Abstract: With the development of industrialization and urbanization, the occurrence of acid rain is more frequent than before. Many stone carvings in Guilin suffer from different degrees of erosion and damage. In order to prepare for the protection of Guilin limestone carvings and provide baseline information, the mechanism of limestone dissolution by acid rain was studied. Pure limestone samples were processed and soaked in acid solutions with different pH values. The pH value, Ca²⁺concentration and limestone mass loss were evaluated, and the dissolution mechanism was analyzed by the chemical thermodynamical calculation. The results show that the scratch dents can promote the dissolution of acid rain to a certain extent. The lower the pH value of acid rain is, the deeper the dissolution degree of limestone is. The greater the mass loss is, which is 2.26～9.21 times of that of acid rain with large pH, and the greater the dissolution degree of sulfuric acid than that of carbonate.

Key words: acid rain, limestone, erosion, gibbs free energy