Cadmium distribution

Figure 4. Cadmium distribution coefiBcient in DH vs. sulfote content of solution for residence times of 1200 (circles) to 3600 s at 60and 70 C...

Kentucky. The cadmium appears to be so distributed in the coal that removal of the high specific gravity fraction of the coal does not affect the cadmium concentration in the remaining coal. This result is different from that encountered with the other trace elements. Other coals will be studied to see if they exhibit the same cadmium distribution as the Hazard No. 4 coal. 

Collier and Edmond, 1984). More labile components of decaying particles have higher Cd P ratios than bulk decaying particles (Knauer and Martin, 1981). Box models of cadmium and phosphorus cycling also require enhanced regeneration of cadmium from particles for the replication of observed cadmium distributions in the ocean (Collier and Edmond, 1984). 

KodamaY (1988) Cadmium distribution in blood and urine of dogs after long-term administration of low doses of cadmium. Toxicol Environ Chem Xl.Ti — 80. 

Cheung MS, Fok EMW, Ng TYT, Yen YF, Wang WX (2006) Subcellular cadmium distribution, accumulation, and toxicity in a predatory gastropod, Thais clavigera, fed different prey. 

Aluminum hydroxide was used as an adsorbent in a number of publications. Coprecipitation of Cd(OH)2 and Al(OH)3 was measured by Simon et al. in the absence [69] and presence [70] of NH3. Shiao et al. [50] demonstrate that cadmium distribution coefficients between liquid and surface are practically uninfluenced by the NaNOs concentration, while NaCl has a remarkable influence. According to Shimada et al. [71] and Packter and Derry [1], coprecipitation leads to the formation of Zn aluminates. Besides investigating various ions [62], Mustafa and coworkers describe sorption on a-Al(OH)3 [72,72], especially that of Zn, at different temperatures. They observed Langmuir isotherms and derived thermodynamic data. Kinetic studies were carried out by Simon et al. [74] using polaro-graphic techniques. In their experiments equilibrium was reached after 3h with two consecutive first-order reactions, in contrast to the findings of Lo and Leckie... 

Throughout the process of cadmium distribution within the body, membrane systems are necessarily involved in helping cadmium to cross ion-tight biological barriers and to permeate cells. A survey of such systems in animals follows. 

Therefore, risk assessment for human health is limited by (i) the scarcity of analytical data and poor predictive power of cadmium distribution in the body in relation to health outcome, (ii) the lack of information about chronic effects of cadmium accumulating over decades in tissues, and (iii) the lack of suitable biomarkers other than for irreversible kidney damage. Thus, the epidemiological studies linking health effects and cadmium exposure suffer from a relative lack of consensus knowledge about the modes of action of cadmium in multi-cellular... 

Metallothionein, a high sulfhydryl-containing protein involved in regulating cadmium distribution... 

The Model 412 PWR uses several control mechanisms. The first is the control cluster, consisting of a set of 25 hafnium metal rods coimected by a spider and inserted in the vacant spaces of 53 of the fuel assembhes (see Fig. 6). The clusters can be moved up and down, or released to shut down the reactor quickly. The rods are also used to (/) provide positive reactivity for the startup of the reactor from cold conditions, (2) make adjustments in power that fit the load demand on the system, (J) help shape the core power distribution to assure favorable fuel consumption and avoid hot spots on fuel cladding, and (4) compensate for the production and consumption of the strongly neutron-absorbing fission product xenon-135. Other PWRs use an alloy of cadmium, indium, and silver, all strong neutron absorbers, as control material. 

Complex equilibria among multiple species are typical also of polyselenide and polytelluride solutions. Aqueous polyselenide solutions have been employed as electrolytes in high-elRciency PEC with photoanodes made of gallium arsenide and cadmium chalcogenides (Chap. 5). Unlike polysulfides, the fundamental equilibria constraining the distribution of polyselenide species have not been meticulously characterized [19]. 

The role of the distribution of species in solution in determining the CdS film composition and structure was studied by Rieke and Bentjen [244], who performed equilibrium analysis of the cadmium-amine-hydroxide system to predict the spe-ciation in solution. The focus was on the formation of Cd(OH)2 and Cd(NH3) species due to their importance in film growfh. If was concluded fhat for deposition of high-quality, adherent, phase-pure CdS films, a surface cafalytically active toward thiourea decomposition is desirable. The Cd(OH)2 film was thought to be responsible for this effect. 

