What links Saharan dust and ecosystems in the Amazon?
The Amazon rainforest and the Sahara are two of the most different environments you could imagine. But scientists have identified an interesting connection between the world’s largest rainforest and the world’s largest nonpolar desert.
Every year, dust from the Sahara makes the astonishing 3,000 mile journey to South America.
A team of researchers led by Hongbin Yu from the University of Maryland and NASA’s Goddard Space Flight Centre have been using satellite data to measure the annual migration of dust to find out what effect its arrival has on the tropical environment of the Amazon basin.
Their results are very interesting.
They show that the dust lifted from the desert carries with it enough phosphorous to replace the rainforest’s nutrients lost when rainfall washes away soil.
When soil is washed away by rain into rivers and streams, it carries with it essential nutrients, including phosphorous. This loss of phosphorous, about 22,000 metric tons a year, would be catastrophic for the fertility of the rainforest as is an essential nutrient for plant growth.
Fortunately, there is lots of phosphorous in the Saharan dust as much of it originates from the Bodélé Depression in Chad, which used to be an ancient lakebed. Microorganisms that once inhabited the lake decomposed and eventually formed rocks loaded with phosphorous. Over time the wind in the desert erodes the rocks into dust and carries it to South America to feed the forests.
The scientists involved in the study plan on doing more research into the role of dust on the local and global climate.