Chemical Integrity: The example of Mercury
The chemical integrity of the Great Lakes is dynamic.
The waters of the Great Lakes are continuously changing
through the addition, interaction, and loss of both natural
and man-made substances. Natural geophysical processes
change these substances' spatial and temporal distribution
within the Great Lakes system. While much is known,
considerable uncertainty remains concerning the chemical
integrity of the Great Lakes and the impacts of various chemicals,
and combinations of chemicals, on the basin's human and other inhabitants.
Mercury, a persistent bioaccumulative toxic metal, provides
an excellent example of the challenges inherent in understanding
impacts on the chemical integrity of the Great Lakes. It occurs
widely in nature, both in concentrated form in cinnabar (ore) and
in small amounts in fossil fuels such as coal. Humans have used
mercury for over 3,000 years in medicine and industry.
1 The Commission's
Great Lakes Water Quality Board in 1985 identified mercury as one
of a "dirty dozen" chemical substances for virtual elimination under
the Great Lakes Water Quality Agreement. The governments included
this list in the 1987 Agreement in Annex 11: Persistent Toxic Substances.
In keeping with this annex the United States and Canada developed a binational
strategy for eliminating releases of 12 toxic substances,
2 including mercury that
provides a framework to achieve specific actions from 1997-2006.