Descrição
An acid metal-contaminated soil from the
Aljustrel mining area (a pyrite mine located in SW
Portugal in the Iberian Pyrite Belt) was subjected to
chemical characterisation and total metal quantiWcation
(Cd, Cr, Cu, Ni, Pb and Zn). Water-soluble metals
were determined and a sequential extraction
procedure was used to investigate metal speciation.
Two bioavailable metal fractions were determined: a
mobile fraction and a mobilisable fraction. Soil ecotoxicity
was studied using a battery of bioassays:
plant growth test and seed germination with cress
(Lepidium sativum L.), earthworm (Eisenia fetida)
mortality, E. fetida avoidance behaviour, luminescent
inhibition of Vibrio Wscheri and Daphnia magna
immobilisation. Although the total content of Cu, Zn and Pb in the soil was large (362, 245 and 1,250 mg/
kg dry matter, respectively), these metals were mostly
structurally bound (87% for Cu, 81% for Zn and 89%
for Pb) and, therefore, scarcely bioavailable. Nonetheless,
the D. magna immobilization test using soil
leachate showed an EC50 (48 h) of 36.3% (v/v), and
the luminescent inhibition of V. Wscheri presented an
EC20 (15 min) of 45.2% and an EC20 (30 min) of
10.7% (v/v), suggesting a considerable toxic eVect. In
the direct exposure bioassays, E. fetida avoided the
mine soil at the highest concentrations (50%, 75%
and 100% v/v). At the same soil concentrations, cress
showed negligible growth. The results suggest the
need to use a battery of toxicity tests, in conjunction
with chemical methods, in order to assess the quality
of mine-contaminated soils correctly.
; Palma, P. 
