Post on 11-Jan-2016
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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