Chemistry of gaseous arsenic emissions

Arsenic concentrations in the atmosphere are usually very low, around 0.4-30 ng m-3 (Mandal and Suzuki, 2002), 207. Urban areas may have 3-180ng m-3. Values may increase to about 1000 ng m-3 close to industrial facilities (Smedley and Kinniburgh, 2002), 533. 

Globally, volcanoes release about 17 150 metric tons (t) of arsenic per year into the atmosphere (It equals 1000 kg (Matschullat, 2000), 300). Other significant natural sources of gaseous arsenic emissions include geothermal vents, wind erosion of soils and sediments, forest and coal seam fires, and sea spray ((Cullen and Reimer, 1989), 740 (Nriagu, 1989) Chapter 3). Under reducing conditions in soils, fungi and 

Other human activities that release arsenic include herbicide use, automobile traffic, marine vessels, glass manufacturing, steel production, waste incineration, Portland cement manufacturing, and the combustion of CCA-preserved wood ((Shih, 2005), 88 (Matschullat, 2000), 302 (Chein et al., 2006 Wasson et al., 2005 Frey and Zhao, 2004) Chapter 7). Total anthropogenic emissions of arsenic to the atmosphere are about 18 800-25 800 t per year (Shih, 2005), 88. 

In most developed countries, coal combustion and smelting facilities are required to treat gaseous and particulate arsenic in flue gases before the gases are released into the atmosphere (Chapters 5 and 7). Potentially effective sorbents for flue gas arsenic include hydrated lime (Ca(OH)2, portlandite), lime (CaO), calcium carbonate, limestone, fly ash, and sometimes activated carbon ((Jadhav and Fan, 2001 Lopez-Anton et al., 2007 Helsen and Van den Bulck, 2004), 287, 289 (Taerakul et al., 2006 Gupta et al., 2007) Chapters 5 and 7). The injection of hydrated lime is especially effective and probably 

Allison, J.D., Brown, D.S. and Novo-Gradac, KJ. (1991) MINTEQA2/PRODEFA2 A Geochemical Assessment Model for Environmental Systems Version 3.0 User s Manual, U.S. Environmental Protection Agency, Washington, DC. 

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