Vadose Zone Journal,
Год журнала:
2022,
Номер
22(1)
Опубликована: Ноя. 17, 2022
Abstract
Biogeochemical
gas
production
resulting
in
free
phase
formation
can
severely
affect
groundwater
and
solute
transport
aquifers.
Such
gas–water
interactions
are
important
aquifers
affected
by
geogenic
As,
which
commonly
associated
with
biogeochemical
CH
4
production.
Additionally,
the
influence
of
aquitards
on
As
concentrations
contaminated
has
recently
been
challenged.
These
observations
prompted
analysis
through
a
heterogeneous
aquitard
overlying
high
−gas‐producing
zone
an
As‐contaminated
aquifer.
A
sediment
core
taken
was
analyzed
for
noble
gases
to
assess
how
physically
contributes
underlying
Results
reveal
that
pore
space
is
unsaturated
two
separate
layers
hanging
water
constrained
air‐like
phase.
This
interlayering
saturated
zones
identifies
aquitard's
stratigraphy
as
key
determining
hydrostatic
pressure—a
main
control
(i.e.,
)
The
partly
conditions
reduce
pressure
30%
compared
fully
conditions.
To
our
knowledge,
this
first
study
applying
examine
physical
state
Further,
such
low
conductivity
might
provide
preferential
pathways
periodic
flow,
fostering
aquitard–aquifer
transport.
Groundwater
samples
additionally
collected
throughout
site
confirm
more
widespread
degassing
than
previously
reported.
Up
90%
expected
atmospheric
lost
from
immediately
below
investigated
core.
Journal of Contaminant Hydrology,
Год журнала:
2022,
Номер
249, С. 104043 - 104043
Опубликована: Июнь 21, 2022
Groundwater
security
is
a
pressing
environmental
and
societal
issue,
particularly
due
to
significantly
increasing
stressors
on
water
resources,
including
rapid
urbanization
climate
change.
arsenic
major
public
health
challenge
impacting
millions
of
people
in
the
Gangetic
Basin
India
elsewhere
globally.
In
rapidly
developing
city
Patna
(Bihar)
northern
India,
we
have
studied
evolution
groundwater
chemistry
under
following
three-dimensional
sampling
framework
multi-depth
wells
spanning
central
urban
zone
close
proximity
River
Ganges
(Ganga)
transition
into
peri-urban
rural
areas
outside
boundaries
further
away
from
river.
Using
inorganic
geochemical
tracers
(including
arsenic,
iron,
manganese,
nitrate,
nitrite,
ammonium,
sulfate,
sulfide
others)
residence
time
indicators
(CFCs
SF6),
evaluated
dominant
hydrogeochemical
processes
occurring
spatial
patterns
redox
conditions
across
study
area.
The
distribution
other
redox-sensitive
parameters
spatially
heterogenous,
elevated
some
locations
consistent
with
mobilization
via
reductive
dissolution
iron
hydroxides.
Residence
evidence
modern
(<~60-70
years)
suggest
important
vertical
lateral
flow
controls
area,
an
apparent
seasonal
reversal
regimes
near
center.
An
overall
accumulation
rate
estimated
be
~0.003
±
0.003
μM.yr-1
(equivalent
~0.3
0.2
μg.yr-1),
based
average
CFC-11,
CFC-12
SF6-derived
models,
highest
rates
observed
shallow,
near-river
groundwaters
also
exhibiting
concentrations
nutrients
ammonium.
Our
findings
implications
management
cities,
potential
future
increased
vulnerability
associated
surface-derived
ingress
large-scale
abstraction
or
higher
permeability
zones
river-groundwater
connectivity.
Journal of Geophysical Research Biogeosciences,
Год журнала:
2022,
Номер
127(8)
Опубликована: Авг. 1, 2022
Abstract
Enrichment
mechanisms
of
high‐arsenic
(>10
μg/L)
groundwater
in
confined
aquifers
with
sand‐gravel
sediments
were
rarely
documented.
Both
and
sediment
sampled
to
investigate
arsenic
mobility
from
the
Songnen
Basin,
China.
The
results
show
that,
although
high
was
present
both
shallow
sandy
(<60
m)
deep
(60–100
m),
relatively
higher
hosted
aquifers.
significantly
proportion
biologically
degradable
organic
carbon
(BDOC)
than
those
unconfined
ones
(
p
=
0.03)
suggests
that
concentrations
associated
DOM
biodegradability.
High‐arsenic
result
Fe(III)
oxide
reduction
facilitated
by
BDOC
degradation.
Arsenic‐rich
pyrite
framboids
observed
aquifers,
which
would
lower
concentrations.
Sand‐gravel
had
remarkably
contents
extracted
oxides
bound
arsenic,
HCl‐extractable
Fe(II)
minerals,
adsorbed
but
considerably
Mn
Mn(II)
minerals
sediments.
Siderite,
is
not
as
efficient
sequestering
dominant
mineral
aquifer.
In
aquifer,
almost
completed
predominated,
resulted
due
arsenic/iron
molar
ratio
oxides.
This
study
proposed
geogenic
can
occur
being
oxide‐bound
poor
under
reducing
conditions.
Water Research,
Год журнала:
2022,
Номер
214, С. 118199 - 118199
Опубликована: Фев. 15, 2022
Groundwater
contamination
of
geogenic
arsenic
(As)
remains
a
global
health
threat,
particularly
in
south-east
Asia.
The
prominent
correlation
often
observed
between
high
As
concentrations
and
methane
(CH4)
stimulated
the
analysis
gas
dynamics
an
contaminated
aquifer,
whereby
noble
reactive
gases
were
analysed.
Results
show
progressive
depletion
atmospheric
(Ar,
Kr
N2)
alongside
highly
increasing
CH4,
implying
that
free
phase
comprised
mainly
CH4
is
formed
within
aquifer.
