2. Status of Emissions and Releases of Mercury from Human Activities in Canada

Mercury from human activities such as industrial processes, use of products containing mercury, and waste management can affect mercury levels in the environment over time.

To evaluate the effectiveness of the risk management measures that Canada has implemented to control mercury releases and achieve the Strategy objective, data on anthropogenic emissions and releases were gathered from the Air Pollutant Emissions Inventory and the National Pollutant Release Inventory for the period of 2007-2017.

2.1 - Air emissions

The Air Pollutant Emissions Inventory includes mercury air emissions data (Table 1). Between 2007 and 2017, national mercury air emissions decreased by 61%. Major industrial sectors decreased by over 50%, with the most notable decreases being coal-fired electric power generation (72%), incineration (92%), and non-ferrous smelting and refining (90%).

Source: Air Pollutant Emissions Inventory (2019)

^a Includes emissions from cigarette smoking, combustion of fossil fuels and biogenic fuels for heating in buildings, heating of construction materials, and mercury in products and facility reported data from sectors that are not included elsewhere.

^b Other industrial sources include emissions from the aluminum, asphalt paving, iron ore, mining and quarrying, manufacturing, and upstream and downstream oil and gas industries.

^c These sources include emissions from natural gas, waste materials, other electric power generation, and combustion of fuel used for transportation and mobile equipment, agriculture, home firewood burning, construction and residential purposes.

^d Totals and percent change may not calculate correctly due to rounding.

Over the period 2007-2017, the picture of major mercury emitters has changed dramatically. Figure 1 presents the breakdown of atmospheric mercury emissions in 2007 and 2017. While emissions from the iron and steel industry make up the largest part of the total mercury emissions in Canada in 2017, emissions from this source have decreased from 2007 by 18%. In addition, as Figure 2 shows, during this period mercury emissions to air decreased in every province.

Over the past ten years, mercury emissions decreased because of the closure of industrial operations (including a smelter in Manitoba in 2010 and coal-fired electricity generation facilities in Ontario), the use of new emission control technologies, and increased use of best management practices.

Mercury emissions to air were the highest in Ontario in 2017, accounting for 34% (1.0 tonne) of the national total. These emissions came mostly from the iron and steel industry and cement and concrete industry, which together accounted for 60% of Ontario’s total.

2.2 - Water releases

The National Pollutant Release Inventory requires facilities to report annually on mercury releases to water if they release 5 kg or more of mercury during their operations. As shown in Figure 3, total reported releases of mercury to water have been relatively low.

Notes: ^a1000 kilograms = 1 tonne.

^bReleases from human activities only. Amounts indicated include elemental mercury and mercury in any compound, alloy, or mixture reported in the National Pollutant Release Inventory based on the inventory reporting criteria. “Other sources” include electric utilities, manufacturing (except pulp and paper), the oil and gas industry, and ore and mineral industries (except non-ferrous smelting and refining), among others (For more details on sources, see data sources and methods used for the inventory).

Excluding 2014, the total annual average release of mercury to water between 2007 and 2017 was 217 kg. Mercury releases declined by 66% from 2007 to 2017. In 2014, total releases were significantly higher, at 2,321 kg, due to the breach of a dam that was securing mine waste in a tailings pond from the Mount Polley mine in central British Columbia (accounting for 92% of mercury released that year).

Between 2007 and 2017, mercury released via wastewater treatment facilities accounted for the majority of total mercury released to water. In 2017, four sectors contributed 119 kg to the 120 kg of total national releases of mercury to water: sewage treatment and waste management, pulp and paper, non-ferrous smelting and refining, and mining and rock quarrying. The largest source was the sewage treatment and waste management sector, representing 81 kg (68%) of the total. This sector does not generate mercury; rather, it releases mercury generated upstream from the use or disposal of products containing mercury.

2.3 - Deposits from foreign sources

Despite reductions from sources across the country, air emissions continue to be a major source of mercury deposits in Canada. Mercury, unlike other metals, easily evaporates. Once mercury is released into the air, it can remain there for six months to a year, where it is carried long distances and is deposited across Canada, including in the Arctic. The Arctic is especially vulnerable to mercury deposition because of its unique chemistry, which results in precipitation of mercury from the air to the snow and ice during the spring.

It can be difficult to distinguish between mercury from foreign and domestic sources because mercury can be transported long distances on wind currents. Environment and Climate Change Canada estimates that in 2015, Canada contributed 0.2% (4.3 tonnes out of 2223 tonnes) of global mercury emissions to the atmosphere from human activities. However, approximately 40 tonnes of mercury from human activities were deposited in Canada in 2015. (Dastoor and Ryjkov, internal communication 2018, Environment Climate Change Canada, 2019). Through modeling and analysis, over 97% of these deposits are estimated to have come from other countries, with approximately 37% from East Asia, 9% from Southeast Asia, 8% from both South Asia and Sub-Saharan Africa, 7% from Europe and 4% from the United States. For this reason, Canada is taking an active role in regional and international efforts to reduce global flows of mercury (particularly through the Minamata Convention; see section 7).

2.4 - Conclusion

It is evident that industrial sectors in Canada have reduced the amount of mercury they release into the environment. Despite domestic reductions, anthropogenic air emissions from foreign sources continue to be a major source of mercury in Canada.