Marine & Environmental Sciences Faculty Articles

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Proceedings of the National Academy of Sciences of the United States of America



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Amazon Basin, Atlantic Ocean, Biomass burning, Dust, Phosphorus


The deposition of phosphorus (P) from African dust is believed to play an important role in bolstering primary productivity in the Amazon Basin and Tropical Atlantic Ocean (TAO), leading to sequestration of carbon dioxide. However, there are few measurements of African dust in South America that can robustly test this hypothesis and even fewer measurements of soluble P, which is readily available for stimulating primary production in the ocean. To test this hypothesis, we measured total and soluble P in long-range transported aerosols collected in Cayenne, French Guiana, a TAO coastal site located at the northeastern edge of the Amazon. Our measurements confirm that in boreal spring when African dust transport is greatest, dust supplies the majority of P, of which 5% is soluble. In boreal fall, when dust transport is at an annual minimum, we measured unexpectedly high concentrations of soluble P, which we show is associated with the transport of biomass burning (BB) from southern Africa. Integrating our results into a chemical transport model, we show that African BB supplies up to half of the P deposited annually to the Amazon from transported African aerosol. This observational study links P-rich BB aerosols from Africa to enhanced P deposition in the Amazon. Contrary to current thought, we also show that African BB is a more important source of soluble P than dust to the TAO and oceans in the Southern Hemisphere and may be more important for marine productivity, particularly in boreal summer and fall.







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We thank ATMO Guyane for collecting filter samples and maintaining the field site in Cayenne, French Guiana ( The authors acknowledge the National Oceanic and Atmospheric Administration (NOAA) Air Resources Laboratory (ARL) for the provision of the HYSPLIT transport and dispersion model and READY website ( We thank National Aeronautics and Space Administration (NASA) for making the CALIPSO and MERRA-2 data available to the scientific community. C.J.G. acknowledges funding provided by the Provost Award from the University of Miami. N.M. and D.S.H. acknowledge the support of the Atkinson Center for a Sustainable Future and the Department of Energy (DE-SC0006791). We thank anonymous reviewers for useful comments and suggestions.

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