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Open AccessArticle
Paleoclimate Controls on West African Dust Inferred from Rb/Sr and Si/Al of Sediments in an Eastern Equatorial Atlantic Marine Core
by
Christopher J. Lepre
Christopher J. Lepre 1,*,
Clara Y. Chang
Clara Y. Chang 2 and
Owen M. Yazzie
Owen M. Yazzie 1
1
School of Earth, Environment and Society, Bowling Green State University, Bowling Green, OH 43403, USA
2
Lamont-Doherty Earth Observatory, Columbia University, New York, NY 10964, USA
*
Author to whom correspondence should be addressed.
Atmosphere 2024, 15(8), 902; https://doi.org/10.3390/atmos15080902 (registering DOI)
Submission received: 30 May 2024
/
Revised: 16 July 2024
/
Accepted: 19 July 2024
/
Published: 28 July 2024
Abstract
Increased dust emissions from dryland areas and their effects on human health, ecosystem viability, and environmental change are a global concern in the face of the growing climate crisis. Dust plume emissions from the West African landmass, Sahara, and Sahel areas comprise a major fraction of the global aerosol budget. Dust plume intensity is closely related to regional winds (e.g., Harmattan, Sahara Air Layer), the Intertropical Convergence Zone, monsoonal seasonality, marine currents, and physiography. To study terrigenous material emitted from the continent over the last ~260 kyr (late Quaternary), we used X-ray fluorescence spectroscopy (XRF) to analyze a ~755 cm long marine sediment core from the eastern equatorial Atlantic Ocean, resulting in nearly 1400 discrete measurements. Spectral analysis results suggest that concentrations of elements (Rb, Sr, Si, Al) preserved in the sediments are correlated to different types of orbital climate forcing. Chemical weathering intensity indicated by the Rb/Sr ratio was sensitive to seasonal insolation variations controlled by precession cycles (23–18 kyr), which presumably reflects the relationship between monsoonal rainfall and sensible heating of the continent. Spectral analysis of silicate mineral grain size (Si/Al) showed significant 40 kyr cycles that were paced by obliquity. Based on these data, we infer that winter tradewind activity accelerated in response to the intertropical insolation gradient induced by high obliquity. High Rb/Sr ratios during the last glacial maximum and penultimate glacial maximum may have been due to a predominance of mechanical weathering over chemical weathering under dry/cool climates or the dissolution of Sr-bearing carbonates by corrosive glacial bottom waters.
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MDPI and ACS Style
Lepre, C.J.; Chang, C.Y.; Yazzie, O.M.
Paleoclimate Controls on West African Dust Inferred from Rb/Sr and Si/Al of Sediments in an Eastern Equatorial Atlantic Marine Core. Atmosphere 2024, 15, 902.
https://doi.org/10.3390/atmos15080902
AMA Style
Lepre CJ, Chang CY, Yazzie OM.
Paleoclimate Controls on West African Dust Inferred from Rb/Sr and Si/Al of Sediments in an Eastern Equatorial Atlantic Marine Core. Atmosphere. 2024; 15(8):902.
https://doi.org/10.3390/atmos15080902
Chicago/Turabian Style
Lepre, Christopher J., Clara Y. Chang, and Owen M. Yazzie.
2024. "Paleoclimate Controls on West African Dust Inferred from Rb/Sr and Si/Al of Sediments in an Eastern Equatorial Atlantic Marine Core" Atmosphere 15, no. 8: 902.
https://doi.org/10.3390/atmos15080902
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