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What is Mercury?

planet 1) The first planet in our solar system
greek god 2) A Greek god with wings on his feet
ford car 3) A model of car, produced by Ford Motor Company
mercury element

4) Mercury (chemical symbol Hg) is also called "quicksilver" because it is one of the few metals that is liquid at room temperature.




5) A global toxic pollutant

Answer. 4 and 5


mad hatter cartoon

Mad-hatter from "Alice in Wonderland."Where did the expression "Mad-As-A-Hatter" come from? (image linked)

Most of us are familiar with mercury as the silver liquid found in old style thermometers. Mercury has unique chemical properties because it is a liquid metal. Like most metals that are solid, it easily conducts electricity. But because it is a liquid and lighter in weight than a solid, it can be used in special circumstances to "flow" a current of electricity between switches. It was once the common component of industrial, automotive, and household batteries.

Mercury is also a fungicide. It was added to paint and cleaning products to help lengthen their shelf life.

Because of its unique properties, mercury has been used in many different applications including devices such as thermometers, thermostats, fluorescent lights, and switches. It is also has been used in paints, preservatives, and some pesticides.


Why Is Mercury one of the Nasty 9?

mercury accumulation
Investigate the health risks associated with mercury. (image linked)

Mercury is a heavy metal and is poisonous to humans as well as many other living organisms. It is also extremely volatile, meaning it can easily be converted from its liquid form into a toxic gas. Mercury is a global contaminant because it is toxic, does not break down in the environment and can build up in living things. In its vapor or gaseous form, mercury can be carried long distances on wind currents, staying in the atmosphere for long periods of time.

Mercury vapor is extremely dangerous to humans, especially to children. Children are most sensitive to mercury poisoning during early development to age six. Children playing with mercury can be seriously poisoned if they breathe the invisible mercury vapors.

Mercury can also affect the unborn children. Some organic mercury compounds such as methylmercury are known to interfere with fetal development, causing birth defects in children born of exposed mothers.

Just how toxic is mercury. According to the United State Environmental Protection Agency, one gram of mercury per year is enough to contaminate all the fish in a lake with surface area of 20 acres.


Sources of Mercury In Lake Superior

The use of mercury for industrial and home use has been significantly reduced as we have learned more about its affect as a persistent toxic chemical.

Mercury still threatens the Lake Superior environmental and human health. Which of the following sources of mercury do you think is the greatest source of mercury contamination for Lake Superior Basin?

mercury element
Mercury Spill? Learn what to do to protect yourself and the environment.

Mercury is the liquid used inside many older style glass household and medical thermometers. We can be exposed to liquid mercury when a thermometer breaks, either by touching the liquid or inhaling mercury as it evaporates. The greatest danger is from mercury gas since as much as 80 percent of it may enter the bloodstream if it is inhaled.

While the amount of mercury in an individual thermometer may seem small, the total amount contained in all of the old style mercury thermometers still being used with the Lake Superior Basin is significant.

Becton Dickenson, a thermometer manufacturer, estimates that 4.3 tons of mercury is contained in the thermometers sold every year to hospitals and consumers in the United States. This is less than one-percent of all of the mercury produced in the United States each year, but it is a source that we can help reduce and eliminate by choosing safer alternatives.

no mercury themometer

Non-mercury containing thermometers, such as digital thermometers, are becoming more popular. Is there still an old style mercury thermometer in your home? Consider a safer alternative, like a non-mercury thermometer.

mercury info standDon't throw the old mercury thermometer away! When mercury thermometers are disposed of in the trash, they can break introducing mercury into the environment. Even greater environmental and health risks occur if the old thermometer is disposed of by burning in an incinerator. Dispose of the old thermometer properly to avoid risks to your family and the environment.


mouth fillings

Amalgam Dental Fillings
An amalgam is an alloy of mercury created by mixing approximately equal measures of mercury and other metals. Dentist use amalgams because they are cheap, easy to use, durable. Amalgam filling material must be disposed of properly to prevent mercury from entering the environment.


fish chart
Investigate more about Mercury in fish.

