MERCURY IN THE ENVIRONMENT

Ben Tong & Angellah AnyieniChem. 450 Advanced Inorganic Chemistry

Winona State University

What is Mercury

Chemical symbol - Hg a silver-colored metallic element & very water

soluble (toxic to living organisms) a liquid, conducts electricity, and mixes easily

with other metals expands and contracts evenly with temperature

changes evaporates to form mercury vapor, a colorless

and odorless gas can cycle in the environment due to its ability to

change forms

Entering in the environment…How?

Atmosphere: evaporation from water and land as well as through coal-fired utility and incinerator emissions

Soil: the natural breakdown of mercury-containing rocks, disposal of mercury in landfills, and atmospheric deposition

Water: runoff, atmospheric deposition, and when mercury products are poured down the drain.

Into living organisms: Once in the water cycle, mercury can convert to methyl mercury. It can accumulate in the tissues of fish and other organisms inhabiting mercury contaminated bodies of water, and may be carried up the food chain.

Mercury Hazards

Through the diet (primarily through fish), Absorption, or through the inhalation of toxic

elemental mercury fumes Health effects due to mercury exposure depend

on the amount consumed, absorbed, or inhaled and the length and frequency of exposures

Signs and symptoms in humans: coughing, shortness of breath, chest pain, vomiting, diarrhea, and fever

Long-term exposure can result in shakiness, loss of muscle control, memory loss, kidney disease, and loss of weight

Control and Regulations

Once mercury is released into the environment it is difficult to remove:

Recycle button batteries or use mercury free ones

Conserve electricity. The lesser the burning of coal and oil in electric plants (that naturally contain mercury), the lesser the mercury emitted into the environment

Use alternatives Thermometers: use alcohol or digital thermometers Old Alkaline-Type Batteries: use rechargeable

Alkaline or Mercury-Free Batteries Some shoes that light up: use mercury-free shoes Contact lens solutions containing thimerosal: use

solutions without thimerosal Lamps (Fluorescent, High Intensity discharge and

mercury vapor lamps): use low mercury fluorescent Lamps, Sulfur lamps, low mercury sodium lamps (energy conserved by using these lights will reduce mercury emissions from coal & oil combustion)

Detection Methods

Testing in water, air, soil samples or biological samples based on wet oxidation followed by a reduction step and then separate quantification of inorganic mercury compounds and organic mercury compounds

Testing in industrial waste by oxidation, purge and trap, and cold vapor atomic fluorescence spectrometry

Mercury Cleanup (always wear gloves)

Drain: mercury collects in sink trap so carefully remove sink trap and throw away in plastic bag labeled “mercury waste”

Hard surfaces: use cardboard pieces to collect beads together and use a dropper to collect the beads. Throw away in plastic bag and label “mercury waste”

Carpet or rug: cut out part of carpet/rug with mercury and throw away in plastic bag with label “mercury waste”

“Nevers” in mercury spillage

Never use a vacuum cleaner to clean up mercury

Never use a broom to clean up mercuryNever pour mercury down a drainNever wash mercury-contaminated items

in a washing machine Never walk around if your shoes might be

contaminated with mercury

Ultimate Fate

Mercury undergoes bioaccumulation. If an organism continually ingests mercury, its body burden reaches toxic levels.

The bioaccumulation effect – the larger predatory game fish will likely have the highest mercury levels.

Mercury concentrates in the muscle tissue of fish. So, unlike organic contaminants (for example PCBs which concentrate in the skin and fat, mercury cannot be filleted or cooked out of consumable game fish.

Two departments (controlling agencies):

EPA – Environmental Protection Agency

FDA – U.S. Food and Drug Administration

References

http://www.mde.state.md.us/Programs/LandPrograms/Hazardous_Waste/mercury/index.asp accessed 12/04

US Department of the Interior URL: http://www.epa-gov/ast/methods/1031.html accessed 12/04

http://www.usgs.gov/themes/factsheet/146-00/index.html accessed 12/04