Driving mechanisms and hydro‐chemical variation for assessing salt‐induced weathering of sandstone in grotto relics

Salt-induced weathering significantly contributes to the deterioration of sandstone in grotto relics, with calcium sulphate and magnesium sulphate accumulation playing a crucial role. This study reveals that the Ca/Mg molar ratio varies between 0.27 at ambient relative humidity (RHam) and 4.13–18.15 under constant RH conditions, indicating distinct hydro-chemical processes influencing salt weathering. Field observations and laboratory experiments on Yungang Grottoes' sandstone showed that partial immersion led to a notable increase in Na+ and Mg2+ concentrations in groundwater (165 mg/L and 120.7 mg/L, respectively), while SO42− concentration decreased by 322.5 mg/L due to capillary-driven migration. Salt efflorescence formation was linked to wetting–drying and dissolution–crystallization cycles driven by fluctuating environmental conditions, providing critical insights for conservation strategies to mitigate salt damage in heritage sites.

Wang, J., Yan, H., & Ren, W. (2024). Driving mechanisms and hydro‐chemical variation for assessing salt‐induced weathering of sandstone in grotto relics. Earth Surface Processes and Landforms, 49(9), 2855–2869. Portico. https://doi.org/10.1002/esp.5862