A NASA satellite has quantified how much dust makes the trans-Atlantic journey from the Sahara Desert to the Amazon rain forest.
Scientists have measured the volume of dust and also calculated how much phosphorus - remnant in Saharan sands from part of the desert's past as a lake bed - gets carried across the ocean from one of the planet's most desolate places to one of its most fertile.
This trans-continental journey of dust is important because of what is in the dust, Yu said.
Specifically the dust picked up from the Bodele Depression in Chad, an ancient lake bed where rock minerals composed of dead microorganisms are loaded with phosphorus.
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Phosphorus is an essential nutrient for plant proteins and growth, which the Amazon rain forest depends on in order to flourish.
But some nutrients, including phosphorus, are washed away by rainfall into streams and rivers, draining from the Amazon basin like a slowly leaking bathtub.
The phosphorus that reaches Amazon soils from Saharan dust, an estimated 22,000 tonnes per year, is about the same amount as that lost from rain and flooding, Yu said.
The new dust transport estimates were derived from data collected by a lidar instrument on NASA's Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation, or CALIPSO, satellite from 2007 through 2013.
The dust then travels 2,574 km across the Atlantic Ocean, though some drops to the surface or is flushed from the sky by rain.
Near the eastern coast of South America, 132 million tonnes remain in the air, and 27.7 million tonnes - enough to fill 104,908 semi trucks - fall to the surface over the Amazon basin.
About 43 million tonnes of dust travel farther to settle out over the Caribbean Sea.