Fourier Transform Raman spectroscopic and scanning electron microscopic study of cryptoendolithic lichens from Antarctica

The Raman microscopic analysis of a cryptoendolithic lichen community in sandstone from East Beacon Ridge, Victoria Land, Antarctica, is described for the first time. The Raman spectra from the crustal, lichen, fungal and accumulation zones were used to assess the strategy adopted by the lichen community under environmentally stressed conditions. Calcium oxalate dihydrate was found only in the upper lichen zone, whereas calcium oxalate monohydrate was found distributed through several zones; this is ascribed to a microenvironmental temperature gradient. The leaching of iron oxide occurs from the crustal surface zone into the accumulation zone. In contradiction with earlier wet chemical destructive analyses of Antarctic cryptoendolithic communities, the presence of calcium carbonate was not confirmed in the lichen or fungal zones. The Raman spectroscopic results were confirmed by scanning electron microscopic x-ray analysis.