Abstract.
This
study
investigated
the
potential
effects
of
inorganics
changes
on
aerosol
water
uptake
and
thus
secondary
organic
(SOA)
formation
in
wintertime
haze,
based
size-resolved
measurements
non-refractory
fine
particulate
matter
(NR-PM2.5)
Xi’an,
Northwest
China.
The
composition
inorganic
showed
significant
winter
2018–2019
compared
to
2013–2014,
shifting
from
a
sulfate-rich
nitrate-rich
profile.
In
particular,
fraction
sulfate
chloride
decreased
but
nitrate
increased
entire
size
range,
while
ammonium
mainly
at
larger
particle
sizes.
These
resulted
size-dependent
evolution
uptake.
Increased
was
observed
most
cases
associated
with
enhanced
contributions
both
ammonium,
highest
increase
ratio
reaching
5–35
%
sizes
higher
relative-humidity
(RH).
non-negligible
influence
also
emphasized.
random
forest
analysis
coupled
Shapley
additive
explanation
algorithm
(SHAP)
further
relative
importance
impacting
SOA
formation.
Aerosol
contributed
2018–2019,
SHAP
value
as
increased,
especially
implies
majority
high
RH
might
facilitate
efficient
aqueous-phase
highlights
key
role
medium
link
organics
their
multiphase
processes.
As
challenges
improve
China's
air
quality
remain
plays
an
increasing
haze
pollution,
these
results
provide
insight
into
characteristics
offer
guidance
for
future
control.
Environmental Science & Technology,
Journal Year:
2023,
Volume and Issue:
57(30), P. 11163 - 11172
Published: July 5, 2023
Optical
characteristics
and
molecular
compositions
of
brown
carbon
(BrC)
were
investigated
during
winter
2019
at
a
rural
site
China
with
focus
on
nitro-aromatic
compounds
(NACs)
imidazoles
(IMs).
The
abundance
gaseous
nitrophenols
relative
to
CO
the
campaign
maximized
noontime,
being
similar
O3,
while
particulate
NACs
haze
periods
strongly
correlated
toluene
NO2,
suggesting
that
in
region
are
largely
formed
from
gas-phase
photooxidation.
Strong
correlations
IMs
dry
mass
ratio
EC/PM2.5
concentration
levoglucosan
observed,
indicating
events
derived
biomass
burning
emissions.
However,
an
increase
increasing
aerosol
liquid
water
content
pH
was
observed
humid
events,
along
much
lower
abundances
K+
PM2.5,
mostly
aqueous
reactions
periods.
These
exponentially
increased
NH3
owing
reaction
carbonyls
free
ammonia.
Our
findings
for
first
time
revealed
enhancing
effect
ammonia
BrC
formation
China,
especially
npj Climate and Atmospheric Science,
Journal Year:
2024,
Volume and Issue:
7(1)
Published: Aug. 30, 2024
Abstract
Aerosol
hygroscopic
behavior
plays
a
central
role
in
determining
climate
effects
and
environmental
influence
of
atmospheric
particulates.
Water-soluble
organic
acids
(WSOAs)
constitute
significant
fraction
aerosols.
These
have
complex
impact
on
aerosol
hygroscopicity
due
to
their
physical
chemical
interactions
with
inorganic
salts.
The
mixing
WSOAs
salts
exerts
multiple
the
growth
phase
behaviors
particles,
largely
depending
composition
ratio,
acid
properties,
particle
size
between
components.
play
critical
water
uptake
characteristics
especially
low
moderate
RH
ranges.
previous
studies
reveal
occurrence
chemistry
related
chloride/nitrate/ammonium
depletions
droplets
containing
potential
recycling
HCl/HNO
3
/NH
depletion
may
contribute
budget
reactive
gases.
A
fundamental
understanding
for
inorganic–WSOA
systems
is
essential
accurate
parameterization
models.
However,
there
still
lack
comprehensive
internally
mixed
systems.
present
review
comprehensively
summarizes
impacts
changes
atmospherically
relevant
particles
under
subsaturated
conditions,
overviews
recent
advances
process
Atmosphere,
Journal Year:
2025,
Volume and Issue:
16(1), P. 98 - 98
Published: Jan. 17, 2025
Oxalic
acid
is
the
most
abundant
low-molecular-weight
dicarboxylic
in
atmosphere,
and
it
plays
a
crucial
role
formation
of
new
particles
cloud
condensation
nuclei.
However,
observational
studies
have
focused
on
particulate
oxalate,
leaving
significant
knowledge
gap
oxalic
vapor.
This
study
investigated
concentrations
vapor
oxalate
PM2.5
at
rural
tropical
coastal
island
site
south
China
across
different
seasons,
based
semi-continuous
measurements
using
an
Ambient
Ion
Monitor-Ion
Chromatograph
(AIM-IC)
system.
We
replaced
default
25
μL
sampling
loop
AIM-IC
with
250
loop,
improving
ability
to
distinguish
signal
from
noise.
The
data
revealed
clear
seasonal
patterns
dependent
daytime
nighttime
vapor,
benefiting
high
signal-to-noise
ratios.
Specifically,
were
0.059
±
0.15
μg
m−3
February
April
2023,
exhibiting
consistent
diurnal
variations
similar
those
O3,
likely
driven
by
photochemical
reactions.
These
values
decreased
0.021
0.07
November
December
higher
related
dark
chemistry
processes,
amplified
accumulation
due
low
mixing
layer
height.
comparable
but
exhibited
(3–7)-day
variations,
superimposed
fluctuations
varying
degrees.
Additionally,
thermodynamic
equilibrium
calculations
performed
data,
independent
size
distributions
upwind
marine
atmosphere
analyzed
support
findings.
Atmospheric chemistry and physics,
Journal Year:
2024,
Volume and Issue:
24(16), P. 9263 - 9275
Published: Aug. 26, 2024
Abstract.
An
enhanced
formation
of
brown
carbon
(BrC)
with
a
non-negligible
warming
effect
at
the
tropopause
has
recently
been
found.
However,
its
mechanism
is
unclear.
Here,
we
report
on
BrC
process
that
happens
during
air
mass
upward
transport
by
conducting
simultaneous
measurements
atmospheric
4
h
time
resolution
mountain
foot
(MF,
400
m
a.s.l.)
and
mountainside
(MS,
1120
Mt.
Hua,
China,
in
2016
summer.
Our
results
showed
daytime
light
absorption
(abs365
nm)
MS
approximately
60
%
lower
than
MF
due
to
dilution
caused
planetary
boundary
layer
expansion,
but
relative
black
about
30
higher
MF,
suggesting
significant
secondary
lifting
from
MS.
Such
accounted
for
>
50
only
27
MF.
Moreover,
N:C
elemental
ratio
was
15
mainly
an
aerosol
aqueous-phase
water-soluble
organic
nitrogen
(WSON)
compounds.
Stable
isotope
composition
further
indicated
such
light-absorbing
WSON
compounds
were
produced
reaction
carbonyls
NH4+.
work
revealed,
first
time,
ammonia-induced
aqueous
reactions
can
significantly
promote
process,
which
probably
responsible
upper
layer.
