Applicability of gold as an atmospheric aerosol tracer

The present paper describes a method to determine the gold content of samples of atmospheric particulate matter. Both integral filter samples as well as size-segregated impactor samples are accessible to the method. Results of the analysis of 29 filter samples and three size-segregated impactor samples, taken at Ispra in Northern Italy, are reported. The frequency distribution of the gold concentrations can be described by a long-normal distribution with a geometric mean concentration of 23.2 pg m−3 and a geometric standard deviation of 2.1. The method is validated by the analysis of a certified reference material, for which a mean recovery of gold of 78% was obtained. Based on the variability of the gold concentration in atmospheric aerosol, the maximum distance to which gold as a tracer can be quantified, assuming specific meteorological conditions, is estimated by means of the Gaussian Dispersion Model. Using Pasquill Stability Classes to characterize atmospheric stability, this distance is 33 and 104 km for stability classes C and D, respectively, for a release of 65 g of gold. References to other tracer experiments are given.