Fertilizing the Amazon and equatorial Atlantic with West African dust

Atmospheric mineral dust plays a vital role in Earth's climate and biogeochemical cycles. The Bodélé Depression in Chad has been identified as the single biggest source of atmospheric mineral dust on Earth. Dust eroded from the Bodélé is blown across the Atlantic Ocean towards South America. The mineral dust contains micronutrients such as Fe and P that have the potential to act as a fertilizer, increasing primary productivity in the Amazon rain forest as well as the equatorial Atlantic Ocean, and thus leading to N2 fixation and CO2 drawdown. We present the results of chemical analysis of 28 dust samples collected from the source area, which indicate that up to 6.5 Tg of Fe and 0.12 Tg of P are exported from the Bodélé Depression every year. This suggests that the Bodélé may be a more significant micronutrient supplier than previously proposed.

[1]  S. Martin,et al.  Transport of North African dust from the Bodélé depression to the Amazon Basin: a case study , 2010 .

[2]  K. Schepanski,et al.  Dust as a tipping element: The Bodélé Depression, Chad , 2009, Proceedings of the National Academy of Sciences.

[3]  R. Engelmann,et al.  Dust and smoke transport from Africa to South America: Lidar profiling over Cape Verde and the Amazon rainforest , 2009 .

[4]  A. Schroth,et al.  Iron solubility driven by speciation in dust sources to the ocean , 2009 .

[5]  N. Drake,et al.  Deflation in the dustiest place on Earth : The Bodélé Depression, Chad , 2009 .

[6]  N. Mahowald,et al.  Global distribution of atmospheric phosphorus sources, concentrations and deposition rates, and anthropogenic impacts , 2008 .

[7]  K. Desboeufs,et al.  Mineralogy as a critical factor of dust iron solubility , 2008 .

[8]  A. Thomas,et al.  The implications for dust emission modeling of spatial and vertical variations in horizontal dust flux and particle size in the Bodélé Depression, Northern Chad , 2008 .

[9]  G. Brunskill,et al.  Phosphorus speciation in the sediment and mass balance for the central region of the Great Barrier Reef continental shelf (Australia) , 2007 .

[10]  Y. Kaufman,et al.  The Bodélé depression: a single spot in the Sahara that provides most of the mineral dust to the Amazon forest , 2006 .

[11]  X. Querol,et al.  Geochemical variations in aeolian mineral particles from the Sahara-Sahel Dust Corridor. , 2006, Chemosphere.

[12]  T. Jickells,et al.  Mineral particle size as a control on aerosol iron solubility , 2006 .

[13]  N. Drake,et al.  Shorelines in the Sahara: geomorphological evidence for an enhanced monsoon from palaeolake Megachad , 2006 .

[14]  Richard Washington,et al.  Dust and the low‐level circulation over the Bodélé Depression, Chad: Observations from BoDEx 2005 , 2006 .

[15]  N. Mahowald,et al.  Atmospheric global dust cycle and iron inputs to the ocean , 2005 .

[16]  Richard Washington,et al.  Atmospheric controls on mineral dust emission from the Bodélé Depression, Chad: The role of the low level jet , 2005 .

[17]  D. Tanré,et al.  Dust transport and deposition observed from the Terra‐Moderate Resolution Imaging Spectroradiometer (MODIS) spacecraft over the Atlantic Ocean , 2005 .

[18]  N. Mahowald,et al.  Global Iron Connections Between Desert Dust, Ocean Biogeochemistry, and Climate , 2005, Science.

[19]  N. Mahowald,et al.  Estimates of atmospheric-processed soluble iron from observations and a global mineral aerosol model: Biogeochemical implications , 2004 .

[20]  Gregory S. Okin,et al.  Impact of desert dust on the biogeochemistry of phosphorus in terrestrial ecosystems , 2004 .

[21]  Matthew M. Mills,et al.  Iron and phosphorus co-limit nitrogen fixation in the eastern tropical North Atlantic , 2004, Nature.

[22]  R. Washington,et al.  Dust-Storm Source Areas Determined by the Total Ozone Monitoring Spectrometer and Surface Observations , 2003 .

[23]  C. Ridame,et al.  Chemical characterization of the Saharan dust end-member: Some biogeochemical implications for the western Mediterranean Sea , 2002 .

[24]  F. Gasse,et al.  Diatom-inferred salinity and carbonate oxygen isotopes in Holocene waterbodies of the western Sahara and Sahel (Africa) , 2002 .

[25]  O. Torres,et al.  ENVIRONMENTAL CHARACTERIZATION OF GLOBAL SOURCES OF ATMOSPHERIC SOIL DUST IDENTIFIED WITH THE NIMBUS 7 TOTAL OZONE MAPPING SPECTROMETER (TOMS) ABSORBING AEROSOL PRODUCT , 2002 .

[26]  Paul Ginoux,et al.  Environmental Characterization of Global Sources of Atmospheric Soil Dust Identified with the NIMBUS-7 TOMS Absorbing Aerosol Product , 2001 .

[27]  A. Johansen,et al.  Chemical characterization of ambient aerosol collected during the southwest monsoon and intermonsoon seasons over the Arabian Sea: Labile-Fe(II) and other trace metals , 1999 .

[28]  S. Taylor,et al.  The geochemical evolution of the continental crust , 1995 .

[29]  Michael Garstang,et al.  Saharan dust in the Amazon Basin , 1992 .

[30]  R. Duce,et al.  Atmospheric transport of iron and its deposition in the ocean , 1991 .

[31]  D. I. Sebacher,et al.  Distribution and geochemistry of aerosols in the tropical north Atlantic troposphere: Relationship to Saharan dust , 1986 .

[32]  P. Sánchez,et al.  Amazon Basin Soils: Management for Continuous Crop Production , 1982, Science.

[33]  under a Creative Commons License. Atmospheric Chemistry and Physics Modelling soil dust aerosol in the Bodélé depression during the , 2006 .

[34]  D. Tanré,et al.  Dust transport and deposition observed from the Terra-MODIS space observations , 2004 .

[35]  T. Jickells,et al.  Atmospheric iron inputs to the oceans , 2001 .