Wet Deposition of Mercury In The US

Wet Deposition of Mercury
In The U.S.
Results from the NADP Mercury Deposition Network, 19962004
David Gay
Illinois State Water Survey, Champaign, IL,
dgay@uiuc.edu
217.244.0462
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).
From Ellen’s Presentation…..
Mercury Emissions Contribute to Exposure to
Mercury
Lake
Ocean
Atmospheric
deposition
Fishing
•
commercial
•
recreational
•
Humans
and
subsistence
wildlife
affected
Emissions
to the Air
Emissions
and
Speciatio
n
•
•
Wet and Dry
Deposition
methylation
methylation
Mercury transforms into methylmercury in
soils and water, then can bioaccumulate
in fish
Atmospheric
Transport and
Deposition
Ecosystem Transport,
Methylation, and
Bioaccumulation
primarily by
eating
contaminated
fish
Consumption
Patters
Impacts
• Best documented
impacts on the
developing fetus:
impaired motor and
cognitive skills
• Possible
cardiovascular,
immune, and
reproductive system
impactsHuman
Exposure
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%).
How Mercury is Wet Deposited
RGM
Hgp
Hgo
Hgp
RGM
Atmospheric Mercury Species Abundance
Hg0 – Elemental Mercury
RGM – Reactive Gaseous Mercury
Hgp – Particulate Bound Mercury
1.4-1.8
ng/m3
Typical Atm. Mercury
Species Abundance
How Mercury is Wet Deposited
Hgo
oxidation
RGM
† Picture of the sampler here
MDN Sites
(2005)
What the Data Show….
Mercury Concentrations in Precipitation
2003
Mercury Concentrations in Precipitation
Mercury Wet Deposition, 2003
Conc. (ng/L)
Regional Average Mercury Concentrations
18.0
16.0
14.0
12.0
10.0
8.0
6.0
4.0
2.0
0.0
Win
Spr
Sum
Season
MW
Fall
NE
NW
SE
SW
Regional Average Mercury Deposition
35.0
Dep. (ug/m2)
30.0
25.0
20.0
15.0
10.0
5.0
0.0
Win
Spr
Sum
Season
MW
Fall
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)
Seigneur and others,
ES&T, 2004, V38, 555-569
WET DEPOSITION
Modeled and Measured
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
Modeling Deposition
DRY DEPOSITION
Seigneur and others,
ES&T, 2004, V38, 555-569
Plans for Dry Deposition
Manually Operated Mercury Species Sampling
Monitoring station for manually-operated
sampling system
EPA Method IO-5
Gold-Trap Method for Hg0 i
Sampling box for
manual system
Automated Hg Speciation
PHg
RGM
Hg0
Methods are:
-Lab Tested
-Widely used
-QA challenged
-EPA Accepted
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, 19962004
David Gay
Illinois State Water Survey, Champaign, IL,
dgay@uiuc.edu
217.244.0462
Anthropogenic Sources of Mercury
†
†
Coal combustion
Incineration
„
„
„
†
†
†
†
†
†
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
„
„
„
„
„
†
Medical
Trash
Cremation
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?