Analysis of Atmospheric Mercury Speciation at HEDO Station, Okinawa

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Analysis of Atmospheric Mercury Speciation at
HEDO Station, Okinawa
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• Beijing

Shanghai
Hong Kong
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Anthropogenic Sources of Hg in 1995Pacyna et
al.- 2003 LRT Workshop

• Hg0 Ton/yr

Hg(II) Ton/yr
PHg Ton/yr
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Atmospheric Mercury Nomenclature

• Hg0 or GEM - Gaseous Elemental Mercury
• PHg Particulate Bound Hg (2.5 um)
• RGM - Reactive Gaseous Mercury - HgCl2?

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Instrument Description Atmospheric Mercury
Speciation
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Measurement vs Model

• Hedo Mean Hg0 2.04 ng/m3
• Hedo Max Hg0 5.47 ng/m3

Seignuer et al., 2004 EST 38555
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Measurement vs Model
Hedo Mean Hg0 2.04 ng/m3 Hedo Max Hg0 5.47
ng/m3
Dastoor and Larocque., 2004 Atmos. Env. 38147
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Measurement vs Model
Hedo RGM Mean 4.51 pg/m3 Hedo RGM Max 32.5
pg/ m3
Seignuer et al., 2004 EST 38555
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Measurement vs Model
Hedo PHg Mean 3.05 pg/m3 Hedo PHg Max 16.5
pg/ m3
Seignuer et al., 2004 EST 38555
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Comparison of Model and Observation of Hg0
Seignuer et al., 2004 EST 38555
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Beijing - China
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LOCAL?
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High Hg0 and CO often begins with rainfall note
also SO4 washout
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Evidence for Biomass Signal?Organic Rich
Sulfate Low
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Evidence for Biomass Signal?Organic Rich
Sulfate Low
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NAAPS Forecast
Smoke
SO4
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No clear observation of a dust event
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NAAPS Forecast over predicts
SO4
Dust
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Low-Level RGM and PHg Emissions results in faster
local removal by Dry Deposition?

• lt 50 Meter Total Hg Emissions (tons/yr)

gt150 Meter Total Hg Emissions (tons/yr)
Pacyna et al.- 2003 LRT Workshop
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Why are RGM values lower than models and
uncorrelated with pollution compounds?

• Hypothesis RGM from anthropogenic emissions are
  preferentially reduced to Hg0 via the complex
  chemistry of S02 gt S03 gt S04 during cloud droplet
  formation and evaporation

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What controls RGM Photochemistry?
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Hg0
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Future Data Interpretation

• More refined analysis of each event with respect
  to AMS and meteorology
• Support hypothesis that SO3 is preferentially
  converting emitted Hg(II) to Hg0 during cloud
  water processing (formation/evaporation)
• Rule out local impacts

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Future Need Hg Deposition Data!

• Inventories coupled to models predict high
  deposition in NW Pacific due to RGM and PHg
  emissions
• Measurements needed to confirm at HEDO and
  elsewhere
• Should be event based at least for intensive
  study periods
• What Hg deposition data is currently being
  collected or published?

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Continuous Mercury Speciation at HEDO

• Depending on support-level we can do complete
  Automated Hg speciation system or only total
  gaseous Hg with select intensive studies