ENVIRONMENTAL SCANNING ELECTRON-MICROSCOPY OF MARINE AGGREGATES

Marine aggregates were examined for the first time in the hydrated sta te using an environmental scanning electron microscope (ESEM). Sample preparation consisted of fixation followed by rinsing with distilled w ater to remove excess salts and fixative. Aggregates were continuously observed at resolutions comparable to conventional scanning electron microscopy through stages of hydration, from completely immersed to de siccated. Because no metallic coating is required, energy-dispersive X -ray spectroscopy (EDXS) can be used to analyse rapidly constituent el ements occurring at low concentrations with no spectral interference. Subtle differences in mineral particles were seen in both EDXS spectra and in direct observation of relative hydration, reflecting apparent differences in mineralogy, ESEM enabled-examination of effects of desi ccation and rehydration on individual particles composed primarily of hydrated polymer and eliminated dehydration artefacts in delicate orga nisms.