Environmental Science & Technology,
Journal Year:
2019,
Volume and Issue:
53(21), P. 12389 - 12397
Published: Sept. 25, 2019
The
light-absorbing
properties
of
atmospheric
brown
carbon
(BrC)
are
poorly
understood
due
to
its
complex
chemical
composition.
Here,
a
black-carbon-tracer
method
was
coupled
with
source
apportionments
organic
aerosol
(OA)
explore
the
primary
and
secondary
BrC
from
North
China
Plain
(NCP).
Primary
emissions
contributed
more
OA
light
absorption
than
processes,
biomass
burning
accounted
for
60%
at
λ
=
370
nm,
followed
by
coal
combustion
(35%)
hydrocarbon-like
(5%).
Secondary
high
in
early
morning
later
decreased
bleaching
chromophores.
Nighttime
aqueous-phase
chemistry
promoted
formation
compounds
production
strongly
absorbing
particles.
Source
analysis
showed
that
NCP
region
most
important
subtypes
study
site.
mean
direct
radiative
forcing
0.15
W
m-2
(0.11
0.04
fractions,
respectively).
This
provides
new
information
on
optical
highlights
importance
oxidation
absorption.
Environmental Science & Technology,
Journal Year:
2019,
Volume and Issue:
53(24), P. 14222 - 14232
Published: Nov. 13, 2019
To
elucidate
the
influence
of
long-range
transported
biomass
burning
organic
aerosols
(BBOA)
on
Tibetan
Plateau,
molecular
compositions
and
light
absorption
HUmic-Like
Substances
(HULIS),
major
fractions
brown
carbon,
were
characterized
during
premonsoon
season.
Under
significant
burning,
HULIS
concentrations
increased
to
as
high
26
times
background
levels,
accounting
for
54%
water-soluble
carbon
(WSOC)
50%
(OC).
The
also
enhanced
up
42
contributing
61%
WSOC
OC
absorption.
Meanwhile,
elevated
nitrogen-containing
compounds
(NOCs)
among
observed.
NOCs
from
fresh
aged
BBOA
unambiguously
identified
level,
through
comparing
with
lab-controlled
field
experiments.
N-Heterocyclic
bases
represent
in
reduced
nitrogen
BBOA,
nitroaromatic
are
important
groups
oxidized
BBOA.
compounds,
including
nitroaromatics
N-heterocyclic
chromophores,
which
contributed
extracted
burning-influenced
periods.
Environmental Science & Technology,
Journal Year:
2021,
Volume and Issue:
55(15), P. 10268 - 10279
Published: July 21, 2021
The
light-absorbing
organic
aerosol
referred
to
as
brown
carbon
(BrC)
affects
the
global
radiative
balance.
linkages
between
its
molecular
composition
and
light
absorption
properties
how
environmental
factors
influence
BrC
are
not
well
understood.
In
this
study,
atmospheric
dissolved
matter
(ADOM)
in
55
samples
from
Guangzhou
was
characterized
using
Fourier
transform
ion
cyclotron
resonance
mass
spectrometry
measurements.
abundant
components
ADOM
were
aliphatics
peptide-likes
(in
structure),
or
nitrogen-
sulfur-containing
compounds
elemental
composition).
of
positively
correlated
with
levels
unsaturated
aromatic
structures.
Particularly,
17
nitrogen-containing
species,
which
identified
by
a
random
forest,
variation
well.
Aggregated
boosted
tree
model
nonmetric
multidimensional
scaling
analysis
show
that
largely
driven
meteorological
conditions
anthropogenic
activities,
among
biomass
burning
(BB)
OH
radical
two
important
factors.
often
accumulate
elevated
BB
emissions
related
secondary
processes,
whereas
photolysis/photooxidation
usually
occurs
under
high
solar
radiance/•OH
concentration.
This
study
first
illuminated
at
level
provided
clues
for
molecular-level
research
future.
Atmospheric chemistry and physics,
Journal Year:
2018,
Volume and Issue:
18(17), P. 12817 - 12843
Published: Sept. 6, 2018
Abstract.
The
Amazon
rainforest
is
a
sensitive
ecosystem
experiencing
the
combined
pressures
of
progressing
deforestation
and
climate
change.
Its
atmospheric
conditions
oscillate
between
biogenic
biomass
burning
(BB)
dominated
states.
further
represents
one
few
remaining
continental
places
where
atmosphere
approaches
pristine
during
occasional
wet
season
episodes.
