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NASA-funded researchers have
discovered that bacteria and fungi are being transported in
plumes of North African dust that cross the Atlantic Ocean and
arrive in the Americas and the Caribbean. Dust storms and the
rising warm air can lift dust 10,000 feet or so above the
African deserts and then out across the Atlantic, many times
reaching as far as the Caribbean where they often require the
local weather services to issue air pollution alerts. Recent
studies have linked disease born illnesses and the decline of
the coral reefs in the Caribbean to the increasing frequency
and intensity of Saharan dust events.
DUST PARTICLE LANDSCAPE - Microbes transported by dust
storms in North Africa have been hitching rides across the
Atlantic--living in the highly irregular nooks and crannies
found in the surfaces of dust particles. These images were
taken by an electron microscope magnified 12,000 & 8,000
times. Notice the moon-like craters which protect the microbes
from exposure to ultraviolet radiation from the Sun.
Scientists also think that upper altitudes of the dust clouds
deflect harmful UV rays, shielding microbes at lower altitudes
as they are transported across the Atlantic Ocean.
Additionally, when dust clouds move over
open water in lower latitudes, the moderate temperatures and
high humidity are known to enhance microbial survival.
Dust Image
Magnified 12,000 Times
Dust Image
Magnified 8,000 Times
Images Courtesy: USGS
ITEM 2) MICROBES RIDE THE DUST
ANIMATION - The dust
comes every year during northern Africa's dry season, when
storm activity in the Sahara Desert and Sahel generate clouds
of dust. The dust originating from fine particles in the arid
topsoil is transported into the atmosphere by winds and may be
carried in excess of 10,000 feet high into the atmosphere by
easterly trade winds. Typically, it takes 5 to 7 days for the
dust clouds to cross the Atlantic Ocean and reach the
Caribbean and Americas. This animation illustrates microbes
hitching rides across the Atlantic in the highly irregular
nooks and crannies found in the surfaces of dust particles and
how they are transported across the Atlantic Ocean
Animation
of dust movement
Animation Courtesy: NASA
TOMS DATA VISUALIZATIONS -
During the peak of the 2000 dust season, scientists collected
samples of airborne pollutants and dust daily on the island of
St. John in the Virgin Islands. The results show that high
levels of microbes were collected on the days that NASA's
Total Ozone Mapping Spectrometer (TOMS) satellite instrument
observed the African dust sweeping into the region, indicating
that the microbes had been transported from Africa. The TOMS
data were rendered and combined with a world map to help
scientists track the progress of the clouds of dust. The tan
and orange colors in these images primarily show high
concentrations of dust. Some aerosols from biomass
burning can also be seen.
Click
here for animation
This animation
shows TOMS July
2000 Aerosol Index.
Click
here for animation
This animation has
TOMS May -
June 14,1983 Aerosol Index (dustiest year on record).
Images Courtesy: NASA
DUST IMAGES FROM AROUND THE
WORLD - The Sea-viewing
Wide Field-of-view Sensor (SeaWiFS) on board the Orb View-2
Satellite, has captured images of dust storms around the
globe. According to the recent studies, high dust frequency is
not necessarily a result of the decreased rainfall, but rather
its cause.
Click
here for animation
Off the northwestern coast of
the African Continent, February, 26th 2000 this animation
shows a dust storm the
size of Spain.
Image Courtesy: NASA/Orbimage
AIR SAMPLING B-ROLL
- Dr. Virginia Garrison, USGS, collects samples of airborne
pollutants and dust daily on the island of St. John in the
Virgin Islands. The samples are then sent to the USGS
laboratory in St. Petersburg, Florida, for microbial analysis.
Click
here for animation
Animation Courtesy: Murphy
Entertainment Group
CULTURING ORGANISMS B-ROLL - Fungi
and bacteria that survive the trans-Atlantic journey in dust
include bacterial or fungal cultures that do not produce
disease mixed with species that do produce disease in both
humans and plants. A fungus, which has been isolated in
African dust, Aspergillus sydowii, has been determined
to cause Sea Fan disease in coral reefs throughout the
Caribbean. Desert dust exposure has also been identified as a
source of terrestrial disease outbreaks including:
Aspergillosis in animals, and Coccidioidomycosis. B-roll of
Drs. Dale Griffin & Christina Kellogg culturing samples
from St. John in lab.
Click
here for animation
Animation Courtesy: Murphy
Entertainment Group
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The accompanying video-file
will air on NASA-TV and can be seen on Direct TV or the Dish
Network. The video files air at noon, 3pm, 6pm, and 9pm
(Eastern Time). On the C-band satellite, NASA-TV coordinates
are GE-2, transponder 9C, C-Band, 85 degrees W longitude,
vertical polarization, 3880.0 Mhtz.
For more information contact:
Deanna Kekesi, Associate NASA-TV Producer, kekesi@pop100.gsfc.nasa.gov,
Tel. 1-301-286-0041.
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