One-Year Monitoring of Microclimatic Environmental Conditions in the Visitor Center of the Sirmium Imperial Palace and Physical, Chemical and Biological Processes in the M34 Mosaic

The aim of the research was to detect the existing microclimatic conditions of the environment in the Visitor Center of the Sirmium Imperial Palace and to determine whether they pose any potential risks to the preservation of the mosaics in room 34 (M34). In order to estimate the microclimatic conditions of the environment and examine their effects on the deterioration processes of the mosaic, the following research methods were applied: one-year microclimatic monitoring of air temperature and relative humidity, monitoring of physical processes in the mosaic and on its surface, determining the presence of soluble salts, the potential biological contamination by aerobiological sampling, and the present biological contamination by using adhesive tape and sterile swabs. The results of microclimatic monitoring indicate that the relative humidity values during January, February, November and December were constantly above 80%. The annual range of temperature values ranged from 0.4 °C to 31.5 °C, while the relative humidity values ranged from 38.9% to 93.9%. The results of microbiological analysis showed high biological contamination of the M34 mosaic, which could be expected because the conditions were favorable for fungal growth throughout the year (a w > 0.6). Soluble salts, i.e., sulfates, nitrates and chlorides, were identified on the mentioned mosaic. It can be concluded that the existing conditions in the Visitor Center of the Sirmium Imperial Palace pose a risk to the preservation of the mosaic and that they need to be improved. Considering the interdependence of the microclimatic conditions of the environment and the physical, chemical and biological processes of mosaic deterioration, microclimatic monitoring must be introduced at archeological sites with mosaics as a mandatory procedure for the purpose of monitoring the microclimatic conditions of the environment and preventive protection.