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Atmospheric mercury monitoring in relation to model testing and validation

This presentation discusses the monitoring of atmospheric mercury species, including mercury in air, wet deposition, and deposition in forested areas. Topics include the availability of monitoring data, methods for measurement, and the need for high time resolution for model validation. Examples of field measurements and mercury in precipitation are also provided.

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Atmospheric mercury monitoring in relation to model testing and validation

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  1. Atmospheric mercury monitoring in relation to model testing and validation John Munthe and Ingvar Wängberg IVL Swedish Environmental Research Institute

  2. Presentation topics • Mercury species in air • Mercury in wet deposition • Mercury deposition in forested areas/throughfall, litterfall • Monitoring needs for model testing and evaluation

  3. Mercury species in air • GEM (Gaseous Elemental Mercury), Hg0, elemental mercury vapour. Normally >98% of total mercury in air, long residence time, global distribution. Sampled on gold traps with filter to remove TPM and denuder to remove RGM • RGM (Reactive Gaseous Mercury), operationally defined but thought to be mainly HgCl2. Sampled on KCl coated denuders. • TPM, (Total Particulate Mercury),HgP,particulate mercury. Hg(II) or Hg0, associated with particles. Sampled on filters, usually quartz. • TGM (Total Gaseous Mercury). Sum of GEM and RGM. Sampled on gold traps without filter and denuder.

  4. Mercury species in air - availability of monitoring data -TGM • TGM at a few sites in Northern Europe with varying time resolution (from hourly to weekly samples) • Manual and automated methods are used • Variability relatively small, hemispherical background of 1.5 ng/m3, peaks of 2-4 ng/m3 from European emission • Need high time resolution for model validation • New EU directive will require more extensive monitoring from 2006/7 • Question of priorities.

  5. Mercury species in air - availability of monitoring data - RGM and TPM • RGM. No routine measurements in Europe. Campaigns as part of research projects. • TPM. Monitoring at few sites in northern Europe • High variability from <2 to 100 pg/m3. • Direct emissions (RGM) from (some) combustion sources, formation in atmosphere (OH, halogens)= large local and temporal variability • Manual and automated methods available but relatively work intensive for RGM, easier for TPM • Voluntary in EU directive, should be at "super stations"

  6. TGM from Mace Head Ralf Ebinghaus, GKSS

  7. TGM from MOE 1997-1998 (5 campaigns)

  8. 40 35 30 25 20 TGM ng m-3 15 10 5 0 13/12 16/12 19/12 22/12 25/12 28/12 31/12 3/1 TGM 600 m from point source (Chlor alkali plant), annual emissions 50 kg/yr

  9. RGM from MOE 1997-1998 (5 campaigns)

  10. TPM from MOE 1997-1998 (5 campaigns)

  11. RGM Automated (NEU) and manual (RÖR) Ralf Ebinghaus, GKSS, J. Sommar, Göteborgs Universitet

  12. TPM, november 1999

  13. Mercury species in air, measurements for modelling purposes • TGM: Methods well developed and available. Need high time resolution to be able to identify small peaks above background. • RGM: Methods relatively complicated, could be simplified? Need data with temporal and spatial resolution, better emission data, better understanding of chemistry • TPM: Methods available. Need data with temporal and spatial resolution, higher time resolution.

  14. MERCYMS Field Measurements at Cabo de Creus, Spain 42o19’ N, 3o 19’ W • FP 5 project, coordinated by N Pirrone, CNR IIA • Measurements at 5 coastal stations, 4 campaigns in 2004 • Several ship cruises • Measurements in Spain conducted by IVL and Göteborg University in cooperation with Ministry of Environment and MCV

  15. Autumn 2003 Winter 2004 20.0 20.0 -3 15.0 -3 15.0 10.0 10.0 TPM pg m TPM pg m 5.0 5.0 0.0 0.0 21 22 23 24 25 26 27 28 29 30 31 1 19 20 21 22 23 24 25 26 27 28 29 30 10 10 10 10 10 10 10 10 10 10 10 11 01 01 01 01 01 01 01 01 01 01 01 01 2003 2004 Summer 2004 Spring 2004 20.0 35.0 30.0 15.0 -3 25.0 20.0 10.0 TPM pg m 15.0 10.0 5.0 5.0 0.0 0.0 19 20 21 22 23 24 25 26 27 28 29 30 31 1 26 27 28 29 30 1 2 3 4 5 6 7 07 07 07 07 07 07 07 07 07 07 07 07 07 08 04 04 04 04 04 05 05 05 05 05 05 05 2004 2004 TPM Results MERCYMS

