Fossil vs Contemporary Carbon Fossil vs Contemporary Carbon at 12 Rural and Urban Sites in at 12 Rural and Urban Sites in

the United Statesthe United States

Bret A. Schichtel (NPS)Bret A. Schichtel (NPS)William C. Malm (NPS)William C. Malm (NPS) Graham Bench (LLNL)Graham Bench (LLNL)

Charles E. McDade (UCD)Charles E. McDade (UCD) Judy C. Chow (DRI)Judy C. Chow (DRI)John Watson (DRI)John Watson (DRI)

Urban & Rural Annual Organic CarbonUrban & Rural Annual Organic CarbonUrban & Rural Annual Organic CarbonUrban & Rural Annual Organic Carbon

Speciated Speciated PM2.5 PM2.5 monitoring monitoring networks:networks:

IMPROVE – Rural sites IMPROVE – Rural sites STN – Urban/suburban STN – Urban/suburban sitessites

Urban & Rural Annual Organic CarbonUrban & Rural Annual Organic CarbonUrban & Rural Annual Organic CarbonUrban & Rural Annual Organic Carbon

Carbon Isotope (Carbon Isotope (1414C/C/1212C) NetworkC) Network

Summer: Jun – Aug ‘04; Winter: Dec ’04 – Feb Summer: Jun – Aug ‘04; Winter: Dec ’04 – Feb ‘05 ‘05 Summer: Jun – Aug ‘05; Winter: Dec ’05 – Feb Summer: Jun – Aug ‘05; Winter: Dec ’05 – Feb ‘06 ‘06 Summer: Jul – Aug ‘02Summer: Jul – Aug ‘02

Lake SugemaBrigantine

Proctor MaplePuget Sound

Mt. Rainier

Sula

Rocky Mt.

Grand Canyon

Phoenix

Tonto

Great Smoky Mt.

Yosemite

Six day HI-Six day HI-VOL PM2.5 VOL PM2.5 samplessamples

Contemporary (Biogenic) Vs Fossil CarbonContemporary (Biogenic) Vs Fossil Carbon

CC1414 half life ~5700 yr half life ~5700 yr ffMM = 0 for fossil C = 0 for fossil C ffMM ~ 1.08 for biogenic C ~ 1.08 for biogenic C Fraction ContemporaryFraction Contemporary

= = ffMM /1.08/1.08 Samples corrected for Samples corrected for

positive organic artifact positive organic artifact on filterson filters

BiogenicAD

SampleM

CC

CCf

195014

14

/

/

Mount Rainier

y = 0.82x

R2 = 0.95

y = 0.18x

R2 = 0.68-0.5

0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

5

0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5

Total Carbon (mg/m3)

Co

nte

mp

ora

ry o

r F

oss

il C

(m

g/m

3)

Contemporary

Fossil

Summer 2004Summer 2004

Seasonal Contemporary and Fossil C (Seasonal Contemporary and Fossil C (mmg/mg/m33))

The error bars represent the range in six day The error bars represent the range in six day concentrationsconcentrations

Seasonal Fraction Contemporary CarbonSeasonal Fraction Contemporary Carbon

The error bars represent the fraction The error bars represent the fraction contemporary range contemporary range

Urban ExcessUrban Excess Puget Sound, WA (Blue) – Mt. Rainier, WA (Red) Puget Sound, WA (Blue) – Mt. Rainier, WA (Red)

Puget Sound fossil carbon is primarily due to local sources Puget Sound fossil carbon is primarily due to local sources during winter and summerduring winter and summer

Summer biogenic carbon is regionally distributedSummer biogenic carbon is regionally distributed ~40% of the winter urban excess is biogenic carbon~40% of the winter urban excess is biogenic carbon

Not all biogenic carbon is “natural”Not all biogenic carbon is “natural”

Summer

0

0.5

1

1.5

2

2.5

3

3.5

4

4.5T

otal

Car

bon

Fos

sil

Bio

geni

c

Car

bo

n (m g

/m3 )

Excess:

1.8 mg/m3

44%

Excess:

1.56 mg/m3

77%

Excess:

0.23 mg/m3

11%

Winter

0

1

2

3

4

5

6

To

tal

Ca

rbo

n

Fo

ssil

Bio

ge

nic

Ca

rbo

n (m g

/m3)

Excess:

4.1 mg/m3

76%

Excess:

2.4 mg/m3

98%

Excess:

1.66 mg/m3

56%

Pu

get

Sou

nd

Mt

Rain

ier

Urban ExcessUrban ExcessPhoenix, AZ (Blue) – Tonto, AZ (Red)Phoenix, AZ (Blue) – Tonto, AZ (Red)

Phoenix fossil carbon is primarily due to local sources during Phoenix fossil carbon is primarily due to local sources during winter and summerwinter and summer

Summer biogenic carbon is regionally distributedSummer biogenic carbon is regionally distributed About half of the winter urban excess is biogenic carbon About half of the winter urban excess is biogenic carbon

Not all biogenic carbon is “natural”Not all biogenic carbon is “natural”

