Abstract
This work presents mineralogical and chemical characteristics of weathering crusts developed on sandstones exposed to various air pollution conditions. The samples have been collected from sandstone tors in the Carpathian Foothill and from buildings in Kraków. It has been stated that these crusts differ in both fabric and composition. The sandstone black crust from tors is rich in organic matter and composed of amorphous silica. Sulphate incrustations accompanied by dust particles have been only sometimes observed. Beneath the black crust, a zone coloured by iron (oxyhydr)oxides occurs. The enrichment of the surface crust in silica and iron compounds protects the rock interior from atmospheric impact. The sandstones from architectonic details are also covered by a thin carbon-rich black crust, but they are visibly loosened. Numerous salts, mainly gypsum and halite, crystallise here, thus enhancing deterioration of the rock. Moreover, spherical particles originated from industrial emissions are much more common. Gypsum in natural outcrops, forms isolated and well-developed crystals, whilst these found on the architectonic details are finer and densely cover the surface. Such diversity reflects various concentrations of acid air pollutants in solutions.
Highlights
The course of weathering of exposed rock surfaces depends on both internal factors, such as mineral composition, structure and texture of the rock considered, and external ones, for instance, climate and anthropogenic pressure
The weathering crusts developed on the Carpathian sandstones exposed to various conditions of air pollution show differences in their development
The sandstone black crust from tors in the Carpathian Foothill is rich in organic matter and composed of amorphous, opal-type silica
Summary
The course of weathering of exposed rock surfaces depends on both internal factors, such as mineral composition, structure and texture of the rock considered, and external ones, for instance, climate and anthropogenic pressure. The impact of anthropogenic factors, of air pollution, increases the intensity of weathering and the formation of secondary minerals These are primarily salts that form black crust and efflorescences on the rock surfaces and accumulate in subsurface layers (Thomachot and Jeannette 2004; Charola et al 2006). Such changes affect various rock types, as limestones (Bede 2000; Marszałek 2000; Belafiore et al 2013), granitoids (Labus 1998; Schiavon 2000), sandstones (Bai et al 2003) and masonry walls (Gentilini et al 2012).
Sign-in/Register to view highlights & summary 
Published Version (
Free)
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
