Association with zinc

Indium is most frequently associated with zinc materials, and it is from these that most commercial indium is now obtained however, it is also found in iron, lead, and copper ores. 

Zinc ligands are soluble in neutral and acidic solutions, so that zinc is readily transported in most natural waters (USEPA 1980, 1987), but zinc oxide, the compound most commonly used in industry, has a low solubility in most solvents (Elinder 1986). Zinc mobility in aquatic ecosystems is a function of the composition of suspended and bed sediments, dissolved and particulate iron and manganese concentrations, pH, salinity, concentrations of complexing ligands, and the concentration of zinc (USEPA 1980). In freshwater, zinc is most soluble at low pH and low alkalinity 10 mg Zn/L of solution at pH 6 that declines to 6.5 at pH 7, 0.65 at pH 8, and 0.01 mg/L at pH 9 (Spear 1981). Dissolved zinc rarely exceeds 40 pg/L in Canadian rivers and lakes higher concentrations are usually associated with zinc-enriched ore deposits and anthropogenic activities. Marine... 

The reversible half wave potential ( 1/2) values became higher with the increase of the concentration of supporting electrolyte, but the a values were practically constant. The rate parameters decreased with increase of radius and charge of the cation of supporting electrolyte at the same ionic strength. The number of water molecules associated with zinc ions in the solutions and with reactant, which directly takes part in the charge-transfer process, was estimated and the following reaction scheme was proposed. 

BASTNASITE. A wax-yellow reddish-brown, greasy mineral of the composition (Ce, La) (COi) F, usually found in contact zones or associated with zinc lodes. Sometimes spelled bastnaesite. 

Although ranking 57th in abundance in the earth s crust tO. 15 ppm), cadmium is not encountered alone, but is always associated with zinc. The only known cadmium minerals are greenockite (sulfide) and otavite (carbonate), both minor constituents of sphalerite (zinc oxide) and smilhsoniie (zinc carbonate), respectively See also Greenockite Smithsonite and Sphalerite Blende. 

Cadmium Associated with zinc minerals By-product of refining zinc spelter Manufacturing alloys protective coating for other metals... 

Studies of carbonate-sulfonate RMs in engine oil on the antiwear performance of ZDDP, using reflectance-absorbance infrared spectroscopy RAIR, X-ray photoelectron spectroscopy XPS and Auger electron spectroscopy AES, showed that the tribofilms were inorganic amorphous phosphates, mainly orthophosphate (P043 ) and pyrophosphate (P2074 ) associated with zinc and magnesium (from the hard-core RMs) (Willermet et al., 1991 and 1992). 

Table III lists results of carcinogenicity studies associated with zinc deficiency. These rats were given 17 doses of MBN, beginning at seven weeks of age. Fifty eight days after the first dose of MBN, all zinc-deficient rats had developed tumors of the esophagus, 83% of which were invasive carcinomas. Five weeks later, all deficient rats had tumors, 33% of which were invasive, clearly, a marked enhancement of carcinogenesis by zinc deficiency.

Uses Cadmium (Cd) (L. cadmia Gr. kadmeia, ancient name for calamine, zinc carbonate) was discovered by Stromeyer in 1817 through an impurity in zinc carbonate. Cadmium most often occurs in small quantities associated with zinc ores, such as sphalerite (ZnS). The important compounds used in industry are cadmium oxide (CdO), cadmium chloride (CdCl2), cadmium nitrate (CdfNCRh), cadmium sulfide (CdS), and cadmium sulfate (CdSC>4). Greenockite (CdS) is the only mineral of any consequence bearing cadmium. Cadmium is also obtained as a by-product in the treatment of zinc, copper, nonferrous metal industry, and lead ores. Cadmium is a highly toxic heavy metal that forms complex compounds with other metals and elements. 

Cadmium is a heavy metal with similar chemical properties to zinc, but is much less common in the environment than zinc. Cadmium occurs in igneous rocks and some sedimentary rocks, and is generally associated with zinc ore minerals like sphalerite, and with a range of copper ore minerals. Traces of cadmium are often present in artificial fertilizers, and this heavy metal may accumulate in soils in areas that have been used for agriculture for long periods. 

