Environmental Science & Technology,
Journal Year:
2022,
Volume and Issue:
56(16), P. 11845 - 11856
Published: Aug. 3, 2022
Microbial
oxidation
of
organic
compounds
can
promote
arsenic
release
by
reducing
soil-associated
arsenate
to
the
more
mobile
form
arsenite.
While
anaerobic
methane
has
been
demonstrated
reduce
arsenate,
it
remains
elusive
whether
and
what
extent
aerobic
(aeMO)
contribute
reductive
mobilization.
To
fill
this
knowledge
gap,
we
performed
incubations
both
microbial
laboratory
cultures
soil
samples
from
arsenic-contaminated
agricultural
fields
in
China.
Incubations
with
showed
that
aeMO
could
couple
reduction,
wherein
former
bioprocess
was
carried
out
methanotrophs
latter
a
non-methanotrophic
bacterium
belonging
novel
uncultivated
representative
Burkholderiaceae.
Metagenomic
analyses
combined
metabolite
measurements
suggested
formate
served
as
interspecies
electron
carrier
linking
reduction.
Such
coupled
bioprocesses
also
take
place
real
world,
supported
similar
stoichiometry
gene
activity
natural
paddy
soils,
up
76.2%
soil-arsenic
mobilization
into
pore
waters
top
layer
soils
where
oxygen
present.
Overall,
study
reveals
previously
overlooked
yet
significant
contribution
Environmental Science & Technology,
Journal Year:
2021,
Volume and Issue:
55(20), P. 14281 - 14293
Published: Oct. 8, 2021
Iron
(Fe)
phases
are
tightly
linked
to
the
preservation
rather
than
loss
of
organic
carbon
(OC)
in
soil;
however,
during
redox
fluctuations,
OC
may
be
lost
due
Fe
phase-mediated
abiotic
processes.
This
study
examined
role
driving
hydroxyl
radical
(•OH)
formation
and
transformation
cycles
paddy
soils.
Chemical
probes,
sequential
extraction,
Mössbauer
analyses
showed
that
active
species,
such
as
exchangeable
surface-bound
low-crystalline
minerals
(e.g.,
green
rust-like
phases),
predominantly
regulated
•OH
cycles.
The
oxidation
strongly
induced
oxidative
OC,
which
accounted
for
15.1–30.8%
CO2
production
oxygenation.
Microbial
processes
contributed
7.3–12.1%
production,
estimated
by
chemical
quenching
γ-irradiation
experiments.
After
five
cycles,
30.1–71.9%
associated
with
species
was
released,
whereas
5.2–7.1%
stabilized
high-crystalline
irreversible
these
Collectively,
our
findings
might
unveil
under-appreciated
more
conservation
soil
fluctuation
events.
Journal of Geophysical Research Biogeosciences,
Journal Year:
2023,
Volume and Issue:
128(2)
Published: Feb. 1, 2023
Abstract
Sources
of
dissolved
organic
matter
(DOM)
triggering
arsenic
enrichment
in
deep
confined
groundwater
is
a
highly
debated
issue.
Along
these
lines,
the
spectroscopic
and
molecular
characteristics
DOM
were
monitored
both
shallow
unconfined
from
Songnen
Basin,
China.
Results
demonstrated
that
with
higher
concentrations
was
characterized
by
more
abundant
labile
compounds
than
groundwater.
The
three‐end‐member
mixing
model
estimated
had
fraction
surface
water,
while
primarily
recharged
lateral
flow.
Groundwater
sources
fluorescence
index
(FI)
values,
which
suggests
sourced
water
stronger
terrestrial
signatures.
However,
mainly
situ
sedimentary
release
or
by‐products
microbial
activity
Higher
values
degradation
(I_deg)
indicate
undergone
greater
extents
one.
anoxic
environments
occurred
via
pathway
where
saturated
low‐molecular‐mass
preferentially
degraded
to
produce
mid‐molecular‐mass
unsaturated,
aromatic,
This
explained
significant
positive
correlations
between
FI
I_deg
values.
A
state
conducive
work
successfully
identified
distinct
DOM,
proposed
paradigm
processing
pathways
during
under
environments.
Ammonium-related
pathways
are
important
for
groundwater
arsenic
(As)
enrichment,
especially
via
microbial
Fe(III)
reduction
coupled
with
anaerobic
ammonium
oxidation;
however,
the
key
(and
microorganisms)
underpinning
ammonium-induced
and
their
contributions
to
As
mobilization
in
still
unknown.
To
address
this
gap,
aquifer
sediments
hosting
high
from
western
Hetao
Basin
were
incubated
15N-labeled
external
organic
carbon
sources
(including
glucose,
lactate,
lactate/acetate).
Decreases
concentrations
positively
correlated
increases
total
produced
Fe(II)
(Fe(II)tot)
released
As.
The
molar
ratios
of
Fe(II)tot
oxidized
ranged
3.1
3.7
all
incubations,
δ15N
values
N2
headspace
increased
ammonium-treated
series,
suggesting
as
end
product
oxidation.
addition
release
by
16.1%
49.6%,
which
was
more
pronounced
when
copresented
electron
donors.
Genome-resolved
metagenomic
analyses
(326
good-quality
MAGs)
suggested
that
system
required
syntrophic
metabolic
interactions
between
bacterial
archaeal
current
results
highlight
significance
ammonium-stimulated
driving
mobilization,
is
underestimated
groundwater.