ABSTRACT
Atmospheric pollution from fossil fuel combustion has increased dramatically over the last century. The ubiquity of particulate contamination worldwide has, however, created a powerful new tool for nuclear forensic analysis — Pb isotope fingerprinting. Lead alkyls, added to gasoline for their antiknock properties, are emitted as micrometer-sized particulates from automobile exhaust and, as the major source of atmospheric Pb, are a wellrecognized imprint of modern society on the Earth’s ecosystem [1]. Lead is composed of four stable isotopes, only one of which (
Pb) is nonradiogenic. The abundances of the other isotopes have increased through time by amounts controlled by the time-averaged U/Th/Pb content of different geologic reservoirs on Earth. The variation of U/Th/Pb in natural materials, together with the large differences in half-lives of the three parent isotopes (
U,
U, and
Th), have produced a large variation in Pb isotope compositions in terrestrial lead deposits [2]. The stable isotopes of Pb provide a powerful isotopic fingerprint for nuclear forensic science because Pb emitted to the atmosphere from industrial sources generally has an isotopic composition distinct from the Pb present in rocks at the Earth’s surface. In addition, in most urban areas, industrial Pb will overwhelm the natural Pb component [1]. Lead is also often associated with the handling of special nuclear materials, providing an added opportunity to use Pb isotope analysis to provide clues about the location of previous handling and storage of the Special Nuclear Material.
