Mercury Hot Spots of North America
Mercury hot spots of North America Mercury (Hg) is a highly toxic liquid metal, Artic sunrise which most people recognize as the shiny liquid in When mercury reaches the Arctic, it undergoes a trans- fever thermometers. It occurs naturally in the formation that causes it to deposit onto the snow at environment, but it’s also generated through such the start of the Arctic sunrise—the first appearance of human activities as the production of electricity the sun after the long, dark winter. Scientists believe from coal-fired power plants, waste incineration, that a significant mass of mercury enters the biotic and fuel combustion and some industrial processes. abiotic environment, and the rest re-enters the atmos- In its most dangerous form, methylmercury, phere. Contamination of Arctic regions and traditional the health effects of its exposure to women of foods that Aboriginal people consume is childbearing age and children can be devastating. a major concern. For instance, in pregnant women methylmercury can accumulate in the fetal brain to cause brain damage. In adults, long-term exposure to the Contaminated water and fish compound can damage the brain and central Eating contaminated fish is the main source of human nervous system, causing loss of motor control, exposure to methylmercury. The mercury released into memory, hearing and vision. the atmosphere generally ends up in water bodies Because mercury is a naturally occurring and where fishing can occur. For instance, it is estimated persistent substance, it can never be completely that 40 percent of the mercury deposited from the eliminated from the environment. Canada, Mexico atmosphere into the Great Lakes basin may be from and the United States are therefore working external sources. together to prevent and reduce mercury pollution due to human activities. On behalf of the three governments, the Commission for Environmental The grasshopper effect Cooperation (CEC) initiated a North American Mercury can be deposited locally to aquatic or Regional Action Plan (NARAP) to achieve the terrestrial ecosystems, or be carried long distances in “virtual elimination” of new sources of mercury. the atmosphere from one country to another. With the Policy changes have already helped cut the right amount of solar energy, toxic substances such as generation of mercury pollution, which has doubled old pesticides and mercury may vaporize and condense in the atmosphere since the beginning of the until they reach an area like the Polar regions where industrial age. The elimination of certain there is insufficient energy to re-vaporize these Health alert mercury-based chemicals used in pulp and paper substances. Some scientists have concluded that this More than 90 percent of fish consumption advisories production in the 1970s led to a big drop in is the reason for high levels of pesticides and mercury are because of mercury contamination. Health officials pollution. And in the 1980s, the elimination of most in areas like the Arctic, far from where they were used. have warned consumers in 41 US states and most mercury in batteries and paints produced further Canadian provinces to limit their intake of certain fish, significant reductions. or avoid eating them altogether. Ten US states advise Today, mercury “hot spots” still dot the North pregnant women to limit the consumption of canned American landscape. This mercury hot spot map A cycle of contamination tuna. Exposure data from women in the US indicate indicates 244 locations where the amount of When mercury is deposited into water, microorganisms that as many as eight percent of women of childbearing mercury contamination exceeds the background, or help convert it to methylmercury. Small organisms, age may be exposed to mercury at levels that exceed naturally occurring, level in the environment. fish and plants ingest this mercury as they feed. US EPA recommendations. This means that It’s the first time such a map has been presented Concentrations increase as it is transferred up the approximately 300,000 babies are born each year in for North America based on national data. food chain to fish, birds, animals, marine mammals the United States with mercury exposures above and humans. recommended levels.
After the gold rush Before modern mining techniques were introduced, Coal-fired power stations the California gold rush that began in 1848 left a legacy The number one source of atmospheric mercury of mercury pollution that continues today. As recently pollution in North America is coal-fired energy as 2001, health officials warned about eating fish from production, with some 91 tonnes emitted directly to the certain lakes and miners still find pockets of liquid atmosphere annually. Smokestack mercury is deposited mercury along rivers and streams. near and far, sometimes traveling thousands of kilometers from the source.
Air Waste incineration Once in the atmosphere, this toxic heavy metal can Municipal and medical incinerators are the second- move thousands of kilometers from its source. The largest source of atmospheric mercury pollution in latest report from the United Nations Environment North America. In addition to contaminating the local Programme indicates that half the mercury falling on environment, the air spreads mercury to rivers, lakes Learn more North America comes from outside the continent. and land across the continent, and beyond. The CEC’s mercury action plan to eliminate new sources of Increased energy use in the Asian region pumps over mercury pollution in North America is available at 1,000 tonnes of mercury into the atmosphere each year,
For more information, please consult the following sites: •Great Lakes Binational Toxics Strategy,
Mercury hot spot. In Canada and Mexico, sites with high mercury concentration were selected as hot spots when the mercury concentration was greater 4 / Trio 9 than 10ppb. In the United States, hot spots are indicated where mercury concentration was above US environmental standards for mercury. Trio 9 / 5