1. Bernhard Rappenglück, Maurice Habram
VOC in the GAW-Network
TFMM-Workshop on the Implementation of the EMEP Monitoring Strategy, Oslo, November 2004
Rainer Steinbrecher
Bernhard Rappenglück, Maurice Habram
and
Volker Mohnen

2. 2 The Concept The GAW Program The GAW-WCC-VOC
The first VOC-Intercomparison within GAW
The GAW-VOC strategy for 2005 to 2007
GAW-VOC and EMEP-VOC 2

3. The GAW Program
GAW- Program
To determine the global composition of the atmosphere
To detect changes in the atmospheric trace compound composition
To suggest mitigation options 3

4. 4 The Components Climate forcing gases (CO2, CH4, N2O, etc.)
GAW- Program
Climate forcing gases (CO2, CH4, N2O, etc.)
Ozone (surface, column, profile)
Precipitation chemistry
Aerosols (optical properties, size distribution, chemical composition)
Reactive gases (VOC, NOx, SO2, CO)
Radiation (UV, visible) 4

5. 5 The Sites 22 global Stations 300 regional Stations
GAW- Program
22 global Stations
300 regional Stations
A sound data quality requires a rigours quality assurance plan 5

6. GAW Quality Assurance
GAW-Program 6

7. Global Atmosphere Watch (GAW)
The GAW-WCCs, Germany
GAW-WCC-VOC
Global Atmosphere Watch (GAW)
QA/SAC Germany operated by the German Environmental Agency (UBA)
Funding
WCC Aerosols
WCC VOCs
WCC N2O
IFT Leipzig IMK- IFU 7

8. The status of the WCC-VOC
GAW-WCC-VOC
The status of the WCC-VOC
Compounds
Sampling
SOP for canister sampling
Analysis
Intercomparison
Audits (Brazil, Finland)
Trainings (GAWTEC) 8 8

9.
GAW-WCC-VOC
Compounds
The GAW Reference Standard used so far at the WCC-VOC is based on a gas mixture containing 73 C2-C11 NMHCs at low ppbv levels in N2 prepared and certified by NCAR (Boulder, USA)
The GAW Reference Standard contains 21 NIST-traceable compounds
With the exception of propyne and 1,3-butadiene, this GAW Reference Standard contains all 30 target NMHCs recommended by WMO (WMO GAW Report No. 111, 1995)
The GAW Reference Standard already contains some NMHCs listed for stage 2 measurements (C10-C14 NMHC; biogenic NMHCs, e.g. α -pinene) 8 9

10.
GAW-WCC-VOC
Sampling
2-valve canister sampling 8 10

11. SOP for Canister Sampling
GAW-WCC-VOC 11

12.
GAW-WCC-VOC
Analysis
The GAW-WCC-VOC reference method 11

13. 6 samples, 1 NCAR-canister, 1 calibration canister Cryogenically:
L = 300 mm, i.d. = 1.5 mm
PFA-tube; no filling
at -30°C
Sample Vol.: ml
Sample Flow: 100 ml/min
Dryers:
Alternatively
(mainly for checks):
Mg(CLO4)2 He
r.(*):
Temp. Progr.(*):
Varian 3600CX
–30°C
2.5 min isothermal
3.5 K/min to –13°C
20 K/min to 8°C
5 K/min to 70°C
10 K/min to 240°C
12.2 min isothermal.
Column B:
CP-SIL 5 CB
l = 50 m, i.d. 0.25mm, df 1 μm
Heated at 60°C
Column A:
PLOT column Gaspro GSC
l = 17 m, i.d mm
Restriction capillary:
l = 1 m; i.d. 0.1 mm, deactivated
50 min
Up to 8 canisters:
Sample preconcentration trap (SPT; Varian)
6 samples,
1 NCAR-canister,
1 calibration canister
(n-butane/benzene)
L = 8 cm; i.d. = 2.1 cm
Carbopack® BHT)
at –120°C (liquid N2)
Desorption at 200°C
sample is backflushed
sample transferred splitless to columns.

