Mercuiy emission

Ability to isolate impacts of confounding factors other than changes in mercuiy emissions and deposition... 

Reductions in U.S. mercuiy emissions from medical and municipal waste incinerators and other industrial sectors have already occurred. Additional emission reductions from some coal-fired power plants have also already begun as co-benefits from technologies used to control SO2 and NO emissions. These mercury emissions from power plants are, however, expected to be reduced further over the next few decades. Meanwhile, changes in mercuiy emissions in other parts of the world may also affect some U.S. ecosystems. 

To assess changes in mercuiy concentrations in the environment, it is important to have a baseline from which to measure change. Due to the fact that mercuiy emissions have already been reduced from a number of sectors in the United States, and that further emission reductions are expected from power plants over the next few decades, it is critical that an assessment program be implemented soon. 

Neville GA (1967) Toxicity of mercuiy vapour. Can Chem Educa, 3, no 1 4-7 Pacyna JM, Munch J (1991) Anthropogenic mercuiy emission in Europe. Water Air Soil Poll, 56 51-61... 

Control of Mercuiy Emissions fiom Coal-fired electric utility boilers an update EPA Air Pollution Prevention and control division. National Risk Management Research Laboratory, ORD Research Triangle Park, NC, Feb 18, 2005 www.epa.gov/ttn /atw/utility/ord whtpaper hgcontroltech oar-2002-0056-6141. pdf Yudovich YE, Ketris MP, Mercuiy in coal a review Part 2. Coal use and environmental problems. International Journal of Coal Geology 2005, 62,135-165. 

Nolan PS, Redinger KE, Amrhein GT, Kudlac GA. Demostration of additive use for enhanced mercuiy emissions control in wet FGD systems. Fuel Process Technol 2004, 85, 587-600. 

Finally, Sec. 112 of the Clean Air Act required that EPA pronml-gate National Emission Standards for Hazardous Air Pollutants (NESHAPs). Between 1970 and 1989, standards were promulgated for asbestos, beiylhum, mercuiy, vinyl chloride, benzene, arsenic, radionuclides, and coke-oven emissions. 

These considerations require an expanded scope for a monitoring program, involving measurements of ancillary environmental conditions in addition to mercuiy data if the objective is not just to document changes in mercuiy concentrations, but also to gain insight into links between emissions and concentration trends in biota. These issues are addressed in each chapter. 

Important link in the pathway between mercury emissions and methyl-mercuiy in biota... 

UV absorption relies on the strong peak absorption of 03 at 254 nm (see Chapter 4.B), which coincidentally overlaps the strong 254-nm emission from low-pressure mercuiy lamps. Commercial instruments based on this absorption are in widespread use. Typically, air is drawn into a cell and the absorption of the 254-nm line from a Hg lamp is measured. The airstream is then switched to pass through a catalyst that destroys 03 and the absorption is again measured to provide / . 

Mercuiy in the Arctic cycles with the seasons between the atmosphere and snow on the ground. In the spring, as the sun reappears after the winter darkness, mercury levels in the troposphere decline for about 3 months. At the same time, the level of mercury in the snow increases 100-fold, both as methylmercury and as inorganic compounds of mercury. Later in the year, as the snow melts, the levels in the snow drop and mercury reappears in the troposphere. The elemental mercury in the atmosphere is converted to particulates or reactive species, parallelling a decrease in atmospheric ozone, and is then deposited in the snow. Later in the summer, the mercury levels in the atmosphere increase, probably due to temperature- or sunlight-induced emission of volatile mercury species from the surface. 

Mass disti ibution of mercuiy across different CUBs has been reported by Lee et al. [SCSI]. This study revealed that over 1% of mercuiy from coal burning is associated with bottom ash, 60% with fly ash, 6% with gypsum and 15-34% is emitted to the atmosphere. Meij et al. [52] reported that for some coal-fired power stations in the Netherlands the mercury is generally partitioned as 25% emitted to the atmosphere and -50% is trapped in fly ash and -25% is trapped in the FGD plant. Other studies have reported emissions of 90% or more of mercury in flue gases to the atmosphere [38,53-54],... 

Kolker A, Senior CL, Quick JC. Mercuiy in coal and the impact of coal quality on mercury emissions from combustion systems, Appl Geochem 2006, 21,1821-36. 

Holmes MJ, Redinger KE, Evans AP, Nolan PS. Control of mercuiy in conventional flue gas emissions control systems, in Fourth international conference on managing hazardous air pollutants, Washington, DC, November 12-14, 1997. 

Amalgam burning is responsible for approximately 70% of the loss of mercury to the environment. The emission of mercuiy vapor is particulary harmful, because it reacts with atmospheric components (humidity, o gen, radiation and suspended matter), oxidizes, and precipitates with rain in a Ughly reactive ionic form. 

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