Beatriz Baselga-‐Cervera& col.
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In this paper we review these surprising evidences.
2. AN EXTREME ENVIRONMENT: THE URANIUM-‐POLLUTED POND AT SAELICES
MINE.
Huge uranium deposits occur in the fracture areas in shale and schist of the
pre-‐Ordovician schist-‐greywacke complex that forms part of the paleozoic
basement of the Hesperian Massif in Iberian Peninsula (8). As anecdotic historian,
the uranium mining of the Hesperian Massif was an important radio supply source
for the experiments conducted by Madame Curie. The most important of these
uranium deposits with a total volume of 25 million cubic meters, and an ore grade
ranging from 400 to 800 mg kg
-‐1
of uranium are in Saelices, Salamanca (Spain)
which were exploited in mining since 1960 until 2000. As a result of these mining
activities of static and dynamic acid lixiviation there are around 30 ha of uranium-‐
polluted ponds containing 1 million m
3
of uranium-‐polluted water (Figure 1).
Figure 1.-‐ Air image of Saelices mine sampled area, located in the Saelices el Chico
municipality, in Salamanca, Spain.
The square indicates the mining evaporation pond from
where the water samples were taken.
We studied a huge evaporation pond at the Saelices mining area from March
2012. This pond is an extreme ecosystem with uranium contamination, pollution
by other heavy metals, acidity and radioactivity as shows in Table 1. Median value
of uranium concentration obtained during a yearly cycle exceeds 833 times the
uranium levels in water considered safe by the EPA. We also studied a natural
pond at Zamarra, without mining activity that can serve as a baseline of pollution
levels in that area before human activity (Table 1).
Table 1.
-‐ Environmental conditions and microalgae diversity in the evaporation pond at the
Saelices mining area versus a natural pond (Zamarra pond) in a near area but without mining
activity.
