Abstract:
Natural stone can undergo disaggregation from various causes, including physical actions
such as freeze–thaw cycles, temperature and humidity variations, chemical actions such as the
solubilization of minerals by organic and inorganic acids, as well as biological actions due to the
colonization of organisms that can produce biocorrosion and biomineralization. This research
investigates the impact of microclimatic conditions and microbial activity on the physical and chemical
integrity of stone heritage, particularly the biodeterioration caused by fungi in the case of a Romanian
rock church. Various analytical techniques were employed, including macroscopic and optical
microscopy, Raman spectroscopy, X-ray diffraction, and culture-based identification methods, to
characterize the mineral composition and microbial contamination of the rock samples. The analyses
revealed that the sandstone consists primarily of quartz (over 90%), muscovite (5–10%), and feldspars.
The identified fungi included Cladosporium herbarium, Aspergillus niger, and Mortierella hyalina. The
SEM images showed fungal hyphae and spores within the kaolinite–illite matrix, indicating significant
microbial colonization and its role in rock deterioration. Additionally, microclimatic data collected
over a 12-week period highlighted the substantial fluctuations in temperature and relative humidity
within the church, which contribute to the physical and chemical weathering of the stone. This study
also noted high levels of particulate matter (PM2
.5 and PM10) and volatile organic compounds, which
can exacerbate microbial growth and stone decay. The comprehensive analysis underscores the need for targeted preservation strategies that consider both microclimatic factors and microbial colonization
to effectively conserve stone heritage sites, ensuring their longevity and structural integrity.
