Mercury

Mercury is a highly toxic element that is found both naturally and as
an introduced contaminant in the environment. Although concentrations in
water are very low, mercury accumulates through the aquatic food chain,
resulting in high concentrations in fish that can threaten the health of people
and wildlife. It is measured in units of nanograms per liter (ng/L) in water and
milligrams per kilogram (mg/Kg) in fish. For more information, see <a
href="http://
www.pca.state.mn.us/air/mercury-about.html">About Mercury</a>