Biocolonizer species are putting the conservation of the granite at Machu Picchu at risk

By applying a non-destructive, multi-analytical methodology, the researchers have determined the role played by the species of lichens, algae, mosses, cyanobacteria, etc. colonizing the Sacred Rock with respect to the conservation problems it is displaying. As Morillas explained, "once these species penetrate the material through some kind of minor deterioration that has been forming, they attach themselves to the material itself so that they can feed off the minerals belonging to the rock, gradually degrading it. As time passes, these micro-organisms can cause minor delamination that could result in the progressive loss of this rock."

Monitoring biogenic pigments to determine depth

After determining the family to which each of the species of micro-organisms found in numerous micro samples of the rock belongs, as well as which biogenic pigments are excreted by each of them, "we carried out in-depth profiling to predict how far these micro-organisms may have penetrated." That way, the researchers have concluded that "there is a wide variety of biocolonizer species in the Sacred Rock, most of which have penetrated through the porous substrate, and which could be one of the factors responsible for the stress being enduring by this rock," said Doctor Morillas, who currently lectures in the UPV/EHU's Department of Mathematics and Experimental Sciences Didactics.

This piece of research is just one of the studies being conducted by the UPV/EHU's group of researchers at this location. In fact, the diagnosis of the conservation state of various buildings, such as temples, houses or meditation areas in the archaeological city, has also begun; at the same time, the building material used throughout Machu Picchu has been analysed and "we are also studying possible alterations in the granitic material owing to possible incorrect restoration carried out in the past in certain places at Machu Picchu." The researcher has also conducted "an ecotoxicity study of the city itself and all the surrounding area of the Archaeological Park where we have analysed the soil, air and rainwater for potential contaminants." What is more, Morillas has analysed rock paintings located in the park and has been able to specify the materials used to produce them; "these paintings are believed to date back much earlier than the pre-Hispanic era." Finally, the researcher added that "thanks to all this we are drawing up the bases of a project with various universities and institutions in other countries to study the conservation of emblematic UNESCO locations."