Atmosphere arsenic

In air, most arsenic particulates consist of inorganic arsenic compounds, often as As+3. Burning of coal and arsenic-treated wood, and smelting of metals are major sources of atmospheric arsenic contamination (i.e., >1 pg/m3). In general, atmospheric arsenic levels are higher in winter, due to increased use of coal for heating (Pershagen and Vahter 1979). 

Nagymajtenyi, L., A. Selypes, and G. Berencsi. 1985. Chromosomal aberrations and fetotoxic effects of atmospheric arsenic exposure in mice. Jour. Appl. Toxicol. 5 61-63. 

Inorganic As(V) and As(III) are the dominant forms of arsenic in most natural waters, wastewaters, contaminated soils and sediments, and solid wastes (Chapter 7). The vast majority (approximately 89-98.6 %) of atmospheric arsenic is associated with particulates rather than existing as vapors. Both gaseous and particulate arsenic are inhalation hazards and may also contaminate surface soils, sediments, and waters... 

Arsenic may occur in the open atmosphere, as well as in the air of buildings, soils, and sediments. The vast majority (approximately 89-98.6%) of atmospheric arsenic is sorbed onto particulates rather than existing as vapors (Matschullat, 2000), 300. At any one time, the Earth s atmosphere has about 800-1740 t of arsenic with approximately 85 % of it in the Northern Hemisphere due to its greater land area and industrialization (Matschullat, 2000), 299-300. The residence time of arsenic in the atmosphere is about 7-10 days (Matschullat, 2000), 300. 

Volcanic eruptions are the major natural source of atmospheric arsenic (about 17 150 tyear-1). Considerable arsenic is also released by burning vegetation (approximately 125-3345 tyear-1), especially forest fires (Matschullat, 2000) (Galasso, Siegel and Kravitz, 2000), 849. Microbial activity in soils is another likely source of extensive arsenic emissions to the atmosphere with perhaps as much as 26 200 tyear-1 (Matschullat, 2000), 300-301. 

Eventually, atmospheric arsenic falls on the Earth s surface through wet and dry deposition. Sweet, Weiss and Vermette (1998) evaluated the deposition of arsenic over lakes Erie, Michigan, and Superior in the Great Lakes of North America. Overall, the wet and dry deposition rates for the lakes were very similar. Specifically, they were 72-94 and 66-91 pgm 2year 1, respectively. 

Deb, M.K., Thakur, M., Mishra, R.K. and Bodhankar, N. (2002) Assessment of atmospheric arsenic level in airborne dust particulates of an urban city of central India. Water Air and Soil Pollution, 140(1-4), 57-71. 

Shotyk W., Cheburkin A. K., Appleby P. G., Erankhauser A., and Kramers J. D. (1996) Two thousand years of atmospheric arsenic, antimony, and lead deposition recorded in an ombrotrophic peat bog profile. Jura Mountains, Switzerland. Earth Planet. Sci. Lett. 145, El -E7. 

Roasting [5.1,5.2,5.8,5.9]. This process can be applied to scheelite and wolfhunite. Treatment of ore concentrates at 660 to 1000 °C in air in rotary furnaces has been proposed to reduce the content of sulfides and/or arsenides by volatilization as sulfur dioxide and AS2O3, respectively. The addition of powdered coke leads to the evaporation of tin as SnO (900-1000 °C). If CO-CO2 or water vapor is added to the roasting atmosphere, arsenic and antimony volatilize. 

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