Much of the mercury that escapes into the environment will change into methyl mercury and eventually be eaten by fish. Bacteria can convert mercury into one of the most toxic forms, methyl mercury. This organic compound is extremely soluble in water and it gets into the food chain poisoning fish and other animals. Over time, methyl mercury bioaccumulates in larger fish, making them unsafe to eat.

Mercury-contaminated fish are the most likely source of mercury poisoning in animals and humans.

Wildlife such as loons, eagles, otters, mink and ospreys eat large quantities of fish. Any mercury contamination in the fish they eat will bioaccumulate in their tissues.

old fish photo
Are there advisories about eating mercury-contaminated fish in your area? Investigate how to protect your health by following the advisory advice.

Research indicates that loons in the Lake Superior Basin may be accumulating mercury to the point that it impairs reproduction. Excess of mercury can lead to neurological impairment, especially damaging for wildlife predators that rely on their speed and coordination to obtain food.

Unfortunately, wildlife cannot change their eating habits in order to avoid mercury contamination, but we can. Learn about mercury advisories for fish consumption and follow them!



Kick Mercury out of your house and school!

Older thermostats, light fixtures, electrical switches
As a highly conductive "liquid metal", mercury seemed a great choice for electrical devices. Most of these older devices contained a much as 3 grams of mercury! If these devices are not disposed of properly, the mercury they contain can enter the environment.


lamp lamp2
Newer mercury lamps are energy efficient and great environment choices as long as they are managed and recycled properl. to keep their mercury out of the environment.



burning barrelBurning Barrels
Burning waste and garbage in burning barrels and home incinerators releases mercury and other critical pollutants into the atmosphere where we can directly inhale these poisonous chemicals. Once in the atmosphere, they can be deposited on Lake Superior through precipitation. If you have a burning barrel in your backyard and use it, it is creating more airborne pollution for its size than modern industrial smokestacks! Burning barrels make a poison linked to cancer and hormone disruption.


paint bucket and brushPaints, fungicides, household products
Mercury is a good disinfectant and fungus killer so it was considered a beneficial additive to many household products including paints and fungicides. Industries that produced these products voluntarily banned mercury-containing paints and fungicides in the early 1990s as the dangers of mercury to humans and the environment became better understood. Supplies of old paints and fungicides that contain mercury, are still stored on farms, businesses, and homes throughout the Basin.

sweep logoThe only save way to dispose of these products, to prevent mercury from entering the environment, is to collect them and dispose of them through a certified Clean Sweep Program. Does your community have a Clean Sweep Program that collects household hazardous wastes? Find out at Earth 911.


Got batteries. Almost every portable device we use, from cell phones to toys, needs them. Before 1996, most batteries contained mercury. When they were disposed of in the trash or burned, mercury entered the environment.

In 1992 and 1993, the use of mercury in round cell, alkaline, and zinc carbon batteries was discontinued, resulting in a 9. percent reduction in mercury from batteries. Batteries still contain some mercury and they should be disposed of in a proper battery disposal facility.


power plantFuel combustion and power plant emissions
Small amounts of mercury are naturally found in coal and oil, which are released when burned. Investigate what Lake Superior region power companies like Xcel Energy are doing to reduce mercury emissions.

We depend on electrical power to run everything from computers to refrigerators. Consider how different your life would be without electricity.

Many electrical power plants burn combustible fuels like coal or oil, to produce steam that turns turbines that produces electricity that our communities need run.

Fuel combustion, particularly burning coal, releases new mercury and dioxin into the atmosphere. Fuel combustion is estimated as the second largest source of mercury emissions within the Lake Superior Basin, but it is a relatively small source of dioxin.

Around the Lake Superior Basin, several types of industries burn fuel for energy. Private and public electrical utilities such as Ontario Hydro and Xcel Energy that burn coal plus mixtures of other combustible fuels at their power plants to create electricity for community needs. The iron ore taconite industry burns fuels at its power plant to create the energy needed to process taconite ore. Pulp and paper mills burn by-products of the paper making process.

The EPA is regulating and reducing power plant mercury emissions for the first time ever. EPA issued the Clean Air Mercury Rule on March 15, 2005. Learn more about this rule and its effect on mercury.


