Arsenic emission sources

21 Arsenic in air and wind-blown sediments 3.21.1 Arsenic emission sources 

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. 

Indoor air in homes and public buildings may contain significant and sometimes dangerous levels of arsenic from coal combustion (Section 3.24.2.3, (Finkelman et al., 2002)), tobacco smoke (Fowles and Dybing, 2003 Chang et al., 2005), or dust (Clayton et al., 1999 Schieweck et al., 2005). 

Location Arsenic concentration (ng m-3) with particle size distributions (diameter in microns, pm)a Reference(s) 

---

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... 

EDLs are very intense, stable emission sources. They provide better detection limits than HCLs for those elements that are intensity-limited either because they are volatile or because their primary resonance lines are in the low-UV region. Some elements like As, Se, and Cd suffer from both problems. For these types of elements, the use of an EDL can result in a limit of detection that is two to three times lower than that obtained with an HCL. EDLs are available for many elements, including antimony, arsenic, bismuth, cadmium, germanium, lead, mercury, phosphorus, selenium, thallium, tin, and zinc. Older EDLs required a separate power supply to operate the lamp. Modern systems are self-contained. EDL lamps cost slightly more than the comparable HCL. 

Table 2 calculates the amount of arsenic emission to the atmosphere from various sources of arsenic [10]. 

The other principal source of arsenic emission to the atmosphere in the US is cotton ginning dust. Cotton ginning dust and the combustion of cotton gin wastes have been reported as creating significant concentration of arsenic in the air downward from these operations [10]. It has also been reported that a seasonal variation of arsenic concentration in the atmosphere is observed which coincides with the cotton farming activities of harvesting and ginning [3]. 

This method is used for the determination of total chromium (Cr), cadmium (Cd), arsenic (As), nickel (Ni), manganese (Mn), beiylhum (Be), copper (Cu), zinc (Zn), lead (Pb), selenium (Se), phosphorus (P), thalhum (Tl), silver (Ag), antimony (Sb), barium (Ba), and mer-cuiy (Hg) stack emissions from stationaiy sources. This method may also be used for the determination of particulate emissions fohowing the procedures and precautions described. However, modifications to the sample recoveiy and analysis procedures described in the method for the purpose of determining particulate emissions may potentially impacl the front-half mercury determination. 

The developed assay was successfully applied for the arsenite and arsenate determination in contaminated waters of the gold recovery plant and in snow covers of the industrial anthropogenic sources vicinities as well. The data produced are in a good agreement with the results of independent methods atomic absorptioin and atomic emission spectrometry and capillary electrophoresis. 

Emissions from sinter plants are generated from raw material handling, windbox exhaust, sinter discharge (associated sinter crushers and hot screens), and from the cooler and cold screen. The primary source of particulate emissions, mainly irons oxides, magnesium oxide, sulfur oxides, carbonaceous compounds, aliphatic hydrocarbons, and chlorides, are due to the windbox exhaust. Contaminants such as fluorides, ammonia, and arsenic may also be present. At the discharge end,... 

Radiation is derived from a sealed quartz tube containing a few milligrams of an element or a volatile compound and neon or argon at low pressure. The discharge is produced by a microwave source via a waveguide cavity or using RF induction. The emission spectrum of the element concerned contains only the most prominent resonance lines and with intensities up to one hundred times those derived from a hollow-cathode lamp. However, the reliability of such sources has been questioned and the only ones which are currently considered successful are those for arsenic, antimony, bismuth, selenium and tellurium using RF excitation. Fortunately, these are the elements for which hollow-cathode lamps are the least successful. 

---