Bernhard Rappenglück, Maurice Habram VOC in the GAW-Network TFMM-Workshop on the Implementation of the EMEP Monitoring Strategy, Oslo, 22-24 November 2004 Rainer Steinbrecher Bernhard Rappenglück, Maurice Habram and Volker Mohnen

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

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 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 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

GAW Quality Assurance GAW-Program 6

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

The status of the WCC-VOC 24.06.2019 GAW-WCC-VOC The status of the WCC-VOC Compounds Sampling SOP for canister sampling Analysis Intercomparison Audits (Brazil, Finland) Trainings (GAWTEC) 8 8

24.06.2019 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

24.06.2019 GAW-WCC-VOC Sampling 2-valve canister sampling 8 10

SOP for Canister Sampling 24.06.2019 GAW-WCC-VOC 11

24.06.2019 GAW-WCC-VOC Analysis The GAW-WCC-VOC reference method 11

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.: 400 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. 0.32 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.

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

Sites VOC-Intercomparison The intercomparison exercise of 2003 involved - 9 different stations/laboratories - 10 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

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

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

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

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

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

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

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

GAW-VOC and EMEP-VOC GAW-VOC/EMEP-VOC DQOs as proposed to the GAW SAG-RG: uncertainty repeatability Alkanes 10% 5% Alkenes 20% 20% Alkynes 10% 5% Aromatics 15% 10% Alcohols 25% 20% Ethers 25% 20% Aldehydes 25% 20% Formaldehyde 20% 10% Ketones 25% 20% Organic Acids 25% 20% Esters 25% 20% mixing ratio < 0.1 ppbv 50% 50% Currently, for all compounds a detection limit of 0.1 ppbC is assumed 23

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

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