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Arsenic incorporation in natural calcite lattice: Evidence from Electron Spin Echo spectroscopy

Research Area: Uncategorized Year: 2006
Type of Publication: Article
Authors:
Journal: EARTH AND PLANETARY SCIENCE LETTERS Volume: 246
Number: 3-4 Pages: 458-465
Month: June
Abstract:
Quaternary travertines of the Middle Pecora Valley (Tuscany, Italy) contain up to 257 ppm arsenic. Such a content is environmentally relevant, but low enough to make the exact chemical speciation of arsenic difficult by applying conventional investigation techniques. The task was addressed by use of the Electron Spin Echo (ESE) spectroscopy, taking advantage from the modulation by the arsenic nucleus of the decay spectrum of the paramagnetic ion Mn(II), occurring as replacement of Ca in the calcite lattice. Interpretation of the spectra suggests that arsenic occurs in the calcite lattice in the position of C, through the substitution CO32- double left right arrow AsO33-. This mechanism of arsenic incorporation by calcite may be an effective limit of arsenic mobility under conditions where immobilization through sorption by iron and/or manganese oxyhydroxides is not operating. (c) 2006 Elsevier B.V. All rights reserved.
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