  16. Autumn 2003 Winter 2004 10 10 Day Day 8 8 Night Night -3 -3 6 6 RGM pg m RGM pg m 4 4 2 2 0 0 22 23 24 25 26 27 28 29 30 31 1 11 19 20 21 22 23 24 25 26 27 28 29 30 10 10 10 10 10 10 10 10 10 10 01 01 01 01 01 01 01 01 01 01 01 01 Spring 2004 Summer 2004 20 10 Manual Manual 16 8 -3 Automatic Automatic -3 12 6 RGM pg m RGM pg m 8 4 4 2 0 0 26 04 28 04 30 04 02 05 04 05 06 05 08 05 19 07 21 07 23 07 25 07 27 07 29 07 31 07 02 08 00:00 00:00 00:00 00:00 00:00 00:00 00:00 00:00 00:00 00:00 00:00 00:00 00:00 00:00 00:00 MERCYMS RGM Results

  17. MERCYMS Summary of results Average mercury concentrations at Cabo de Creus Season TGM TPM Manual Autom DGM RGM RGM -3 -3 -3 -3 -3 ng m pg m pg m pg m ng m Autumn 1.64 9.6 2.3 - - Winter 1.47* 9.1 0.2 - - Spring 2.00* 9.5 1.2 1.9 - Summer 2.13* 11.2 1.3 4.8 24 *0.5 h average values collected within the wind sector 300-90o at wind speeds > 4 m s-1

  18. Mercury in precipitation-examples from Swedish network • Monthly sampling period • Bulk samplers • HCl preservatives added • 2 samplers in parallel • Analysis using CVAFS • 4 stations in Sweden, 1 in Finland (1999) • 3 stations in Sweden, 1 in Finland (2001) • 2 stations in Sweden, 1 in Finland (2004) • 1 station in Sweden, 1 in Finland (2005)

  19. Wet deposition

  20. Precipitation amounts using different collectors 100 EMEP 90 Hg bulk 80 HM bulk 70 60 50 40 30 20 10 0 01 03 05 07 09 11 Total Total Total Total Total Total

  21. Investigation of sampler design and collection efficiency • Investigation conducted at 33 stations in Sweden • Parallel samplers at all sites • Bucket and funnel in summer and “snow sack” during winter

  22. Precipitation amounts at different stations and %difference between 2 funnel & bottle collectors

  23. Precipitation amounts at different stations and %difference between 2 snow sack collectors

  24. Precipitation measured with 4 different samplers

  25. Precipitation sampling • Occasional large variability in individual samples between different types of samplers • Not systematic • “Snow sack” samplers give higher total precipitation amounts • Need standardised methods and/or correct to common precipitation fields

  26. Deposition in forested ecosystems OF 10 g/km2 Litterfall 20 g/km2 TF 20 g/km2 Reemission ? g/km2 Runoff 2 g/km2 Total deposition = wet + dry-reemission = Throughfall + litterfall - reemission = 40 g/km2

  27. Deposition of total mercury in forests

  28. Deposition in relation to critical loads • 2 different critical load models for Hg, one based on limitations in fish concentrations, the other on accumulation in soil • For calculating accumulation in soils, need total deposition • EMEP measurements only wet deposition, total deposition 2-4 times higher in forested areas • Reemissions unknown • Models include the above but very little data available to verify and test model output.

  29. Final words • A successful implementation of protocols on mercury will require larger efforts on measurements from most countries • Air concentrations (species), wet deposition, total deposition in forested ecosystems, air surface exchange • Super stations are recommended (see conclusions from previous TFM&M meetings and CLRTAP Heavy metal workshops) • Currently no EU funded research projects on atmospheric mercury - FP7? • EU directive may lead to better situation

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