bioRxiv (Cold Spring Harbor Laboratory),
Journal Year:
2023,
Volume and Issue:
unknown
Published: June 13, 2023
ABSTRACT
Groundwater
biogeochemistry
in
coastal
areas
is
spatially
and
temporally
dynamic
because
fluctuations
groundwater
level
may
cause
alternate
redox
between
distinct
hydrological
conditions.
Recent
studies
have
proposed
connections
large-scale
processes,
specifically
focusing
on
the
role
of
redox-active
compounds
changing
oxidation
state
during
flooding
draining
events.
While
water
saturation
generally
results
a
shift
from
electron
donors
to
acceptors,
specific
mechanisms
underlying
transition
oxidizing
reducing
conditions
response
are
uncertain.
To
determine
effects
levels
dynamics,
we
monitored
potential
across
terrestrial-aquatic
interface
Lake
Erie
throughout
high
low-water
seasons.
In
contrast
previously
observed
responses
soils,
our
revealed
patterns
potentials
high-water
periods.
Furthermore,
short-term
table
significantly
impacted
when
dissolved
oxygen
increased,
dynamics
displayed
voltage
hysteresis
most
Based
these
findings,
propose
that
for
improved
predictions
microbial
functions
biogeochemical
cycles,
redox-informed
models
should
incorporate
antagonistic
changes
balance
compared
soils
consider
time
lags
fluctuations.
Graphical
Abstract
Conceptual
diagram
ecosystems.
Large
derived
by
inputs
smaller
more
frequent
led
sensitive
species
leaching
topsoil.
Environmental Science & Technology,
Journal Year:
2024,
Volume and Issue:
58(5), P. 2185 - 2203
Published: Jan. 18, 2024
The
groundwater
table
fluctuation
(GTF)
zone
is
an
important
medium
for
the
hydrologic
cycle
between
unsaturated
soil
and
saturated
aquifers,
which
accelerates
migration,
transformation,
redistribution
of
contaminants
further
poses
a
potential
environmental
risk
to
humans.
In
this
review,
we
clarify
key
processes
in
generation
GTF
examine
its
links
with
variation
hydrodynamic
hydrochemistry
field,
colloid
mobilization,
contaminant
migration
transformation.
Driven
by
recharge
discharge,
regulates
water
flow
movement
capillary
fringe,
control
advection
dispersion
groundwater.
addition,
formation
reactive
oxygen
species
(ROS)
waterfall
are
impacted
GTF.
changing
ROS
components
partially
determine
characteristic
transformation
solutes
dynamic
microbial
population.
facilitates
(such
as
nitrogen,
heavy
metals,
non-aqueous
phase
liquids,
volatile
organic
compounds)
through
co-migration
effect,
fields.
conclusion,
review
illustrates
limitations
current
literature
on
GTF,
significance
zones
underground
environment
underscored
expounding
future
directions
prospects.
Previous
studies
along
the
banks
of
tidal
Meghna
River
Ganges-Brahmaputra-Meghna
Delta
demonstrated
active
sequestration
dissolved
arsenic
(As)
on
newly
formed
iron
oxide
minerals
(Fe(III)-oxides)
within
riverbank
sands.
The
sand
with
high
solid-phase
As
(>500
mg/kg)
was
located
intertidal
zone
where
robust
mixing
occurs
oxygen-rich
river
water.
Here
we
present
new
evidence
that
upwelling
groundwater
through
a
buried
silt
layer
generates
products
reductive
dissolution
Fe(III)-oxides,
including
As,
while
mobilization
DOC
by
prevents
their
reconstitution
in
lowering
redox
state.
A
three
end-member
conservative
model
between
above
layer,
and
An
electrochemical
mass
balance
confirmed
Fe(III)-oxides
were
primary
electron
acceptor
driving
oxidation
sourced
from
sediment
organic
carbon
silt.
Thus,
presence
an
intercalating
riverbanks
rivers
can
represent
biogeochemical
hotspot
release
preventing
its
retention
hyporheic
zone.
Frontiers in Environmental Science,
Journal Year:
2023,
Volume and Issue:
11
Published: July 7, 2023
Vernal
ponds
are
ephemeral
landscape
features
that
experience
intermittent
flooding
and
drying,
leading
to
variable
saturation
in
underlying
soils.
Redox
potential
(E
h
)
is
an
important
indicator
of
biogeochemical
processes
changes
response
these
hydrological
shifts;
however,
high-resolution
measurements
E
variably
inundated
environments
remain
sparse.
In
this
study,
the
responses
soil
ponding,
rewetting
a
vernal
pond
were
investigated
over
5-month
period
from
late
spring
through
early
autumn.
Soil
was
measured
at
10-min
frequencies
multiple
depths
(2–48
cm
below
surface)
shallow
deep
sections
within
seasonally
ponded
lowland
unsaturated
soils
surrounding
upland.
Over
study
period,
average
surface
(0–8
cm)
oxidizing
upland
(753
±
79
mV)
but
relatively
reducing
(369
49
(198
37
mV).
Reducing
conditions
<300
prevailed
for
up
6
days
24
after
water
dried
out.
Intermittent
reflooding
resulted
shifts
between
while
remained
following
reflooding.
uplands
consistently
with
transient
increases
rain
events.
greater
Fe-oxide
dissolution
release
dissolved
Fe
P
into
porewater
than
uplands.
We
determined
change
depth
alone
not
good
,
additional
factors
such
as
clay
composition
should
be
considered
when
predicting
how
responds
drying.
These
findings
highlight
spatial
temporal
variability
have
implications
ecosystem
function
impacted
by
hydrology
terrestrial-aquatic
interfaces.
