A recent study, conducted by researchers at the University of Miami (UM) Rosenstiel School of Marine and Atmospheric Science, found that smoke from fires in Africa may be the key source of a key nutrient ̵
Nutrients found in atmospheric particles, called aerosols, are transported by winds and deposited in the sea and on land, where they stimulate the productivity of marine phytoplankton and terrestrial plants and lead to the sequestration of atmospheric carbon dioxide.
"Saharan dust has been thought to be the major fertilizer for the Amazon Basin and the tropical Atlantic by supplying phosphorus to both ecosystems," said study lead author Cassandra Gaston, an assistant professor at the Department of Atmospheric Sciences at UM Rosenstiel School. "Our results show that biomass incineration emissions from Africa represent a potentially more important source of phosphorus for these ecosystems than dust."
To conduct the study, the researchers analyzed aerosols collected on filters from a hill in French Guiana on the north coast of Guayana northern edge of the Amazon basin, for mass concentrations of wind dust and their total and soluble phosphorus content. They then tracked the smoke that traveled through the atmosphere using satellite remote sensing instruments to understand the long-distance transport of smoke from Africa during periods of elevated levels of soluble phosphorus. Using a transport model, they were able to estimate the phosphorus deposits in the Amazon basin and in the oceans from African aerosols for the combustion of biomass.
The analysis revealed that the smoke from widespread biomass burning in Africa is mainly the result of land clearing, burning and industrial combustion emissions may be a more important source of phosphorus for the Amazon rainforest, the tropical Atlantic and the southern oceans than dust from the Sahara.
"To our surprise, we discovered that phosphorus is associated with smoke. Southern Africa can be blown out to the Amazon and possibly across the Southern Ocean, where it impacts on primary productivity and carbon degradation in both ecosystems," said Anne Barkley , Graduate of the UM Rosenstiel School study.
"Aerosols play an important role in the Earth's climate, but there is a lot we do not understand how they affect radiation, clouds and biogeochemical cycles that affect our ability to accurately predict future global temperature increases," Gaston said , "These new findings will affect what this process might look like in the future as combustion and fire emissions in Africa and dust transport patterns and volumes change with the changing climate and population."
This study builds on more than 50 years of groundbreaking aerosol research in the Caribbean and Latin America by Emeritus UM Rosenstiel School Professor Joe Prospero, which is being continued by Gaston. In addition, it is an interdisciplinary collaboration within the UM Rosenstiel School, in which Professor Paquita Zuidema, Department of Atmospheric Sciences, published extensive biomass combustion measurements to demonstrate the seasonality of smokeshifting, Associate Professor Ali Pourmand and Assistant Professor Amanda Oehlert Department of Marine Geosciences analyzed samples in the Neptune mass spectrometer, Deputy Professor Kim Popendorf, Department of Ocean Sciences, helped measure soluble phosphorus in aerosols, and Pat Blackwelder, Deputy Director of the Institute of Chemistry at the College of Arts and Sciences of the University of Miami Microscopy delivered its expertise in Scanning Electron Microscopy to image the micron-sized filter samples.
UM researchers launch a field campaign to study the effects of smoke on the Earth's climate
The burning of African biomass is an important source of phosphorus deposition in the Amazon, PNAS (2019). DOI: 10.1073 / pnas.1906091116
African smoke fertilizes Amazon rainforest and oceans, study results (2019, July 29)
retrieved on July 29, 2019
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