Trace metals mercury

Acetic acid, fp 16.635°C ((1), bp 117.87°C at 101.3 kPa (2), is a clear, colorless Hquid. Water is the chief impurity in acetic acid although other materials such as acetaldehyde, acetic anhydride, formic acid, biacetyl, methyl acetate, ethyl acetoacetate, iron, and mercury are also sometimes found. Water significantly lowers the freezing point of glacial acetic acid as do acetic anhydride and methyl acetate (3). The presence of acetaldehyde [75-07-0] or formic acid [64-18-6] is commonly revealed by permanganate tests biacetyl [431-03-8] and iron are indicated by color. Ethyl acetoacetate [141-97-9] may cause slight color in acetic acid and is often mistaken for formic acid because it reduces mercuric chloride to calomel. Traces of mercury provoke catastrophic corrosion of aluminum metal, often employed in shipping the acid. 

Mercury layers plated onto the surface of analytical electrodes serve as Hquid metal coatings. These function as analytical sensors (qv) because sodium and other metals can be electroplated into the amalgam, then deplated and measured (see Electro analytical techniques). This is one of the few ways that sodium, potassium, calcium, and other active metals can be electroplated from aqueous solution. In one modification of this technique, a Hquid sample can be purified of trace metals by extended electrolysis in the presence of a mercury coating (35). 

Hazardous air pollutants (HAPs) are substances that may cause immediate or long-term adverse effects on human health. HAPs can be gases, particulates, trace metals such as mercui y, and vapors such as benzene. For coal-fired power plants, the HAPs of most concern are metals such as mercury, arsenic, and vanadium. 

The Alclad alloys have been developed to overcome this shortcoming. Alclad consists of a pure aluminum layer metallurgically bonded to a core alloy. The corrosion resistance of aluminum and its alloys tends to be very sensitive to trace contamination. Very small amounts of metallic mercury, heavy-metal ions, or chloride ions can frequently cause rapid failure under conditions which otherwise would be fully acceptable. When alloy steels do not give adequate corrosion protection—particularly from sulfidic attack—steel with an aluminized surface coating can be used. 

In the decomposer, deionized water reacts with the amalgam, which becomes the anode to a short-circuited cathode. The caustic soda produced is stored or evaporated, if higher concentration is required. The hydrogen gas is cooled by refrigeration to remove water vapor and traces of mercury. Some of these techniques are employed in different facilities to maximize the production of chlorine, minimize the consumption of NaCl, and also to prevent the buildup of impurities such as sulfate in the brine.26 The production of pure chlorine gas and pure 50% sodium hydroxide with no need for further concentration of the dilute solution is the advantage that the mercury cell possesses over other cells. However, the cell consumes more energy and requires a very pure brine solution with least metal contaminants and above all requires more concern about mercury releases into the environment.4... 

Drasch G, Wanghofer E, Roider G. 1997. Are blood, urine, hair, and muscle valid biomonitors for the internal burden of men with the heavy metals mercury, lead and cadmium Trace Elements and Electrolytes 14(3) 116-123. 

C. Belmont, M.L. Tereier, J. Buffle, G. Fiaccabrino, and M. Koudeldahep, Mercury-plated iridium-based microelectrode arrays for trace metals detection by voltammetry optimum conditions and reliability. Anal. Chim. Acta 329, 203-214 (1996). 

Bond et al. [791 ] studied strategies for trace metal determination in seawater by ASV using a computerised multi-time domain measurement method. A microcomputer-based system allowed the reliability of the determination of trace amounts of metals to be estimated. Peak height, width, and potential were measured as a function of time and concentration to construct the database. Measurements were made with a potentiostat polarographic analyser connected to the microcomputer and a hanging drop mercury electrode. The presence of surfactants, which presented a matrix problem, was detected via time domain dependent results and nonlinearity of the calibration. A decision to pretreat the samples could then be made. In the presence of surfactants, neither a direct calibration mode nor a linear standard addition method yielded precise data. Alternative ways to eliminate the interferences based either on theoretical considerations or destruction of the matrix needed to be considered. 

Sipos et al. [789] have described a procedure for the simultaneous determination of copper and mercury in seawater down to the ng/1 range using differential pulse ASV at a gold electrode. Pretreatment is necessary, and comprises UV irradiation to release the trace metal bound to dissolved organic matter. 

