Spectroscopic speciation of selenium in the environment

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Selenium is essential in trace amounts in the diet to maintain the health of humans and other animals. Selenium is required for many essential enzymes and has been shown to provide protection against cancer. Selenium also has important interactions with several elements of concern, including arsenic, mercury and cadmium, in many cases reducing their toxicity. Canada's prairie soils are rich in selenium, yielding valuable selenium-fortified crops. However, the difference in dietary levels between "sufficient" and "excess" selenium is perhaps smaller than for any other element. Relatively low levels of selenium in the environment can bioaccumulate within an ecosystem, causing defects especially in birds and fish. There is growing concern in Canada over elevated selenium in the environment, especially associated with mining activities. Selenium in the environment is thus both an asset and a liability for Canada. When high soil selenium leads to crops rich in selenium, this may increase their nutritional benefit and hence their value for export to regions with low selenium status. However, elevated selenium in mining impacted areas may threaten our pristine northern environments, causing problems especially in fish and birds. Both aspects of selenium have significant economic consequence for Canada.