²¹⁰Po and ²¹⁰Pb as atmospheric tracers

Atmospheric ²²²Rn from the ²³⁸U series generates prominent radionuclides such as ²¹⁰Pb and ²¹⁰Po that have proven particularly useful to trace aerosols and their scavenging processes as recently reviewed. While the early efforts were directed toward understanding the transport and fate of nuclear weapons debris in the atmosphere, they initially provided key insights on the mixing proportions and residence times of atmospheric aerosols. A range of atmospheric programs and modern instrumentation have used these nuclides to quantify the rates of gas and particulate exchange aerosol mixing, scavenging and fallout. Such information have been used to trace the transport and fate of natural materials such as dust and anthropogenic emissions, including C, N and S gases, hydrocarbons, and metals. The ²¹⁰Pb and ²¹⁰Po nuclides with their range of half-lives and distinct chemical properties allow one to track the sources, dispersion and scavenging times of atmospheric pollutants. Noted examples include lead emissions from gasoline combustion and elemental mercury from smelting and coal combustion. The use of numerical models, combined with atmospheric dynamics in time and space should improve the characterization of nuclide sources and dispersion and by proxy, the distribution other trace elements. Increased information on the production of volatile ²¹⁰Po species and emission would contribute to its atmospheric budget that should allow development of an air-sea exchange metric. (author)