A third family, the -carbonic anhydrases, also has been identified, initially in the archaeon Methanosarcina thermophila. The crystal structure of this enzyme reveals three zinc sites extremely similar to those in the a-carbonic anhydrases. In this case, however, the three zinc sites lie at the interfaces between the three subunits of a trimeric enzyme (Figure 9.31). The very striking left-handed P-helix (a P strand twisted into a left-handed helix) structure present in this enzyme has also been found in enzymes that catalyze reactions unrelated to those of carbonic anhydrase. Thus, convergent evolution has generated carbonic anhydrases that rely on coordinated zinc ions at least three times. In each case, the catalytic activity appears to be associated with zinc-bound water molecules. 

A variety of symptoms, not mentioned earlier, have also been associated with zinc deficiency. Zinc deficiency is thought to delay woxmd healing, impair the senses of taste and smell, and impair the functions of the immune system. (The impaired sense of taste is called hypogettsia.) Severe zinc deficiency results in impairment of the immune system and increased infections. These problems have been found in the severe deficiencies that occur in starvation (marasmus) and acrodermatitis enteropathica and in studies with animals. The immune system involves a large array of hormones, hormone receptor proteins, signaling proteins, and DNA-binding proteins, some of which require zinc for activity. It is not clear which of these components is most sensitive to zinc deficiency. 

A schizophrenic patient died after ingesting 461 coins, the first reported case of a death associated with zinc intoxication (21). The patient presented with clinical manifestations consistent with the local corrosive as well as systemic effects of zinc intoxication and died 40 days after admission with multisystem organ failure. Many British post-1981 pennies, which contain mostly... 

Analyses of in situ DNA synthesis of Euglena gracilis identify zinc-dependent steps in the eukaryotic cell cycle and show that the derangements in RNA metabolism are critical determinants of the growth arrest associated with zinc deficiency. Combined use of microwave-induced emission spectrometry and micro gel emulsion chromatography shows the presence of stoichiometric amounts of zinc essential to the function of E. gracilis and yeast RNA polymerases, the reverse transcriptases" from avian myeloblastosis, murine leukemic and woolly type C viruses, and E. coli methionyl tRNA synthetase. These results stress the importance of zinc to both nucleic acid and protein metabolism. Transient-state kinetic studies of carboxypeptidase A show that zinc functions in the catalytic step of peptide hydrolysis and in the binding step of ester hydrolysis. 

Zinc is an essential trace element and is commonly ingested as a nutritional supplement. Divalent zinc is one of the most important of the micronutrients. More than 100 enzymes are zinc dependent for example, carboxypeptidase, carbonic anhydrase (which is responsible for the exchange of carbonic acid in the blood and the exhalation of carbon dioxide), and the alcohol dehydrogenase (which metabolizes alcohol). Deficiency of zinc, especially in newborns, results in impaired growth, loss of hair, skin eruptions, and often impaired or delayed sexual maturation. Many medical problems are also associated with zinc deficiencies (e.g., ulcerative colitis, chronic renal disease, and anemia). 

Atoms absorb light at wavelengths specific to each element and this property is used in the analytical technique of atomic absorption spectroscopy. For example, in the determination of zinc, when a solution containing zinc compounds is sprayed into a flame at about 1000 °C, zinc atoms are produced. These will absorb light at the specific wavelengths associated with zinc. 

Thermal analysis experiments have clearly shown that tin-based fire retardants markedly alter both the initial pyrolysis and the oxidative burn off stages that occur during polymer breakdown These changes have been interpreted as being indicative of an extensive condensed phase action for the tin additive, in which the thermal breakdown of the polymer is altered to give increased formation of a thermally stable carbonaceous char at the expense of volatile, flammable products. The consequent reduction in the amount of fuel supplied to the flame largely accounts for the beneficial smoke-suppressant properties associated with zinc stannates and other tin-based fire retardants. 

The rotational barrier associated with zinc was 1.67 kJ mol and with BDC 1 kJ mol, higher than single-walled carbon nanotubes (0.105 kJ mof ). The width of the rotational band (4 cm ) was much less than for carbon (20 cm ) showing a lower dihydrogen mobility and hence stronger binding in [Zii4(BDC)30] than carbon. 

In their classic study they were able to modify specifically tyrosine 248 in the zinc metalloenzyme, carboxypeptidase A, to give the azotyrosine derivative, arsanilazotyrosine 248 carboxypeptidase A (AA-CPA-Zn), shown in Figure 3A. The native Zn is shown explicitly in order to differentiate it from externally incorporated Co as will be discussed. They found that at intermediate pH s, where the enzyme exhibits maximal activity, the azotyrosine is chelated to the intrinsically bound active site zinc. A distinct red color is associated with zinc chelation in contrast to the yellow and orange colors of the enzyme due to the presence of the free azophenol (low pH) and azophenolate (high pH), respectively (7). 

