DBPapers
DOI: 10.5593/sgem2012/s20.v5004

ACCUMULATION OF TUNGSTEN IN NATIVE PLANTS OF MINING AREAS RELATED WITH THEIR MOBILITY AND BIOAVAILABILITY IN SOILS AND TAILINGS (NORTHERN PORTUGAL)

P. FAVAS, J. PRATAS
Wednesday 1 August 2012 by Libadmin2012

References: 12th International Multidisciplinary Scientific GeoConference, www.sgem.org, SGEM2012 Conference Proceedings/ ISSN 1314-2704, June 17-23, 2012, Vol. 5, 21 - 28 pp

ABSTRACT

The mechanisms relating to the mobility and bioavailability of tungsten have been
explored using chemical extraction techniques. The procedure adopted in this study
allows the separation of the water-soluble fraction, so the extracted chemical elements
must be considered highly bioavailable because they are easily mobilized. The elements
extracted from the so-called exchangeable fractions, which in this study were leached
through the use of NH4 OAc, are an important part of the potentially available elements
and can be considered as an estimate of bioavailability. We compared five mining areas
of Northern Portugal with distinctive paragenesis for bioavailable levels of tungsten in
soils and the resulting bioaccumulate levels in six species of plants (Erica arborea L.,
Halimium umbellatum (L.) Spach, Pinus pinaster Aiton, Pteridium aquilinum (L.)
Kuhn, Pterospartum tridentatum (L.) Willk. and Quercus faginea Lam.). Tungsten
appears to be relatively immobile in most studied sites, but soils of Tarouca mine show
significant increases in bioavailable fraction. The soils of the Tarouca mine area stand
out by their higher content of W in the bioavailable fraction. Probably as a result of
easier fragmentation and dissolution of scheelite, compared to wolframite. This is
reflected in the bioaccumulated concentrations in the tissues of the studied species at
this site. It’s in the samples of Tarouca mine that occur higher bioaccumulated levels of
W than all five mines. This exemplifies the importance of soil mineralogy, controlling
the biogeochemical distribution of elements.

Keywords: abandoned mine, bioaccumulation, mobility, sequential chemical extraction