GEOSCAN, résultats de la recherche


TitreEffects of soil composition and mineralogy on the bioaccessibility of arsenic from tailings and soil in gold mine districts of Nova Scotia
AuteurMeunier, L; Walker, S R; Wragg, J; Parsons, M B; Koch, I; Jamieson, H E; Reimer, K J
SourceEnvironmental Science & Technology (ES & T) vol. 44, no. 7, 2010 p. 2667-2674,
Séries alt.Secteur des sciences de la Terre, Contribution externe 20090357
Documentpublication en série
Mediapapier; en ligne; numérique
Sujetssols; études pédologiques; géochimie du sol; contamination des métaux lourds; arsenic; concentration; géochimie des résidus; analyses des résidus; résidus; analyse environnementales; etudes de l'environnement; analyses minéralogiques; géologie de l'environnement; pédologie; minéralogie
Illustrationstables; histograms
ProgrammeEcosystems Risk Mitigation, Géoscience de l'environnement
Résumé(disponible en anglais seulement)
Bioaccessibility tests and mineralogical analyses were performed on arsenic-contaminated tailings and soils from gold mine districts of Nova Scotia, Canada, to examine the links between soil composition, mineralogy, and arsenic bioaccessibility. Arsenic bioaccessibility ranges from 0.1% to 49%. A weak correlation was observed between total and bioaccessible arsenic concentrations, and the arsenic bioaccessibility was not correlated with other elements. Bulk X-ray absorption nearedge structure analysis shows arsenic in these near-surface samples is mainly in the pentavalent form, indicating that most of the arsenopyrite (As1-) originally present in the tailings and soils has been oxidized during weathering reactions. Detailed mineralogical analyses of individual samples have identified up to seven arsenic species, the relative proportions of which appear to affect arsenic bioaccessibility. The highest arsenic bioaccessibility (up to 49%) is associated with the presence of calcium-iron arsenate. Samples containing arsenic predominantlyasarsenopyrite or scoroditehavethe lowest bioaccessibility (<1%). Other arsenic species identified (predominantly amorphous iron arsenates and arsenic-bearing iron(oxy)hydroxides) are associated with intermediate bioaccessibility (1 to 10%). The presence of a more soluble arsenic phase, even at lowconcentrations, results in increased arsenic bioaccessibility from the mixed arsenic phases associated with tailings and mineimpacted soils.