Environmental Science & Technology,
Год журнала:
2025,
Номер
unknown
Опубликована: Апрель 4, 2025
Hypoxia
is
observed
and
projected
to
expand
in
many
aquatic
environments,
largely
due
excess
anthropogenic
nutrient
inputs
climate
change,
thus
influencing
biogeochemical
processes.
Denitrification,
generally
an
anaerobic
process,
removes
bioavailable
nitrogen
produces
nitrous
oxide
(N2O).
However,
limited
observations
of
the
effect
oxygen
on
denitrification
restrict
our
ability
estimate
changes
amount
N2O
emissions
under
perturbations
change.
Here,
we
show
that
all
steps
increased,
while
production
yield
from
decreased
with
decreasing
Chesapeake
Bay
-
largest
estuary
United
States.
The
different
responded
similarly
Bay,
unlike
open
ocean
minimum
zones,
implications
for
accumulation
or
depletion
intermediates
such
as
nitrite
N2O.
Our
also
suggest
current
model
parametrizations
likely
overestimate
removal
presence
oxygen,
which
would
bias
evaluation
cycling,
ecosystem
productivity,
extent
hypoxia.
Overall,
newly
derived
sensitivities
could
be
used
improve
constrain
budget
estuarine
coastal
environments
experiencing
Frontiers in Marine Science,
Год журнала:
2025,
Номер
12
Опубликована: Март 14, 2025
Coastal
eutrophication
has
become
a
persistent
environmental
crisis
around
world
driven
by
human
activities
and
climate
change.
Nowadays,
frequent
intense
tropical
typhoon
disturbances
strongly
affected
the
distribution
composition
of
nutrients
in
land-ocean
interface,
resulting
risk
coastal
water.
However,
mechanistic
links
between
land-based
sources
transport
have
not
been
well
understood
due
to
complex
processes.
In
this
study,
nutrient
concentration,
flux
three
estuaries
one
sewage
outlet
Zhanjiang
Bay
(ZJB)
were
analyzed.
Before
typhoon,
average
concentrations
dissolved
inorganic
nitrogen
(DIN),
phosphorus
(DIP)
silicate
(DSi)
source
ZJB
61.77
±
28.56
μmol/L,
6.79
4.61
113.26
64.52
respectively.
The
concentration
DIN
decreased
approximately
41.8%,
DIP
increased
46.2%,
DSi
1.7%
after
Typhoon
Kompasu
made
landfall.
At
same
time,
DIN/DIP
DIN/DSi
outlets
estuary
landfall
much
smaller
than
Redfield
ratio,
indicating
different
degrees
limitation.
addition,
significant
spatial
temporal
variations
fluxes
observed
before
typhoon.
total
input
DIN,
DIP,
outfall
9.98
×
10
4
mol/h,
1.38
9.78
contrast,
3.21
3
3.01
5.20
mol/h.
After
entering
sea
from
changed
significantly
compared
with
those
Moreover,
model
discharge
established,
which
can
estimate
based
on
field
investigation.
This
study
reveals
effects
event
into
semi-enclosed
ZJB,
provides
scientific
basis
for
further
research
impacts
typhoons
enrichment
waters,
as
deepening
understanding
ecosystem
under
Water Resources Research,
Год журнала:
2025,
Номер
61(3)
Опубликована: Март 1, 2025
Abstract
Phosphorus
fertilization
has
supported
remarkable
improvements
in
agricultural
productivity
but
also
degraded
water
quality.
Watershed
simulation
models
have
been
broadly
instrumental
to
crafting
phosphorus
management
responses.
However,
simulation‐based
studies
rely
on
predesigned
watershed
scenarios
(e.g.,
initial
conditions
and
actions)
are
blind
outcomes
that
might
only
emerge
from
unseen
scenarios.
Meanwhile,
efforts
restore
quality
routinely
failed.
In
contrast
methods,
here
we
implement
optimal
control
reachability
methods
describe
trajectories
for
any
condition
fertilizer
strategy.
The
trade‐off
is
these
new
require
simplification
of
the
system's
dynamics.
For
a
two‐pool
model,
define
dual
target
where
(a)
plant‐available
satisfies
crop
demand
(b)
total
losses
meet
goals.
From
this
target,
compute
backwards‐reachable
sets
indicate
minimum
time
which
can
be
reached
all
conditions.
typical
U.S.
corn
belt,
find
it
will
take
at
least
42
years
reach
joint
target.
We
show
(time‐minimizing)
rate
strategy
drives
roundabout
trajectory
toward
soil
violates
threshold
during
interim
time.
even
small,
short‐term
sacrifices
profoundly
hasten
progress
long‐term,
These
results
complement
traditional
provide
managers
with
richer
characterization
uncertainty
options.
Environmental Science & Technology,
Год журнала:
2025,
Номер
unknown
Опубликована: Апрель 4, 2025
Hypoxia
is
observed
and
projected
to
expand
in
many
aquatic
environments,
largely
due
excess
anthropogenic
nutrient
inputs
climate
change,
thus
influencing
biogeochemical
processes.
Denitrification,
generally
an
anaerobic
process,
removes
bioavailable
nitrogen
produces
nitrous
oxide
(N2O).
However,
limited
observations
of
the
effect
oxygen
on
denitrification
restrict
our
ability
estimate
changes
amount
N2O
emissions
under
perturbations
change.
Here,
we
show
that
all
steps
increased,
while
production
yield
from
decreased
with
decreasing
Chesapeake
Bay
-
largest
estuary
United
States.
The
different
responded
similarly
Bay,
unlike
open
ocean
minimum
zones,
implications
for
accumulation
or
depletion
intermediates
such
as
nitrite
N2O.
Our
also
suggest
current
model
parametrizations
likely
overestimate
removal
presence
oxygen,
which
would
bias
evaluation
cycling,
ecosystem
productivity,
extent
hypoxia.
Overall,
newly
derived
sensitivities
could
be
used
improve
constrain
budget
estuarine
coastal
environments
experiencing
