Another source of soluble salts in urban environments due to recent social behaviour pattern in historical centres

In this study, the process of anthropic decay on stone materials and on the lithobiontic microbial colonization associated was investigated by means of both laboratory simulation (granite) and field experiments (dolostone ́s historical quarry), all of them stone materials traditionally used in heritage construction. A wide variety of salts including sulphates, phosphates and chlorides resulted from the interaction between urine and stones after a several month urine treatment under controlled conditions. Moreover, the structure of lithobiontic lichen thalli was investigated, after the direct application of human urine in a field experiment carried out in a historical quarry under the most real conditions, revealing cellular damage in the upper cortex and in the photobiont layer.