Three North African dust source areas and their geochemical fingerprint
North Africa produces more than half of the world’s atmospheric dust load. Once entrained 24 into the atmosphere, this dust poses a human health hazard locally. It also modifies the 25 radiative budget regionally, and supplies nutrients that fuel primary productivity across the 26 North Atlantic Oce...
| Published in: | Earth and Planetary Science Letters |
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| Main Authors: | , , , , , , , , , |
| Format: | Article in Journal/Newspaper |
| Language: | English |
| Published: |
Elsevier
2021
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| Subjects: | |
| Online Access: | https://eprints.bbk.ac.uk/id/eprint/41057/ https://eprints.bbk.ac.uk/id/eprint/41057/1/Jewell_etal_PSAs_Manuscript_revised.pdf https://eprints.bbk.ac.uk/id/eprint/41057/2/Jewell_etal_PSAs_Figures.pdf https://doi.org/10.1016/j.epsl.2020.116645 |
| Summary: | North Africa produces more than half of the world’s atmospheric dust load. Once entrained 24 into the atmosphere, this dust poses a human health hazard locally. It also modifies the 25 radiative budget regionally, and supplies nutrients that fuel primary productivity across the 26 North Atlantic Ocean and as far afield as the Amazonian Basin. Dust accumulation in deep 27 sea and lacustrine sediments also provides a means to study changes in palaeoclimate, 28 particularly those associated with rainfall climate change. Systematic analysis of satellite 29 imagery has greatly improved our understanding of the trajectories of long-range North 30 African dust plumes, but our knowledge of the dust-producing source regions and our ability 31 to fingerprint their contribution to these export routes is surprisingly limited. Here we 32 report new radiogenic isotope (Sr and Nd) data for sediment samples from known dust33 producing substrates (dried river and lakes beds), integrate them with published isotope 34 data and weight them for dust source activation. We define three isotopically distinct 35 preferential dust source areas (PSAs): a Western, a Central and an Eastern North African 36 PSA. More data are needed, particularly from the Western PSA, but our results show a 37 change in PSA dust source composition to more radiogenic Nd- and less radiogenic Sr38 isotope values from west to east, in line with the overall decreasing age of the underlying 39 bedrock. Our data reveal extreme isotopic heterogeneity within the Chadian region of the 40 Central PSA, including an extremely distinctive geochemical fingerprint feeding the Bodélé 41 Depression, the most active dust source on Earth. Our new analysis significantly improves 42 the reliability by which windblown dust deposits can be geochemically fingerprinted to their 43 distant source regions. |
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