Speleo-aerosols were isolated by ultra-filtration from the atmospheres of some caves of the Moravian Karst. Significant differences in composition were found. The matter collected on ultra-filters in the Soupsko-oůvská Caves had high contents of sulfur (calcium sulfate) and were black colored. The ultra-filter matter from the Císařská Cave, on the other hand, was typically light-gray colored and contained only small quantities of sulfur. In the matter of both localities, heavy metals and chlorine were occasionally found. The resources of sulfur, chlorine, and heavy metals are unknown
