Biological and Environmental Research - Earth and Environmental System Sciences
Earth and Environmental System Modeling
24 June 2020

Disproving the Bodélé Depression as the Primary Source of Dust Fertilizing the Amazon Rainforest

Sources of dust fertilizing the Amazon.

Science

The study demonstrates that El Djouf is a greater source of dust transport across the Atlantic Ocean to the Amazon Rainforest than is the Bodélé depression.

Impact

The current trajectory modeling approach enables a realistic simulation of the three-dimensional atmospheric distribution of transported dust and provides an observation-constrained benchmark for testing the assumptions made by previous satellite-based investigations of trans-Atlantic dust transport and for constraining chemistry transport models.

Summary

North African deserts have been reported to export ~200 million tons of dust per year to the tropical Atlantic Ocean, degrading air quality over the Caribbean Islands in boreal summer and supplying nutrients to fertilize the Amazon Rainforest in boreal winter and spring through trans-Atlantic dust transport. It has been assumed that the Bodélé depression is the main contributor to this trans-Atlantic dust transport and Amazonian dust fertilization in boreal winter. However, these claims have not been supported by geochemical analysis.  This ongoing debate motivates the current investigation of the relative contribution of specific North African dust sources to the trans-Atlantic dust transport to the Amazon Basin.

We integrate a suite of satellite observations into a novel trajectory analysis framework to investigate dust transport from the leading two North African dust sources, namely the Bodélé depression and El Djouf and provide the first-ever observation-constrained quantification of the dust’s dry and wet deposition along its transport pathways. The approach yields the novel observational finding that the El Djouf in Mauritania and Mali is the preferred source of inter-continental transport across the Atlantic Ocean rather than the Bodélé depression in Chad, bridging the geochemical impact of North African minerals on the Amazon Basin to the specific dust origin.

The inclusion of dry and wet deposition processes in the current trajectory modeling enables a realistic simulation of the three-dimensional atmospheric distribution of transported dust and provides an observation-constrained benchmark for testing the assumptions made by previous satellite-based investigations of trans-Atlantic dust transport and for constraining chemistry transport models.

Contact
Yan Yu
Princeton University
Publications
Yu, Y, OV Kalashnikova, MJ Garay, H Lee, M Notaro, JR Campbell, J Marquis, P Ginoux, and GS Okin.  2020.  "Disproving the Bodélé Depression as the Primary Source of Dust Fertilizing the Amazon Rainforest."  Geophysical Research Letters 47.  https://doi.org/10.1029/2020GL088020.