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PROGRESS IN OC/EC MEASUREMENTS WITHIN EMEP Fabrizia Cavalli, J.-P. Putaud and the EUSAAR community

PROGRESS IN OC/EC MEASUREMENTS WITHIN EMEP Fabrizia Cavalli, J.-P. Putaud and the EUSAAR community. The goal of EUSAAR / NA2 is to define a standardized artifact-free procedure for

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PROGRESS IN OC/EC MEASUREMENTS WITHIN EMEP Fabrizia Cavalli, J.-P. Putaud and the EUSAAR community

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  1. PROGRESS IN OC/EC MEASUREMENTS WITHIN EMEP Fabrizia Cavalli, J.-P. Putaud and the EUSAAR community

  2. The goal of EUSAAR / NA2 is to define a standardized artifact-free procedure for determining particulate organic and elemental carbon, validated for all kinds of regional background sites Europe. EUSAAR Standard Operating Procedure for the sampling and thermal – optical analysis of atmospheric particulate organic and elemental carbon • Successful achievement of 5 years work within EUSAAR • EMEP community represents our main customer • SOP submitted to CCC for check and approval • Detailed description available: www.eusaar.net

  3. EUSAAR SOP: Sampling atmospheric particulate OC and EC 1. BEST AFFORDABLE SAMPLING TRAIN: 1.1 Positive artifact mitigation 1.2 Denuder penetration efficiency and lifetime 1.3 Negative artifact assessment

  4. 1.1 Positive artifact mitigation Without denuder: 14 – 70 %

  5. 1.1 Positive artifact mitigation Denuder efficiency: 43 – 93 %

  6. 1.1 Positive artifact determination With denuder: 1 -21 % Contribution of positive artifacts remains the largest at sites where the concentration of TC is the lowest

  7. 1.3 Negative Artifacts assessment - Activated carbon impregnated glass fiber filters: no more manufactured - Activated carbon impregnated cellulose fiber filters: cannot be tested - ZORFLEX: lead to problems with the Carbon analyser - XAD impregnated quartz fiber filters: not suitable for monitoring - Annealed quartz fiber filters: - the only possibility - theory says semi-volatile OCs should condense - used at the SEARCH network

  8. 1.3 Negative Artifacts assessment TESTS: IT04 in springtime • Denuder’s effect on negative artifacts: use of the denuder does not magnify negative artifacts • Annealed quartz fiber back up filter efficiency: 49 ± 12% • Range (upper limit) negative artifact: 0.9% - 4.5% 2.2% - 7.6%, if we account for quartz filter efficiency Being further investigated in SE11

  9. EUSAAR SOP 2. Thermal – optical analysis of atmospheric particulate organic and elemental carbon • EUSAAR_2 optimised protocol for determining OC and EC defined and published (Cavalli et al., 2010) • EUSAAR_2 protocol in use in a large number of laboratories in Europe (8 EUSAAR partners and, at least, 5 National Reference Laboratories) • EUSAAR_2 is recognised as one of the major protocols for OC + EC analyses • (considered by CEN as a potential reference method together with IMPROVE and NIOSH)

  10. 2.1 EUSAAR_2 protocol & Carbonate Carbon interference Natural calcite: 15 μg CC Cavalli et al., 2010 Jankosky et al., 2008 ▪ Carbonate carbon evolves in the He-mode of the EUSAAR_2 analysis (at 650°C) even for concentrations expected during severe dust outbreaks (Jankosky, 2008; Cavalli 2010; and Karanasiou et al., 2011 submitted) ▪ if present, CC would interfere with OC

  11. needle septum cap He or N to CO2 detection chain of the OCEC analyser 2 carrier gas filter punch H PO 3 4 conc. 2.1 Carbonate Carbon determination Proposed set-up for carbonate determination • CC recovery is 99% over the range 1.8 – 12 µg CC • Applied for CC determination in samples from Athens and Barcelona (Karanasiou et al., 2011) • measured CC substracted to OC (EUSAAR_2 protocol)

  12. 2.2 Intercomparison IMPROVE, EnvCan, and EUSAAR protocols for the particulate OC and EC analysis ▪ 27 ambient PM1 aerosol samples from rural/semi-urban sites in Canada ▪EUSAAR_2 (650°C max temp in He) vs. IMPROVE_A (580°C max temp in He) ▪ Reproducibility in TC determination better than 10% among “expert” labs EUSAAR TOR OR TOT EC conc. (μg/m3) IMPROVE TOR EC conc. (μg/m3) ▪ Systematic difference EC_EUSAAR_2 (TOT) vs. EC_IMPROVE_A (TOR) = 0.57 (R2 = 0.72) ▪ mainly due to optical correction (transmittance vs. reflectance) than to the thermal protocol

  13. EUSAAR Standard Operating Procedure for the sampling and thermal – optical analysis of atmospheric particulate organic and elemental carbon EUSAAR_2 protocol - minimises biases inherent to TOA - validated for regional background sites in Europe Positive artifact mitigation Negative artifact assessment

  14. 3.2 Comparability for OC /EC/TC measurement within the network (2010) - 18 participants among which 15 EMEP laboratories - 8 samples collected at four sites (Ispra, Birkenes, K-Pustza and Montseny)

  15. 3.2 OC / EC / TC intercomparison 3.2.1 TC amounts (µg / cm²) TC μg C / cm2

  16. 3.2 OC / EC / TC intercomparison 3.2.1 TC relative to average outliers excluded TC_ ratio to average outliers excluded 13 among 15 EMEP laboratories determine TC within ±13% on average

  17. 3.2 OC / EC / TC intercomparison 3.2.2 EC/TC ratios EC / TC ratio Difference range: a factor of 3 to 12 (all participants using thermal-optical analysis)

  18. 3.2 OC / EC / TC intercomparison EC/TC ratios relative to average all outliers excluded 9 among 15 EMEP laboratories determine EC/TC within ±20% on average

  19. FUTURE INTERCOMPARISONS • TC / OC / EC intercomparison: every year in collaboration with ACTRIS and CCC • Mandatory participation for EMEP laboratories reporting OCEC data • EMEP/CCC report • NEXT INTERCOMPARISON: • Materials: natural aerosol and reference material (e.g. BC RM by Olga Popovicheva) • Samples (2 high volume samples in 4 sites) to be collected 15th June • 4 volunteers needed to collected samples • Results to be delivered by 1st November

  20. THANK YOU

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