The Amazon rainforest owes its fertility in great part to the tons of dust that make a lengthy journey over the Atlantic Ocean every day. Where does this dust come from? From no less than Africa, of course. The valley of Bodélé, situated in the north of Chad, Sahara desert, is a narrow, rapid and very effective dust-machine.
The valley of Bodélé has unique geographical characteristics that make it the biggest supplier of dust in the world. Two almost parallel mountain chains shape this natural "wind tunnel", which gets thinner and thinner as it approaches the Atlantic coast. When the wind penetrates the valley, as it picks up increasing speed and dust, it has been known to stir up dust clouds able to be observed by satellite. The narrow valley itself supplys 56% of the total dust arriving annually to the Amazon, at the same time contributing various mineral nutrients, fertilizing the soil. In the end, this means that 50 million tons of particles finer than sand make the 10, 000 kilometer journey across the sea each year, to feed life on the other side of the world.
The dust does not only enrich the forest soils, but, incidentally, is also associated with the cycle of proliferation of plankton in the Atlantic ocean through its contribution of nutrients required for their breeding.
The "Bad Side" of the Dust
The valley of Chad doesn't just stop at spreading its dust to the Brazilian jungle. Its gusts often make it as far as the Gulf of Mexico, Cuba and the Canary Islands—among other places. Furthermore, the earth's atmosphere gets loaded with this dust, adding more to what is already produced in other parts of the world. According to some scientists, this dust, which increases its volume between 2000 and 3000 millions of tons annually, intensifies respiratory problems, contributes to climate change, and is responsible in great part for the phenomena known as "red tide" (where plankton density becomes so great so as to color the sea red). This problem is caused by the ingestion of toxic microalgae in the Caribbean, which the snails consume, who then pass the damage onto their predators (fish), and consequently, to man.
Dust is a born traveller. It can set off from the Sahara and make it to the United States, or from China and go all the way to Europe. Everything depends on which direction the wind blows. When it deposits itself in fresh soil it can bring with it sicknesses, and when it ends up in the sea it can alter the reproductive cycle of animals. The north and south poles also receive their share of punishment from the atmospheric dust, diminishing their capacity for refracting light, in this way upping one of the factors responsible for the greenhouse effect.
The storms of dust and sand also swallow up entire cities and villages, lasting hours, sealing off the sky with a profound darkness. This factor, together with the relative frequency of deaths, means that some people see these phenomena as "divine warnings."
Where Does The Dust Come From?
The production of African dust (700 000 tons daily) has increased by no less than 10 times in the last 50 years. But as we have already indicated, the dust does not only come from Africa. Then, to what is the increase owed? Essentially to deforestation and draughts. Other lesser factors that can add a few tons are: the pollution coming from vehicles, the emissions of toxic smoke from factories, as well as other factors related to human technology. Maybe the old notion that man is the cause of his own misfortune, or that 'you reap what you sow,' is quite appropriate in this case.
Feeds