Long-term Observation of CO2 concentration and its isotope ratios over the Western Pacific

H. Mukai, Y. Nojiri, Y. Tohjima, T. Machida, Y. Shibata and H. Kitagawa

Center for Global Environmental Research,National Institute for Environmental Studies

AndNagoya University

Monitoring by using commercial cargo ships Atmospheric CO2 samples from wide range of latitude can be

colleted.

Frequent commercial cargo ship service enable us to observed seasonal variation of CO2 in addition to long-term variation.

Japan-Oceania cruise can provide us a good chance to observe latitudinal difference in behavior of CO2 from Northern Hemisphere to Southern Hemisphere.

Relatively economic monitoring if it goes as planed.

92 93 94 95 96 97 98 99 00 01 　 02 03 04 05 06 07

Japan -N America(30N-55N)

Japan –Oceania(30N-35S)

NOV

Hakuba

SKAUBRYN （ Seaboard)

Southern Cross

SKAUGRAN　（ Seaboard) PYXIS(TOYOFUJI)

FUJITRANS WORLD

MOL　 Glory

Golden Wattle(MOL)

Alligator Hope（MOL)

Trans Future

Special thanks to MOL, Toyofuji, Fuji Trans, Nihhon Usen,Seaboard International Shipping Co.

FUJITRANS WORLD

PYXIS

FUJITRANS WORD and PYXIS routes2003 Sep – 2004 Nov

1) Bottle Sampling : Stainless-steel bottle 3L (+ Glass bottle 2.5L ) ~10 times/y since 1995 ~ 3 samples / 10 degree in latitude 2) Gas analysis in the bottle: CO2, N2O, CH4 (NDIR, GC-ECD, GC-FID)

delta 13C, delta 18O (MAT252, dual inlet) 14C is measured by Accelerator MASS in NIES

Air Inlet

Temperature sensorGPS sensor

(1) Metal bellows pump

GPS receiver

(2) Cooler (-45 oC)

(3) Sampling Flask Box

Sampling Controller

CO2 analyzer

12CO213CO2

C3 plant

C4 plant

14CO2

Soil

Isotope signature of CO2 (13C, 14C, 18O)will provide important clues about CO2 budget and climatic effects on CO2 uptake mechanism

H218O 12C18O2

(N40-N50)

-2.4-2

-1.6-1.2-0.8-0.4

00.40.81.2

1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005

Del

ta O

18 (p

er m

il)

(N20-N30)

-2.4-2

-1.6-1.2-0.8-0.4

00.40.81.2

1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005

Del

ta

O18

(per

mil)

(0-N10)

-2.4-2

-1.6-1.2-0.8-0.4

00.40.81.2

1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005

Del

ta

O18

(per

mil)

(S20-S10)

-2.4-2

-1.6-1.2-0.8-0.4

00.40.81.2

1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005

Del

ta O

18 (p

er m

il)

(N40-N50)

350

355

360

365

370

375

380

385

1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005

CO

2 (p

pm)

(N20-N30)

350

355

360

365

370

375

380

385

1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005

CO

2 (p

pm)

(0-N10)

350

355

360

365

370

375

380

385

1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005

CO

2 (p

pm)

(S20-S10)

350

355

360

365

370

375

380

385

1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005

CO

2 (p

pm)

(N40-N50)

-8.8

-8.6

-8.4

-8.2

-8

-7.8

-7.6

-7.4

1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005

Del

ta C

13 (p

er m

il)

(S20-S10)

-8.8

-8.6

-8.4

-8.2

-8

-7.8

-7.6

-7.4

1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005

Del

ta C

13 (p

er m

il)

(N20-N30)

-8.8

-8.6

-8.4

-8.2

-8

-7.8

-7.6

-7.4

1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005

Delta

C13

(per

mil)

(0-N10)

-8.8

-8.6

-8.4

-8.2

-8

-7.8

-7.6

-7.4

1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005

Del

ta C

13 (p

er m

il)CO2 Delta 13C Delta 18O

40N-50N

20N-30N

0-10N

20S-10S

Carbon isotope ratio

-1

0

1

2

3

4

5

6

-40 -20 0 20 40 60

Latitude

CO

2 d

evia

tion fro

m 3

5S

(ppm

)CO2 concentration

-0.35

-0.25

-0.15

-0.05

0.05

-40 -20 0 20 40 60

Latitude

Delta 1

3C

devia

tion f

rom

35S

(per

mil)

Delta 13C

Latitudinal distribution

0

0.5

1

1.5

2

2.5

3

3.5

19

95

19

96

19

97

19

98

19

99

20

00

20

01

20

02

20

03

20

04

20

05

CO

2 G

row

th r

ate

(p

pm

/y)

30S-10S

10S-10N

10N-30N

30N-50N

-0.1

-0.08

-0.06

-0.04

-0.02

0

0.02

0.04

199

5

199

6

199

7

199

8

199

9

200

0

200

1

200

2

200

3

200

4

200

5

delta

13

C c

ha

ng

e r

ate

(p

er

mil/

y)

30S-10S

10S-10N10N-30N

30N-50N

CO

2 gr

owth

rat

e (p

pm

/y)

Del

ta 1

3C c

han

ge r

ate

(per

mil/

y)

Simple Global Flux Estimation 12C flux dCa/dt 　 = CF + CNs + CNb 　　 ------------------(1)

13C flux dδ13Ca/dt = CFδF+ CNs(δa +εas) + CNb(δa +εab)

+ CGs(δs –δa) + CGb(δb –δa) ------(2)

CF = anthropegenic input ( Fossil combustion and Cement production)CNs = Net Sea flux CNb = Net land biological flux CGS = Gross exchange flux between Sea and atmosphereCGb = Gross exchange flux between land biosphere and atmosphere

Isotope disequilibrium term CGs(δs –δa) + CGb(δb –δa)

= 93 Gt-C per mli / year (Francey et al )

BiologicalDiscrimination

-4

-2

0

2

4

6

8

1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005

Flux

(Gt-C

/ y)

, SO

IAnthropogenic CO2 input Land

Ocean CO2 in the atmosphere

Land

Ocean

Atmosphere

Preliminary estimation of flux

Atmosphere

Land Biosphere

Ocean

Anthropogenic input

-4

-2

0

2

4

6

8

1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005

Flux

(Gt-C

/ y)

, -S

OI

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

Glo

bal T

emp.