Copper miners in Michigan's Upper Peninsula Central Mine, ca. 1880's.

Mining and Processing
The Lake Superior Basin is rich with copper and iron ore deposits. Native Americans "mined" copper from shallow pits centuries before the first Europeans realized the land's mineral wealth.

By the 1880's, copper and iron mining were among Lake Superior Basin's biggest industries. The jobs and income that mining brought helped to grow and support the region's communities. While mining may have been an economic boom, the process of smelting and processing the ore also released toxic mercury into the environment.

Postcard of the smelter at Houghton, MI

By 1995, most of the iron and copper mines and smelters within the Lake Superior Basin were closed. There was still plenty of demand for ore, but either the ore was mined out or other cheaper sources could be found elsewhere. Mining could no longer sustain many communities within the Lake Superior Basin.

While the mine closures meant economic hardships for families and communities that depended on mining for jobs, closing ore processing and smelting operations both in Canada and the United States meant decreased amounts of toxic mercury emissions.

white pine mineHowever, mercury emissions continue at relatively high levels from remaining mining operations and fuel combustion associated with electrical generation.

Case Study in Sustainability: The White Pine Mine. Read one story about what happened to a town when a copper mine and smelter that caused environmental concerns closed. What were the costs and benefits from closing the mine?

The White Pine Copper Mine copper smelter in Michigan and Algoma Ore Division iron sintering facility in Ontario are now closed. This has significantly reduced mercury air emissions in the Lake Superior Basin.

Taconite iron ore

Taconite iron ore production continues to be a substantial source of mercury emissions in the U.S. side of the Lake Superior Basin.

The taconite industry is projected to grow in the next 10 years and so is the per person consumption of electricity. Currently, there are no mercury emission limits governing these industries. Cost-effective technologies are still under development to limit emissions from taconite processing facilities and coal-fired utilities.


The largest contributing sources of mercury within the Lake Superior Basin are from mercury-bearing products; emissions from the mining sector and fuel combustion.


When products containing mercury are disposed of in landfills, the mercury may eventually be released as to the environment through volatilization. In 1999, researchers estimated that an average of 15 percent of the mercury contained in products is released during the waste disposal process.


trashcan cartoonWhat we put into our garbage eventually finds its way to the landfill, but it doesn't always stay underground.

The best way to keep mercury out of the landfill and out of the environment is to dispose of mercury through Clean Sweep programs or to use alternative products that do not contain mercury.


Is Mercury A Problem in Your Community?


Our goal is to reduce the amount of mercury being discharged into the Lake Superior Basin to 0. Here's the progress report and what needs to be done.

1990. Baseline Year. Research estimated that 2444 kg/year or 5,377 pounds or 2.5 tons of mercury is entering the Lake Superior Basin each year. This amount is called the "baseline" since it was the first estimate of mercury entering this environment.

mercury report
Investigate what some WIsconsin communities are doing to achieve Zero Discharge of Mercury.

2000. Goal. Reduce mercury releases by 60% over the 1990 baseline amount

√ Achieved: A 1999 estimate showed 1964 pounds/year (819 kg/yr) of mercury was released into the Lake Superior Basin. This is a 66 percent reduction from the 1990 estimate of 5,377 pounds/year (2,444 kg/yr). This meets goal of reducing mercury releases by 60 percent reduction by the year 2000.

2010. Goal. Reduce mercury releases by 80% over the 1990 baseline amount.

2020. Goal. Reduce mercury releases by 100% to achieve a goal of Zero Discharge of mercury into the Lake Superior Basin.





man on beach CREATE... your own service learning experience to protect and restore aquatic communities. This section provides you with a template to get started in developing your own service learning project.
girl with net ACT... Take action to help restore and sustain aquatic communities and learn about what others are doing in the Lake Superior Basin and your community. This section will give you hands-on things you can do to help!
group reflects REFLECT.... Share and celebrate your experiences with others. This section lets you share what you learned with others.



Mercury and Schools curriculum

Symptoms of Mercury Poisoning

Learn more about Mercury

Mercury Cycle

What To Do If You Spill Mercury

Environmental Protection Agency Mercury Home



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