Trends of Atmospheric POPs Deposition to the Great Lakes

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Trends of Atmospheric POPs Deposition to the
Great Lakes
P. Blanchard1, C.V. Audette1, S. Backus1, K.A.
Brice1, F.A. Froude1, M. Neilson1, M. L.
Hulting2, T. Nettesheim2, I. Basu3 and R. A.
Hites3 1 Environment Canada - Science and
Technology Branch 2 Environmental Protection
Agency-Great Lakes National Program
Office 3Indiana University
www.msc.ec.gc.ca/iadn/
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Integrated Atmospheric Deposition Network

• Publish loadings report every two years for 25
  compounds.
• Last report 2004 included data to 2000
• Next report 2006 data to end of 2004

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Atmospheric Deposition Processes
Wet Deposition
Dry Deposition
Precip x Rp
Filter x Vd

kol(PUF or XADxRT) kolPOPwater H
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PAHs and Trace Metals

• Wet deposition important.
• Lower MW PAHs absorption
• Higher MW PAHs partition to aerosols, dry
  deposition becomes more important
• As, Cd, Pb, Se measured at Canadian sites
• Rp from at station to overlake

Precip x Rp
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PAHs Wet Deposition BaP
Eagle Harbour
Burnt Island
Sleeping Bear Dune
Point Petre
Sturgeon Point
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Metals Wet Deposition Pb
Burnt Island
Point Petre
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Dry Deposition
Filter x Vd

• Vd 0.2 cm/s
• Zhang et al. (2001) size-segretated
  resistance-analogy model.
• Considers brownian diffusion, impaction,
  interception, sedimentation, particle rebound and
  particle growth under wet condition, 26 land-use
  categories.
• Size distributions
• Metals Impactor experiments at Point Petre
  (2002) (H.Wong, EC)
• PAHs Offenberg and Baker (1999)

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Dry Deposition Lake OntarioPreliminary Results
Lead
BaP
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Atmospheric Deposition Processes
Precip x Rp
Filter x Vd
kol(PUF or XADxRT) kolPOPwater H
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OC Pesticides and PCBs

• Gas exchange important
• Wind speed from at station to overlake
• Updated Hs
• Latest EC and EPA water concentration data

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a-HCH Absorption and Volatilization
Eagle Harbour
Burnt Island
Sleeping Bear Dune
Point Petre
Sturgeon Point
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Suite PCB Absorption and Volatilization
Eagle Harbour
Burnt Island
Sleeping Bear Dune
Sturgeon Point
Point Petre
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Gas Exchange Uncertainty
PCBs

• Hoff,1994 uncertainty of 50-150
• Bruhn et al.,2003 Q fw/fa
• (1-4(eCw2eH2))Q2-2Q(1-4eCa2)0
• eCa,eCw0.15 (0.25) eHLC0.3
• Volatilization (95 CI) if Q3.1 (Q4.7)

a-HCH
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Summary

• Wet deposition for PAHs and trace metals no
  trend
• Dry deposition velocity improvements
• Banned pesticides decreasing absorption trends
  tending towards equilibrium for all Lakes
• PCBs decreasing absorption tending towards
  equilibrium for Huron and Superior
• Gas Exchange uncertainty
• Legacy chemicals, urban impacts and emerging
  substances

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Acknowledgements

• EC and USEPA GLNPO for funding
• American and Canadian IADN Field and laboratory
  personnel!
• EC Bob Vet, Leiming Zhang, Julie Narayan, Henry
  Wong