Cadmium occurrence

Upon the formation of CdS colloids, at the point when the colloidal particles stop their growth and the system reaches the quasiequilibrium state, the total amount of cadmium is distributed over CdS particles and the aqueous phase of the solution, where it appears both as activated Cd2+ ion and as the compounds with complexing admixtures. One may assume the thermodynamic equilibrium is reached between the different possible forms of cadmium occurrence. Assuming the presence of only one complexing agent L, which participates in a stepwise complexing, we may describe the above equilibrium by a system of chemical equations ... 

ISOTOPES There are 52 isotopes of cadmium. Forty-four are radioactive and artificially produced, ranging from Cd-96 to Cd-131. Of these 52 isotopes, there are five stable isotopes plus three naturally occurring radioactive isotopes with extremely long half-lives that are considered as contributing to the element s natural occurrence in the Earth s crust. The three naturally radioactive isotopes (Cd-106, Cd-113, and Cd-116) are the longest known beta emitters. They are two million years older than when the solar system was formed about 4.5 billion years ago. The five stable isotopes and their proportional contributions to the elemenfs existence on Earth are as follows Cd-108 = 0.89%, Cd-110 = 12.49%, Cd-111= 12.80%, Cd-112 = 24.13%, and Cd-114 = 28.73%. 

Fassett DW Cadmium Biological effects and occurrence in the environment. Annu Rev Pharmacol 15 425 35, 1975... 

Suzuki, S., Fukagawa, T. Takama, K. (1992). Occurrence of tributyltin-tolerant bacteria in tributyl tin- or cadmium-containing seawater. Applied and Environmental Microbiology, 58, 3410-12. 

The SSM sample was spiked with seven different heavy metals. The concentrations of each spike were followed arsenic - 500 mg/kg, cadmium-1000 mg/kg, chromium - 1500 mg/kg, copper - 9500 mg/kg, lead - 14,000 mg/kg, nickel - 1000 mg/kg, and zinc - 22,500 mg/kg. The concentrations used were based on the occurrence, frequency and concentration of contaminants commonly found in Superfund soils. 

Cadmium is readily taken up by most plants. The occurrence of cadmium in motor oils, car tyres, phosphorus fertilisers and zinc compounds explains its... 

Colella, C., DeGennarao, M., Langella, A., and Pansini, M. (1995). Cadmium removal from wastewaters using chabazite and phillipsite. Natural zeolites 93 occurrence, properties, and use, D. W. Ming and F. A. Mumpton, eds., International Committee on Natural Zeolites, Brockport, NY, 377-384. 

The most spectacular and publicized occurrence of cadmium poisoning resulted from dietary intake of cadmium by people in the Jintsu River Valley, near Fuchu, Japan. The victims were afflicted by itai, itai disease, which means ouch, ouch in Japanese. The symptoms are the result of painful osteomalacia (bone disease) combined with kidney malfunction. Cadmium poisoning in the Jintsu River Valley was attributed to irrigated rice contaminated from an upstream mine producing lead, zinc, and cadmium. 

It has been observed in the past that the rate of emission of these trace metals into the atmosphere is low due to their low volatility. However, with the advent of large-scale metal mining and smelting as well as fossil-fuel combustion in the twentieth century, the emission rate of these metals has increased dramatically. As most of these emissions are released into the atmosphere where the mammals live and breathe, we see a great increase in the occurrence of health problems such as lead (Pb) poisoning, cadmium (Cd) Itai-itai disease, chromium (Cr), and nickel (Ni) carcinogenesis. 

Hem J. D. (1972) Chemistry and occurrence of cadmium and zinc in surface water and ground water. Water Resour. Res. 8, 661-679. 

Cadmium levels in blood are generally recognised as a biomarker of recent exposure to cadmium. It can also be used as biomarker of cumulative internal dose and accumulation of cadmium, buf only when fhere is long-term (decade long) continuous exposure, for example in subsistence farmers consuming their own crops. Cadmium levels in urine are a widely recognised biomarker of cumulative internal dose, kidney and body burden of Cd. Dose-response relationships between urinary Cd and occurrence of kidney effects are described in the subsequent sections of this chapter "Sweden", "Japan", "Belgium", and "Other countries". 

Occurrence A greenockite (cadmium sulfide) ore containing zinc sulfide also in lead and copper ores containing zinc. Canada, central and western U.S., Peru, Australia, Mexico, Zaire. 

Subsequent studies90 focused on the population structure of fish presenting tumors as well as the role of heavy metals. Overall neoplasm prevalence appears to be stable at about 22% of the population. No juvenile fish, out of 2000 + examined, exhibited tumors. Likewise, tumor prevalence did not appear to be seasonal or site specific within the Lake of the Arbuckles. Water, sediment and fish tissues were collected from the Lake of the Arbuckles, a reference lake outside the drainage, and were analyzed for total recoverable metals (cadmium, chromium, copper, nickel and lead) by graphite furnace atomic absorption. Chromium, copper and nickel were found in the water samples at concentrations of > 1 — 8.6 /xg/1. Low concentrations (>1-13.6 /xg/g wet weight) of all the metals were found in the sediment and liver tissues from both sites. Based on these concentrations, heavy metal contamination does not appear linked to neoplasm occurrence. 

For the essential elements the amounts in the body are normally controlled by physiological mechanisms, but for the non-essential, non-beneficial elements there are no such controls and the amounts in the body generally reflect the natural occurrence of the elements in food and water. For many such elements we may consider that there is a base load in the human body which reflects the natural intake of the elements in the diet. For some elements, industrial, mining or other human activities, may release metals into the environment. Such activities may result in a civilization-related load being added to the natural base load in some circumstances this civilization-related load may be very much greater than the base load. For example, the natural concentrations of the highly toxic metal cadmium in soils are generally quite low, yet in the... 

The occurrence of polymorphic forms and the persistence of the metastable state are facts of the highest practical and theoretical importance. In the case not only of tin, but also a number of other metals, e.g. bismuth, cadmium, copper, silver, and zinc, allotropic modifications exist with transition points at temperatures above the ordinary and, owing to the slowness of transformation, these metals exist, at the ordinary temperature, in a metastable state. On this fact depends the practical, everyday use of these metals. ... 

Sulphur is less electronegative than oxygen, and in consequence no sulphide of composition AS2 crystallizes with any of the typically ionic structures commonly found among the oxides A02. A number of sulphides have the cadmium iodide layer structure, but many others, particularly those of the transition metals, have structures unrepresented among the compounds so far considered. A few of these are of sufficiently common occurrence to warrant discussion. 

In China, increased occurrence of tubular proteinuria has been reported in Cd contaminated areas. In an area in southeast China, high dietary exposure via the intake of high cadmium containing rice, contaminated by the effluents of a smelter, an increased excretion of tubular proteinuria was reported that for P2-microglobulin and albumin correlated in a dose-related pattern with the urinary Cd excretion [7]. Urinary P2-microglobulinuria and N-acetyl-P-D-glucos-aminidase excretion was evident also at relatively low urinary Cd concentrations [138]. 

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