Carbon isotope exchange during calcite sulphation

Sulphation of limestone and carbonaceous sandstone is a well-known process in the deterioration of natural stone, playing havoc with our cultural heritage over bygone decades. The overall mechanism in this process is not completely understood. Current studies using a laser-ablation technique followed by mass spectrometry indicated a surprising shift in carbon isotopes after sulphation. Naturally weathered century-old carbonaceous sandstone as well as laboratory exposed fresh stone of the same rocktype showed a consistent change in carbon isotopes (δ13C) during sulphation, indicating that atmospheric CO2 plays a part in the process.