Arsenic and Lead

Arsenic is a poison for vanadia SCR catalysts known from stationary power plants where it is present as AS2O3 in gas-phase or in fly ashes [65]. AS2O3 is captured irreversibly to the V2O5 surface causing deactivation of the catalyst [59]. However, since As is not a common compound in diesel exhaust, this type of poisoning is not seen in mobile SCR applications. 

---

As shown in Table 2.4, atomic absorption is extremely sensitive. It is particularly suited to the analyses of arsenic and lead in gasolines, for sodium in fuel oils (where it is the only reliable method) and for mercury in gas condensates. 

Other salts include lead arsenates and lead arsenites (see Insect control technology), lead chromates and lead sihcochromates (see Pigments), lead cyanide (see Cyanides), lead 2-ethyIhexanoate (see Driers and metallic soaps), and lead fluoroborate (see Fluorine compounds, inorganic). 

Heavy metals on or in vegetation and water have been and continue to be toxic to animals and fish. Arsenic and lead from smelters, molybdenum from steel plants, and mercury from chlorine-caustic plants are major offenders. Poisoning of aquatic life by mercury is relatively new, whereas the toxic effects of the other metals have been largely eliminated by proper control of industrial emissions. Gaseous (and particulate) fluorides have caused injury and damage to a wide variety of animals—domestic and wild—as well as to fish. Accidental effects resulting from insecticides and nerve gas have been reported. 

Arsenic and lead are conveniently co-precipitated and removed with the cobalt precipitate. Finally, copper is separated from solution as copper(II) sulfide by stirring in nickel powder and elemental sulfur... 

Bishayi, B. and Sengupta, M., Synergism in immunotoxicological effects due to repeated combined administration of arsenic and lead in mice, International Immunopharmacology, 6, 454, 2006. 

Davis A, Ruby MV, Bergstrom PD. 1992. Bioavailability of arsenic and lead in soils from the Butte, Montana, mining district. Environmental Science Technology 26 461-468. 

Pineda-Zavela, A.P. et al., Nitric oxide and superoxide anion production in monocytes from children exposed to arsenic and lead in region Lagunera, Mexico, Toxicol. Appl. Pharmacol. 198, 283, 2004. 

Heat Transfer The movement and dispersion of heat by conduction, convection, or radiation. Heavy Metals High-density metallic elements generally toxic to plant and animal life in low concentrations (e.g. mercury, chromium, cadmium, arsenic, and lead). 

In animal models, dimercaprol prevents and reverses arsenic-induced inhibition of sulfhydryl-containing enzymes and, if given soon after exposure, may protect against the lethal effects of inorganic and organic arsenicals. Human data indicate that it can increase the rate of excretion of arsenic and lead and may offer therapeutic benefit in the treatment of acute intoxication by arsenic, lead, and mercury. 

If species such as sodium, potassium, chloride, and sulfate are tolerable in a fairly large range, other toxic species such as arsenic and lead have narrower limits. For arsenic and lead, the limits in pharmacopeial compendia are generally set between 1 and 10 ppm in fact, these limits are high for such harmful species. 

Mercury nitrate, corrosive sublimate, white arsenic, and lead acetate are occasionally used as reagents, and soap is described as an indication of hard waters, as when added to them a decomposition takes place, the acid unites with alkali, and the oil is disengaged such waters as these are generally called hard waters, and are unfit for washing cloaths, as also for boiling pulse and the harder kinds of flesh. 18 The list of qualitative reagents for the many constituents of natural waters comprises the principal reagents in use at present. 

