1
Reference
Document:
"
Sources
of
carbon
in
PM
2.5
based
on
14C
and
tracer
analysis,"
Edgerton,
Eric
S.,
John
J.
Jansen,
Mei
Zheng
and
Benjamin
E.
Hartsell
(
September
2004),
8th
International
Conference
on
Carbonaceous
Particles
in
the
Atmosphere,
Vienna,
Austria.

SOURCES
OF
CARBON
IN
PM2.5
BASED
ON
14C
AND
TRACER
ANALYSIS
Eric
S.
Edgertona,
John
J.
Jansenb,
Mei
Zhengc
and
Benjamin
E.
Hartselld
aAtmospheric
Research
&
Analysis,
Inc.,
Cary,
NC
27513,
USA,
bSouthern
Company,
Birmingham,
AL
35291­
8195,
USA,
cSchool
of
Earth
and
Atmospheric
Sciences,
Georgia
Institute
of
Technology,
Atlanta,
GA
30332­
0340,
USA,
dAtmospheric
Research
&
Analysis,
Inc.,
Plano,
TX
75074,
USA.

ABSTRACT
Ambient
particulate
organic
carbon
(
OC)
consists
of
hundreds,
if
not
thousands,
of
individual
compounds
in
a
dynamically
evolving
medium
of
water,
inorganic
ions,
elemental
carbon
(
EC),
crustal
and
trace
elements.
The
sources
of
OC
include
primary
emissions
from
motor
vehicles,
forest
fires
and
other
forms
of
combustion,
as
well
as
secondary
production
from
gas
phase
precursors
(
e.
g.,
sesquiterpenes
and
aromatics).
This
presentation
synthesizes
data
from
various
measurements
to
estimate
major
source
categories
for
OC
at
research
sites
in
the
southeastern
U.
S.
Measurements
include:
14C
analyses,
tracer/
CMB
analysis
for
primary
carbon
species
and
continuous
CO
and
EC.
The
analysis
hinges
on
the
notion
of
a
source
matrix
for
OC.
In
its
simplest
form,
the
OC
source
matrix
is
a
2x3
grid
with
primary,
secondary
and
total
carbon
along
the
rows,
modern
and
fossil
carbon
along
columns.
Other
categories
can
be
used
for
the
columns,
if
desired,
and
these
can
be
subdivided
to
add
detail
as
data
and
creativity
permit.
Thus,
the
simplified
source
matrix
contains
six
cells
and
specification
of
any
four
solves
for
the
remaining
two.
14C
analysis
differentiates
between
modern
and
fossil
carbon
and
is
a
more
or
less
direct
measure
of
total
(
i.
e.,
primary
plus
secondary)
OC
in
each
category.
Exploratory
14C
measurements
at
three
SEARCH
sites
in
the
southeastern
U.
S.
show
that
modern
sources,
on
average,
contribute
>
80%
and
>
60%
of
OC
observed
at
rural
and
urban
sites,
respectively,
and
that
this
percentage
is
surprisingly
constant
across
seasons.
Differentiation
between
primary
and
secondary
OC
requires
detailed
chemical
analysis
of
tracer
species
in
air
samples.
Zheng
et
al.
(
2002)
have
used
the
former
approach
and
recently
published
seasonal
estimates
for
major
sources
of
OC
at
SEARCH
sites.
Results
for
wintertime
samples
show
that
primary
sources
can
account
for
virtually
all
OC
in
air
samples.
Results
for
summer,
in
contrast,
consistently
show
that
primary
sources
cannot
account
for
observed
OC,
thus
providing
indirect
evidence
of
secondary
production.
Sources
used
in
the
above
analyses
can
also
be
classified,
to
a
first
approximation,
into
fossil
and
modern
categories,
and
then
combined
with
carbon­
14
results
in
the
OC
source
matrix.
Preliminary
results
from
this
approach
show
interesting
contrasts
across
sites
and
seasons.
2
Winter
data
for
rural
southern
MS
show
that
OC
is
almost
entirely
primary­
modern.
Summer
data
for
Atlanta,
GA
suggest
that
OC
is
about
35%
primary­
modern,
35%
primary­
fossil,
25%
secondary­
modern
and
<
5%
secondary
fossil.
The
presentation
will
summarize
measurements
performed
during
several
campaigns
in
the
summer
and
fall
of
2003.

Zheng,
M.
et
al.
Source
apportionment
of
fine
particle
air
pollutants
in
the
southeastern
United
States
using
solvent­
extractable
organic
compounds
as
tracers.
Environ.
Sci.
Technol.
2002,
36,
2361­
2371.
