Mercury in the Environment and Water Supply




Mercury Analysis (Univ. of Alberta)













Mercury in Water and Drinking Water

Elemental mercury is typically released from industrial processes, agricultural processes, household, commercial and medical products containing mercury, sewage discharge and sediment. Elemental mercury vapor may cause nervous system damage when exposed at high concentrations.

Inorganic mercury is found in batteries and is used in the chemical industry and it is produced from elemental mercury through the process of oxidation. Inorganic mercury is the most common form that is present in drinking water but is not considered to be very harmful to human health, in terms of the levels found in drinking water. However, kidney damage may result from exposure to inorganic mercury through other sources.


Organic mercury (primarily methyl mercury) is produced by specific bacterial organisms in surface waters that convert inorganic mercury into organic mercury, which is the form of mercury that poses a significant threat to human health. Methyl mercury is ingested typically by fish and bioaccumulates both in the tissues of fish and the humans that eat these fish. Large predatory fish can contain as much as 100,000 times more methyl mercury than the surrounding water medium. This form is rarely present in drinking water but is a very common contaminant in the tissues of fish and causes damage to the nervous system as well as teratogenesis. Both inorganic and organic mercury are considered to have a more detrimental effect on children due to the fact that both forms are more easily absorbed into their system.

In 1974, the EPA established the Safe Drinking Water Act that set specific guidelines on contaminants that are commonly found in drinking water. However, it was not until 1992 that mercury, in particular, became regulated. Both the Maximum Contaminant Level Goal and the Maximum Contaminant Level were set at 2 parts per billion because current technology allows public water suppliers to detect and remove mercury levels that low. The monitoring of mercury levels must take place every three months if the level is higher than the set guideline and specific measures must be taken to reduce these levels if they are exceeded persistently. Approved methods of removing mercury from the drinking water supply are the following: Coagulation/Filtration, Granular Activated Carbon, Lime softening and Reverse osmosis.