Some methane is manufactured hv the distillation of coal. Coal is a combustible nick formed from the remains of decayed vegetation. Ii is ihe only rock containing significant amounls of carbon. The elemental composition of coal varies between 60% and 95% carbon. Coal also contains hydrogen and oxygen, with small concentrations of nitrogen, chlorine, sulfur, and several metals. Coals are classified by the amount of volatile material they contain, that is. by how much of Ihe mass is vaporized when the coal is healed to about 900 C in the absence of air. Coal that contains more than 15% volatile material is called bituminous coal. Substances released from bituminous coal when it is distilled, in addition to methane, include water, carbon dioxide, ammonia, benzene, toluene, naphthalene, and anthracene In addition, the distillation also yields oils, tars, and sulfur-containing products. The non-volatile component of coal, which remains after distillation, is coke. Coke is almost pure carbon and is an excellent fuel, However, it may contain metals, such as arsenic and lead, which can he serious pollutants if ihe combustion products are released into the atmosphere. 

U.S. Environmental Protection Agency (US EPA) (1996) Bioavailability of Arsenic and Lead in Environmental Substrates. 1. Results of an Oral Dosing Study of Immature Swine. EPA 910/R-96-002, Superfund/Office of Environmental Assessment. 

Dubey, B. and Townsend, T. (2004) Arsenic and lead leaching from the waste derived fertilizer ironite. Environmental Science and Technology, 38(20), 5400-404. 

Shih and Lin (2003) investigated the solidification/stabilization of arsenic-rich flyash from an abandoned copper smelter in northern Taiwan. The flyashes (2-40 % total arsenic, mostly as As(III)) were collected from three flue gas discharge tunnels. Extremely high cement dosages (cement/waste mass ratio of greater than 6) were required to stabilize the wastes so that they would pass the US TCLP for arsenic (<5 mg L 1 Appendix E). (The TCLP is often used in research outside of the United States.) Cement dosages could be reduced and the mixtures would still pass the TCLP for both arsenic and lead if municipal waste incinerator flyash was added. Lime alone was able to stabilize arsenic and pass the TCLP however, the leachates exceeded the TCLP lead standard of 5mgL 1. The immobilization of arsenic in lime may be due to the formation of sparsely water-soluble calcium arsenites and arsenates, such as CaHAsC>3 //1LO or Ca3(AsC>4)2 H20, where n > 0 (Shih and Lin, 2003, 692). 

Hower, J.C., Robertson, J.D., Wong, A.S. et al. (1997) Arsenic and lead concentrations in the pond creek and fire clay coal beds, eastern Kentucky coal field. Applied Geochemistry, 12(3), 281-89. 

Rodriguez, R., Armienta, A., Berlin, J. and Mejia, J.A. (2002) Arsenic and lead pollution of the Salamanca Aquifer, Mexico origin, mobilization and restoration alternatives, in Groundwater Quality Natural and Enhanced Restoration of Groundwater Pollution (eds S.F. Thornton and S.E., Oswald), IAHS-AISH Publication, Vol. 275, pp. 561-65. 

COPC concentrations greater than the AEL were considered indicative of moderate effects, while concentrations greater than 10 x AEL were considered indicative of severe effects. Contamination by metals, PAHs and PCBs was widespread in the study area. Concentrations of copper, mercury and zinc were greater than AELs for all surface sediment stations. Arsenic and lead concentrations exceeded the AEL for all but one station, while nickel and silver concentrations exceeded the AEL at approximately half of the stations. PAH and PCB concentrations exceeded their respective AEL benchmark at all stations except one. 

Calderdn J, Navarro ME, Jimenez-Capdeville ME, Santos-Diaz MA, Golden A, Rodriguez-Leyva I, Borja-Aburto VH, Diaz-Barriga F (2001) Exposure to arsenic and lead and neuropsychological development in Mexican children. Environ Res, 85 69-76. 

Carrizales L, Razo I, Tellez-Hernandez Jl, Torres-Nerio R, Torres A, Batres LE, Cubillas AC, Diaz-Barriga F (2006) Exposure to arsenic and lead of children living near a copper-smelter in San Luis Potosi, Mexico. Importance of soil contamination for exposure of children. Environ Res, 101(1) 1-10. 

Y fiez L, Garcia-Nieto E, Rojas E, Carrizales L, Mejia J, Calderbn J, Razo I, Diaz-Barriga (2003) DNA damage in blood cells from children exposed to arsenic and lead in a mining area. Environ Res, 93 231-240. 

---