The Science of The Total Environment,
Journal Year:
2022,
Volume and Issue:
848, P. 157606 - 157606
Published: July 25, 2022
In
recent
years,
carbonaceous
aerosols
(CA)
have
been
recognized
as
a
significant
contributor
to
the
concentration
of
particles
smaller
than
2.5
μm
(i.e.,
PM2.5),
with
negative
impact
on
public
health
and
Earth's
radiative
balance.
this
study,
we
present
method
for
CA
apportionment
based
high-time-resolution
measurements
total
carbon
(TC),
black
(BC),
spectral
dependence
absorption
coefficient
using
recently
developed
Carbonaceous
Aerosol
Speciation
System
(CASS).
Two-year-long
at
two
different
locations
within
California's
Los
Angeles
Basin
are
presented.
was
apportioned
its
optical
properties,
organic
or
elemental
composition,
primary
secondary
origin.
We
found
that
(SOA),
average,
represent
>50
%
in
study
area,
presumably
resulting
from
oxidation
anthropogenic
biogenic
volatile
components.
Remarkable
peaks
SOA
summer
afternoons
were
observed,
fractional
contribution
up
90
%.
On
other
hand,
peak
emitted
CA,
consisting
BC
aerosol
(POA),
contributed
>80
during
morning
rush
hours
winter
working
days.
The
light
dominated
over
brown
(BrC),
which
20
10
lower
wavelength
370
nm
nights
afternoons,
respectively.
highest
BrC,
50
%,
observed
wildfire
periods.
Although
uncertainty
levels
can
be
high
some
components
(such
split
between
formed
BrC
nights),
further
research
focused
properties
may
help
better
constrain
parameters
used
studies.
believe
CASS
system
combined
presented
offer
simplified
cost-effective
insights
into
composition
aerosols.
ACS Earth and Space Chemistry,
Journal Year:
2021,
Volume and Issue:
5(4), P. 722 - 748
Published: April 5, 2021
Emitted
by
numerous
primary
sources
and
formed
secondary
sources,
atmospheric
brown
carbon
(BrC)
aerosol
is
chemically
complex.
As
BrC
ages
in
the
atmosphere
via
a
variety
of
chemical
physical
processes,
its
composition
optical
properties
change
significantly,
altering
impacts
on
climate.
Research
past
decade
has
considerably
expanded
our
understanding
reactions
both
gas
condensed
phases.
We
review
these
recent
advances
aging
chemistry
with
focus
phase
leading
to
formation,
aqueous
in-cloud
particle
reactions.
Connections
are
made
between
single
component
proxies
more
complex
mixtures
as
well
laboratory
field
measurements
chemistry.
General
conclusions
that
can
darken
particles
over
short
time
scales
hours
close
source
considerable
photobleaching
oxidative
whitening
will
occur
when
day
or
removed
from
source.
Nature Communications,
Journal Year:
2021,
Volume and Issue:
12(1)
Published: Jan. 12, 2021
Uncertainty
in
the
representation
of
biomass
burning
(BB)
aerosol
composition
and
optical
properties
climate
models
contributes
to
a
range
modeled
effects
on
incoming
solar
radiation.
Depending
model,
top-of-the-atmosphere
BB
effect
can
from
cooling
warming.
By
relating
absorption
relative
extinction
carbonaceous
12
observational
datasets
nine
state-of-the-art
Earth
system
models/chemical
transport
models,
we
identify
varying
degrees
overestimation
absorptivity
by
these
models.
Modifications
refractive
index,
size,
mixing
state
improve
Community
Atmosphere
Model
version
5
(CAM5)
agreement
with
observations,
leading
global
change
direct
radiative
-0.07
W
m-2,
regional
changes
-2
m-2
(Africa)
-0.5
(South
America/Temperate).
Our
findings
suggest
that
current
less
warming
than
previously
thought,
largely
due
treatments
state.
Environmental Science & Technology,
Journal Year:
2021,
Volume and Issue:
55(4), P. 2511 - 2521
Published: Jan. 27, 2021
This
study
provides
molecular
insights
into
the
light
absorption
properties
of
biomass
burning
(BB)
brown
carbon
(BrC)
through
chemical
characterization
tar
condensates
generated
from
heated
wood
pellets
at
oxidative
and
pyrolysis
conditions.
Both
liquid
separated
"darker
oily"
"lighter
aqueous"
immiscible
phases.
The
composition
these
samples
was
investigated
using
reversed-phase
chromatography
coupled
with
a
photodiode
array
detector
high-resolution
mass
spectrometer.
results
revealed
two
sets
BrC
chromophores:
(1)
common
to
all
four
(2)
specific
"oily"
fractions.
chromophores
consist
polar,
monoaromatic
species.
oil-specific
include
less-polar
nonpolar
polyaromatic
compounds.
most-light-absorbing
oily
phase
(PO)
aerosolized
size-separated
cascade
impactor
compare
optical
bulk
versus
BrC.
coefficient
(MAC300-500
nm)
PO
increased
compared
that
bulk,
due
gas-phase
partitioning
more
volatile
less
absorbing
chromophores.
were
consistent
previously
reported
ambient
BB
measurements.
These
suggest
darkening
atmospheric
following
non-reactive
evaporation
transforms
aged
aerosols.
Environmental Science & Technology,
Journal Year:
2022,
Volume and Issue:
56(6), P. 3340 - 3353
Published: March 1, 2022
We
investigate
the
chemical
composition
of
organic
light-absorbing
components,
also
known
as
brown
carbon
(BrC)
chromophores,
formed
in
a
proxy
anthropogenic
secondary
aerosol
generated
from
photooxidation
naphthalene
(naph-SOA)
absence
and
presence
NOx.
