Mineralogical,geochemical and microfabric evidences of gypsum crusts: a case study from Budapest |
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| Authors: | Siegfried Siegesmund Akos Török Andre Hüpers Christian Müller Werner Klemm |
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| Institution: | 1.Geoscience Centre,University of G?ttingen,G?ttingen,Germany;2.Department of Construction Materials and Engineering Geology,Budapest University,Budapest,Hungary;3.Institute for Mineralogy,Technical University Bergakademie Freiberg,Freiberg,Germany |
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| Abstract: | High levels of SO2 and particulate pollution enable the rapid development of gypsum-rich weathering crusts in Budapest. Two types of white crusts,
thin and thick ones, and two forms of black crusts, laminar and framboidal ones, were studied in limestone buildings of the
parliament and Citadella. The percentage of crust cover and damage categories were documented on selected walls. Petrographic,
XRD, XRF and sulphur isotope analyses were performed under laboratory conditions to understand the mechanism of crust formation.
White crusts found both on exposed and sheltered walls display a calcite-rich layer with gypsum, while black crusts are enriched
with gypsum. The sulphur isotopic composition of white and black crusts overlaps, but the crusts are slightly enriched in
heavy isotopes compared to rainwater. S content, Si/Al ratios and particulates in black crusts suggest that air pollution
(SO2, dust) contributes to black crust formation. The accumulation of sulphur and Zn enrichment of white crusts were also documented
indicating that under high pollution levels, even these compound can accumulate on exposed facades. |
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| Keywords: | Air pollution Weathering crust Gypsum Geochemistry Limestone |
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