Toxic Metals: Mercury

Mercury, or "quicksilver", is one example of a toxic metal. Its atomic number is 80 and its symbol is Hg. Mercury has several qualities which make it unique. For instance, it is the only metal that is liquid at standard atmospheric conditions, aka room temperature. However, like many other metals mercury is toxic to humans.

There are both natural and man made sources of mercury emissions. In nature, volcanoes release mercury into the atmosphere when they erupt. Mercury is also released by human industries, specifically through combustion based power plants. Historically, coal-fired power plants have been a major culprit due to the fact that atmospheric mercury is a bi product of the coal burning process. However, new technology together with stricter regulations have significantly reduced mercury output by American power plants. The US Clean Air Act listed mercury as one of the toxic substances that would be monitored and limited. Plant Scherer in Macon, which provides power to most of the middle Georgia area, has in recent years reduced its mercury output to almost zero. 

Another major environmental threat posed by mercury is its tendency to bio-accumulate in fish. Fish absorb the toxic metal when it is introduced into their environment and it accumulates in their tissues.  This can cause health problem in humans who eat the fish. Public health officials advise limiting consumption of certain fish that are known to accumulate large amounts of mercury as is evidenced by the chart below.

Because mercury poisoning is a painful and scary threat, communities often react with fear when cases are reported. The media also feeds into this by frequently airing stories about local detection of mercury in fish. Below is an example of one such news cast.

The presence of mercury in our environment is important to monitor because of its impact on human health. However, history has taught us that as we learn more about its dangers, technology responds. As is demonstrated by the introduction of products such as non-mercury thermometers and emission "scrubbers" for power plants.