Ano

mal

y

Anthropogenic CO2 input LandOcean CO2 in the atmosphereSOI Temp Anomaly

LandOcean

Atmosphere

-SOI

Temp

25N

15S

Biomass burning signal can be detected ?

A preliminary guess of net Carbon flux budget (PgC/y) to assess isotope signature and its usability

These values for terrestrial and oceanic sinks may have a large uncertainty (over +1Pg/y)

Terrestrial Oceanic Atmospheric Anthropogenic1996 -1.5 -2.1 2.9 6.51997 -0.1 -3.0 3.6 6.71998 0.1 -2.1 4.7 6.71999 -1.6 -1.5 3.4 6.52000 -2.5 -1.3 2.9 6.72001 -1.4 -1.6 3.9 6.82002 -0.1 -1.6 5.3 7.02003 -0.9 -1.3 4.8 7.02004 -2.7 -1.1 3.2 7.0

Avearge -1.2 -1.7 3.9 6.8

Assessment of isotopic balance equationAssessment of isotopic balance equation Oceanic sink looked too variable. Oceanic sink variation = +1 PgC and decrease trend ???

c.f. Reported oceanic variation on flux is about +0.4 PgC What is possible causes ?

If we set Oceanic sink variation to be Zero How much percent we have to change the parameters such as Discrimination factor? It is most important for both disequilibrium and biological uptake term.1) Discrimination for CO2 uptake by plants fractionation factor decreases? C4 plant fraction to C3 plant increase? 2) Gross primary production decreases or increase?

-19.1

-19

-18.9

-18.8

-18.7

-18.619

95

1996

1997

1998

1999

2000

2001

2002

2003

2004

2005

Dis

crim

inat

ion

expe

cted

(per

mil)

-12

-10

-8

-6

-4

-2

0

2

SO

I

0.2 per mil decrease can be possibleby high T and low humidity , but Gross primary production can not decrease by corresponding amount (over 50%)

SOI

Apparent variation of oceanic sink can be compensated by biological discrimination adjustment by up to 0.2 per mil

-1.5

-1

-0.5

0

0.5

1

1.5

219

95

1996

1997

1998

1999

2000

2001

2002

2003

2004

2005

delta

18O

tren

d (p

er m

il)

-19

-16

-13

-10

-7

-4

-1

2

-25

-15

-5

5

15

25

35

45

55

SOI

Delta 18O trend showed some increase over 10 years

SOI

El N

ino

Increase delta 18O of water? GPP decrease?

Conclusion

(1) Ten-year observation of CO2 and isotopes over Western Pacific from 30S to 50N was conducted by using 8 commercial cargo ships.

(2) By simple carbon budget equations using isotopic data, oceanic and terrestrial uptake amounts were estimated. Oceanic sink was relatively stable but still had 1Pg-C variation. Terrestrial sink seemed to decrease rapidly by higher and more dry condition at El Nino event. Apparent oceanic fluctuation may be partly caused by the change of C isotopic discrimination due to climatic condition.

(3) Oxygen isotope ratio showed increasing trends in all latitude during 10 years. It was different tendency from that of 1990’s. It may be related to high

temperature and low humidity tendency including lower GPP in recent years.

(4) Carbon-14 measurements will give an another angle to look at carbon budget. Further analysis is needed.

(5) Seasonal variations of CO2 and carbon isotope ratio were large in Northern Hemisphere but small in Southern Hemisphere. Isotope fractionation factor was about –19 per mil on average, but –14 per mil in 20S, which showed some C4 plants effect at that latitude. (not shown)

-30-28-26-24-22-20-18-16-14-12-10

-30 -20 -10 0 10 20 30 40 50

Latitude

delta

13C

(per

mil)

Keeling Geometric mean Tanskeeling classic Delta (Tans )Delta (Keeling Classic) Delta (Geometric mean)

Seasonal component and biological discrimination

Source and sink delta 13C

Apparent Biological discrimination -19 per mil

CF: Merland

δF: -28 per mil (estimated)

εas: 1.8 per mil

εab: 19 per mil

Gb: 125PgC/y

Go: 90PgC/y

Disequilibrium Sea-Atmosphere: 0.6 per mil

Disequilibrium Terrestrial biosphere-Atmosphere: 0.394 as standard case

355

360

365

370

375

380

385

1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005

CO

2 tre

nd (p

pm)

-25

-15

-5

5

15

25

35

45

55

CO2 trend in each latitude

-8.5

-8.4

-8.3

-8.2

-8.1

-8

-7.9

-7.8

1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005

delta

13C

trend

(per

mil)

-25

-15

-5

5

15

25

35

45

55

13C isotope ratio trend in each latitude

Oxygen isotope ratiode

lta 18

O

-4

-2

0

2

4

6

8

1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005

Flux

(Gt-C

/ y)

, SO

IAnthropogenic CO2 input Land

Ocean CO2 in the atmosphere

Land

Ocean

Atmosphere

Sampling inlet