Lead isotope ratio and quantitative trace element analysis of individual coal fly ash particles using SIMS

Coal fly ash particles were obtained from the electrostatic precipitators of three Illinois Basin area United States coal fired power plants and seven Western United States coal fired power plants. Lead isotope ratios and trace element concentrations were determined on individual particles using Secondary Ion Mass Spectrometry (SIMS) in an effort to test the feasibility of using this information as an endogenous coal fly ash tracer in the atmosphere. It was determined that the surface lead concentration on Illinois Basin area coal fly ash is sufficiently high to allow precise measurement of lead isotope ratios on single particles and a distinct variation of the average isotope signatures between the three Illinois Basin area coal fired power plants was found. Western coal fly ash particles, however, contain a low surface concentration of lead, thereby yielding errors in analysis, which are dictated by counting statistics, large enough as to cause overlap in the lead isotope ratios. As a result, differentiation between western plants was not possible. Trace element concentrations on individual particles were found to be heterogeneous from a single source, and would therefore not provide an appropriate measurement for differentiation between point sources.