Environment arsenic

Whereas studies have been carried out on the factors (surface coverage, residence time, pH) which influence the desorption of arsenate previously sorbed onto oxides, phyllosilicates and soils (O Reilly et al. 2001 Liu et al. 2001 Arai and Sparks 2002 Violante and Pigna 2002 Pigna et al. 2006), scant information are available on the possible desorption of arsenate coprecipitated with iron or aluminum. In natural environments arsenic may form precipitates or coprecipitates with Al, Fe, Mn and Ca. Coprecipitation of arsenic with iron and aluminum are practical and effective treatment processes for removing arsenic from drinking waters and might be as important as sorption to preformed solids. 

Arsenic is historically the poison of choice for many murders, both in fiction and reality (e.g., Christie 1924 CNN 1998). The element is considered a metalloid (having both metallic and nonmetallic properties) and is widely distributed in the earth s crust. Arsenic occurs in trace quantities in all rock, soil, water, and air (WHO 2001). Under reducing conditions, arsenite (As ") is the dominant form, while arsenate (As ) generally is the stable form in oxygenated environments. Arsenic salts exhibit a wide range of solubilities, depending on pH and the ionic environment. 

Health Canada - Arsenic in Drinking Water. Online. Available HTTP (accessed 9 April 2003). 

Like estuary and marine sediments, arsenic may also migrate into deeper sediments where bacteria reduce sulfate to sulfide (Figure 3.4). In such highly reducing environments, arsenic might be incorporated into relatively stable sulfide minerals (Ford, Wilkin and Hernandez, 2006). 

Mobilization of arsenic can be promoted by the presence of other solutes and their interaction with arsenic to form complexes, as detailed above for NOM. As(V) has been documented to form complexes with calcium and magnesium in brackish water and seawater (Cullen and Reimer, 1989). Arsenic commonly forms complexes with sulfide, such as As3S3(SH)3° (Bostick, Fendorf and Manning, 2003) (Chapter 3). These complexes may exist in slightly sulfidic environments. Arsenic-fluoride complexes (e.g. AsC F2-and HAsC F-) can also form in high-fluoride waters ((Apambire and Hess, 2000 Bundschuh, Bonorino and Viero, 2000), Chapter 3). 

The reactions that follow illustrate the production of organoarsenic compounds by bacteria. In a reducing environment, arsenic(V) is reduced to arsenic(IH) ... 

In oxidizing environments, arsenate is more strongly adsorbed than arsenite in neutral to acidic... 

Arsenic moves between ditferent environmental compartments (rock-soil-water-air-biota) from the local to the global scale partly as a result of pH and redox changes. Being a minor component in the natural environment, arsenic responds to such changes rather than creating them. These changes are driven by the major (bio)geochemical cycles. 

Arsenic is widely distributed in the environment. It ranks twentieth in the abundance of elements in the Earth s crust. In the environment, arsenic is mainly associated with sulfide minerals. Soils contain arsenic usually in the range of 0.5 to 35 mg/kg [98]. Arsenic levels in gold ore deposits in Zimbabwe attain 20 g/kg in soils [99]. 

Chromated copper arsenate (CCA) is still used in the USA in home construction and renovation, and also in commercial applications. It may pose risks if wood recycling products such as mulch and GCA-treated wood boards are used, as these might release Cu, Cr and arsenic into the environment. Arsenic-release studies with GCA-treated wood surfaces (Stillwell et al. 2003) and wood mulch (Townsend et al. 2003) showed some, but not very toxicologically significant effects. However, the US EPA announced in early 2002 that the wood industry had voluntarily decided to eliminate arsenical wood preservatives just from residential applications by year-end 2003 (US EPA 2002b). Despite not eliminating all uses, this decision is expected to reduce significantly the future consumption of... 

Arsenic is a naturally occurring element widely distributed in the earth s crust. In the environment, arsenic is combined with oxygen, chlorine, and sulfur to form inorganic ar.senic compounds. Arsenic in animals and plants combines with carbon and hydrogen to form organic arsenic compounds. 

Hydrochemistry of groundwater from the Tierra de Pinares region (Douro basin, Spain) affected by high levels of arsenic. Proceedings of Arsenic 2008, 2 International Congress on arsenic in the environment Arsenic from nature to humans, pp. 83-84, Valencia, Spain... 

Many inorganic and organic chemicals can undergo oxidation or reduction reactions in the soil. An indicator of a compound s abihty to be oxidized or reduced is provided by its oxidation potential (EO), which is the voltage at which it is transformed to its reduced state. A similar measure of a soil s ability to reduce a compound is provided by the redox potential (pE), which is a measure of electron activity. Redox potentials are relatively high and positive in oxidized environments (e.g., surface waters), and low and negative in reduced environments (e.g., aquatic sediments and the subsurface soil layers). These environmental conditions are especially important for inorganic chemicals that are rarely present in their elemental form in the environment. Arsenic, for example, exists primarily in its oxidized form (arsenate) in the atmosphere and in surface waters and in its reduced form (arsenite) in sediments. 