In
contrast,
Helium
(He)
are
(gas)
producing
zone,
suggesting
longer
(groundwater)
residence
times.
We
hypothesized
severely
detracts
local
groundwater
(flow)
significantly
reduces
water
renewal
zone.
in-line
with
this
hypothesis,
however,
second
hypothesis
has
been
developed,
which
focuses
on
potential
transport
He
from
adjacent
aquitard
into
This
was
formulated
as
it
resolves
observed,
since
external
solute
input
overlying
heterogeneous
cannot
be
excluded.
proposed
feedback
hydraulics
provides
plausible
explanation
anti-intuitive
spatially
patchy
distribution
dissolved
aquifers.
Furthermore,
increased
time
would
allow
for
dissolution
more
crystalline
As-hosting
iron(Fe)-oxide
phases
conjunction
formation
stable
secondary
Fe
minerals
hydraulically-slowed
(i.e.,
producing)
zone;
subject
calls
further
investigation.
ACS Earth and Space Chemistry,
Год журнала:
2021,
Номер
5(6), С. 1278 - 1287
Опубликована: Июнь 3, 2021
We
integrated
microscopy,
spectroscopy,
culturing
and
molecular
biology,
aqueous
chemistry
techniques
to
evaluate
arsenic
(As)
accumulation
in
hydroponically
grown
Schizachyrium
scoparium
inoculated
with
endophytic
fungi.
grows
historically
contaminated
sediment
the
Cheyenne
River
Watershed
was
used
for
laboratory
experiments
As(V)
ranging
from
0
2.5
mg
L–1
at
circumneutral
pH.
Arsenic
regional
plants
has
been
a
community
concern
several
decades,
yet
mechanisms
affecting
As
associated
fungi
remain
poorly
understood.
Colonization
of
roots
by
supported
better
external
vascular
cellular
structure,
increased
biomass
production,
root
lengths
P
uptake,
compared
noninoculated
(p
value
<0.05).
After
exposure
As(V),
an
80%
decrease
detected
solution
accumulated
mainly
(0.82–13.44
kg–1)
plants.
Endophytic
mediated
intracellular
uptake
into
cells
translocation
As.
Electron
microprobe
X-ray
mapping
analyses
Ca–P
Mg–P
minerals
on
surface
exposed
plants,
suggesting
that
these
could
lead
adsorption
through
complexation
or
coprecipitation.
Our
findings
provide
new
insights
regarding
biological
physical–chemical
processes
risk
assessment
applications
bioremediation
strategies.
Geochemistry Exploration Environment Analysis,
Год журнала:
2022,
Номер
22(4)
Опубликована: Ноя. 15, 2022
Understanding
the
process
and
influencing
factors
of
oxidation
pyrite
is
beneficial
for
management
environmental
problems
in
mining
areas.
In
this
study,
we
investigated
morphology
geochemistry
related
goethite
from
weathering
crust
Shangmanggang
(SMG)
gold
deposit,
SW
China,
via
petrographic
work,
electron
microprobe
analysis,
X-ray
diffraction
PHREEQC
geochemical
modelling.
The
profile
SMG
composed
unweathered
Carlin-type
zone,
semi-weathered
highly
weathered
red-clay
different
types
pyrite,
framboidal
(Py1),
cube
(Py2)
zoned
(Py3),
were
differentially
oxidized
transferred
into
corresponding
pyrite–pseudomorphic
commonly
comprised
early
late
phase.
Furthermore,
stronger
to
more
with
Al
Si
content.
ubiquitous
dolomite
buffer
kept
pH
pore
fluid
neutral,
resulting
precipitation
accumulation
a
coating
around
which
further
reduced
rate
formed
ultimately
coupled
dissolution–reprecipitation
reactions.
addition,
mineralogical
properties
resulted
differential
such
that
smaller
grains
faster,
As
within
accelerated
oxidation.
Moreover,
rate-limited
under
carbonate
prevents
acid
mine
drainage
forming
limits
release
arsenian
external
environment.
Supplementary
material:
Supplement
1,
EMPA
data
SMG;
2,
size
3,
code
are
available
at
https://doi.org/10.6084/m9.figshare.c.6267700
Vadose Zone Journal,
Год журнала:
2022,
Номер
22(1)
Опубликована: Ноя. 17, 2022
Abstract
Biogeochemical
gas
production
resulting
in
free
phase
formation
can
severely
affect
groundwater
and
solute
transport
aquifers.
Such
gas–water
interactions
are
important
aquifers
affected
by
geogenic
As,
which
commonly
associated
with
biogeochemical
CH
4
production.
Additionally,
the
influence
of
aquitards
on
As
concentrations
contaminated
has
recently
been
challenged.
These
observations
prompted
analysis
through
a
heterogeneous
aquitard
overlying
high
−gas‐producing
zone
an
As‐contaminated
aquifer.
A
sediment
core
taken
was
analyzed
for
noble
gases
to
assess
how
physically
contributes
underlying
Results
reveal
that
pore
space
is
unsaturated
two
separate
layers
hanging
water
constrained
air‐like
phase.
This
interlayering
saturated
zones
identifies
aquitard's
stratigraphy
as
key
determining
hydrostatic
pressure—a
main
control
(i.e.,
)
The
partly
conditions
reduce
pressure
30%
compared
fully
conditions.
To
our
knowledge,
this
first
study
applying
examine
physical
state
Further,
such
low
conductivity
might
provide
preferential
pathways
periodic
flow,
fostering
aquitard–aquifer
transport.
Groundwater
samples
additionally
collected
throughout
site
confirm
more
widespread
degassing
than
previously
reported.
Up
90%
expected
atmospheric
lost
from
immediately
below
investigated
core.
