Presented at the 3rd ICOS Science Conference in Prague, Czech Republic, 11-13 Sep 2018.

1. Characterisation of δ13
CH4 source signatures from
methane sources in Germany using mobile
measurements
A. Hoheisel, C. Yeman, F. Dinger, H. Eckhardt and M. Schmidt
Institute of Environmental Physics Heidelberg University
September 13, 2018
September 13, 2018 1 / 13

2. Motivation
Global Atmospheric CH4 Mole Fraction and δ13
C
HS
GAW
HS
NOAA-ESRL
1980 1990 2000 2010
1800
1700
1600
-47.8
-47.6
-47.4
-47.2
-47.0
Year Year
[CH4](p.p.b.)
δ13
C(Atm)(‰) 1980 1990 2000 2010
(Schaefer et al., 2016)
September 13, 2018 2 / 13

3. Motivation
δ13
CH4 Isotopes
isotope ratio R and δ-notation
13
R =
13CH4
[12CH4 ]
δ =
Rsample
Rstandard
− 1 · 1000
main formation processes of CH4
biogenic −55 to −70 e.g. wetlands, landfills, WWTPs and
ruminants
thermogenic −25 to −45 e.g. main component of natural gas
pyrogenic −13 to −25 e.g. incomplete combustion of organic
matter
September 13, 2018 3 / 13

4. Motivation
CH4 Sources
Berlin
Hamburg
Frankfurt on the Main
Cologne
Stuttgart
Amsterdam
Brussels
Munich
dairy farm in Kleve
deep coal mine in Bottrop
opencast mine Hambach
measuring sites
near Heidelberg
dairy farm in Weinheim
dairy farm in Ladenburg
natural gas storage and
compressorstations
Hähnlein/Gernsheim
natural gas storage
Sandhausen landfill in Sinsheim
WWTP in
Heidelberg
biogas plant in
Heidelberg
Heidelberg
Weinheim
Sinsheim
Mannheim
358 km
22.4 km
measuring sites
near Heidelberg
Berlin
Frankfurt on the Main
Cologne
Stuttgart
Amsterdam
Brussels
Kleve
Bottrop
Weinheim
Ladenburg
Sandhausen
Sinsheim
Heidelberg
Heidelberg
Weinheim
Sinsheim
Mannheim
400 km 20 km
Munich
Hähnlein/Gernsheim
Heidelberg
dairy farm
biogas plant
wastewater
treatment plant
landfill
natural gas storage
and compressor
stations
deep coal mine
measuring sites
September 13, 2018 4 / 13

5. Measurement Setup
Measuring Principle
September 13, 2018 5 / 13

6. Measurement Setup
Measuring Principle
September 13, 2018 5 / 13

7. Measurement Setup
Measuring Principle
2
3
4
5
6
CH4[ppm]
0 2 4 6 8 10 12
time [min]
September 13, 2018 5 / 13

8. Measurement Setup
Measuring Principle
2
3
4
5
6
CH4[ppm]
−65
−60
−55
−50
−45
−40
0 2 4 6 8 10 12
time [min]
δ13
CH4[‰]
September 13, 2018 5 / 13

9. Measurement Setup
Measuring Principle
7
15s mean:
raw:
September 13, 2018 5 / 13

10. Measurement Setup
Mobile Measurement Setup
AirCore
Picarro G2201-i
(Yeman,2015)
September 13, 2018 6 / 13

11. Measurement Setup
Mobile Measurement Setup
filter
air
inlet
three-way
valve
Nafion
dryer
critical orifice
AirCore
needle pump
CRDS
laptop
filter
valve
AirCore
volume: 1.77 l
length: 25 m
diameter: 9.5 mm
flow through instrument
monitoring mode: 0.16 l/min
AirCore measurement: 0.10 l/min
September 13, 2018 7 / 13

12. Measurement Setup
AirCore Measurements
2
3
4
5
6
CH4[ppm]
monitoring mode AirCore measurement
0 2 4 6 8 10 12 14
δ13
CH4[‰]
-65
-50
-55
-45
-60
-40
time [min]
CRDS
Nafion
dryer
AirCore
air
inlet
September 13, 2018 8 / 13

13. Data Analysis
Determination of δ13
CH4 Signature
δ13
CH4 Correction and Calibration
CH4 interference → no effect
CO2 interference → no effect
H2O interference → drying unit
C2H6 interference → corrections
September 13, 2018 9 / 13

14. Data Analysis
Determination of δ13
CH4 Signature
δ13
CH4 Correction and Calibration
H2O interference → drying unit
C2H6 interference → corrections
Fit Method
Miller-Tans Approach
δ13
CH4M · CH4M = CH4B δ13
CH4B − δ13
CH4S + δ13
CH4S · CH4M
York fit
September 13, 2018 9 / 13

