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2021年01月29日 12:12
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安全生产述职报告-不文明现象
A fern that hyperaccumulates arsenic(
这是题目，
百
度一下就能找到原文好，
原文还有表格，
我没有
翻译
)
A hardy, versatile, fast- growing plant helps to remove arsenic from
contaminated soils
Contamination of soils with arsenic,which is both toxic and carcinogenic,
is widespread1. We have discovered that the fern Pteris vittata (brake fern)
is extremely efficient in extracting arsenic from soils and translocating it
into its above-ground biomass. This plant
—
which, to our knowledge, is
the first known arsenic hyperaccumulator as well as the first fern found to
function as a hyperaccumulator
—
has many attributes that recommend it
for use in the remediation of arsenic-contaminated soils.
We found brake fern growing on a site in Central Florida contaminated
with
chromated
copper
arsenate
(Fig.
1a).
We
analysed
the
fronds
of
plants
growing
at
the
site
for
total
arsenic
by
graphite
furnace
atomic
absorption
spectroscopy.
Of
14
plant
species
studied,
only
brake
fern
contained large amounts of arsenic (As;3,280
–
4,980 p.p.m.). We collected
additional
samples
of
the
plant
and
soil
from
the
contaminated
site
(18.8
–
1,603
p.p.m.
As)
and
from
an
uncontaminated
site
(0.47
–
7.56
p.p.m. As). Brake fern extracted arsenic efficiently from these soils into
its fronds: plants growing in the contaminated site contained 1,442
–
7,526
p.p.m.
Arsenic
and
those
from
the
uncontaminated
site
contained
11.8
–
64.0
p.p.m.
These
values
are
much
higher
than
those
typical
for
plants
growing
in
normal
soil,
which
contain
less
than
3.6
p.p.m.
of
arsenic3.
As
well
as
being
tolerant
of
soils
containing
as
much
as
1,500
p.p.m.
arsenic, brake fern can take up large amounts of arsenic into its fronds in
a
short
time
(Table
1).
Arsenic
concentration
in
fern
fronds
growing
in
soil
spiked
with
1,500
p.p.m.
Arsenic
increased
from
29.4
to
15,861
p.p.m. in two weeks. Furthermore, in the same period, ferns growing in
soil containing just 6 p.p.m. arsenic accumulated 755 p.p.m. Of arsenic in
their fronds, a 126-fold enrichment. Arsenic concentrations in brake fern
roots
were
less
than
303
p.p.m.,
whereas
those
in
the
fronds
reached
7,234 p.p.m.
Addition
of
100
p.p.m.
Arsenic
significantly
stimulated
fern
growth,
resulting in a 40% increase in biomass compared with the control (data
not shown).
After 20 weeks of growth, the plant was extracted using a solution of 1:1
methanol:water
to
speciate
arsenic
with
high-performance
liquid
chromatography
–
inductively coupled plasma mass spectrometry. Almost
all
arsenic
was
present
as
relatively
toxic
inorganic
forms,
with
little
detectable
organoarsenic
species4.
The
concentration
of
As(III)
was
greater in the fronds (47
–
80%) than in the roots (8.3%), indicating that
As(V) was converted to As(III) during translocation from roots to fronds.
As
well
as
removing
arsenic
from
soils
containing
different
concentrations of arsenic (Table 1), brake fern also removed arsenic from
soils containing different arsenic species (Fig. 1c). Again, up to 93% of
the
arsenic
was
concentrated
in
the
fronds.
Although
both
FeAsO4
and
AlAsO4 are relatively insoluble in soils1, brake fern hyperaccumulated
arsenic derived from these compounds into its fronds (136
–
315 p.p.m.)
at levels 3
–
6 times greater than soil arsenic.
Brake
fern
is
mesophytic
and
is
widely
cultivated
and
naturalized
in
many
areas
with
a
mild
climate.
In
the
United
States,
it
grows
in
the
southeast and in southern California5. The fern is versatile and hardy, and
prefers
sunny
(unusual
for
a
fern)
and
alkaline
environments
(where
arsenic
is
more
available).
It
has
considerable
biomass,
and
is
fast
growing, easy to propagate,and perennial.
We believe this is the first report of significant arsenic hyperaccumulation