Biological and microclimatic diagnosis in cultural heritage conservation.

This work presents the application of a methodological model based on an integrated system for biological and microclimatic monitoring to assess and prevent biodegradation risks. The integrated system was implemented inside the Derossiana room of the Palatina historic library in Parma, ltaly. Brological and microclimate monitoring were performed during summer and winter 2012. Samples were collected at a height of 1 m, 2 m and 4 m. The concentration of microorganisms in the air was measured by active sampling (DUO-SAS 360) and expressed as CFU/m3. The number of airborne microorganisms settling on surfaces was measured by passive sampling (Petri dishes) to determine the lndex of Microbial Air contamination (lMA). Airborne particles 0.3, 0.5, 1.0 and 5.0 micrometers in diameter were counted with a laser particle counter. The surface contamination of ancient manuscripts and shelves was measured using nitrocellulose membranes to determine the Microbial Buildup (MB total number of microorganisms accumulated on a surface prior to the sampling) and the Hourly Mrcrobial Fallout (HMF, number of microorganisms that settle on a surface during I hour). A spore trap sampler (VPPS 1000) was used for direct microscope detection of fungal spores, both viable and nonviable, and to measure the temporal distribution of the particulate. Microbiologicàl contaminants were analysed by means of cultural and molecular biology techniques. A wide variabilily of air microbial and particle contamination was observed. Air microbial contamination expressed in CFU/m3 was significantly higher in summer (p <0.001), while no significant differences in IMA values were observed between the two seasons. The comparison between 1 metre and 2 metres showed a significantly higher concentration at 1 metre for particles measuring 0.5 micrometers and 1micrometers (p=0.007). The most frequently isolated microfungi genera were Cladosporium, Alternaria and Aspergillus. Bacteria genera such as Streptomyces, Bacillus, Sphingomonas, Pseudoclavibacter as well as unculturable bacteria were identified by polymerase chain reaction (PCR). Microclimatic parameters (air temperature, relative humidity, air velocity and mean radiant temperature) were recorded. The Computational Fluid Dynamics (CFD) simulations based on a multi-physics approach were used to study the tracing and diffusion of particles inside the room. Results from the thermal analysis simulation show that the room appears to be well insulated from external conditions, maintaining a constant temperature throughout the air domain. This interdisciplinary research represents a contribution towards the definition of standardized methods for assessing the biological and climate quality of indoor heritage environments, preserving cultural property and safeguarding the health of operators and visitors.