Various surface analysis techniques [scanning electron microscopy/energy dispersive X-ray microanalysis (SEM EDX), electron spectroscopy for chemical analysis were evaluated in a correlative regimen for the chemical characterization of particulate pollutants. Analytical capabilities were demonstrated by using particles derived from steel blast furnaces. The ESCA studies of "bottom ashes" suggest highly water-soluble species enriched in sulfates on particles consisting primarily of iron oxides. Comparisons of SEM/EDX and SIMS data for selected metals (e.g., Cr, Cu, Fe, Mn, Mo, Pb, and Zn) in unleached and water-leached particles were used to estimate the extent of enrichment and aqueous solubility of surface species. Accessibility to the environment (via washout, rainout, groundwater leaching, lung fluids, etc.) is governed by both metal surface accessibility (extent of surface enrichment) and metal surface solubility (surface speciation). The unique combination of direct surface analysis and time-resolved solvent leaching experiments enables the relative importance of the two factors to be estimated for individual elements of environmental interest.

K E Y WORDS. Ion beam sputtering, plasma etching, SEM, TEM, ultrastructure, frog skeletal muscle, preferential sputtering, ion microanalysis, surface topography. SUMMARY Three dry etching techniques (Ar+ ion beam, Oz+ ion beam, 0 2 radiofrequency electrodeless discharge) were compared with respect to preferential etching and damage to the ultrastructure of glutaraldehyde-fixed Epon-embedded frog skeletal muscle sections. SEM and TEM studies were performed on both unstained and stained (osmium tetroxide, uranyl acetate) sections. Etching effects were observed to differ for the various ion beam or plasma etching techniques. Whereas selective retention of electron dense structures (e.g. Z lines, nuclear heterochromatin) was observed for oxygen plasma etching, preferential etching of these components was observed using Ozf ion beam bombardment. Selectively etched Z lines and etch-resistant nucleoli were observed for both reactive ( 0 2 + ) and inert (Ar+) ion beam sputtering after sufficiently high ion doses. The above suggest that selective etching under keV ion beam irradiation is related more to physical sputtering processes (momentum transfer) than to the chemical reactivity of the incident ion. Heavy metal post-fixation and staining had no qualitative effect on the nature of the selective etching phenomena. The above findings are significant in that they potentially influence both electron and ion microprobe measurements of etched biological specimens.

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