EFFECT OF ACID-RAIN ON SANDSTONE - THE ROYAL PALACE AND THE RIDDARHOLM CHURCH, STOCKHOLM

The deterioration of two kinds of sandstone is discussed for two 18:th century buildings in central Stockholm: the Royal Palace, and the Roy al Carolean Burial Chapel (Karolinska gravkoret) annexed to the mediae val Riddarholm church. The facades of calcitic Gotland sandstone show many signs of serious decay, such as gypsum formation, pulverized surf ace, exfoliation, discolouration, and salt efflorescence. The socles a re built of the more resistant quartzitic Roslagen sandstone, displayi ng some discolouration, cracks, and slight exfoliation. In total about 300 samples have been analysed. The surface concentration of sulphur is highest at ground level and at rain-sheltered positions. Chemical a nd sulphur isotope data indicate that the stone decay to a large part may be attributed to anthropogenic sources like acid deposition and ca r traffic.