Wet Deposition of Mercury In The U.S. Results from the NADP Mercury Deposition Network, 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?

 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 Speciatio n Atmospheric Transport 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 Atmospheric deposition 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 Hg o RGM Hg p RGM

Atmospheric Mercury Species Abundance Hg 0 – Elemental Mercury RGM – Reactive Gaseous Mercury Hg p – Particulate Bound Mercury Typical Atm. Mercury Species Abundance ng/m 3

How Mercury is Wet Deposited oxidation Hg o 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

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 DEPOSITION Modeled and Measured Seigneur and others, ES&T, 2004, V38,

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, 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-5 Gold-Trap Method for Hg 0 i

Automated Hg Speciation Methods are: -Lab Tested -Widely used -QA challenged -EPA Accepted PHg RGM Hg 0

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, 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?