FIGURE 20.5 Distribution of molecular and ionic species of divalent cadmium at different pH values. (From U.S. EPA, Assessing the Geochemical Fate of Deep-Well-Injected Hazardous Waste A Reference Guide, EPA/625/6-89/025a, U.S. EPA, Cincinnati, OH, June 1990.)... 

Bloom NS, Crecelius EA, 1987. Distribution of silver, mercury, lead, copper, and cadmium in Central Puget Sound sediments. Marine Chemistry 21 377-390. 

Gerhardsson L, Brune D, Nordberg GF, et al. 1986a. Distribution of cadmium, lead, and zinc in lung, liver, and kidney in long-term exposed smelter workers. Sci Total Environ 50 65-85. 

Lauwerys R, Buchet J-P, Roels HA, et al. 1978. Placental transfer of lead, mercury, cadmium, and carbon monoxide in women I. Comparison of the frequency distributions of the biological indices in maternal and umbilical cord blood. Environ Res 15 278-289. 

Most trace metals may be precipitated with phosphate into insoluble metal phosphates (Table 7.5). Most metal phosphates have low solubility. High localization of phosphates reduces the bioavailability of Zn in arid soils. The banded application of P near the seeds depresses Zn uptake by com (Adriano and Murphy, 1970 Grant and Bailey, 1993), causing Zn deficiency. However, both N and P fertilizers increase Cd concentration in plants. Cadmium and Zn are antagonistic in root uptake and distribution within plants. 

Bewers J.M., Barry P.J., MacGregor D.J. Distribution and Cycling of Cadmium in the Environment. In Cadmium in the Aquatic Environment, J.O. Nriagu, J.B. Sprague, eds. New York John Wiley Sons, 1987. 

Candelaria L.M., Chang A.C. Cadmium activities, solution speciation, and solid phase distribution of Cd in cadmium nitrate and sewage sludge-treated soil systems. Soil Sci 1997 162 (10) 722-732. 

Hardiman R.T., Jacoby B., Banin A. Factors affecting the distribution of cadmium, copper and lead and their effect upon yield and zinc content in bush beans (Phaseolus vulgaris L.). Plant Soil 1984a 81 17-27. 

Jiao Y., Bailey L.D., Grant C.A. Effects of phosphorus and zinc fertilizer on cadmium uptake and distribution in flax and durum wheat. J Sci Food Agri 2004 84 777-785. 

Martinez Garcia M.J., Moreno-Grau S., Martinez Garcia J.J., Moreno J., Bayo J., Guillen Perez J.J., Moreno-Clavel J. Distribution of the metals lead, cadmium, copper and zinc in the top soil of Cartagena, Spain. Water Soil Soil Pollut 2001 131 329-347. 

Wakefield Z.T. Distribution of Cadmium and Selected Heavy Metals in Phosphate Fertilizer Processing (Bulletin Y-159), National Fertilizer Development Center, TVA, 1980. 

Webber J.H., Beauchamp E.G. Cadmium concentration and distribution in com (Zea mays L) growing on a calcareous soil for three annual sludge applications. J. Environ Sc Health B 1979 14 459 174. 

In mammals, as in yeast, several different metallothionein isoforms are known, each with a particular tissue distribution (Vasak and Hasler, 2000). Their synthesis is regulated at the level of transcription not only by copper (as well as the other divalent metal ions cadmium, mercury and zinc) but also by hormones, notably steroid hormones, that affect cellular differentiation. Intracellular copper accumulates in metallothionein in copper overload diseases, such as Wilson s disease, forming two distinct molecular forms one with 12 Cu(I) equivalents bound, in which all 20 thiolate ligands of the protein participate in metal binding the other with eight Cu(I)/ metallothionein a molecules, with between 12-14 cysteines involved in Cu(I) coordination (Pountney et ah, 1994). Although the role of specific metallothionein isoforms in zinc homeostasis and apoptosis is established, its primary function in copper metabolism remains enigmatic (Vasak and Hasler, 2000). 

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