Tagging In-Stack Suspended Particles from a Coal-fired Power Plant with an Enriched Isotopic Tracer

A device was constructed for tagging coal fly-ash particles with enriched isotopes of Nd for use in atmospheric tracer experiments by thermally degrading vapor of the 2,2,6,6-tetramethyl 3,5-heptanedione chelate of the metal in the presence of fly-ash laden flue gas. Microanalysis measurements of individual fly-ash particles verify the surface residence of the tracer material and show that particle surfaces are devoid of individual Nd particles. The prototype device was used to release 148 Nd- and 145 Nd-tagged fly-ash particles for an urban-scale field test at isotope delivery rates of 25-54 mg/h.