High-performance
liquid
chromatography
equipped
with
photodiode
array
detector
electrospray
ionization
high-resolution
mass
spectrometer
is
employed
to
characterize
naph-SOA
its
BrC
components.
provide
molecular-level
insights
into
optical
properties
individual
components
their
relevance.
This
work
reveals
formation
strongly
absorbing
nitro-aromatic
chromophores
under
high-NOx
conditions
describes
degradation
during
atmospheric
aging.
NOx
addition
enhanced
light
absorption
while
reducing
wavelength-dependence,
seen
by
coefficient
(MAC)
Ångström
exponent
(AAE).
Optical
parameters
low-
showed
range
values
MACOM
405nm
∼
0.12
m2
g–1
AAE300–450nm
8.87
(low-NOx)
0.19
7.59
(high-NOx),
consistent
"very
weak"
"weak"
classes,
respectively.
The
weak-BrC
class
commonly
attributed
biomass
smoldering
emissions,
which
appear
have
comparable
naph-SOA.
Molecular
contributing
were
identified
substantial
nitro-aromatics,
indicating
that
these
species
may
be
used
source-specific
markers
related
emissions.
Nature Geoscience,
Journal Year:
2023,
Volume and Issue:
16(8), P. 683 - 688
Published: Aug. 1, 2023
Wildfires
emit
large
amounts
of
black
carbon
and
light-absorbing
organic
carbon,
known
as
brown
into
the
atmosphere.
These
particles
perturb
Earth's
radiation
budget
through
absorption
incoming
shortwave
radiation.
It
is
generally
thought
that
loses
its
absorptivity
after
emission
in
atmosphere
due
to
sunlight-driven
photochemical
bleaching.
Consequently,
atmospheric
warming
effect
exerted
by
remains
highly
variable
poorly
represented
climate
models
compared
with
relatively
nonreactive
carbon.
Given
wildfires
are
predicted
increase
globally
coming
decades,
it
increasingly
important
quantify
these
radiative
impacts.
Here
we
present
measurements
ensemble-scale
particle-scale
smoke
plumes
from
western
United
States.
We
find
a
type
dark
contributes
three-quarters
short
visible
light
half
long
absorption.
This
strongly
absorbing
aerosol
species
water
insoluble,
resists
daytime
photobleaching
increases
night-time
processing.
Our
findings
suggest
parameterizations
need
be
revised
improve
estimation
forcing
associated
warming.
Environmental Science & Technology,
Journal Year:
2024,
Volume and Issue:
58(2), P. 1236 - 1243
Published: Jan. 3, 2024
Aqueous-phase
reactions
of
α-dicarbonyls
with
amines
or
ammonium
have
been
identified
as
important
sources
secondary
brown
carbon
(BrC).
However,
the
kinetics
BrC
formation
and
effects
pH
are
still
not
very
clear.
In
this
study,
by
aqueous
(glyoxal
methylglyoxal)
ammonium,
amino
acids,
alkylamines
in
bulk
solution
at
different
values
investigated.
Our
results
reveal
pH-parameterized
production
rate
constants,
kBrCII
(m–1
[M]−2
s–1),
based
on
light
absorption
between
300
500
nm:
log10(kBrCII)
=
(1.0
±
0.1)
×
–
(7.4
1.0)
for
glyoxal
(6.3
0.9)
methylglyoxal.
The
linear
slopes
closing
to
1.0
indicate
that
is
governed
nitrogen
nucleophilic
addition
pathway.
Consequently,
absorptivities
produced
increase
exponentially
pH.
from
methylglyoxal
higher
(≥6.5)
exhibits
optical
properties
comparable
biomass
burning
coal
combustion,
categorized
"weakly"
absorbing
BrC,
while
lower
(<6.0)
(pH
5.0–7.0)
falls
into
"very
weakly"
BrC.
pH-dependent
feature
significantly
affects
solar
ability
thus
atmospheric
photochemical
processes,
e.g.,
7.0
absorbs
14–16
times
more
power
compared
5.0,
which
turn
could
lead
a
decrease
1
order
magnitude
photolysis
constants
O3
NO2.
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.
Environmental Science & Technology,
Journal Year:
2021,
Volume and Issue:
55(5), P. 2878 - 2889
Published: Feb. 17, 2021
Nighttime
oxidation
of
biogenic
volatile
organic
compounds
(BVOCs)
by
nitrate
radicals
(NO3·)
represents
one
the
most
important
interactions
between
anthropogenic
and
natural
emissions,
leading
to
substantial
secondary
aerosol
(SOA)
formation.
The
direct
climatic
effect
such
SOA
cannot
be
quantified
because
its
optical
properties
atmospheric
fate
are
poorly
understood.
In
this
study,
we
generated
from
NO3·
a
series
BVOCs
including
isoprene,
monoterpenes,
sesquiterpenes.
were
subjected
comprehensive
online
offline
chemical
composition
analysis
using
high-resolution
mass
spectrometry
measurements
novel
broadband
(315–650
nm)
cavity-enhanced
spectrometer,
which
covers
wavelength
range
needed
understand
potential
contribution
radiative
forcing.
contained
significant
fraction
oxygenated
nitrates
(ONs),
consisting
monomers
oligomers
that
responsible
for
detected
light
absorption
in
315–400
nm
range.
created
β-pinene
α-humulene
was
further
photochemically
aged
an
flow
reactor.
has
photochemical
bleaching
lifetime
>6.2
h,
indicating
some
ONs
may
serve
as
atmosphere-stable
nitrogen
oxide
sinks
or
reservoirs
will
absorb
scatter
incoming
solar
radiation
during
daytime.
