David Gay Illinois State Water Survey, Champaign, IL, dgay@uiuc 217.244.0462
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Transcript of David Gay Illinois State Water Survey, Champaign, IL, dgay@uiuc 217.244.0462
Wet Deposition of Mercury In The U.S.
Results from the NADP Mercury Deposition
Network, 1996-2004
David Gay
Illinois State Water Survey, Champaign, IL,
Goal of this Presentation….
To introduce you to the Mercury Deposition Network.
Show what we know about the deposition of mercury.
What is the Mercury Deposition Network?
A Cooperative Research Program
Part of National Atmospheric Deposition Network 92 sites Federal, State, Local and Tribal Governments
members, private organizations Measuring wet deposition of mercury
Our Charge: to determine if trends exist in wet deposition of
mercury over time
Federal Agency Members
University Members
Tribal Organizations
Other Organizations
and States
Why monitor Mercury in Precipitation?
Why monitor Mercury in Precipitation?
Atmospheric transport and deposition is the dominant pathway to most aquatic ecosystems.
Between 50 and 75% of the mercury input to lakes and streams is by wet deposition (probably less in the West).
Mercury Emissions Contribute to Exposure to Mercury
• The primary pathway of human exposure to mercury in the U.S. is through eating contaminated fish.• Power plants emit approximately 48 tons of mercury and are the largest source of mercury emissions in
the U.S. (approximately 41%).
Wet and Dry Deposition
Emissions and
Speciation
AtmosphericTransport and
Deposition
Ecosystem Transport, Methylation, and Bioaccumulation
Consumption Patters
Human Exposure
Fishing• commercial• recreational • subsistence
Mercury transforms into methylmercury in soils and water, then can bioaccumulate
in fish
Atmosphericdeposition
Impacts • Best documented
impacts on the developing fetus: impaired motor and cognitive skills
• Possible cardiovascular, immune, and reproductive system impacts
Emissions to the Air
Humans and wildlife affected primarily by eating contaminated fish
Ocean
methylation
Lake
methylation
From Ellen’s Presentation…..
How Mercury is Wet Deposited
Hgo
RGMHgp
Hgp
RGM
Atmospheric Mercury Species Abundance
Hg0 – Elemental Mercury
RGM – Reactive Gaseous Mercury
Hgp – Particulate Bound Mercury
Typical Atm. Mercury Species Abundance
1.4-1.81.4-1.8ng/mng/m33
How Mercury is Wet Deposited
oxidationHgo
RGM
Picture of the sampler here
MDN Sites(2005)
What the Data Show….
Mercury Concentrations in Precipitation2003
Mercury Concentrations in Precipitation
Mercury Wet Deposition, 2003
Regional Average Mercury Concentrations
0.02.04.06.08.0
10.012.014.016.018.0
Win Spr Sum Fall
Season
Con
c. (n
g/L)
MW NE NW SE SW
Regional Average Mercury Deposition
0.0
5.0
10.0
15.0
20.0
25.0
30.0
35.0
Win Spr Sum Fall
Season
Dep
. (ug
/m2)
MW NE NW SE SW
Possible Reasons for High Mercury Deposition in the Summer
Higher rainfall amounts Higher temperatures Higher oxidant levels Southerly air flow Strong thunderstorms Higher emissions (ocean)
WET DEPOSITIONModeled and Measured
Seigneur and others, ES&T, 2004, V38, 555-569
Trends In Wet Deposition
Trends
Seasonal Kendall and Sen’s (non-parametric)
5 years of data for 4 seasons Run seasonally Very small, slight changes, but
none significant
Dry Deposition
Measurements of Dry Deposition
?•Very few measurements•Very few calculations of dry deposition
DRY DEPOSITION
Seigneur and others, ES&T, 2004, V38, 555-569
Modeling Deposition
Sampling box for
manual system
Monitoring station for manually-operated sampling system
Plans for Dry Deposition Manually Operated Mercury Species
Sampling
EPA Method IO-5Gold-Trap Method for Hg0 i
Automated Hg Speciation
Methods are:-Lab Tested-Widely used-QA
challenged-EPA Accepted
PHg
RGM
Hg0
Future Directions for MDN
Expand network coverage in the western U.S., southern Canada, and Mexico
Provide “before” and “after” mercury deposition data related to future controls on mercury emissions
Develop better methods to monitor dry deposition of mercury
Monitor additional trace metals
Wet Deposition of Mercury In The U.S.
Results from the NADP Mercury Deposition
Network, 1996-2004
David Gay
Illinois State Water Survey, Champaign, IL,
Anthropogenic Sources of Mercury
Coal combustion Incineration
Medical Trash Cremation
Industrial emissions (chlor-alkali) Cement production (Hg in lime) Hg use in gold and silver mining (amalgam formation) Mining of Hg Automobile Recycling Mercury in Landfills
Fluorescent lamps dental amalgams (also in sewers) Thermometers Batteries Discarded electrical switches
Others will surface Other carbon fossil fuels (gas/oil/diesel)?
Natural Sources of Mercury
Volcanoes (St. Helens) Naturally enriched ores/soils
Plate tectonic boundaries Cinnabar (HgS), taconite, others
Soils and rocks (0.5 ppm in crust) Evaporation
Soils Fresh water and OCEANS
Natural forest fires (wood fire places?) Mine tailings Tree bark, volatilization from rocks?
Many Mercury Sources
Coal combustion Incineration Industrial emissions
(chlor-alkali) Cement production
(lime) Hg use in mining and
Mining of Hg Automobile Recycling
Mercury in Landfills Fluorescent lamps dental amalgams (also
in sewers) Thermometers, batteries electrical switches
Taconite
Volcanoes (St. Helens) Enriched ores/soils
Tectonic (plate) boundaries
Cinnabar (HgS), taconite, others
Soils and rocks (0.5 ppm in crust)
Evaporation Soils Fresh water and Oceans
Forest fires (wood fire places?)
Tree bark, volatilization from rocks?