Posted on 11/18/2006 4:22:58 PM PST by blam
The African source of the Amazon's fertilizer
Sid Perkins
In the winter months in the Northern Hemisphere, massive dust storms from the African Sahara waft southwest across the Atlantic to drop tons of vital minerals on the Amazon basin in South America. Now, scientists have pinpointed the source of many of those dust storms and estimated their dust content.
ON THE WAY. Satellite photo shows dust (arrow), bound for the Amazon, blowing away from the Sahara's Bodélé depression. NASA
The Amazonian rainforest depends on Saharan dust for many of its nutrients, including iron and phosphorus (SN: 9/29/01, p. 200: http://www.sciencenews.org/articles/20010929/bob9.asp). "If it weren't for those nutrients, the Amazon would be a wet desert," says Ilan Koren, an atmospheric scientist at the Weizmann Institute in Rehovot, Israel.
Using satellite measurements of dust clouds, Koren and his colleagues estimate that 40 million tons of Saharan dust reaches South America each year. The images indicate that more than half of that dust originates from the Bodélé depression, a now-dry basin on the southern edge of the Sahara that in wetter times held a body of water the size of Lake Erie.
Although the depression is only 0.2 percent of the Sahara's surface area, it's a prodigious dust source, the researchers report in the October–December Environmental Research Letters. Dust storms arise from the area on 40 percent of winter days. On average, the storms loft more than 700,000 tons of dust each day, says Koren.
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My namesake at work. on a macro project.
Wow, who'd a thunk it?
I once heard an Oklahoman arguing with a Texan over which state was better; after awhile, the Texan got mad and said that Texas dirt could grow anything and Oklahoma dirt couldn't grow 'nothing'; the guy from Oklahoma, never missing a beat, shot back: "No wonder, it was all up here before the dust storms blew it down there!"
The Amazonian rainforest depends on Saharan dust for many of its nutrients, including iron and phosphorus.* "If it weren't for those nutrients, the Amazon would be a wet desert," says Ilan Koren, an atmospheric scientist at the Weizmann Institute in Rehovot, Israel.Note: this topic is from two years ago -- 2006.
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So when the Sahara was wet, was the Amazon basin dry?
Amazing!
For contrast, what blows out of Washington DC won’t grow ANYTHING worthwhile.
This same dust is iron rich and is believed to be the source of the 'Red Tide' algae bloom in the Gulf Of Mexico each year.
When I lived in Florida (Melbourne), having orange dust on my car was pretty common.
Also, I've read that live virus from Africa do make the oceanic trip to the Americas aboard this dust. So...
So what’s a wet desert like? My imagination is failing me. Maybe something like Arctic tundra?
Lotta rain, no vegetation because the soil is depleted by the rain. :’) One view is that bromeliads and carniverous plants got to be the way they are because of depleted soils.
Evolution in Your FaceLake Victoria, Africa's largest lake, is home to more than 300 species of cichlids. These fish, which are popular in aquariums, are deep-bodied and have one nostril, rather than the usual two, on each side of the head. Seismic profiles and cores of the lake taken by a team headed by Thomas C. Johnson of the University of Minnesota, reveal that the lake dried up completely about 12,400 years ago. This means that the rate of speciation of cichlid fishes has been extremely rapid: something on average of one new species every 40 years!
by Patrick Huyghe
Omni
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There is talk of making it a crime for American farmers to raise dust.
http://www.freerepublic.com/focus/f-news/2196849/posts
Loess makes some of the best soil. Dust in the wind.... Somewhere I have also seen the birth of a hurricane in East Africa.
I’ve read that the topsoil blown in from Russia has created a layer of topsoil in Ukraine that is 150 feet deep.
Most of the Upper Snake River Valley, where I am at, is blown in soil. We even have sand dunes. Lots of people up there doing stupid things riding around. My brother, who lives close to them, says the ambulances run all summer long.
It is no surprise pathogens can be carried to the Americas from Africa. Wouldn’t it be great (not) if one of the hurricanes brought a different kind of death and destruction to our shores. Maybe it has in the past. Maybe some of the early cultures of the Amazon Basin got wiped out by an African virus. Food for thought.
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