Abstract: Mass concentrations, water-soluble ions, and total carbon (TC) of total suspended particle (TSP) were investigated from both indoor and outdoor conditions in Mogao Grottoes, Dunhuang, from April 30 to May 10, 2006. The average outdoor mass concentration was 1138.4 μg m-3, while the indoor average mass concentrations were relatively very lower, about 228.5 and 286.4 μg m-3 for non-opening time and opening time, respectively. The water-soluble ions are predominated by Ca2+, SO42-, Na+ and Cl-. The concentrations of water-soluble ions from outdoor aerosols were higher than those from indoor aerosols and the concentrations of water-soluble component varied significantly during the long-term vacation period. The TC concentrations collected during the opening time were higher than those collected during the non-opening time and those collected from the outside of the Grottoes. The concentrations of NH3 and HNO3 gasses were also obtained in this study. Our study showed that there was a remarkable increase in the pollution material concentrations at the peak of the tourist populations, indicating the significant influence from the tourists.

Key words: Dunhuang Mogao Grottoes, TSP, Water-soluble ion, Carbonaceous aerosols, Harmful air