Mercury Releases to Water
Mercury (Hg) is a naturally occurring metal that is used to manufacture products like fluorescent lights and dental amalgam. Mercury can be released directly to water in wastewater from human activities like sewage treatment, production of pulp and paper, and processing of metals.
Mercury can be transformed by microorganisms into methylmercury, a toxic form of mercury that is harmful to both humans and wildlife. Methylmercury can bioaccumulate in the food chain and enter our bodies through the ingestion of contaminated food. Mercury is listed as toxic[1] according to the Canadian Environmental Protection Act, 1999 (CEPA 1999).
In 2010, the amount of Hg released to water was 269 kilograms (kg), a decrease of 22%, or 76 kg from 2009 and 29% (112 kg) lower than in 2003, the baseline year of this time series.
The decrease in the amount of Hg released to water between 2009 and 2010 was a result of many facilities reporting lower releases to the NPRI in 2010; in addition, two facilities that had high values in 2009 did not report in 2010. The spike in 2005 is attributed to an unusually high amount reported to have been released by a single wastewater treatment plant.
Mercury release to water, Canada, 2003 to 2010
Note: The indicator includes only the releases from facilities that reported to the National Pollutant Release Inventory (NPRI).
Source: Environment Canada (2012) National Pollutant Release Inventory.
Sources of mercury releases to water
Water, sewage and other systems, which includes sewage treatment facilities, water supply and irrigation systems and steam and air-conditioning supply, released 51% (138 kg) of the total mercury released (269 kg) in 2010. Second were the pulp, paper and paperboard mills, representing 30% (80 kg) of the total. The non-ferrous production and processing (excluding aluminum) industry ranked third, releasing 9% (24 kg) of the total.
Mercury release to water by source, Canada, 2010
Note: The indicator includes only the releases reported to the National Pollutant Release Inventory (NPRI) from facilities that are required to report based on the NPRI reporting criteria for mercury to water. Categories follow the North American Industry Classification System (NAICS), except “Other Sources,” which represents a group of sources for which releases are not individually mentioned in this chart.
Source: Environment Canada (2012) National Pollutant Release Inventory.
Mercury releases to water by province and territory
Facilities in Alberta released the most mercury to water in 2010, representing 34% (92 kg) of the national total (269 kg). Mercury in Alberta came mainly from one pulp and paper plant and from wastewater treatment plants. Ontario facilities, namely, wastewater treatment plants, were next, contributing 32% (85 kg) of the national total. British Columbia ranked third, with 19% (52 kg) of the national release to water originating mostly from a non-ferrous production and processing plant and wastewater treatment plants.
Mercury release to water by province and territory, Canada, 2010
Note: The indicator includes only the releases reported to the National Pollutant Release Inventory (NPRI) from facilities that are required to report based on the NPRI reporting criteria for Hg to water. No facilities in Prince Edward Island, Yukon Territory, Northwest Territories, Newfoundland and Labrador, or Nunavut reported releases of Hg to the NPRI for 2010.
Source: Environment Canada (2012) National Pollutant Release Inventory.
Related indicators
Other information
- Mercury and the Environment
- List of Toxic Substances Managed under CEPA 1999 (Schedule 1) - Mercury
- Mercury and its Compounds – Chemical Substances
[1] Section 64 of CEPA 1999 defines a substance as toxic if it is entering or may enter the environment in a quantity or concentration or under conditions that: a) Have or may have an immediate or long-term harmful effect on the environment or its biological diversity; b) Constitute or may constitute a danger to the environment on which life depends; or c) Constitute or may constitute a danger in Canada to human life or health.
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