Lichen biodeterioration of ecclesiastical monuments in northern Spain.
Seven highly-coloured lichen species belonging to the genera Caloplaca, Candelariella, Aspicilia and Xanthoria from ecclesiastical buildings in northern Spain have been analysed non-destructively by FT-Raman spectroscopy. The vibrational band assignments in the spectra of the specimens, which were still attached to their limestone or sandstone substrata, were accomplished with the assistance of the chemical compositions obtained from wet chemical extraction methods. beta-Carotene was found in all specimens as the major pigment, and the characteristic spectral signatures of calcium oxalate monohydrate (whewellite) and dihydrate (weddelite) could be identified; chemical signatures were found for these materials even in lichen thalli growing the non-calcareous substrata, indicating, probably, that the calcium was provided here from wind-or-rain-borne sources. The Raman spectral biomarkers found in the lichens broadly agreed with the chemical extraction profiles as expected, but the present study indicates that some form of non-destructive taxonomic identification based on Raman spectroscopy was possible.
Villar
Susana E Jorge
SE
Department of Chemical and Forensic Sciences, University of Bradford, Bradford BD7 1DP, UK. seju@ubu.es
Edwards
Howell G M
HG
Seaward
Mark R D
MR
D002118:Calcium / Q000737:chemistry; D002119:Calcium Carbonate; D002129:Calcium Oxalate / Q000737:chemistry; D003252:Construction Materials; D019015:Geologic Sediments; D008011:Lichens / Q000737:chemistry*; D008956:Models, Chemical; D010070:Oxalates / Q000737:chemistry; D013030:Spain; D017550:Spectroscopy, Fourier Transform Infrared / Q000379:methods*; D013059:Spectrum Analysis, Raman / Q000379:methods*; D019207:beta Carotene / Q000378:metabolism
D010070:Oxalates; D019207:beta Carotene; D002129:Calcium Oxalate; D002119:Calcium Carbonate; D002118:Calcium