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ATMOS 397GATMOS 397GBiogeochemical Cycles and Global ChangeBiogeochemical Cycles and Global Change

Lecture 22: MercuryLecture 22: Mercury

Don WuebblesDon Wuebbles

Department of Atmospheric SciencesDepartment of Atmospheric Sciences

University of Illinois, Urbana, ILUniversity of Illinois, Urbana, IL

April 24, 2003April 24, 2003

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MercuryMercury

Mercury is a volatile naturally occurring toxic element with unique properties.

It is the only common metal that is a liquid at ordinary temperatures.

The primary ore is cinnabar (HgS).

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Element of destruction. Mercury from natural and man-made sources is released into air, soil, and water. Bacteria convert mercury to methylmercury, which accumulates in fish that are eaten by humans and may cause adverse health effects.

Increase in environmental burden has led to major local, regional and global concerns.

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Food Chain in the Great Lakes

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Uses of MercuryUses of Mercury

In the making of thermometers, barometers, diffusion pumps and many other instruments.

In making mercury-vapor lamps and advertising signs

In electrical appliances

In making pesticides

In production of caustic soda and chlorine

In dental preparations

In Antifouling paint

in Batteries

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Compounds of mercury in useCompounds of mercury in use

HgCl2 (corrosive sublimate – a violent poison),

Mercurous chloride (Hg2Cl2, calomel, occasional still

used in medicine),

Mercury fulminate (Hg(ONC)2) a detonator widely used

in explosives, and

Mercuric sulfide (HgS, vermillion, a high-grade paint

pigment).

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Mercury is a naturally occurring element that is present in trace amounts throughout the environment. Much of it is isolated in coal and other geological deposits.

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North Carolina

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U.S. Sources of Mercury

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Total Mercury emissions in 1992 ( T yr -1)World Total : 2199

North America Central & South America

Western Europe Eastern Europe and former U.S.S.R

Africa Asia

Oceania

Data source: Pirrone, Keeler and Nriagu, Atmos. Environ. Vol. 30, No. 17, pp. 2981 – 2987, 1996

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Comparison of North America and Asia Mercury Emissions in 1992

0

50

100

150

200

250

300

350

400

450

Tota

l Mer

cury

Em

issi

on (

Ty-1

)

North America

Asia

Data source: Pirrone, Keeler and Nriagu, Atmos. Environ. Vol. 30, No. 17, pp. 2981 – 2987, 1996

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Total Global Mercury Emission

1000

2000

1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992

Year

To

tal

Mer

ccu

ry E

mis

sio

n (

Tyr

-1)

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1995 Total Global Mercury Emission Inventory

Source : Global Emission Inventory Activity (GEIA)

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Mercury in the environment is recycled through a biogeochemical cycle.

The cycle has six major steps:

Degassing of mercury from rock, soils, and surface waters, or emissions from volcanoes and from human activities;

movement in gaseous form through the atmosphere;

deposition of mercury on land and surface waters;

conversion of the element into insoluble mercury sulfide;

precipitation or bioconversion into more volatile or soluble forms such as methylmercury (MeHg);

Either re-entry into the atmosphere or bioaccumulation in food chains

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Transformation and Chemistry of Atmospheric Mercury

Ref: Schroeder and Munthe, Atmos. Environ. Vol. 32. No.5 pp. 809 – 822, 1998

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Mercury exists in three oxidation states: 0, +1 and +2. In the atmosphere, exists

predominantly in the elemental form with oxidation state 0 (Hg (0) or Hg0) and in the oxidation state +2 (Hg (II)) with oxidation state +1 very rare if it exists at all.Hg(0) is stable with a

lifetime in the range 0.5 – 2 years and is thus capable of distribution on a global scale. Hg(II) and H(p) are more

readily deposited on local to regional scales via wet or dry processes.

Ref: Lindqvist and Rodhe, Tellus (1985), 37B, 136 - 159

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Atmospheric Mercury is a global pollutant

because of its relatively long atmospheric lifetime of 0.5 to 2.0 years.

Hg in the environment is deposited and re-volatilized many times, with a residence time in the atmosphere of at least a few days. In the volatile phase it can be transported hundreds of kilometers.

Tokos, J.J. Atmos. Environ. Vol. 32, No. 5, pp. 823 – 827, 1998

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Biogeochemical Cycle of Mercury

Reference: Bullock, O. R. Fuel Processing Technology 65 –66 (2000) 459 - 471

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Typical Concentrations of Atmospheric MercuryGlobally, average concentration: 2 – 10*

USSR : 10 *

Japan, non-industrial regions : 0 – 14*

Seoul, Korea 1.4 – 9.2#

Pallas, Finland 2.07**

Italy, Industrial Area 8.2 – 86.3%

Here in U.S.

Denver: 2.0 – 5.0*

Florida, rural 3 – 300%

San Francisco: 0.5 – 50.0*

New York City: 1.0 – 41.0*

Indoor New York: 6.5 – 523$

Chicago (particle-bound Hg): 3 – 39*

NOTE: All concentrations in ngm-3 (nanogram per cubic meters)*http://www.speclab.com/elements/mercury.htm

**Berg, et al., Atmos. Environ. 35 (2001) 2569 - 2582

# Kim & Kim, Atmos. Environ. 35 (2001) 49-59

$Carpi and Chen, Environ. Sci. Technol. 2001, 35, 4170 – 4173

% Lindqvist,Tellus (1985), 37B, 136 – 159

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Why do we study Mercury in the environment?

Global concerns about atmospheric mercury stems from its detrimental health effects in humans. Mercury,

Deteriorates nervous system

Impairs hearing, speech, vision and gait

Causes involuntary muscles movements and skeletal muscle degeneration

Corrodes skin and mucous membrane

Renal toxicity

Nephritis – inflammation of the kidney

Elevated blood pressure

Dermatitis – skin inflammation

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