Environmental Science & Technology Letters,
Journal Year:
2024,
Volume and Issue:
11(11), P. 1214 - 1219
Published: Nov. 3, 2024
Biomass
burning
(BB)
is
a
major
source
of
aerosols
and
black
carbon,
thereby
exerting
an
important
impact
on
climate
air
quality.
Levoglucosan
the
most
well-recognized
organic
marker
compound
BB
has
been
used
to
quantitatively
assess
BB's
contribution
ambient
aerosols.
However,
little
known
about
levoglucosan's
evaporation
under
atmospheric
conditions,
primarily
due
uncertainty
its
effective
saturation
vapor
concentration
(
Chemical Society Reviews,
Journal Year:
2025,
Volume and Issue:
unknown
Published: Jan. 1, 2025
The
light-absorbing
chemical
components
of
atmospheric
organic
aerosols
are
commonly
referred
to
as
Brown
Carbon
(BrC),
reflecting
the
characteristic
yellowish
brown
appearance
aerosol.
Biomass
burning
organic
aerosol
(BBOA),
containing
brown
carbon
chromophores,
plays
a
critical
role
in
atmospheric
chemistry
and
climate
forcing.
However,
the
effects
of
evaporation
on
BBOA
volatility
viscosity
under
different
environmental
conditions
remain
poorly
understood.
This
study
focuses
molecular
characterization
laboratory-generated
proxies
from
wood
pyrolysis
emissions.
The
initial
mixture,
"pyrolysis
oil
(PO
ACS ES&T Air,
Journal Year:
2025,
Volume and Issue:
2(3), P. 406 - 415
Published: Feb. 27, 2025
Brown
carbon
(BrC)
components
of
biomass
burning
organic
aerosol
(BBOA)
absorb
sunlight
at
visible
wavelengths.
However,
it
is
not
clear
whether
the
total
light
absorption
this
BrC
simply
sum
contributions
individual
or
can
bind
noncovalently
to
give
additional
through
charge
transfer.
Here,
intermolecular
interactions
between
guaiacol
and
quinones
(1,4-benzoquinone
1,4-naphthoquinone)
were
identified
in
proxies
nonpolar,
water-insoluble
phase
BBOA,
using
UV-vis
spectroscopy.
Guaiacol
its
derivatives
are
some
most
abundant
emissions
smoldering
coniferous
species.
Enhanced
occurred
instantaneously
upon
mixing
colorless
with
either
quinone
n-heptane
did
increase
time,
contrast
absorbance
changes
that
would
be
expected
for
a
covalent
product.
This
enhancement
decreased
by
about
25%
as
temperature
increased
from
303
323
K,
consistent
exothermic
association
complexes,
yielding
enthalpies
complexation
-13.3
±
0.6
-12.3
0.4
kJ
mol-1
benzoquinone
naphthoquinone,
respectively.
Enhancement
was
also
observed
gas-liquid
partitioning
into
thin
films
guaiacol,
example,
thickness
20
μm.
multiphase
processing,
mimicking
liquid
produced
comparable
moderately
absorbing
other
sources,
suggestive
atmospheric
relevance
these
interactions.
Environmental Science & Technology,
Journal Year:
2024,
Volume and Issue:
58(49), P. 21702 - 21715
Published: Nov. 27, 2024
Biomass
burning
events,
including
wildfires,
can
emit
large
amounts
of
phenolic
compounds
such
as
guaiacol.
These
undergo
oxidation
by
nitrate
radicals
(NO
ACS ES&T Air,
Journal Year:
2025,
Volume and Issue:
unknown
Published: March 31, 2025
Biomass
burning
is
one
of
the
most
significant
sources
organic
aerosol
in
atmosphere.
(BBOA)
has
been
observed
to
undergo
liquid–liquid
phase
separation
(LLPS)
give
core–shell
morphology
with
hydrophobic
encapsulating
hydrophilic
phase,
potentially
impacting
evolution
light-absorbing
components,
i.e.,
brown
carbon
(BrC),
through
multiphase
processes.
Here,
we
demonstrate
how
processing
differs
between
water-soluble
(i.e.,
hydrophilic)
and
insoluble
hydrophobic)
phases
BBOA
terms
reactive
uptake
ozone
a
coated-wall
flow
tube.
Effects
relative
humidity
(RH)
ultraviolet
(UV)
irradiation
were
investigated.
Experimental
timeseries
used
inform
simulations
using
multilayer
kinetic
modeling.
Among
non-irradiated
thin
films,
coefficient
was
greatest
for
at
75%
RH
(3
×
10–5,
corresponding
diffusion
BrC,
DBrC,
3
10–9
cm2
s–1)
least
same
0%
(1
DBrC
1
10–10
s–1).
The
water-insoluble
fell
these
two
(about
1.5
10–5),
regardless
RH,
increased
only
slightly
(8
s–1
9
RH).
coefficients
both
decreased
significantly
after
UV
irradiation,
consistent
transition
from
viscous
liquid
solid
supported
by
qualitative
microscopy
observations.
Modeling
oxidation
primary
BrC
components
atmosphere
demonstrated,
first,
that
LLPS
may
extend
lifetime
encapsulated
species
factor
moderate
high
and,
also,
more
than
2.5.
Understanding
the
viscosity
and
phase
state
of
biomass-burning
organic
aerosol
(BBOA)
from
wildfires
pyrocumulonimbus
(pyroCb)
events
in
stratosphere
is
critical
for
predicting
their
role
stratospheric
multiphase
chemistry
ozone
depletion.
However,
BBOA
under
conditions,
including
interactions
with
sulfuric
acid
(H2SO4),
remain
largely
unquantified.
In
this
study,
we
combine
laboratory
data
a
thermodynamic
model
to
predict
conditions.
Our
results
suggest
that
H2SO4-to-BBOA
mass
ratio
0.37─an
estimated
upper
limit
pyroCb
smoke
lower
after
two
months
aging─is
highly
viscous
frequently
exists
glassy
state.
Even
at
higher
0.79─an
nine
aging─BBOA
can
still
transition
certain
state,
bulk
reactions
are
suppressed,
may
be
limited
particle
surfaces.
We
also
highlight
key
areas
future
research
needed
better
constrain
its
subsequent
impact
on
ozone.
Biomass
burning
organic
aerosol
(BBOA)
is
a
major
contributor
to
in
the
atmosphere.
The
impacts
of
BBOA
on
climate
and
health
depend
strongly
their
physicochemical
properties,
including
viscosity
phase
behaviour
(number
types
phases);
these
relationships
chemistry,
are
not
yet
fully
characterized.
We
collected
field
samples
during
2021
British
Columbia
wildfire
season
constrain
at
range
relative
humidities,
compared
them
laboratory
generated
made
from
smoldering
pine
wood.
Particles
all
exhibited
two-phased
with
higher
polarity
hydrophilic
core
lower
hydrophobic
shell.
used
poke-flow
technique
estimate
particles.
found
that
both
phases
had
viscosities
>10
8
Pa
s
humidities
up
50%,
which
more
viscous
than
any
or
proxies
previously
measured.
Aerosol
mass
spectrometry
showed
were
oxidized
those
lab,
likely
explanation
for
viscosity.
two
high
have
implications
how
should
be
treated
atmospheric
models