Toxicity. Antimony has been found not to be a carcinogen or to present any undue risk to the environment (9). However, because antimony compounds also contain minor amounts of arsenic which is a poison and a carcinogen, warning labels are placed on all packages of antimony trioxide. 

The best protection for wood against the attack of decay fungi, insects, or marine borers is obtained by applying preservatives under pressure before installation (61,62). Both oil-type preservatives, such as creosote or petroleum solutions of pentachlorophenol, and waterborne preservatives, such as copper-chrome arsenate and ammoniacal-copper arsenate, are used when wood is to be in direct contact with the ground or in the marine environments. 

Control of metalloid content in natural objects, foodstuff and pharmaceuticals is an important task for modern analytical chemistry. Determination of elements such as Arsenic is necessary for evaluation of object toxicity, since their content in environment may exceed MCL (maximum contaminant level), posing hazard to human health. Elements such as Selenium in definite doses are healthy, but in greater quantities they produce toxic effect. 

THE USE OF BIOSENSORS ON THE BASE OF E.coli FOR ARSENIC DETECTION IN ENVIRONMENT... 

Many shell-and-tube condensers use copper alloy tubes, such as admiralty brasses (those containing small concentrations of arsenic, phosphorus, or antimony are called inhibited grades), aluminum brasses, and cupronickel austenitic stainless steel and titanium are also often used. Utility surface condensers have used and continue to use these alloys routinely. Titanium is gaining wider acceptance for use in sea water and severe service environments but often is rejected based on perceived economic disadvantages. 

Admiralty brass (70% Cu, 29% Zn, 1% Sn, 0.05% As or Sb) and arsenical aliuninum brass (76% Cu, 22% Zn, 2% Al, 0.05% As) are resistant to dezincification in most cooling water environments. In the recent past, heat exchangers have virtually always been tubed with inhibited grades of brass. Brasses containing 15% or less zinc are almost immune to dezincification. Dezincification is common in uninhibited brasses containing more than 20% zinc. Inhibiting elements include arsenic, antimony, and phosphorus. Without inhibiting elements. 

In any specific environment, only certain alloys are affected. Substitution of more resistant materials does not always necessitate major alloy compositional changes. Adding as little as a few hundredths of a percent of arsenic, for example, can markedly reduce dezincification in cartridge brass. Antimony and phosphorus additions up to 0.1% are similarly efficacious. 

The most common toxic metals in industrial use are cadmium, chromium, lead, silver, and mercury less commonly used are arsenic, selenium (both metalloids), and barium. Cadmium, a metal commonly used in alloys and myriads of other industrial uses, is fairly mobile in the environment and is responsible for many maladies including renal failure and a degenerative bone disease called "ITA ITA" disease. Chromium, most often found in plating wastes, is also environmentally mobile and is most toxic in the Cr valence state. Lead has been historically used as a component of an antiknock compound in gasoline and, along with chromium (as lead chromate), in paint and pigments. 

Toxic Effects on the Blood-Forming Tissues Reduced formation of erythrocytes and other elements of blood is an indication of damage to the bone marrow. Chemical compounds toxic to the bone marrow may cause pancytopenia, in which the levels of all elements of blood are reduced. Ionizing radiation, benzene, lindane, chlordane, arsenic, chloramphenicol, trinitrotoluene, gold salts, and phenylbutazone all induce pancytopenia. If the damage to the bone marrow is so severe that the production of blood elements is totally inhibited, the disease state is termed aplastic anemia. In the occupational environment, high concentrations of benzene can cause aplastic anemia. 

Ruch, R.R. Kennedy, E.J. Shimp, N.E. Distribution of Arsenic in Unconsolidated Sediments from Southern Lake Michigan. Environ. Geol. 1979 Notes 37, 1-16. 

Shukla, S.S. Kyers, J.K. Armstrong, D.E. Arsenic Interference in the Determination of Inorganic Phosphate in Lake Sediments. J. Environ. Quality, 1972, 1, 292-295. 

Mercury, tin, lead, arsenic, and antimony form toxic lipophilic organometallic compounds, which have a potential for bioaccumulation/bioconcentration in food chains. Apart from anthropogenic organometallic compounds, methyl derivatives of mercury and arsenic are biosynthesized from inorganic precursors in the natural environment. 

Craig, PJ. (Eid.) (1986). Organometallic Compounds in the Environment—collection of detailed chapters on the environmental chemistry and hiochemistry of organometallic compounds. Environmental Health Criteria 18 Arsenic Environmental Health Criteria 85 Lead Environmental Aspects Environmental Health Criteria 86 Mercury, Environmental Aspects Environmental Health Criteria 101 Methylmercury Environmental Health Criteria 116 Tributyltin... 

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