Summer

00.5

11.5

22.5

33.5

44.5

5

Tot

alC

arbo

n

Fos

sil

Bio

geni

c

Car

bo

n (m

g/m

3)

Excess:

1.94 mg/m3

45%

Excess:

1.53 mg/m3

81%

Excess:

0.42 mg/m3

17%

Winter

0

2

4

6

8

10

12

Tot

alC

arbo

n

Fos

sil

Bio

geni

c

Car

bo

n (m g

/m3 )

Excess:

9.6 mg/m3

89%

Excess:

5.1 mg/m3

94%

Excess:

4.5 mg/m3

84%

Ph

oen

ixT

on

to

IMPROVE Fine Particulate CarbonIMPROVE Fine Particulate Carbon

On average HiVol total carbon was 10-20% greater than IMPROVEOn average HiVol total carbon was 10-20% greater than IMPROVE

All monitors were collocated with IMPROVE monitors measuring All monitors were collocated with IMPROVE monitors measuring OC and EC using thermal optical reflectance (TOR)OC and EC using thermal optical reflectance (TOR)

IMPROVE collects 24-hour PM2.5 samples every third dayIMPROVE collects 24-hour PM2.5 samples every third day

y = 1.2x

R2 = 0.50

0

1

2

3

4

5

6

7

8

0 2 4 6 8IMPROVE - TOR (µg/m3)

HiV

ol

- A

MS

(µ

g/m

3)

y = 1.12x

R2 = 0.84

0

1

2

3

4

5

6

7

8

0 2 4 6 8

IMPROVE - TOR (µg/m3)

HiV

ol

- A

MS

(µ

g/m

3)

Total Carbon: Summer

Total Carbon: Winter

Fraction Biogenic Vs EC/TCFraction Biogenic Vs EC/TC

Summer EC/TCSummer EC/TC Fossil ~ 0.36Fossil ~ 0.36 Biogenic ~ 0.12Biogenic ~ 0.12

Winter EC/TCWinter EC/TC Fossil ~ 0.45Fossil ~ 0.45 Biogenic ~ 0.19Biogenic ~ 0.19

Winter/SummerWinter/Summer Fossil: 1.25Fossil: 1.25 Biogenic: 1.58Biogenic: 1.58

Seasonal AveragesSeasonal Averages

6-Day Averages6-Day AveragesSummer 2004

0

0.1

0.2

0.3

0.4

0.5

0 0.2 0.4 0.6 0.8 1 1.2Fraction Biogenic (from C-14)

IMP

RO

VE

EC

/TC

y = -0.21x + 0.35

Winter 2004- '05

0

0.1

0.2

0.3

0.4

0.5

0 0.2 0.4 0.6 0.8 1 1.2Fraction Biogenic (from C-14)

IMP

RO

VE

EC

/TC

y = -0.23x + 0.43

Summer 2004

y = -0.24x + 0.36

R2 = 0.77

0

0.1

0.2

0.3

0 0.2 0.4 0.6 0.8 1

Fraction Biogenic (from C-14)

IMP

RO

VE

EC

/TC

Winter 2004-05

y = -0.26x + 0.45

R2 = 0.86

0

0.1

0.2

0.3

0.4

0 0.2 0.4 0.6 0.8 1

Fraction Biogenic (from C-14)

IMP

RO

VE

EC

/TC

EC/TC Ratios from IMPROVE Data Edge AnalysisEC/TC Ratios from IMPROVE Data Edge Analysis

Rural 10Rural 10thth %-ile edge ~ Biogenic %-ile edge ~ Biogenic EC/TC EC/TC Summer – 0.07Summer – 0.07 Winter – 0.16Winter – 0.16

Urban 90Urban 90thth %-ile edge ~ Fossil EC/TC %-ile edge ~ Fossil EC/TC Summer – 0.41Summer – 0.41 Winter – 0.44Winter – 0.44

IMPROVE Rural Carbon 6/04 - 2/06

0

1

2

3

4

5

0 5 10 15 20 25Total Carbon (µg/m3)

Ele

men

tal

Car

bo

n (

µg

/m3)

EC summer EC winter

IMPROVE Urban Carbon 6/04 - 2/06

0

1

2

3

4

5

0 5 10 15 20 25

Total Carbon (µg/m3)

Ele

men

tal

Car

bo

n (

µg

/m3)

EC summer EC winter

Measured Primary EC/TC RatiosMeasured Primary EC/TC Ratios Mobile Sources – Fossil CarbonMobile Sources – Fossil Carbon

Adjusted Roadside: EC/TC = 0.39 (Chow et al., 2004)Adjusted Roadside: EC/TC = 0.39 (Chow et al., 2004) 1996 Sepulveda. CA tunnel study: EC/TC = 0.57 (Gillies et al., 2001)1996 Sepulveda. CA tunnel study: EC/TC = 0.57 (Gillies et al., 2001) Light duty vehicle: EC/TC = 0.3 (Cadle et al., 1997)Light duty vehicle: EC/TC = 0.3 (Cadle et al., 1997) Heavy Duty Diesel: EC/TC = 0.63 (Lowenthal et al. 1994)Heavy Duty Diesel: EC/TC = 0.63 (Lowenthal et al. 1994)

