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Three North African dust source areas and their geochemical fingerprint

Research output: Contribution to journalArticlepeer-review

Amy M. Jewell, Nick Drake, Anya J. Crocker, Natalie L. Bakker, Tereza Kunkelova, Charlie S. Bristow, Matthew J. Cooper, J. Andrew Milton, Paul S. Breeze, Paul A. Wilson

Original languageEnglish
Article number116645
JournalEARTH AND PLANETARY SCIENCE LETTERS
Volume554
DOIs
Accepted/In press2020
Published15 Jan 2021

Bibliographical note

Funding Information: This work was supported by the Natural Environment Research Council [grant number NE/L002531/1 to AMJ and NE/L002485/1 to NLB] and Royal Society Challenge Grant CH160073 and Royal Society Wolfson Merit Award to PAW. Research by PSB and ND utilised in this paper was funded by the Leverhulme Trust (grants RPG-2016-115 & ECF-2019-538). We thank Prof. Zongbo Shi and Clarissa Baldo from the University of Birmingham and Thomas Baird from University College London for their kind assistance. We are indebted to Dr. Moussa Abderamane from the University of N'Djamena and Dr Ahmed Adam from the University of Khartoum for their help arranging fieldwork and sample permits. We thank two anonymous referees for their constructive comments which helped improve the final manuscript. Funding Information: This work was supported by the Natural Environment Research Council [grant number NE/L002531/1 to AMJ and NE/L002485/1 to NLB] and Royal Society Challenge Grant CH160073 and Royal Society Wolfson Merit Award to PAW. Research by PSB and ND utilised in this paper was funded by the Leverhulme Trust (grants RPG-2016-115 & ECF-2019-538 ). We thank Prof. Zongbo Shi and Clarissa Baldo from the University of Birmingham and Thomas Baird from University College London for their kind assistance. We are indebted to Dr. Moussa Abderamane from the University of N'Djamena and Dr Ahmed Adam from the University of Khartoum for their help arranging fieldwork and sample permits. We thank two anonymous referees for their constructive comments which helped improve the final manuscript. Publisher Copyright: © 2020 Elsevier B.V. Copyright: Copyright 2020 Elsevier B.V., All rights reserved.

King's Authors

Abstract

North Africa produces more than half of the world's atmospheric dust load. Once entrained into the atmosphere, this dust poses a human health hazard locally. It also modifies the radiative budget regionally, and supplies nutrients that fuel primary productivity across the North Atlantic Ocean and as far afield as the Amazonian Basin. Dust accumulation in deep sea and lacustrine sediments also provides a means to study changes in palaeoclimate, particularly those associated with rainfall climate change. Systematic analysis of satellite imagery has greatly improved our understanding of the trajectories of long-range North African dust plumes, but our knowledge of the dust-producing source regions and our ability to fingerprint their contribution to these export routes is surprisingly limited. Here we report new radiogenic isotope (Sr and Nd) data for sediment samples from known dust-producing substrates (dried river and lake beds), integrate them with published isotope data and weight them for dust source activation. We define three isotopically distinct preferential dust source areas (PSAs): a Western, a Central and an Eastern North African PSA. More data are needed, particularly from the Western PSA, but our results show a change in PSA dust source composition to more radiogenic Nd- and less radiogenic Sr-isotope values from west to east, in line with the overall decreasing age of the underlying bedrock. Our data reveal extreme isotopic heterogeneity within the Chadian region of the Central PSA, including an extremely distinctive geochemical fingerprint feeding the Bodélé Depression, the most active dust source on Earth. Our new analysis significantly improves the reliability by which windblown dust deposits can be geochemically fingerprinted to their distant source regions.

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