AIR POLLUTANT INTRUSION INTO THE WIELICZKA SALT MINE

The Wieliczka Salt Mine World Cultural Heritage Site contains many roc k salt sculptures that are threatened by water vapor condensation from the mine ventilation air. Gaseous and particulate air pollutant conce ntrations have been measured both outdoors and within the Wieliczka Sa lt Mine, along with pollutant deposition fluxes to surfaces within the mine. One purpose of these measurements was to determine whether or n ot low deliquescence point ionic materials (e.g., NH4NO3) are accumula ting on surfaces to an extent that would exacerbate the water va por c ondensation problems in the mine. It was found that pollutant gases in cluding SO2 and HNO3 present in outdoor air are removed rapidly and al most completely from the air within the mine by deposition to surfaces . Sulfur isotope analyses confirm the accumulation of air pollutant-de rived sulfur in liquid dripping from surfaces within the mine. Particl e deposition onto interior surfaces in the mine is apparent, with resu lting soiling of some of those sculptures that have been carved from t ranslucent rock salt. Water accumulation by salt sculpture surfaces wa s studied both experimentally and by approximate thermodynamic calcula tions. Both approaches suggest that the pollutant deposits on the scul pture surfaces lower the relative humidity (RH) at which a substantial amount of liquid water will accumulate by 1% to several percent. The extraordinarily low SO2 concentrations within the mine may explain the apparent success of a respiratory sanatorium located deep within the mine.