14. The First GAW VOC-Intercomparison
Sites
Procedure
Data quality objectives
Results
Conclusions 14

15. Sites
VOC-Intercomparison
The intercomparison exercise of 2003 involved different stations/laboratories instruments (offline and online) - 7 countries (Brazil, Canada (2 labs), Czech Republic, Finland, Germany (2 labs; 3 instruments), Ireland, and Slovakia), - representing GAW, EMEP, CAPMoN and LBA programs 15

16. Procedure
VOC-Intercomparison
Standard gas canisters provided by the WCC-VOC with 73 VOCs in N2 prepared and certified by NCAR, Boulder.
The participating laboratories were expected to identify and quantify as many compounds of the WCC-VOC standard canister as possible based on their routine identification and calibration methods.
A standard questionnaire for air sampling, Analytical system and method, reporting results was circulated for completing 16

17. Data Quality Objectives
VOC-Intercomparison
alkanes and alkynes: uncertainty: 10% repeatability: 5%
alkenes: uncertainty: 20% repeatability: 20%
aromatics: uncertainty: 15% repeatability: 10% 17

18. Results: Repeatability
VOC-Intercomparison
Results that did not meet the DQOs are shown in red 18

19. Results: Deviation [%] from the WCC-VOC reference values
VOC-Intercomparison
Results that did not meet the DQOs are shown in red 19

20. Results: Ranking of properly identified and quantified VOCs
VOC-Intercomparison
X: related to all participants; Y: related to all participants who identified this specific VOC NIST traceable compounds are listed in green 20

21. VOC-Intercomparison
Conclusions:
Results of the VOC intercomparison excercise show large variations for most of the compounds and foster strong future efforts in the harmonization process of VOC measurements
The quality of the GAW reference standard needs to be re-assessed. Use of a common GAW-calibration source should be considered (NPL?)
The DQOs must be approved with the newly established Scientific Advisory Group Reactive Gases (SAG RG). However, this SAG is still in its initial phase (no meeting so far) 21

22. The GAW-VOC strategy for 2005 to 2007
To establish DQOs and begin developing SOPs in co-operation with EMEP for VOCs and NOx.
To enlarge the VOC measurement program in stages, proceeding from the easiest measurements to those that are more difficult - C2‑C9 hydrocarbons (operational at 5 GAW-sites, 3 EMEP-sites) - C10‑C14 hydrocarbons (including higher homologues as well as biogenic hydrocarbon compounds) - oxygenated VOCs (including alcohols, carbonyls, and carboxylic acids) 22

23. GAW-VOC and EMEP-VOC
GAW-VOC/EMEP-VOC
DQOs as proposed to the GAW SAG-RG: uncertainty repeatability Alkanes % % Alkenes % % Alkynes % % Aromatics % % Alcohols % % Ethers % % Aldehydes % % Formaldehyde % % Ketones % % Organic Acids % % Esters % % mixing ratio < 0.1 ppbv % % Currently, for all compounds a detection limit of 0.1 ppbC is assumed 23

24. GAW-VOC and EMEP-VOC
GAW-VOC/EMEP-VOC
Additional VOCs - oxyVOC (C1-C4, MVK/MAC, …?) - other biogenic compounds (limonene, etc?) - tracers (acetylene, acetonitril, terpenes, etc.?) - particle precursors (challenging!!; which compounds?) - …
Data reporting - necessary but only tow stations “online” - Data protocol? - …
Data use - compound ratio analysis (benzene/toluene, etc.) - routine trajectory analysis - Model input as well as Model output validation - … 24

25. GAW-VOC and EMEP-VOC
GAW-VOC/EMEP-VOC
Training and Audits - harmonised training programs (GAWTEC others?)? - standardised audit procedures?
QA exercises - ACCENT OxyVOC intercomparison FZ-Jülich, January 2005 25