Vol. 32 – 2006 - Ecologia Mediterranea

BOUAMAR BAGHDAD, MUSTAPHA NAIMI, ABDELHAK BOUABDLI, PHILIPPE SONNET, STANLEY LUTTS
90
that root concentration of heavy metals were
especially high in plants harvested 50 to
200 m from the tailing suggests that plant
exposure to heavy metal contamination did
not result from aerial contamination through
particle transported to the plant foliage but
rather, than contaminant are present in the
substrate (as a result of erosion occurring
before plant development).
The restriction of heavy metal translocation
from roots to shoots is a well-known strategy
adopted by plant to cope with high external
contamination in order to protect photosynthetic
tissues from heavy metal accumulation
(Brune Urbach & Dietz 1995). It may be
hypothesized that the transporter involved in
xylem loading are saturated while those
involved in root absorption were not, thus
leading to root accumulation as previously
recorded for Cd (Varga et al. 1999).
Results of this work suggest that levels of
heavy metals were not naturally high before
mining activities and a study of the pedo-geochemical
background is therefore necessary
in order to draw MTE inheritance of local
soils (Baize 1997; Baize & Paquereau 1997).
Heavy metal concentrations in soils and in
plant tissues suggest that a consistent portion
of toxic ions are available to plant uptake. We
demonstrated that both plants were able to
accumulate important concentration of heavy
metals. Tolerance of those plants may be, at
least partly, linked to the fact that those
species are well adapted to harsh environments
and are reported to be able to tolerate
several environmental constraints (Maestre &
Cortina 2004; Ramírez et al. 2006). This suggests
that those species may be used for rehabilitation
and phytostabilisation of the mining
area. Since tussock grass is frequently grazed
by livestock (Maestre & Cortina 2004) and
since A. herba-alba is commonly used by
local populations as an important component
of traditional pharmacopoeia (Jouad et al.
2001), this also implies that specific measures
should be undertaken in this area in order to
avoid contamination in the food chain.
Conclusion
A detailed study of oxide composition of tailings
and a precise mapping of the contamination
in soils and plants of the high Moulouya
taking into account different parameters will
facilitate the delineation of high risk areas and
will ease the rehabilitation of such areas. Further
analyses will try to evaluate whether
MTE in soil present a risk for the environment
(water and grazed plants).
Acknowledgments
This work has been supported financially by
the Ministry of Higher Education in Morocco
through its program (Programme thématique
d’appui à la recherche scientifique, PROTARS
II) and the technical Cooperation of Belgium
(CTB).
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ecologia mediterranea – Vol. 32 – 2006