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Results of principal component analysis (PCA) of the main impurity elements in biodeposits on the surface of stone: I—bifilms with a predominance microscopic fungi and algae; II—biofilms with a predominance lichens; III—vegetative biomass of the moss; IV—primary soil under the moss cover. The main contribution to the statistical model for PC 1 is made by TiO2, Na2O, Al2O3 and for PC 2 by MgO, K2O, and MnO.
