The areas in Canada most vulnerable to the impact of climate change on mercury processes are the sub-Arctic and the Arctic. Mercury levels in monitored fish, birds, and mammals in Canada have shown varying trends, with differences among species and geographical regions. The pathway from emission sources (where pollutants are discharged to the environment) to accumulation in fish is complex; therefore, predicting how changes in sources will affect the level of mercury in fish requires considerable knowledge from many different fields of expertise. Mercury from mining is generally released in an insoluble inorganic form, and certain aquatic conditions are required for the mercury to be methylated. Over the 40 years in Canada, mercury levels in wildlife and fish have shown increasing, stable, or decreasing trends, with variation among monitored species and regions (Figure 9). It begins with anthropogenic emissions of mercury, followed by a discussion of the many processes that mercury undergoes, including surface exchange, atmospheric, aquatic, terrestrial, and marine processes. However, root uptake of mercury by forest vegetation and transfer of this mercury into wood is low. The Great Lakes region has shown both the largest and most numerous declines in mercury levels in individual populations (40% of fish and seabird populations reported). and mercury accumulation in biota? Canadian emissions in 2010 were 5 300 kg to air and 240 kg to water. This Executive Summary is a short document highlighting the results from the science assessment and prominent issues relating to mercury in Canada. However, in areas close to point sources (such as coal-burning power plants and metal smelters) of mercury emissions, the local contribution of domestic emissions to mercury deposition can be much higher. Methylmercury, the organic form of mercury, is of greatest concern for human and environmental health because of its high toxicity and its ability to accumulate in the tissues of living organisms and become more concentrated following transfer from prey to predators. Thanks to our wonderful copy editors, Carolyn Brown and Sheila Bourque, who made everything sound so much better! Coloured circles are used to identify areas in Canada where scientists have assessed the risk level of mercury exposure for piscivorous fish (i.e. The main processes that mercury undergoes in the ecosystem. Sediment mercury levels are highest downstream from current and past mining and smelting activities and lowest in the Arctic and high alpine areas. Europe, South Asia, Africa, South America, and Australia all contribute at similar levels to mercury deposition in Canada. Efforts in the last 20 years have greatly improved our understanding of the sources, transport, fate, and effects of mercury in the Canadian environment. The dashed red, green and blue coloured lines branch off from the solid lines from 2007 onwards. Saskatchewan and Manitoba contain a high density of teal dots with some green and yellow dots interspersed. Ecological risks of mercury increase from west to east across Canada, and mercury poses significant risks to the health and reproductive success of common loons (Figure 3) and predatory fish (Figure 4) in parts of southeastern Canada. Greater decreases are found in regions that have experienced large decreases in anthropogenic emissions such as urban areas, Flin Flon, Manitoba, and the Great Lakes region. Methylmercury production in the marine water column is likely important, and, in coastal regions, sediments are also production sites. , chemical, and thus risk, certain populations of wildlife and humans tend to offset these.! 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