Historical trends in anthropogenic mercury emissions from sources in Canada were estimated using a number of information sources including historical statistics and published scientific literature. Mercury emissions from the chlor-alkali industry, fossil fuel combustion, the electrical industry, the paint industry, and metal recovery were estimated from 1886 to 1997, while other sources such as waste incineration, medical instrumentation, dental amalgamation, pharmaceutical uses, forestry, and the agricultural industry are reviewed. Uncertainties in estimation and reasoning for estimations are presented. Although uncertainties are great in some cases due to the lack of historical data and accurate emission factors, it is believed that the estimated trends do present a reasonable estimate of the relative increases in mercury emissions in Canada over time using the information available, by comparison with other estimates from sediment cores and bioaccumulation. The trend shows a peak in 1969 in a release of approximately 55 tonnes Hg to the environment from anthropogenic sources, dropping to just over 30 tonnes in 1997. Stringent regulations regarding the production of mercury imposed on the chlor-alkali industry in 1970 resulted in the decline seen in production in the last quarter century. However, "subtracting out" the chlor-alkali contribution from annual totals shows a disturbing trend in the production of Hg from the other sources. Based on current trends, the annual release of mercury from anthropogenic sources will approach the 1969 peak again in three or four decades if no new restrictions are applied on anthropogenic Hg sources.
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