Wood Smoke – Biogenic Carbon (McDonald et al., 2000)Wood Smoke – Biogenic Carbon (McDonald et al., 2000) Softwood in fireplace: EC/TC = 0.2Softwood in fireplace: EC/TC = 0.2 Hardwood in fireplace: EC/TC = 0.1Hardwood in fireplace: EC/TC = 0.1 Hardwood in woodstove: EC/TC = 0.11Hardwood in woodstove: EC/TC = 0.11 Texas grass and soft and hardwood: EC/TC = 0.2 (Chow et al., 2004)Texas grass and soft and hardwood: EC/TC = 0.2 (Chow et al., 2004)

CookingCooking EC/TC = 0.1 (Chow et al., 2004)EC/TC = 0.1 (Chow et al., 2004)

Secondary organic aerosolSecondary organic aerosol EC/TC = 0EC/TC = 0

Comparison of EC/TC estimatesComparison of EC/TC estimates

Projected fossil and biogenic EC/TC ratios are in line with other estimatesProjected fossil and biogenic EC/TC ratios are in line with other estimates Summer Fossil EC/TC ratio is on low side Summer Fossil EC/TC ratio is on low side

Literature summer EC/TC higher than C 12/14 and EC/TC edge analyses Literature summer EC/TC higher than C 12/14 and EC/TC edge analyses Literature examined primary aerosolLiterature examined primary aerosol

Fossil and Biogenic EC/TC is smaller in the summer than the winter indicating Fossil and Biogenic EC/TC is smaller in the summer than the winter indicating some summertime SOA formation for bothsome summertime SOA formation for both

Summer

0

0.1

0.2

0.3

0.4

0.5

0.6

Fossil Biogenic

EC

/TC

Rat

io

Carbon 12/14 Edge Analysis Literature

Winter

0

0.1

0.2

0.3

0.4

0.5

0.6

Fossil Biogenic

EC

/TC

Rat

io

Carbon 12/14 Edge Analysis Literature

Winter

0

0.1

0.2

0.3

0.4

0.5

0.6

Fossil Biogenic

EC

/TC

Rat

io

Carbon 12/14 Edge Analysis Literature

Summer

0

0.1

0.2

0.3

0.4

0.5

0.6

Fossil Biogenic

EC

/TC

Rat

io

Carbon 12/14 Edge Analysis Literature

Fraction Biogenic - Summer 2004-05Fraction Biogenic - Summer 2004-05

The summer (June-August) IMPROVE carbon data were partitioned into fossil and biogenic carbon using the derived fossil and biogenic EC/TC ratios

Fraction Biogenic - Winter 2004-06Fraction Biogenic - Winter 2004-06

The summer (December - February) IMPROVE carbon data were partitioned into fossil and biogenic carbon using the derived fossil and biogenic EC/TC ratios

Estimating Secondary Organic Carbon Estimating Secondary Organic Carbon (SOC)(SOC)

Assume:Assume: All elemental carbon is primaryAll elemental carbon is primary Winter organic carbon is Winter organic carbon is primary (PC)primary (PC) Summer organic carbon is pSummer organic carbon is primary + secondaryrimary + secondary

1int

Summer

erW

Summer TCEC

TCEC

PC

SOC

1

1

SOCPCTC

SOC

Summer

1

1

Summer

Summer

Summer TCEC

TCSOC

OC

SOC

Fraction Secondary Organic Carbon for Fraction Secondary Organic Carbon for Summer MonthsSummer Months

42% of the summertime organic carbon is secondary42% of the summertime organic carbon is secondary 32% of the summertime fossil carbon is secondary32% of the summertime fossil carbon is secondary If some winter organic carbon is secondary than these summer If some winter organic carbon is secondary than these summer

SOC contributions are lower boundsSOC contributions are lower bounds

0

0.1

0.2

0.3

0.4

0.5

SOC / TC SOC / OC

Fra

ctio

n S

eco

nd

ary

OC Fossil Biogenic

SummarySummary Biogenic carbon accounts for Biogenic carbon accounts for

80-95% of the total carbon at the rural sites80-95% of the total carbon at the rural sites 70-80% of total carbon at near urban sites70-80% of total carbon at near urban sites 50% of total carbon at urban sites50% of total carbon at urban sites

Little seasonality and total variation in fraction Little seasonality and total variation in fraction modern carbon modern carbon

Urban fossil carbon is primarily due to local sources Urban fossil carbon is primarily due to local sources during the winter and summerduring the winter and summer

Summer biogenic carbon is regionally distributedSummer biogenic carbon is regionally distributed 40-50% of the winter urban excess is biogenic carbon 40-50% of the winter urban excess is biogenic carbon

Not all biogenic carbon is “natural”Not all biogenic carbon is “natural”

SummarySummary

42% or more of the summertime organic 42% or more of the summertime organic carbon is secondarycarbon is secondary

32% or more of the summertime fossil carbon 32% or more of the summertime fossil carbon is secondaryis secondary

Finished