Mart et al. [793] and Valenta et al. [794] have described two differential pulse ASV methods for the determination of cadmium, lead, and copper in arctic seawater. After a previous plating of the trace metals into a mercury film on a rotating electrode with a highly polished glassy carbon as substrate, they were stripped in the differential pulse mode. The plating was done in situ. 

Figure 5.2 Mercury concentrations in livers of tour species of pinniped mammals. (From Eisler, R. 1984. Trace metal changes associated with age of marine vertebrates. Biol. Trace Elem. Res. 6 165-180. With permission.)... 

Eisler, R. 1978. Mercury contamination standards for marine environments. Pages 241-272 in J.H. Thorp and J.W. Gibbons (eds.). Energy and Environmental Stress in Aquatic Systems. U.S. Dep. Energy Symp. Ser. 48, CONF-771114. Available from Natl. Tech. Infor. Serv., U.S. Dep. Commerce, Springfield, VA 22161. Eisler, R. 1981. Trace Metal Concentrations in Marine Organisms. Pergamon Press, NY. 687 pp. 

Jenkins, D.W. 1980. Biological monitoring of toxic trace metals. Volume 2. Toxic trace metals in plants and animals of the world. Part II. Mercury. U.S. Environ. Protection Agen. Rep. 600/3-80-091 779-982. 

Wagemann, R., R.E.A. Stewart, W.L. Lockhart, and B.E. Stewart. 1988. Trace metals and methyl mercury associations and transfer in harp seal (Phoca groenlandica) mothers and their pups. Mar. Mammal Sci. 4 339-355. 

Heavy metals are widely used as catalysts in the manufacture of anthraquinonoid dyes. Mercury is used when sulphonating anthraquinones and copper when reacting arylamines with bromoanthraquinones. Much effort has been devoted to minimising the trace metal content of such colorants and in effluents from dyemaking plants. Metal salts are used as reactants in dye synthesis, particularly in the ranges of premetallised acid, direct or reactive dyes, which usually contain copper, chromium, nickel or cobalt. These structures are described in detail in Chapter 5, where the implications in terms of environmental problems are also discussed. Certain basic dyes and stabilised azoic diazo components (Fast Salts) are marketed in the form of tetrachlorozincate complex salts. The environmental impact of the heavy metal salts used in dye application processes is dealt with in Volume 2. 

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... 

Stripping voltammetry or stripping analysis has a special place in electrochemistry because of its extensive application in trace metal analysis. Stripping voltammetry (SV) is a two-step process as shown schematically in Fig. 18b. 12. In the first step, the metal ion is reduced to metal on a mercury electrode (thin mercury film on glassy carbon or a HMDE) as amalgam. 

They showed that metallic mercury vapour and trace amounts of phenylmercury acetate were present in the air surrounding phenylmercury acetate-treated soil. About equal amounts of the vapours... 

The technique is useful for the quantitation of many metals including lead, copper, mercury, cadmium and zinc with detection limits as low as lOpg. Its sensitivity makes it a very suitable method for trace metal analysis in biological samples. 

The atmospheric load is delivered to the sea surface via two processes dry and wet deposition. Dry deposition is mostly gravitational when winds weaken, solid particles fall to the sea surface. Wet deposition involves incorporation into a raindrop that falls to the sea surfece. Particulate trace elements can become entrained in raindrops and thereby carried to the sea surfece. Along the way, some of the trace elements can dissolve. Gaseous trace elements, such as mercury, can also be dissolved directly into raindrops. Thus, rainwater can contain dissolved trace metals. 

Trace metals (arsenic, cadmium, chromium, copper, nickel, lead, mercury, zinc) Industrial and municipal wastewaters runoff from urban areas and landfill erosion of contaminated soils and sediments atmospheric deposition Toxic effects including birth defects, reproductive failure, cancer, and systemic poisoning. 

Turner A, Martino M, Le Roux SM (2002) Trace metal distribution coefficients in the Mersey Estuary UK Evidence for salting out of metal complexes. Environ Sci Technol 36 4578 584 Turner A, Millward GE, LeRoux SM (2001) Sediment-water partitioning of inorganic mercuries in estuaries. Environ Sci Technol 35 4648-4654... 

Schroeder HA, Mitchener M. 1975. Life-term effects of mercury, methyl mercury and nine other trace metals on mice. J Nutr 105 452-458. 

---