Storm
events
can
mobilize
nitrogen
species
from
landscapes
into
streams,
exacerbating
eutrophication
and
threatening
aquatic
ecosystems
as
well
human
health.
However,
the
transport
pathways
storm
responses
of
different
forms
remain
elusive.
We
used
high-frequency
chemical
isotopic
sampling
to
partition
sources
stormwater
runoff
determine
multiple
in
an
agricultural
catchment.
Bayesian
mixing
modeling
reveals
shallow
subsurface
water
dominant
source
runoff,
contributing
74%
flux
72,
71,
79%
total
(TN),
dissolved
(TDN),
nitrate
(NO
Water Resources Research,
Journal Year:
2025,
Volume and Issue:
61(3)
Published: March 1, 2025
Abstract
Hydrologic
regimes
are
affecting
terrestrial
carbon
transformation,
chemical
weathering
and
lateral
transport.
However,
its
impacts
on
dissolved
export
patterns
remains
elusive.
In
this
study,
we
collected
a
2‐year
high‐frequency
inorganic
(DIC)
organic
(DOC)
dataset,
namely
wet
year
(Rainfall
=
1,158
mm)
dry
603
mm).
The
results
showed
that
drought
led
to
significant
decrease
in
concentration
discharge
during
the
monitoring
period.
During
non‐storm
periods,
DIC
DOC
shifted
from
dilution
chemostatic
enrichment
years,
respectively.
were
reversed
storm
periods.
dominated
by
chemostatic,
respectively,
while
both
year.
Structural
equation
models
revealed
aridity
index
temperature
may
affect
patterns.
We
further
classified
events
into
three
major
types
conceptualized
catchment‐scale
transport
mechanisms
for
carbon.
Dry‐AMCs
result
behavior,
whereas
Wet‐AMCs
behavior
due
increased
hydrological
connectivity.
third
type
corresponds
extreme
events,
where
larger
overland
flow
often
but
behavior.
These
findings
reveal
predominant
role
of
altering
decreasing
concentrations
fluxes
modifying
Water Resources Research,
Journal Year:
2025,
Volume and Issue:
61(3)
Published: March 1, 2025
Abstract
Northern
temperate
forests
are
experiencing
changes
from
climate
and
acidification
recovery
that
influence
catchment
nitrate‐nitrogen
(N)
flushing
behavior.
N
behavior
is
characterized
by
metrics
such
as:
(a)
time—the
exponential
decrease
in
stream
concentration
during
the
peak
snowmelt
episode;
(b)
(C)
discharge
(Q)
hysteresis
metrics—flushing
index
(FI)
(HI)—representing
slope,
direction,
amplitude
of
C‐Q
loop.
We
hypothesized
climate‐driven
hydrologic
intensification
results
longer
times,
lower
FI
(less
to
more
diluting),
HI
proximal
distal
sources).
tested
this
hypothesis
using
four
decades
data
two
headwater
catchments.
Hydrologic
was
estimated
ratio
potential
evapotranspiration
precipitation
actual
precipitation.
From
1982
2005,
a
period
decline
atmospheric
acidic
deposition,
we
observed
C
Q.
This
led
stable
patterns
reflected
(positive
FI)
sources
HI).
However,
2006
2019,
de‐intensification
coupled
with
an
ongoing
deposition
associated
continued
but
increase
Q,
leading
unstable
shift
HI)
toward
(negative
instability
less
variable
large
wetland,
indicating
wetlands
buffer
against
changing
conditions.
