The Pb, Nd, and Sr isotopic characterisation of dust sources in North Africa and Western Asia.

Mineral dust is a key component of Earth’s climate system; it influences the global radiation budget, fertilises ecosystems, and constitutes a threat to human health. Accumulation of windblown dust in marine archives provides a means to assess past change in Earth’s continental hydroclimate. However, interpretations of these records are often undermined by an attribution problem: the uncertainty of provenance. Here we report new radiogenic isotope data (Sr, Nd, and Pb) from unconsolidated surface sediments sampled from active dust sources and integrate them with published geochemical and satellite-derived datasets (such as dust source activation frequency (DSAF)) to define preferential source areas (PSAs) across the Northern Hemisphere dust belt. Our analysis shows that pairing Pb with Nd or Sr isotope data allows clearer discrimination between source regions that overlap in Nd-Sr space. We also show that Pb data are particularly helpful to discriminate between sources when presented as D²⁰⁷Pb/²⁰⁴Pb and D²⁰⁸Pb/²⁰⁴Pb: deviations of Pb from the Northern Hemisphere Reference Line (NHRL) that defines the Pb isotopic evolution of the Northern Hemisphere’s mantle. Comparison with published Pb isotope data reveals major limitations in spatial coverage and suggests that application of more consistent cleaning protocols is merited including removal of anthropogenic Pb. Nevertheless, our new data help to discriminate among the dust sources of East Africa and Western Asia more clearly than before, improving our ability to interpret past continental hydroclimate change recorded in marine sediment cores from the northern Indian Ocean.