South African dust contribution to the high southern latitudes and East Antarctica during interglacial stages

Abstract

Mineral dust is a natural tracer of atmospheric composition and climate variability. Yet, there is still much to be known about the Southern Hemisphere dust cycle. Major efforts have attempted to solve the puzzle of the origin of the potential source areas contributing dust to the Southern Ocean and East Antarctica. Here we present a comprehensive geochemical characterization of a source area, whose role as a dust supplier to high latitude environments has significantly been underestimated. Sediments collected within the major dust-producing areas along the Namibian coast in Southern Africa (Kuiseb, Omaruru and Huab river catchments and the Namib Sand Sea region), were analyzed for radiogenic isotope ratios and rare earth element concentrations. We find that during warm periods, the Southern African dust signature can be found in archives of the Southern Hemisphere, especially in the Atlantic sector of the Southern Ocean and peripheral areas of the East Antarctic plateau.

Systematic changes in circumpolar dust transport to the Subantarctic Pacific Ocean over the last two glacial cycles

“…The model provides comprehensive mass balance constraints by including the compositional range of the endmembers and multiple isotope ratios ( 52 , 99 , 100 ). This is an improvement compared to previous dust provenance work using simple mass balance calculations with only two isotope ratios ( 26 , 33 , 34 , 45 , 46 , 50 , 51 , 64 , 65 ). The uncertainty of the model output is predominantly driven by the isotopic variability of the endmembers included in the model ( SI Appendix , Table S2 ), and the 2SE of individual source contributions is typically <±0.5%.…”

“…2 D ), which may indicate an influence from grain size and/or mineral sorting effects on the Pb isotope composition of the dust fraction samples from core PS75/056-1. However, the influence of sorting effects on the Pb isotope composition of Southern Hemisphere PSA ( 33 , 65 ) and far-traveled dust in the South Pacific is typically low ( 51 ). Moreover, there is no systematic correspondence between the Pb isotope shifts with complementary Sr isotope and grain size data that would support a role for sorting effects ( Figs.…”

“…The uncertainty of the model output is predominantly driven by the isotopic variability of the endmembers included in the model ( SI Appendix , Table S2 ), and the 2SE of individual source contributions is typically <±0.5%. Due to the three different isotope systems used in this study, we include previously published Nd, Sr, and Pb concentration data ( 26 , 51 , 65 ) for the dust endmembers used in our model setup ( SI Appendix , Table S2 ). All endmembers used for the modeling were defined based on their reported significance as dust sources in the Southern Hemisphere and their geochemical differences following previous approaches ( 51 , 52 ).…”

“…1 ) ( 51 ). We revised the previously used endmember value for Southern Africa based on a more comprehensive dataset from Namibia ( 65 ) ( SI Appendix , Table S2 contains more details). Western Australia was excluded as a potential source as the contributions from this region were below 2% throughout and therefore negligible ( 52 ).…”

Late Holocene Dust Deposition Fluxes Over the Entire South Atlantic Ocean

“…In southern Africa, the main dust sources include the Makgadikgadi Depression in the lowest part of the Kalahari Desert in Botswana, and the Etosha Pan in northern Namibia (Li et al., 2008; Prospero et al., 2002), but also several coastal sources in Namibia from which the dust is transported toward the South Atlantic Ocean with strong Berg winds (Gili et al., 2022). Dust emitted from southern African sources is not transported as far south as from South American sources due to less efficient dust‐transporting winds and therefore has a limited influence on the Southern Ocean and Antarctica (Neff & Bertler, 2015).…”