Mercury speciation in Pinus nigra barks from Monte Amiata (Italy): An X-ray absorption spectroscopy study

This study determined, by means of X-ray absorption near-edge structure (XANES) spectroscopy, the speciation of mercury (Hg) in black pine (Pinus nigra) barks from Monte Amiata, that were previously shown to contain exceptionally high (up to some mg kg−1) Hg contents because of the proximity to the...

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Bibliographic Details
Published in:Environmental pollution (1987) 2017-08, Vol.227, p.83-88
Main Authors: Chiarantini, Laura, Rimondi, Valentina, Bardelli, Fabrizio, Benvenuti, Marco, Cosio, Claudia, Costagliola, Pilario, Di Benedetto, Francesco, Lattanzi, Pierfranco, Sarret, Géraldine
Format: Article
Language:English
Subjects:
Adsorption
Ecotoxicology
Environmental Monitoring
Italy
Life Sciences
Mercury - analysis
Mining
Pinus - chemistry
Soil Pollutants - analysis
Toxicology
X-Ray Absorption Spectroscopy
X-Rays
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Summary:This study determined, by means of X-ray absorption near-edge structure (XANES) spectroscopy, the speciation of mercury (Hg) in black pine (Pinus nigra) barks from Monte Amiata, that were previously shown to contain exceptionally high (up to some mg kg−1) Hg contents because of the proximity to the former Hg mines and roasting plants. Linear fit combination (LCF) analysis of the experimental spectra compared to a large set of reference compounds showed that all spectra can be fitted by only four species: β-HgS (metacinnabar), Hg-cysteine, Hg bound to tannic acid, and Hg0. The first two are more widespread, whereas the last two occur in one sample only; the contribution of organic species is higher in deeper layers of barks than in the outermost ones. We interpret these results to suggest that, during interaction of barks with airborne Hg, the metal is initially mechanically captured at the bark surface as particulate, or physically adsorbed as gaseous species, but eventually a stable chemical bond is established with organic ligands of the substrate. As a consequence, we suggest that deep bark Hg may be a good proxy for long term time-integrated exposure, while surface bark Hg is more important for recording short term events near Hg point sources. [Display omitted] •Mercury speciation with XANES spectroscopy of Hg rich tree barks from Monte Amiata.•deep Pinus nigra bark Hg may be a good proxy for regional and global Hg exposure.•surface Pinus nigra bark Hg is representative of near Hg point sources.
ISSN:0269-7491
1873-6424
DOI:10.1016/j.envpol.2017.04.038