In the case of in situ conservation of tumuli and historic sites, mold is often found growing on soil and stones because of their high humidity condition, high water content, bad ventilation, rich nutrient and difficulty of complete sterilization. When mold growths are found on such substrates, disinfection treatment are carried out. Ethanol, formalin or other fungicides are often applied as disinfection agents. But sometimes mold re-outbreaks in a few days, even though disinfection treatment was done with commonly recognized effective agents at proper concentration. We investigated suitable disinfection treatment on soil and stone for in situ conservation of tumuli and historic sites. We selected ethanol, formalin, benzalconium chloride and KathonTM CG as disinfenction agents with appropriate concentration, and applied each agent (200μL) on mold contaminated soil (mound covering soil taken from Kitora Tumulus; 400mg, φ12mm) and stone (tuff stone similar to that of Takamatsuzuka Tumulus stone chamber; 15*15mm, 10mm thick) samples. Disinfected samples were stored under a similar condition of in situ conservation of tumuli and historic sites. The disinfection effect of each agent was estimated by measuring survival spores after disinfection treatment at 1 hour, 3 days, 7 days and 14 days later. From the experiments on mold contaminated soil samples, it was found that every agent could not achieve complete disinfection and survival spores increased in few days. However anhydrous ethanol, 10% formalin/anhydrous ethanol solution and 1% Kathon CG/anhydrous ethanol solution showed better disinfection effect. From these results, it was concluded that appropriate disinfection treatments are to apply these agents, then confirm the consequence of treatment 3-4 days (7-14 days for KathonTM CG) later and reapply the agent before mold forms significant spores. From the experiments on mold contaminated stone samples and chemical properties of agents (metal corrosiveness, discoloration of pigment, toxicity, etc.), it was concluded that appropriate disinfection treatment is to apply anhydrous ethanol, then confirm the consequence after 7-11 days and reapply the agent before mold forms significant spores
