Mercury is an earth element and can also come from human sources. Mercury continually rises to the surface of the Earth's crust, due to the high temperature of the Earth's mantle, which can make mercury a very mobile source. Surface rocks may contain high levels of concentrated mercury, which may add to mercury emission standard levels. Natural sources can come from the earth's crust, volcanoes and erosion. Others are due to bad weather, floods and wildfires. This type of contamination is beyond human control and should be considered part of the mercury levels in our atmosphere. To date, scientists have struggled to separate the two from human involvement in natural mercury production. Other mercury emissions in our atmosphere are of anthropogenic origin, which corresponds to the influence of nature by man. Some of these included mines, coal-fired power plants, cement production plants, caustic soda production plants, ore processing, medical waste, chemical production facilities, and wildfires. Volcanoes can vary in the amount of mercury released into the atmosphere, and this can depend on whether they are in the erupting or outgassing phase. Researchers measure mercury emissions by the Hg/SO2 (mercury/sulfur dioxide) ratio, in the eruption columns of volcanoes. Some researchers say this approach is not accurate due to lack of data and the instability of volcanoes. Some researchers say this area needs more research, to get a better idea of ​​how much mercury is actually being released into our atmosphere. Bidirectional flows or simply flow means that gaseous mercury can either spread through the air or move down. Small amounts of outgassing can release gaseous mercury into the lowest part of the atmosphere, which can have a lasting effect...... middle of paper ...... 1 page(s) 45- 61Woodruff, L., Cannon, W. (2010). Immediate and long-term effects of fire on total mercury in forest soils of northeastern Minnesota. Environ Science Technolgy.44(14):5371–5376.Lee, Yonggoo and Rahman, Md Moklesur and Kim, Guebuem and Han, Seunghee. (2011). Mass balance of total mercury and monomethylmercury in coastal bays of a volcanic island: significance of submarine groundwater discharge. Environmental science and technology. www.biomedsearch.com/nih/Mass-balance-total-mercury-monomethylmercury/21973173.html(5)Pirrone, N., Cinnirella, S., Feng, X., Finkelman, RB, Friedli, HR, Leaner, J ., & Telmer, K. (2010). Global atmospheric mercury emissions from anthropogenic and natural sources. Atmospheric Chemistry and Physics, 10(13), 5951-5964. World Coal Organization. http://www.worldcoal.org/coal/uses-of-coal/coal-combustion-products/