| Summary: | Pb/S, Tl/S and Bi/S ratios were measured in eruptive and fumarolic volcanic gases and indexed to the global flux of volcanic S to characterize approximate global volcanic emissions of these three metals to the atmosphere, which are about 1200 tons Pb/yr, 600 tons Tl/yr, and 4000 tons Bi/yr. This volcanic Pb input is similar to the magnitude of natural soil dust Pb input, which is about 1400 tons Pb/yr during the Holocene Interglacial. Both are negligible compared to annual industrial inputs of ~ 300,000 tons Pb/yr which maintain the present tropospheric reservoir of Pb. However, polar ice records indicate that thousands of years ago the atmospheric Pb reservoir was only ~ 1% of its present size, which means that volcanic Pb was the source of about half the Pb in the atmosphere during preindustrial Holocene times. © 1987 Pergamon Journals Ltd. Received May 2, 1986; accepted in revised form December 10, 1986. This work was supported by Grant No. OCE-8404559, Division of Ocean Sciences, NSF. Contribution No. 4275, Division of Geological and Planetary Sciences, California Institute of Technology. We are indebted to our colleagues in the NSF-SEAREX program for their scientific collaboration and logistical support, especially W. Fitzgerald, University of Connecticut, C. Unni and B. Ray, University of Rhode Island, P. Buat-Ménard, CNRS, France, and K. Turekian, Yale University. We are also indebted to F. LeGuern, CNRS, France, T. Hinkley, USGS, W. Giggenbach, New Zealand DSIR, and L. P. Greenland, USGS, for field guidance, logistical support, and scientific collaboration. Editorial handling: R. A. Schmitt
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