Heavy Metals and Coal
Carbon Footprint Aside, Coal is not Environmentally Friendly
Nov 23, 2009 Eilene Toppin Ording
Much talk lately has pointed to the burning of coal in America and Asia as the source of much of the greenhouse gasses that may be responsible for global warming. It is also true that burning coal is adding to heavy metal concentration in the Arctic and in the oceans.
A study that analyzed ice cores taken in Greenland measured the concentrations of heavy metals at each layer of ice. Indications were that heavy metal deposition picked up after 1860, with the highest concentrations in the early 1900s. There is concern that the higher use of coal in Asia currently will begin to raise the global level of heavy metals substantially.
What's in the Coal
Coal contains many environmentally and biologically toxic elements. Among them are lead, mercury, nickel, tin, cadmium, antimony and arsenic. Radio isotopes of thorium and strontium are typical as well.
Burning coal produces airborne compounds of these elements which settle out or wash out of the atmosphere into the oceans. Fly ash and coal ash are heavily contaminated with the oxides of these heavy metals.
Rain falling on coal storage piles and ash piles can leach out heavy metal compounds into ground water or lakes and streams. West Virginia coal fields have contaminated drinking water sources with breaks in slurry impoundments.
Toxic Effects of Heavy Metals
The result is bioaccumulation in plants and animals. Tuna and other fish absorb mercury. Lead poisoning is possible from too much contact with soil. Drinking water is tested regularly for lead. Arsenic is known the world over as an effective poison and arsenic levels are also a concern.
Lead and mercury affect nervous systems and brain development in children and young animals. Mercury concentrations have been found to affect the young of nesting loons in Wisconsin. In the Florida Everglades, mercury levels have been high enough to affect the behavior of young egrets.
What Can Be Done
Current air pollution control methods are aimed at collecting solids and scrubbing out sulfur or nitrogen oxides. Research is being conducted to try to control lead and mercury emissions with better efficiency. Wet scrubbers can reduce some emissions, but they create contaminated slurry that must be handled as well.
Burying coal ash back in the mines where the coal is extracted has been suggested as a way of limiting the leaching of toxics from the ash. At present it may be stored outside or sent to the landfill.
Although coal is not the only source of heavy metal pollution, the reliance of humans on coal to generate most of the electricity used increases the emission of toxic chemicals greatly. Conservation is needed as well as alternative fuel sources and clean technologies. Conservation of electricity is something everyone can practice immediately and save money at the same time.
Resources:
Natural Resource Defense Council
Sludge Safety Project, West Virginia
United States Environmental Protection Agency, Research on controlling mercury emissions in coal burning facilities.
Coal Burning Leaves Toxic Heavy Metal Legacy in the Arctic, McConnell, Joseph R. and Edwards, Ross, Desert Research Institute inProceedings of the National Academy of Sciences, 2008
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