North African mineral dust across the tropical Atlantic Ocean: Insights from dust particle size, radiogenic Sr-Nd-Hf isotopes and rare earth elements (REE)

Michèlle van der Does*, Ali Pourmand, Arash Sharifi, Jan Berend W. Stuut

*Corresponding author for this work

Research output: Contribution to JournalArticleAcademicpeer-review

Abstract

Large amounts of mineral dust are exported from North Africa across the Atlantic Ocean, impacting the atmosphere and ocean during transport and after deposition through biogeochemical processes. In order to characterize the isotopic signature of dust from different seasons and years, in relation to their bulk particle size, and to obtain a general idea of its provenance, Saharan dust was collected using subsurface sediment traps moored in the tropical North Atlantic Ocean in 2012–2013, and by shipboard aerosol collection during three trans-Atlantic research cruises in 2005, 2012 and 2015. The samples were analysed for radiogenic Strontium (Sr), Neodymium (Nd), and Hafnium (Hf) isotopes, rare earth element (REE; La-Lu) abundances and particle size. In addition, soil sediments from Mauritania, a potential source area, were analysed and compared to the Atlantic dust samples. The results indicate no relation between Sr and Nd isotopic compositions and dust particle size. In contrast, Hf isotopic compositions show a strong relation with particle size, associated to the so-called zircon effect. We explored alternative sources of lithogenic particles to the sediment traps such as Amazon River sediments. Our results reveal that the sediment-trap samples bear distinctly different geochemical signatures from sediments from the Amazon Basin and Amazon River tributaries, and confirm that the primary source of lithogenic particles is northern Africa. The collected dust samples show close relations to African dust aerosols collected at Barbados and samples from the Bodélé Depression, although differences between seasons are observed, which we relate to differences in source areas.

Original languageEnglish
Pages (from-to)106-116
Number of pages11
JournalAeolian Research
Volume33
DOIs
Publication statusPublished - 1 Aug 2018
Externally publishedYes

Funding

This project was funded by NWO (project no. 822.01.008, TRAFFIC) and ERC (project no. 311151, DUSTTRAFFIC) awarded to JBS, and in part by NSF National Science Foundation Grant EAR-1003639 to AP. MvdD was partially funded by the International Association of Sedimentologists ( IAS ). The captains, crews and scientists of FS Meteor cruise M65, M89, RV Pelagia cruises 64PE378 and 64PE395, and NIOZ technicians are thanked for deployment and retrieval of the sediment-trap moorings and collection of shipboard aerosols. K. Wetterauer is thanked for particle-size analysis of 64PE395 dust samples. The Mauritania fieldtrip was funded by Europrox . D. McGee is thanked for sharing the leaching protocol for marine sediments and useful discussions. Appendix A

FundersFunder number
NSF National Science Foundation
H2020 European Research Council
Institute of Advanced Studies, University of Bristol
European Research Council311151
Nederlandse Organisatie voor Wetenschappelijk Onderzoek822.01.008
International Association of Sedimentologists
National Science FoundationEAR-1003639

    Keywords

    • Atlantic Ocean
    • Mineral dust
    • Rare earth elements
    • Sahara
    • Sr-Nd-Hf isotopes

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