Tall
Tower
Observatory
(ATTO)
has
been
established
in
central
Amazonia
to
investigate
complex
interactions
atmosphere.
Physical
chemical
aerosol
properties
have
analyzed
continuously
since
2012.
This
paper
provides
an
in-depth
analysis
aerosol's
optical
at
ATTO
based
on
data
from
2012
2017.
following
key
results
obtained.
scattering
absorption
coefficients
637
nm,
σsp,637
σap,637,
show
pronounced
seasonality
with
lowest
values
clean
(mean
±
SD:
σsp,637=7.5±9.3
M
m−1;
σap,637=0.68±0.91
m−1)
highest
BB-polluted
dry
(σsp,637=33±25
σap,637=4.0±2.2
m−1).
single
albedo
ω0,
(ω0=0.87±0.03)
(ω0=0.93±0.04).
retrieved
BC
mass
cross
sections,
αabs,
are
substantially
higher
than
widely
used
literature
(i.e.,
6.6
m2
g−1
nm
wavelength),
likely
related
thick
organic
or
inorganic
coatings
cores.
Wet
αabs=11.4±1.2
(637
nm)
αabs=12.3±1.3
were
BB
mixture
rather
fresh
smoke
local
fires,
somewhat
aged
regional
strongly
African
fires.
influence
appears
be
substantial,
its
maximum
August
October.
interplay
vs.
South
American
emissions
determines
(e.g.,
fractions
black
brown
carbon,
BrC).
By
analyzing
diel
cycles,
it
was
found
that
particles
elevated
aerosol-rich
layers
mixed
down
canopy
level
early
morning
particle
number
concentrations
decrease
towards
end
day.
Brown
carbon
370
σap,BrC,370,
earlier
day,
due
photo-oxidative
processes.
BC-to-CO
enhancement
ratios,
ERBC,
reflect
variability
burnt
fuels,
combustion
phases,
removal
A
wide
range
ERBC
4
15
ng
m−3
ppb−1
observed
season,
corresponding
ω0
levels
(0.86–0.93).
2009/2010
2015/2016
El
Niño
periods
associated
increased
fire
activity
by
means
9-year
σsp
σap
time
series
(combination
ZF2
data).
Significant
Niño-related
enhancements
observed:
24±18
48±33
m−1
σap,
3.8±2.8
5.3±2.5
m−1.
Ångström
exponent,
åabs,
representing
wavelength
dependence,
mostly
<1.0
episodic
increases
upon
advection.
parameterization
åabs
as
function
BC-to-OA
ratio
for
Amazonian
ambient
measurements
presented.
(BrC)
contribution
obtained
calculating
theoretical
resulting
BrC
contributions
17
%–29
%
(25th
75th
percentiles)
entire
measurement
period.
27
%–47
events
under
drought
September
November
2015.
presented
here
may
serve
basis
understand
aerosols
terms
their
solar
radiation
physical
chemical-aging
processes
they
undergo
transport.
Additionally,
last
two
offer
insights
could
help
assess
change-related
potential
forest-dieback
feedbacks
warmer
drier
conditions.
Environmental Science & Technology,
Journal Year:
2019,
Volume and Issue:
53(21), P. 12389 - 12397
Published: Sept. 25, 2019
The
light-absorbing
properties
of
atmospheric
brown
carbon
(BrC)
are
poorly
understood
due
to
its
complex
chemical
composition.
Here,
a
black-carbon-tracer
method
was
coupled
with
source
apportionments
organic
aerosol
(OA)
explore
the
primary
and
secondary
BrC
from
North
China
Plain
(NCP).
Primary
emissions
contributed
more
OA
light
absorption
than
processes,
biomass
burning
accounted
for
60%
at
λ
=
370
nm,
followed
by
coal
combustion
(35%)
hydrocarbon-like
(5%).
Secondary
high
in
early
morning
later
decreased
bleaching
chromophores.
Nighttime
aqueous-phase
chemistry
promoted
formation
compounds
production
strongly
absorbing
particles.
Source
analysis
showed
that
NCP
region
most
important
subtypes
study
site.
mean
direct
radiative
forcing
0.15
W
m-2
(0.11
0.04
fractions,
respectively).
This
provides
new
information
on
optical
highlights
importance
oxidation
absorption.
