. And PSC rocks fall far faster than feathery-light PSC particles, so the rocks can efficiently ferry nitrogen out of some layers of the stratosphere, leaving active chlorine and bromine behind to have their way with ozone.
The discovery of PSC rocks is "the first time we've clearly seen reactive nitrogen being stripped from the polar arctic stratosphere," says James Anderson of Harvard University. He adds that "the most important question" is how this system will respond as greenhouse gases build. If these rocks remove enough ozone-protecting nitrogen, ozone destruction over the Arctic might continue even after PSCs disappear in the spring. As greenhouse gases alter stratospheric climate so as to encourage PSC rock formation, Fahey and his colleagues say, the big particles could delay recovery of arctic ozone.