15. Data Analysis
Determination of δ13
CH4 Signature
δ13
CH4 Correction and Calibration
H2O interference → drying unit
C2H6 interference → corrections
Fit Method
Miller-Tans Approach
δ13
CH4M · CH4M = CH4B δ13
CH4B − δ13
CH4S + δ13
CH4S · CH4M
York fit
Limitation Factors:
precision of the analyser
number of data points → importance of AirCore
CH4 range
Criterion:
uncertainty of δ13
CH4
lower than 5
September 13, 2018 9 / 13

16. Data Analysis
Limitation Factors
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0 1 2 3 4 5 6 7 8 9 10
CH4 range [ppm]
δ13
CH4[‰]fiterrorof
40
35
30
25
20
15
10
5
0
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0
10
20
30
40
0.0 0.2 0.4 0.6 0.8 1.0
CH4 range [ppm]
●
δ13
CH4[‰]fiterrorof
simulations
measured data}
number of
data points
10
20
40
70
140
210
280
25-280
Criterion:
uncertainty of δ13
CH4
lower than 5
September 13, 2018 10 / 13

17. Data Analysis
δ13
CH4 Signature of CH4 Sources
79 AirCore measurements on 21 days between July 2016 to July 2017
q
q
−70 −65 −60 −55 −50 −45 −40
δ13
CH4 [‰]
natural gas facility Sandhausen
natural gas facility Hähnlein/Gernsheim
bituminous deep coal mine Bottrop
WWTP Heidelberg
landfill Sinsheim (plume)
landfill Sinsheim (on landfill)
biogas plant Heidelberg
dairy farm Ladenburg
dairy farm Kleve
dairy farm Weinheim
q qq q qq
qq q
q qqq q qqq q
q qqq q q
qq qqqq qq
qqq qqq qqqq qqq q
qq q q qq q q
qqq qqqq q
q q
q qq qqqqqq qq
q q
qq
q q
q qq qqqqqq qq
q q
qq
q qqq qq
qqq q qqqq q q
q qq q qq
qq qq
qq
q
q
q
q
qq
q
q
single mobile result
mean mobile result
direct sample result
September 13, 2018 11 / 13

18. Data Analysis
Samples from Natural Gas Distribution Network Heidelberg
δ13
CH4[‰]
−50
−45
−40
−35
−30
sample date
12/2016 03/2017 06/2017 09/2017 12/2017 03/2018 06/2018
winter
(Levin et al., 1999)
summer
(Levin et al., 1999)
−43.1 ± 0.8‰ 12/2016 to 02/2018
−40.3 ± 3.0‰ 1991 to 1996 (Levin et al., 1999)
(Lowry et al., 2001)
-48‰ to -54‰
(Cramer et al., 1998)
North Sea gas
Russian gas
-34 ± 3‰
September 13, 2018 12 / 13

19. Conclusion
Conclusion
development and test of a mobile instrument setup
results of mobile campaigns are in good agreement with direct
samples and values from other studies
advantages:
measurements can be done downwind of emission source
consent of the owner is not necessary
measurements can be done where it is not possible to take direct
samples
September 13, 2018 13 / 13

