Page 121 - 79_04

Beatriz
Baselga-­-Cervera&
col.

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
m3
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.

636