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Environ Sci Pollut Res Int. 2016 May;23(10):9598-613. doi: 10.1007/s11356-016-6113-7. Epub 2016 Feb 4.

Determination of the distribution and speciation of selenium in an argillaceous sample using chemical extractions and post-extractions analyses: application to the hydrogeological experimental site of Poitiers.

Author information

1
Institut de Chimie des Milieux et Matériaux de Poitiers (IC2MP), Université de Poitiers/CNRS, UMR 7285, Bâtiment B8, rue Michel Brunet, 86022, Poitiers Cedex, France. joseph.bassil@univ-poitiers.fr.
2
Platform for Research and Analysis in Environmental Sciences, Doctoral School of Science and Technology, Faculty of Sciences, Lebanese University, P.O. Box 5, Campus Rafic Hariri, Hadath, Beirut, Lebanon. joseph.bassil@univ-poitiers.fr.
3
Institut de Chimie des Milieux et Matériaux de Poitiers (IC2MP), Université de Poitiers/CNRS, UMR 7285, Bâtiment B8, rue Michel Brunet, 86022, Poitiers Cedex, France.
4
Laboratoire de Chimie analytique Bio-Inorganique et Environnement (LCABIE), Université de Pau et des Pays de l'Adour/CNRS, UMR 5254, IPREM, Hélioparc, 2 Avenue du Président Angot, 64053, Pau Cedex 9, France.
5
Platform for Research and Analysis in Environmental Sciences, Doctoral School of Science and Technology, Faculty of Sciences, Lebanese University, P.O. Box 5, Campus Rafic Hariri, Hadath, Beirut, Lebanon.

Abstract

To better understand selenium's dynamics in environmental systems, the present study aims to investigate selenium speciation and distribution in black argillaceous sediments, partially fulfilling karstic cavities into the Hydrogeological Experimental Site of Poitiers. These sediments are suspected to be responsible for selenium concentrations exceeding the European Framework Directive's drinking water limit value (10 μg L(-1)) in some specific wells. A combination of a sequential extractions scheme and single parallel extractions was thus applied on a representative argillaceous sample. Impacts of the extractions on mineral dissolution and organic matter mobilization were followed by quantifying major cations and total organic carbon (TOC) in the aqueous extracts. The nature of the released organic matter was characterized using thermochemolysis coupled with gas chromatography-mass spectrometry (GC-MS). About 10 % of selenium from the black argillaceous studied matrix could be defined as 'easily mobilizable' when the majority (around 70 %) revealed associated with the aliphatic and alkaline-soluble organic matter's fraction (about 20 %). In these fractions, selenium speciation was moreover dominated by oxidized species including a mixture of Se(VI) (20-30 %) and Se(IV) (70-80 %) in the 'easily mobilizable' fraction, while only Se(IV) was detected in alkaline-soluble organic matter fraction.

KEYWORDS:

Black clay; Chemical extractions; Distribution; Selenium; Speciation; Thermochemolysis

PMID:
26846236
DOI:
10.1007/s11356-016-6113-7
[Indexed for MEDLINE]

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