APPLICATION OF X-RAY ELEMENT MAPPING ACROSS THE LICHEN-ROCK INTERFACE

The application of element mapping in the scanning electron microscope with electron probe microanalysis across the lichen-rock interface is described with reference to Trapelia involuta growing on a granite su bstratum. The preparation of samples containing both organic and miner al components required the development of specialized techniques to ma intain both chemical and structural integrity at the 2 mu m resolution of the X-ray element maps. X-ray element maps show the distribution o f entrained rock particles at the lichen-rock interface and chemical l ocalization which is strongly related to anatomical structure for the essential elements S, Fe, Ca, Na, It and P. The ability to map element distribution across the lichen-rock interface has wide-ranging potent ial applications in studies such as the biodeterioration of buildings and monuments and the mobilization and uptake of toxic elements from c ontaminated substrata.