Arsenic preservation

Arsenic pentoxide (wood ashes treated with arsenic preservative)... 

USA Virginia, New York, and Florida soils within distances of 300 mm from 19 utility poles coated with ammoniacal copper zinc arsenate preservatives <1 to 10.3 11.3 Morrell, Keefe and Baileys (2003)... 

GC) of organic species, ICP-MS, and HG-ICP-AES. Of these, HG-AFS and ICP-MS are probably the most widely used methods. Like arsenic, there are no generally accepted ways of preserving selenium speciation in water samples, and even fewer studies of the factors controlling the stability of the various species. Many of the precautions for arsenic-preserved species (Section 9.02.2.2.3) are also likely to apply to the preservation of selenium species. 

Chou C.K, Chandler J.A. and Preston R.D, (1973) Microdistribution of metal elements in wood impregnated with a copper-chrome-arsenic preservative as determined by analytical electron microscopy. Wood Sci. Technol., 7, 151-160. 

A copper chromium arsenic preservative is used in industrial pretreatment of timber. This process creates the potential for operator exposure (Garrod etal. 1999) as well as the need to remediate soil contaminated with the preservative (Balasoiu etal. 2001). Potentially, further remediation is needed when the wood might be recycled for wood chips (Velizarova et al. 2002). 

Bacterial attack has been observed in wood exposed in soil. The studies have mainly concerned posts treated with copper-chrome-arsenic preservatives. The reports show that erosion, tunneling, and cavitation forms of bacterial attack may occur 91, 92, 109-112). Extensive attack by bacteria in preservative-treated water-cooling slats was also reported by Greaves (100). 

Anon. (1981). Corrosion of metal fasteners used in conjunction with CCA (copper/ chrome/arsenic) preservative treated timbers. Development Materials Bulletin, Greater London Council, December (135), 4/1-4/3. 

Burning of wood products treated with arsenical preservatives... 

When sulphur is melted viscosity changes occur as the temperature is raised. These changes are due to the formation of long-chain polymers (in very pure sulphur, chains containing about 100 (X)0 atoms may be formed). The polymeric nature of molten sulphur can be recognised if molten sulphur is poured in a thin stream into cold water, when a plastic rubbery mass known as plastic sulphur is obtained. This is only slightly soluble in carbon disulphide, but on standing it loses its plasticity and reverts to the soluble rhombic form. If certain substances, for example iodine or oxides of arsenic, are incorporated into the plastic sulphur, the rubbery character can be preserved. 

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. 

The predominant use of arsenic ia the United States is ia the manufacture of chemicals. During the 1980s, the market for arsenic chemicals had shifted from cotton farming, where its use is now restricted because of environmental considerations, to wood (qv) preservatives for the protection of lumber and other wood products. Arsenic trioxide is the basic commodity of commerce from which a number of important chemicals are manufactured. 

The commercial uses of arsenic compounds in 1988, measured in terms of elemental arsenic, are wood (qv) preservatives, 69% agricultural products (herbicides (qv) and desiccants (qv)), 23% glass (qv), 4% nonferrous alloys and electronics, 2% and animal feed additives and pharmaceuticals (qv), 2% (see Feeds AND feed additives). Chromated copper arsenate (CCA) [11125-95-4] is the most widely used arsenic-based wood preservative. The Environmental Protection Agency has, however, restricted the use of arsenical wood preservatives to certified appHcators. 

Wood Preservation. The use of chromium compounds ia wood preservation is largely because of the excellent results achieved by chromated copper arsenate (CCA), available ia three modifications under a variety of trade names. The treated wood (qv) is free from bleeding, has an attractive ohve-green color, and is paintable. CCA is widely used, especially ia treating utility poles, bull ding lumber, and wood foundations. About 62% of all the chromic acid produced ia the United States is consumed by the wood preservation industry (77,167) (see Building materials, survey). 

Tlie use of As comjiounds as herbicides and pest controls in agriculture is now considerably restricted because of environmental considerations though arsenic acid itself. AsO(OH).v, is still used in die formulation of wood preservatives. The oxide is widely used to decolorize glass. 

Zinc in contact with wood Zinc is not generally affected by contact with seasoned wood, but oak and, more particularly, western red cedar can prove corrosive, and waters from these timbers should not drain onto zinc surfaces. Exudations from knots in unseasoned soft woods can also affect zinc while the timber is drying out. Care should be exercised when using zinc or galvanised steel in contact with preservative or fire-retardant-treated timber. Solvent-based preservatives are normally not corrosive to zinc but water-based preservatives, such as salt formulated copper-chrome-arsenic (CCA), can accelerate the rate of corrosion of zinc under moist conditions. Such preservatives are formulated from copper sulphate and sodium dichromate and when the copper chromium and arsenic are absorbed into the timber sodium sulphate remains free and under moist conditions provides an electrolyte for corrosion of the zinc. Flame retardants are frequently based on halogens which are hygroscopic and can be aggressive to zinc (see also Section 18.10). 

Yamamoto et al. [6] studied preservation of arsenic- and antimony-bearing samples of seawater. One-half of the sample (201) was acidified to pH 1 with hydrochloric acid immediately after sampling, and the remaining half was kept without acidification. In order to clarify the effect of acidification on storage, measurements were made over a period of a month after sampling. Results are given in Table 1.1. In this study, a standard addition method and calibration curve method were used for comparison and it was proven that the two gave the same results for the analyses of seawater. 

Bardgett, R.D., T.W. Speir, DJ. Ross, G.W. Yeates, and H.A. Kettles. 1994. Impact of pasture contamination by copper, chromium, and arsenic timber preservative on soil microbial properties and nematodes. Biol. Fertil. Soils 18 71-79. 

Weis, P., J.S. Weis, and J. Couch. 1993a. Histopathology and bioaccumulation in oysters Crassostrea virginica living on wood preserved with chromated copper arsenate. Dis. Aquat. Organ. 17 41 -46. 

Arsenic geochemistry in Chesapeake Bay, Maryland, depends on anthropogenic inputs and phytoplankton species composition (Sanders 1985). Inputs of anthropogenic arsenic into Chesapeake Bay are estimated at 100 kg daily, or 39 tons/year — probably from sources such as unreported industrial discharges, use of arsenical herbicides, and from wood preservatives (Sanders 1985). The chemical form of the arsenic in solution varies seasonally and along the axis of the bay. Arsenic is present only as arsenate in winter, but substantial quantities of reduced and methylated forms are present in summer in different areas. The forms and distribution patterns of arsenic... 

Cores were collected from the NATA and adjacent wetland. Solid material was obtained from the aquifer beneath the NATA by filtering water samples from MW17. Pore water was squeezed from cores in a hydraulic press. Groundwater, surface and lake water samples were filtered (0.2 pm) in the field. Sub-samples were acidified to preserve cations. Arsenic species were separated on site by passing filtrate through SAX cartridges (Le et al. 2000). 

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