SCIENCE

On one side of the Atlantic is one of the driest splotches of land on Earth. On the other side is one of the wettest and most fertile. Despite the miles of open ocean separating the Sahara and Amazon, the two locales do share a commonality—nutrient-rich dust. (UPI)

Take a look at a satellite photo of the so-called Sahara dust layer.

Teachers, scroll down for a quick list of key resources in our Teachers’ Toolkit, including today’s MapMaker Interactive map.

Discussion Ideas

• Take a look at the awesome video above, then take a look at our map of prevailing wind patterns. What is the name of the prevailing winds that transport all that dust from the Sahara to the Amazon?
  • Northeasterly trade winds consistently blow from the Sahara across the Atlantic.

• The worlds biggest dry desert (the Sahara) and the world’s biggest tropical rain forest (the Amazon) are both in the tropics—they’re a similar distance from the Equator. And, according to new information from the good folks at NASA, they even share millions of tons of dust. What is the leading climate factor contributing their wildly different climate zones and ecosystems? Take a look at the layers today’s MapMaker Interactive for some help. (Be sure to adjust the transparencies and check the legend!)
  • Precipitation and land cover contribute to the different climate zones.
    • The dry, arid climate of the Sahara (“Climate Zones” layer) features bare ground (“Land Cover” layer) and fewer than 400 milliliters of rainfall each year (“Precipitation and Land Cover” layer).
    • The humid equatorial climate of the Amazon (“Climate Zones” layer) is covered by forests (“Land Cover” layer) and up to 2,000 milliliters of rainfall each year (“Precipitation and Rainfall” layer).

• Why is Saharan dust so important to the Amazon rain forest?
  • It’s not the dust, it’s the nutrients the dust carries. Specifically, the Saharan dust is rich in phosphorus—it’s the P in the CHNOPS group of vital plant nutrients.

• Why is the Amazon so deficient in phosphorus and other fairly common soil nutrients?
  • Competition. According to UPI, “Because of the high competition for nutrients in the Amazon, the soil there is depleted. Aside from the dust-delivered phosphorous, decomposing plant materials are the only way the soil gets replenished.”
  • Flooding. The Amazon and its tributaries wash away thousands of tons of nutrient-rich topsoil every year. According to NASA, “[t]he phosphorus that reaches Amazon soils from Saharan dust, an estimated 22,000 tons per year, is about the same amount as that lost from rain and flooding.”

• Why is the Sahara so rich in phosphorus? Check out the marker in today’s MapMaker Interactive map for some help.
  • Parts of the Sahara used to be lakes, where sediment made of organic materials accumulated over millions of years. According to NASA, the dust is carried from “the Bodélé Depression in Chad, an ancient lake bed where rock minerals composed of dead microorganisms are loaded with phosphorus.”

TEACHERS’ TOOLKIT

UPI: The Amazon is fertilized with the dust of the Sahara

NASA: NASA Satellite Reveals How Much Saharan Dust Feeds Amazon’s Plants

Nat Geo: Sahara Dust Layer

Nat Geo: Prevailing Winds

Nat Geo: Climate Conditions in the Sahara and Amazon map