Correlation analysis between hygrothermal environment and mural diseases distribution in a Chinese emperor tomb.

Qin Tomb, one of the most important cultural heritages in China, was built for an emperor 1000 years ago and decorated with murals and stone sculptures. After the excavation in the 1950s, multiple diseases such as salt efflorescence, powdering, and biodeterioration appeared and led to irreversible damage to the murals. These degradation phenomena are closely related to the microclimate change in the tomb. Therefore, this study conducted a one-year environment monitoring as well as a monthly survey on the disease's distribution to clarify the correlation between the temporal and spatial distribution of mural diseases and environment characteristics. The monitoring results showed a gradient distribution in the hygrothermal environment from the entrance to the back chamber. The front chamber has the greatest annual fluctuation in temperature, from 8.9 °C to 28.6 °C. The back chamber (0.1 m) has the greatest annual fluctuation in relative humidity, from 29.6% to 100%, while the back chamber (3.0 m) has the smallest annual fluctuation, from 66.5% to 100%. The corresponding diseases were a large amount of condensation on the roof in summer and salt crystallization on the murals near the entrance in winter respectively. Correlation analysis of disease distribution and environment characteristics showed that the air exchange through the entrance is the main factor that causes the hygrothermal environment changes and murals deterioration in the tomb. Therefore, an environmental control strategy was proposed to reduce the air exchange rate and mitigate mural deterioration. [ABSTRACT FROM AUTHOR]