Jinzu Valley, Japan. One of the most infamous cases of contaminated land and health occurred in Japan and the effects were most prominent immediately after the Second World War. Around the end of the 19th century, soils in the Jinzu River basin, part of the Toyama prefecture, became contaminated with cadmium as a result of activities upstream at the Kamioka mines. The main activity at this mine was the mining and processing of zinc (cadmium is often associated with zinc ores) with the result that wastewater rich in heavy metals was discharged into the Jinzu River. Contaminants from this industry moved down-stream and caused contamination of soils in paddy fields as a result of abstraction of river water into fields in order to cultivate the local rice crop. Under favourable conditions, cadmium can be a fairly mobile heavy metal, particularly in soils with low pH, and increases in soil cadmium can often result in an increase in the uptake of cadmium by plants. This in turn results in an increase in dietary exposure and the consumption of contaminated agricultural crops can be a major pathway of human exposure. 

The sensitivity of plants to zinc deficiency is variable among species. For example, oats, wheat, barley, and rye are not very sensitive, whereas potatoes, tomatoes, lucerne, and red clover have a medium sensitivity. By contrast, maize, hops, flax, and soybeans require a high level of zinc supply (Viets 1966 see also Table 3.29-3, p. 612 in Henkin 1984). Soils associated with zinc deficiency in plant are usually low in organic matter content and neutral to alkaline in reaction (Pais and Jones 1997). In Asia, zinc deficiency has been identified as the most widespread micronutritional disorder of wetland rice which occurs on sodic, calcareous, and poorly drained soils. 

Indium — (from the brilliant indigo line in its spectrum). In at. wt. 114.818(3) at. no. 49 m.p. 156.60°C b.p. 2072°C sp. gr. 7.31 (20°C) valence 1,2, or 3. Discovered by Reich and Richter, who later isolated the metal. Indium is most frequently associated with zinc materials, and it is from these that most commercial indium is now obtained however, it is also found in iron, lead, and copper ores. Until 1924, a gram or so constituted the world s supply of this element in isolated form. It is probably about as abundant as silver. About 4 million troy ounces of... 

Cadmium is widely distributed in the earth s crust at an average concentration of about 0.1-0.2 mg/kg and is commonly found in association with zinc. Volcanic activity is major natural source of cadmium release to the atmosphere. The annual global flux from this source has been estimated to be 820 tons. Deep sea volcanism is also a source of environmental cadmium release, but the role of this process in the global cadmium cycle remains to be quantified (OECD, 1994). About 10-15% of total airborne cadmium emissions arise from natural processes (WHO, 1992a). 

Lee, F.Y.. Kittrick, J.A., 1984. Electron microprobe analysis of elements associated with zinc and copper in an oxidising and an anaerobic soil environment. Soil Sci. Soc. Am. J. 48,, 548-554. 

Cadmium is a relatively rare metal and its abundance in the earth s crust is estimated at less than 1 mg kg Cadmium is closely related to zinc in its chemical properties and in nature is always found associated with zinc. It is a divalent metal, readily forming halides of which chloride is the most reactive. It is soluble in most inorganic and some organic acids, but insoluble in alkalies. In the presence of sulfide, cadmium precipitates out of solution as cadmium sulfide (Figure 12.16). Cadmium is toxic to living organisms in virtually all of its chemical forms. The environmental presence of cadmium is... 

Currently in the United States, most of the lead produced comes from mines in Missouri, Alaska, Idaho, and Montana, primarily from lead-zinc and lead ores (361, 362). Worldwide, major lead deposits exist in association with zinc, silver, and/or copper (362). There are five major geological types of lead deposits volcanic-hosted massive sulfide deposits [Canada, Cyprus, Japan, Australia (Tasmania), Turkey] sediment-hosted deposits of sulfides interbedded with shales, and so on, formed in an anaerobic marine environment [Australia, Canada, Germany, United States (Alaska)] strata-bound carbonate deposits containing sulfide minerals [United States (Mississippi Valley), southern European Alps, Canada, Poland] sandstone-hosted deposits of finely crystalhne sulfides (Canada, France, Morocco, Sweden) and vein deposits of coarsely crystalline sulfide aggregates (western United States, Germany, Japan, Mexico, Peru) (364). The wide variety of compositions seen for lead minerals is illustrated by the representative lead minerals listed in Table XV (3,47). Below, we discuss the lead minerals that are most prevalent in nature in more detail. 

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