NASA Reveals How Sahara Dust Fertilizes Amazon Rainforests

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The phosphorus transported from Sahara to Amazon is almost the same amount that is lost due to rain and flooding.

What is the connection between the Earth’s largest tropical rainforest and its largest temperate desert? The answer is an estimated 22,000 tons of phosphorus every year. A NASA satellite has quantified in 3D how much dust is carried from Sahara desert to the Amazon rainforest every year. For the first time, NASA scientists have measured the volume of dust that makes the trans-Atlantic journey from Sahara to Amazon.

Amazonian soils have short supply of nutrients

Researchers have also calculated how much phosphorus gets carried from one of the most desolate places on the planet to one of its most fertile. Phosphorus is present in dust picked up from the Bodele Depression in Chad, which was an ancient lake bed where rock minerals composed of dead microbes are rich in phosphorus.

Hongbin Yu, a researcher at NASA’s Goddard Space Flight Center, said it was the first satellite-based estimate of the phosphorus transport over several years. This trans-continental journey of Saharan dust is very important because it contains phosphorus. Phosphorus is a nutrient necessary for plant growth, and Amazon rainforest depends on it to flourish.

Amazonian soils do not have sufficient supply of nutrients. Fallen leaves and other organic matter are responsible for the majority of nutrients. But the rainfall washes away many important nutrients, including phosphorus, into streams and rivers. Researchers found that the phosphorus that reaches Amazon rainforests, approximately 22,000 tons a year, is almost the same amount that is lost due to rain and flooding.

The data come from NASA’s CALISPO satellite

In 2006, NASA launched a satellite called the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALISPO) to collect data on clouds and airborne particles across the globe. Yu and his colleagues used data from CALISPO for years between 2007 and 2013 to calculate the dust transport estimates.

NASA satellite data show that weather and winds pick up 182 million tons of dust, equivalent of 689,290 semi-trucks filled with dust, from the Saharan desert every year. While traveling across the Atlantic ocean, a large chunk of dust is flushed from the sky by rain or simply drops to the surface. About 27.7 million tons of dust, enough to fill 104,908 semi-trucks, falls over the Amazon rainforest.

Findings of the study were published in the latest issue of the journal Geophysical Research Letters.

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