| Summary: | Anthropogenic emissions completely overwhelmed natural marine lead (Pb) sources duringthe past century, predominantly due to leaded petrol usage. Here, based on Pb isotopemeasurements, we reassess the importance of natural and anthropogenic Pb sources to thetropical North Atlantic following the nearly complete global cessation of leaded petrol use.Significant proportions of up to 30–50% of natural Pb, derived from mineral dust, areobserved in Atlantic surface waters, reflecting the success of the global effort to reduceanthropogenic Pb emissions. The observation of mineral dust derived Pb in surface waters isgoverned by the elevated atmospheric mineral dust concentration of the North African dustplume and the dominance of dry deposition for the atmospheric aerosol flux to surfacewaters. Given these specific regional conditions, emissions from anthropogenic activities willremain the dominant global marine Pb source, even in the absence of leaded petrolcombustion.
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