Thenardite and gypsum precipitated in wall of brick building in campus of University of the Ryukyus, Okinawa

概要

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Fine-grained white sulphates were precipitated in wall of brick building in the campus of the University of the Ryukyus, Okinawa. The sulphate samples scratched by knife were investigated by X-ray diffraction analysis (XRD), optical microscopy, and scanning electron microscopy (SEM). The precipitated sulphates are thenardite and gypsum. These minerals were precipitated by evaporitic reaction between sulphate (SO42-) in acid rain and cations. Sodium (Na+) would be supplied from salt (NaCl) dissolved in rain and calcium (Ca2+) would be leached from the brick. Accidentally, we found massive precipitation of gypsum and taylorite along the brick wall under the agricultural fertilizer, laid on a shelf-like place in the building, which had supplied SO42-, K+ and NH42+ during raining.
日本堆積学会の論文