Trends of Mercury Flow over the USwith Emphasis on Florida

Background

Goal:

• Develop a trend database for mercury flow over the US. Special emphasis on:– Mercury flow through fuels

– Time epoch 1980-2000 and

– Geographic region of Florida.

Approach:

• Materials flow methodology. Mercury budgeting from the production (mining) through processing, consumption to the disposal in air, land and water.

Trend of the US ‘Apparent’ Mercury Supply, 1970-1998

• Apparent supply is = primary and secondary production + net imports + gov. stockpile to

Sznopek and Goonan, 2000

Mining Production Consumption

Recycling

Stock

Mine Production Secondary Production

Net Import

Stock Release

Mercury in consumer goods and coal

• 1940-1970 mercury in industrial goods was not well categorized.

• 1970-1990 electrical and electronic instruments category (including batteries) was the dominant Hg industrial consumer.

• Hg consumption for industrial goods was reduced from around 2000 Mg/yr in 1980 to about 500 Mg/yr in 1995.

Mercury in consumer goods and coal

0

500

1,000

1,500

2,000

2,500

3,000

1940 1945 1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000

Hg

, Mg

/yr

Coal Mined Clor-alkaliC PaintC Lab useC PharmC

AgricultureC ElectricalC ControlC DentalC OtherC

Mercury in US consumer goods and coal in 1990s

• Chlor-alkali and electrical and electronic instruments are still dominant users of mercury.

• Coal mined and consumed in US contributes

Mercury in consumer goods and coal

0

200

400

600

800

1,000

1990 1991 1992 1993 1994 1995 1996

Hg

, M

g/y

r

Coal Mined Clor-alkaliC PaintC

Lab useC PharmC AgricultureC

ElectricalC ControlC DentalC

OtherC

Mercury Releases to the Atmosphere, 1995Total = 144 Mg/yr

Coal, 66

Oil, 10

Mun. Waste, 27

Med. Waste, 14.6

Haz. Waste, 6.4

Cement, 4.4

Other, 1.3

Industrial, 13.9

Atmospheric Emissions of Mercury

EPA Mercury Study Report to Congress, 1997

Mercury Flow through Coal over the US

• Introduction

• Approach

US Coal Production by Region

• Coal production in the US occurred over five major producing regions.• The coal production over the eastern US has remained roughly constant throughout the century.• The sharp increase since the 1980s is due to the addition of western coal.

Mercury Content of US Coals

• Each coal producing region has a well defined range of coal mercury content.

• Evidently the pattern of coal mercury content is highly variable.

• USGS has an extensive database of coal mercury content covering most of the regions.

Mercury Mobilization by Coal Producing Region

• The mercury mobilization follows the pattern of national coal production.

• Since the beginning of the century there was a slight decline (from 0.18 to 0.14 ppm) of average coal mercury concentration due to shifts in regional production.

• There was a sharp rise since the 1980s. In 1995 the mercury mobilization by coal was 144 Mg/yr.

• This constitutes an upper bound on coal mercury emissions to the atmosphere.

Average Hg in US Coal, ppm

Mercury Flow through Coal in Florida

• Introduction

• Approach:– Determine the origin of the coal used in Florida

– Assign mercury concentration to each coal source

– Estimate the fraction of Hg retained at the mines and fly ash (25-50%)

– Calculate the coal mercury emission rate for 1985 and 1998.

Origin of Coal in Florida

Coal Origin:

• In 1985, the coal consumed in Florida was from Eastern Kentucky, Western Kentucky and Illinois

• In 1998, the coal consumed in Florida was more diverse. About 20% originated from Wyoming, West Virginia, Virginia

Origin of Coal Hg in Florida

Coal Hg Origin:

• Coal mercury in Florida is dominated by Eastern Kentucky coal with contributions from Western Kentucky and Illinois

• In 1998, the coal mercury included contributions from Wyoming, West Virginia, Virginia

Approximate Trend of Mercury in Coal Consumed in Florida

• The coal mercury content in Florida exhibits a slow rise between 1960 and 1980, sharp rise between 1980 and 1990, followed by constant levels in the 1990s.

• The 1998 estimated mercury content of mined coal used in Florida was about 4 Mg/yr.

• For the approximate historical trends an average coal mercury concentration of 0.15 ppm was assumed.

• The mercury emitted to the atmosphere is only a fraction (0.5-0.75) of the mined coal mercury due to the retention at the mines (coal washing) and at the combustion plant as fly ash.

• The estimated coal mercury emission to the atmosphere in the 1990s was about 2-3 Mg/yr.

Summary and Plans

Summary of Activities• Studied and evaluated the recent literature on mercury flows over the US.

• Begun reconstruction of the coal mercury flow over the US. It is found that the relative contribution of coal mercury compared to other sources has been increasing over the 1990s.

• The coal mercury emission trends were crudely estimated, showing a sharp rise since the 1980s and leveling off in the 1990s.

Immediate Plans• Compile coal distribution and mercury content data.

• Estimate oil mercury flows.

Multimedia Mercury Flow, 1996 (incomplete)

• Tentative multimedia flow diagram of mercury for the US.

• Neither the flow chart, nor the flow rates and stocks are fully developed

Supply Production Consumption

Recycling

Air Land Water

Hg Stocks

76

446

144 295

Export/Import Export/Import

372

Sznopek and Goonan, 2000

Alternative Mercury Flow Diagram (In Progress)

Supply Production Consumption

Recycling

AirLand Land

Fuels Industrial

29553

446

372