More Power, More Mercury?

Kimberly Farias

Mercury is a toxic element which can have grave effects on humans and the environment. It bio accumulates in ecosystems causing harm to high trophic level organisms. In humans, long term exposure to mercury gradually causes side effects. Symptoms include shaking of the eyelids, hands, jaws, lips, and tongue, swollen gums and mouth sores. It may also cause headaches, memory loss, indecisiveness, loss of intelligence, irritability, trouble sleeping, and personality change. Mercury is a substance being released into the atmosphere, as a result of human energy production, which can cause some serious damage. Coal fired power plants are responsible for majority of atmospheric mercury emissions. In Canada, 19% of energy is derived from burning coal.
North Carolina State University researchers found that the vicinity to coal fired power plants has an effect on mercury found in fish tissue. A recent study focused on fourteen lakes in North Carolina, seven within 10km, and seven over 30km away from a coal fired power plant. The far lakes were out of the area of local influence of the power plants, as determined by the North Carolina Division of Air Quality. In each lake they collected largemouth bass, and bluegill, fish which represent distinct trophic levels. These fish species are extensively scattered, and regularly consumed by wildlife and humans. They examined the fish tissue for mercury, and they took into account proximity to power plants, trophic position, pH, nitrogen, fish size, fish age, and tissue selenium. The study aimed to dissect the effects of the point sources of mercury in the environment. The results of the study showed that the higher trophic fish, the largemouth bass, always had higher mercury levels. The lakes further away from the power plants had higher levels of mercury in both types of fish. The connection between mercury and selenium is undeniable. Lakes with high selenium, like those closer to power plants, have lower levels of mercury. Researchers predict this is due to selenium inhibiting bacteria by binding with the mercury; it eliminates the mercury from the fish tissue. Although this may seem positive for human health, the high selenium content in these areas may negatively affect fish eating wildlife. In addition this consequence is extremely localized, affecting only a small fragment of the landscape. The far lakes had much higher mercury levels in both fish. It is evident that the mercury spreads through the environment and is not concentrated around the point sources. Since the majority of atmospheric mercury emissions come from these point sources, it is crucial that these emissions are reduced. Bio accumulation in aquatic animals, due to the increasing of global mercury, can and will happen far away from point sources. This risks environments sensitive to mercury around the world.
With economic growth occurring in many third world nations coal, a cheap energy source, is being developed emitting more mercury into the atmosphere. China has recently surpassed the United States in coal consumption. Burning coal as a source of power not only releases mercury and selenium into the atmosphere, it also emits copious amounts of greenhouse gases. Coal is one of the dirtiest forms of power production; almost every aspect, from mining to burning, creates harmful effects on people and the environment. Canada has goals to phase out old coal burning plants in favour of greener more renewable power sources. Thirty-three of Canada’s fifty-one coal plants will reach the end of their economic viability by 2025. If these plants are not updated they will be shut down, as a result of newly created clean-power standards.
In conclusion, coal fired power plants emit many terrible things into the atmosphere as well as contributing to the global mercury pool. Mercury spreads from point sources, like coal-fired power plants, and bio accumulates in the environment affecting organisms high on the food chain. Canada is trying to reduce their dependence on coal, but expanding nations are increasing their consumption due to the cheapness and readiness of coal as a power source. It is important to decrease coal consumption to protect humans, and the delicate ecosystems that can be affected by mercury.

References
Sackett, D.K., Aday, D.D., Rice, J.A., Cope, W.G. and Buchwalter, D. 2010. Does proximity to coal-fired power plants influence fish tissue mercury? Ecotoxicology, 19

Hagget, S. 2010. Canada to phase-out older coal-fired power plants. The Economist. http://www.reuters.com/article/idUSTRE65O41620100625