Skip to comments.Oceans clear air pollution, scientists say
Posted on 08/19/2002 8:01:39 AM PDT by BallandPowder
WASHINGTON (AP) - That salty spray from the ocean gives the air more than a refreshing tang. It appears to provide a scrubbing, too.
A team of Israeli researchers reports that, by encouraging increased rainfall, the sea spray helps wash pollution from the air.
"The conclusion stands that the air that we breathe near the surface remains clean because of the fact that the oceans are salty," said Daniel Rosenfeld of Hebrew University in Jerusalem.
"We have discovered a process by which nature apparently cleanses the ... air pollution quite effectively when it spills from land over to the oceans," he said
Practically all the pollutants are removed at the lower layer of the atmosphere, Rosenfeld said. That is one reason why the air in Hawaii is always so pristine, except during volcanic eruptions, he said.
Rosenfeld and his colleagues used satellite data to study the air over the Indian Ocean, where massive amounts of particles from burning, urban air pollution and desert dust are blown from southern Asia.
But such effects "are not unique to that part of the world," he said.
Nearly three-fourths of the Earthfs surface is covered by water, and the winds are constantly moving air from land onto the oceans and from the oceans onto land worldwide.
Rosenfeldfs findings are reported in Fridayfs issue of the journal Science.
"The paper presents an interesting point which has not been discussed for some time," said John Porter of the Hawaii Institute for Geophysics and Planetology.
Porter said the idea of coarse sea salt initiating rainfall was proposed as early as the 1950s, but studies in the 1970s seemed to show it was not an important factor. Rosenfeldfs work appears to support the earlier research, he said.
Porter, who was not on Rosenfeldfs team, said his own research indicated salt helped to increase rainfall in relatively clean air but was less effective in more polluted conditions.
In other papers in the same issue of Science:
A team of British scientists reports finding a source of methyl and ethyl nitrates in the Atlantic Ocean. These compounds play an important role in regulating the amount of ozone in the atmosphere. It is not clear how the compounds were produced, but it is the first indication of an oceanic source for them, said team leader Adele Chuck of the University of East Anglia.
Ariel Anbar and colleagues at the University of Rochester in New York report that during the Proterozoic eon, 2.5 billion to 543 million years ago, the oceans were oxygenated only near the surface and contained sulfides in the deeper waters.
They say that means primitive forms of cellular life probably could only have lived near shore where trace metals needed for nutrition were available.
In his paper, Rosenfeld explained that tiny specks of air pollution can suppress rain by serving as nuclei on which moisture can condense. They form such tiny droplets that they can remain suspended in the air without falling.
But the salty sea spray attracts water into larger droplets, which can merge with the tiny ones, growing big enough to form rain and wash the pollutants out of the air.
If salty spray does help create rainfall over the ocean, could it also be used to increase rain in the desert, Rosenfeld was asked.
"There is no reason why we canft do artificially over land what happens naturally over oceans. In fact, we have started in Israel an experiment of cloud seeding" using brine from the Dead Sea, he said in an interview via e-mail.
Smoke pole clouds eaten by salt rain... The amazing disappearing global warming theory!
Global warming bump!
Global warming bump!
Global warming bump!
"There is no reason why we can't do artificially over land what happens naturally over oceans. In fact, we have started in Israel an experiment of cloud seeding using brine from the Dead Sea. . . ."
I wonder whether this has any possible application to firefighting in the western U.S.?