20. Thank you for your attention.
September 13, 2018 13 / 13

21. δ13
CH4 Signature of CH4 Sources
location δ13CH4 signature δ13CH4 signature of peak hight* number of number of mobile measuring
due to mobile measurements direct gas samples AirCores** visits** period/dates
average range
[ ] [ ] [ ] [ppm] [MM-YY]
biogas plant
Heidelberg −62.4 ± 1.2 −67.4 to −59.0 −61.5 ± 0.1 3.4 to 14.1 17 (25) 7 (10) Aug-16 to Mar-17
−64.1 ± 0.3
dairy farm
Weinheim (on farm) −64.9 ± 1.6 −66.0 to −62.6 8.3 to 8.9 3 (3) 2 (2) Oct-16 and Nov-16
Weinheim (plume with biogas plant) −54.0 ± 8.0 −62.6 to −43.1 3.9 to 13.1 10 (12) 5 (5) Sep-16 to Feb-17
Ladenburg (on farm) −63.2 ± 1.4 −64.0 to −61.6 4.1 to 7.3 3 (3) 1 (1) Oct-16
Ladenburg (plume with biogas plant) −44.4 ± 0.8 −55.1 to −40.3 3.9 to 8.2 3 (8) 1 (3) Nov-16 to Feb-17
Kleve −63.5 ± 1.6 −65.1 to −61.7 4.7 to 13.6 5 (5) 1 (1) Mar-17
landfill
Sinsheim (plume) −58.7 ± 3.3 −62.2 to −54.2 −59.5 ± 0.1 2.4 to 2.6 4 (18) 4 (8) Jul-16 to Mar-17
Sinsheim (on landfill) −59.5 ± 0.5 −59.9 to −59.1 3.9 to 7.2 2 (4) 1 (1) Jul-17
−66.5 ± 2.5 −69.3 to −64.0 2.6 to 6.0 4 (4) 1 (1) Jul-16
WWTP
Heidelberg −52.5 ± 1.4 −56.3 to −49.4 −51.3 ± 0.2 3.5 to 6.0 7 (13) 5 (5) Oct-16 to Feb-17
natural gas facilities
Sandhausen −45.5 ± 5.2 −49.2 to −41.5 3.0 and 10.0 3 (9) 2 (10) Jul-16 and Mar-17
H¨ahnlein/Gernsheim −46.6 ± 6.8 −57.4 to −41.1 3.3 to 8.2 9 (21) 5 (5) Sep-16 to Feb-17
bituminous deep coal mine
Bottrop (active) −56.0 ± 2.3 −59.5 to −54.7 3.4 to 7.6 4 (4) 1 (1) Mar-17
Bottrop (closed) −50.0 ± 6.3 −50.0 2.6 1 (1) 1 (1) Mar-17
next to lignite opencast mine
Hambach −82.0 ± 2.6 −84.8 to −79.7 4.6 to 7.1 3 (4) 1 (1) Mar-17
September 13, 2018 13 / 13

22. Correction and Calibration Schema
C2H6RAW
C2H6CAL
C2H6COR
=C2H6RAW
+Amoist/dry·H2O+B·CH4 +C·CO2
C2H6CAL
=H·C2H6COR
+I
δCH4RAW
δ13
CH4COR1
=δ13
CH4RAW
+Wmoist/dry·H2O
δ13
CH4COR2
= δ13
CH4COR1
- D·
δ13
CH4CAL
= δ13
CH4COR2
·
δCH4CAL
C2H6CAL
CH4
δ13
CH4Nominal
δ13
CH4Standard
September 13, 2018 13 / 13

23. Laboratory Setup
13
5
7
9
out
rotary-valve
1115
13
flowmeter
sample bag
condensation trap
cooled by cryostat
Standard MSTD PR
TARGET
Standard HIGH PR
PR
ambient air
intake line
condensation trap
cooled by cryostat
pump
CRDS
laptop
September 13, 2018 13 / 13

24. Allan Standard DeviationAllanstd.dev.
ambient
10 ppm CH4air
5 ppm C2H6
10−3
10−2
10−1
100
101
100
101
102
103
averaging period [sec]
CH4 [ppb]
C2H6 [ppm]
δ13
CH4 [‰]
September 13, 2018 13 / 13

25. CH4 Interference on δ13
CH4δ13
CH4[‰]
−43
−42
−41
−40
2 4 6 8 10
CH4 [ppm]
●
●●
●
●
●
●
●●
●●
●
●
●
September 13, 2018 13 / 13

26. CO2 Interference on δ13
CH4
δ13
CH4[‰]
−42.2
−42.0
−41.8
−41.6
−41.4
−41.2
−41.0
0 100 200 300 400
CO2 [ppm]
10 9 8 7 6 5 4 3
CH4 [ppm]
●
●
●
●
●
●
September 13, 2018 13 / 13

27. C2H6 Interference on δ13
CH4
0
5
10
15
20
25
0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7
∆inδ13
CH4[‰]
C2H6 calib / CH4
[‰]Slope: 40.87 ± 0.49
September 13, 2018 13 / 13

28. CH4 and CO2 Interference on C2H6
q
reportedC2H6[ppm]
0.0
0.5
1.0
1.5
2.0
0 2 4 6 8 10
CH4 [ppm]
qqqqqq
qq
q
qqqqqq
q
qq
q
q
q
q
q
q
q
q
q q
q
q
q q q
q
0 200 400 600
CO2 [ppm]
q
qqqqqqq q
q
qqq
qq
qq q
q
q
q
q
q
q q
qq
q
q q
September 13, 2018 13 / 13

29. Linearity of C2H6
0.0
0.5
1.0
1.5
2.0
2.5
3.0
0 1 2 3 4 5
C2H6theo[ppm]
C2H6 corrected [ppm]
Slope: 0.538 ± 0.002
Intercept: 0.070 ± 0.005
September 13, 2018 13 / 13