African Smoke Is Fertilizing Amazon Rainforest and Oceans, New Study Finds

A new study led by researchers at the University of Miami’s (UM) Rosenstiel School of Marine and Atmospheric Science found that smoke from fires in Africa may be the most important source of a key nutrient—phosphorus—that acts as a fertilizer in the Amazon rainforest, Tropical Atlantic and Southern oceans.

Nutrients found in atmospheric particles, called aerosols, are transported by winds and deposited to the ocean and on land where they stimulate the productivity of marine phytoplankton and terrestrial plants leading to the sequestration of atmospheric carbon dioxide. 

“It had been assumed that Saharan dust was the main fertilizer to the Amazon Basin and Tropical Atlantic Ocean by supplying phosphorus to both of these ecosystems,” said the study’s senior author Cassandra Gaston, an assistant professor in the Department of Atmospheric Sciences at the UM Rosenstiel School. “Our findings reveal that biomass burning emissions transported from Africa are potentially a more important source of phosphorus to these ecosystems than dust.”

To conduct the study, the researchers analyzed aerosols collected on filters from a hilltop in French Guiana, at the northern edge of the Amazon Basin, for mass concentrations of windborne dust and their total and soluble phosphorus content. They then tracked the smoke moving through the atmosphere using satellite remote sensing tools to understand the long-range transport of smoke from Africa during time periods when elevated levels of soluble phosphorus were detected. They were then able to estimate the amount of phosphorus deposited to the Amazon Basin and the global oceans from African biomass burning aerosols using a transport model.

Read more at Rosenstiel School of Marine and Atmospheric Science