Toxicity of mercury

Mercury ion (Hg(II)) has a unique character. It binds strongly with many chemicals, especially those containing the so-called thiol group. The thiol group is S-H, that is, sulfur (S) bound with hydrogen. Some of the commonly occurring compounds with S-H are hydrogen sulfide (H-S-H which smells of a rotten egg, because a rotten egg actually produces this compound) and cysteine (HS-CH2(NH2)COOH), one of the 

15 Environmental Issues Heavy Metal Pollutants and Others 

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Improved sensitivities can be attained by the use of longer collection times, more efficient mass transport or pulsed wavefomis to eliminate charging currents from the small faradic currents. Major problems with these methods are the toxicity of mercury, which makes the analysis less attractive from an eiivironmental point of view, and surface fouling, which coimnonly occurs during the analysis of a complex solution matrix. Several methods have been reported for the improvement of the pre-concentration step [17,18]. The latter is, in fact. 

The biochemical basis for the toxicity of mercury and mercury compounds results from its ability to form covalent bonds readily with sulfur. Prior to reaction with sulfur, however, the mercury must be metabolized to the divalent cation. When the sulfur is in the form of a sulfhydryl (— SH) group, divalent mercury replaces the hydrogen atom to form mercaptides, X—Hg— SR and Hg(SR)2, where X is an electronegative radical and R is protein (36). Sulfhydryl compounds are called mercaptans because of their ability to capture mercury. Even in low concentrations divalent mercury is capable of inactivating sulfhydryl enzymes and thus causes interference with cellular metaboHsm and function (31—34). Mercury also combines with other ligands of physiological importance such as phosphoryl, carboxyl, amide, and amine groups. It is unclear whether these latter interactions contribute to its toxicity (31,36). 

Mercury thermometers are being phased out because of the toxicity of mercury vapor. A common replacement for mercury is the organic liquid iso amyl benzoate, which boils at 262°C. What is its boiling point in °F K ... 

C19-0014. The mercury battery, use of which is being discontinued because of the toxicity of mercury, contains HgO and Zn in contact with basic aqueous solution. The redox products are Hg and ZnO. Determine the oxidation and reduction half-reactions and the overall reaction for these batteries. 

Standards imposed to the industrial waste streams charged in heavy metals are more and more drastic in accordance with the updated knowledges of the toxicity of mercury, cadmium, lead, chromium... when they enter the human food chain after accumulating in plants and animals (Forster Wittmann, 1983). Nowadays, the use of biosorbents (Volesky, 1990) is more and more considered to complete conventional (physical and chemical) methods of removal that have shown their limits and/or are prohibitively expensive for metal concentrations typically below 100 mg.l-i. 

Scheuhammer AM. 1990. Accumulation and toxicity of mercury, cadmium and lead in vertebrates. In Workshop to Design Baseline and Monitoring Studies for the OCS Mining Program, Norton Sound, Alaska — Workshop Proceedings, US Dept, of the Interior Minerals Management Service, OCS Study, mms90-059. 

Olson, K.R. and R.C. Harrel. 1973. Effect of salinity on acute toxicity of mercury, copper, and chromium for Rangia cuneata (Pelecypoda, Mactridae). Contrib. Mar. Sci. 17 9-13. 

Dave, G. and R. Xiu. 1991. Toxicity of mercury, copper, nickel, lead, and cobalt to embryos and larvae of zebrafish, Brachydanio rerio.Arch. Environ. Contam. Toxicol. 21 126-134. 

Glickstein, N. 1978. Acute toxicity of mercury and selenium to Crassostrea gigas embryos and Cancer magister larvae. Mar. Biol. 49 113-117. 

Talmage, S.S. and B.T. Walton. 1993. Food chain transfer and potential renal toxicity of mercury to small mammals at a contaminated terrestrial field site. Ecotoxicology 2 243-256. 

Huckabee, J.W. and N.A. Griffith. 1974. Toxicity of mercury and selenium to the eggs of carp (Cyprinus carpio). Trans. Amer. Fish. Soc. 103 822-825. 

Klaverkamp, J.F., W.A. Macdonald, W.R. Lillie, and A. Lutz. 1983b. Joint toxicity of mercury and selenium in salmonid eggs. Arch. Environ. Contam. Toxicol. 12 415-419. 

Owing to the toxicity of mercury and its disposal problem, solid electrodes are now very popular. In particular, electrodes made of carbon such as glassy carbon, graphite, carbon paste, and carbon fibers have gained popularity. Mercury, gold, bismuth, and other metals can be deposited as thin metal films on carbon and serves as thin metal film electrodes (TMFE) with excellent analytical advantages in trace metal analysis. The choice of working electrode is determined by the redox... 

Oral or parenteral administration of mercuric chloride promotes lipid peroxidation [127-129], possibly via a reduction of glutathione peroxidase activity. However, several studies argue against lipid peroxidation being responsible, at least for the early hours of cell toxicity of mercury [130-133]. 

Zalups RK, Lash LH Advances in understanding the renal transport and toxicity of mercury. 7 Toxicol Environ Health 42 1M4, 1994... 

Caution. Due to the toxicity of mercury compounds, both starting materials and products must be handled with care to avoid any skin contact. Due to the toxicity of carbon monoxide gas, this reaction must also be carried out in a well-ventilated hood. 

The biochemical basis for the toxicity of mercury and mercury compounds resulls from its ability to form covalent bonds with sulfur. Even In low coiiccninilinns divalent mercury is capable of inaelivaiing enzymes containing suirhydrvl I —Nil) groups, causing iiileil crcncc with cellular metabolism and function. 

The toxicity of mercury compound has caused a drastic reduction in their use. They were once of considerable importance in agriculture and medicine but their use is now restricted in most parts of the world. Hence their use as fungicides in crop and seed protection is prohibited in many countries and the pharmaceutical applications are very limited. 

A major limitation of field-based stripping sensing is the toxicity of mercury (used as the working electrode). Intensive research efforts... 

Because of the high toxicity of mercury vapor, it is important to clean up mercury as thoroughly as possible, especially in confined areas. Wear nitrile rubber gloves,... 

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