Accumulation of barium

The average adult human body contains 22 mg Ba, of which 93% is present in bone (47). The remainder is widely distributed throughout the soft tissues of the body in very low concentrations. Accumulation of barium also takes place in the pigmented parts of the eyes. 

Barium oxide is toxic by subcutaneous route. Because of its affinity for moisture, the compound is corrosive to skin. Contact with water or CO2 evolves much heat. Therefore, any use of CO2 to extinguish a BaO fire may cause further incandescence. Accumulation of barium oxide or peroxide dust... 

Some nut trees accumulate mineral elements. Hickory nut is notable as an accumulator of aluminum compounds (30) the ash of its leaves contains up to 37.5% of AI2O2, compared with only 0.032% of aluminum oxide in the ash of the Fnglish walnut s autumn leaves. As an accumulator of rare-earth elements, hickory greatly exceeds all other plants their leaves show up to 2296 ppm of rare earths (scandium, yttrium, lanthanum, dysprosium, holmium, erbium, thulium, ytterbium, and lutetium). The amounts of rare-earth elements found in parts of the hickory nut are kernels, at 5 ppm shells, at 7 ppm and shucks, at 17 ppm. The kernel of the Bra2d nut contains large amounts of barium in an insoluble form when the nut is eaten, barium dissolves in the hydrochloric acid of the stomach. 

Table 9 compares the contents of heavy metals in the ash of various grass and tree species from the Savanna ecosystems of East Africa. We can see that nickel, barium, and strontium accumulate in the tree organs (twigs), whereas the accumulation of other metals is pronounced in grasses. 

Lithium.—In order to extract lithium from the silicate minerals—petalite, lepidolite, spodumene, amblygonite, etc.—J. J. Berzelius 3 fused the finely powdered mineral with twice its weight of calcium or barium carbonate. L. Troost fused a mixture of finely powdered lepidolite with an equal weight of barium carbonate, half its weight of barium sulphate, and one-third its weight of potassium sulphate. In the latter case, two layers were formed lithium and potassium sulphates accumulated in the upper layer from which they were extracted by simple lixiviation. The sulphates are converted to chlorides by treatment with barium chloride. The filtered liquid is evaporated to dryness, and the chlorides extracted with a mixture of absolute alcohol, or pyridine. The lithium chloride dissolves, the other alkali chlorides remain as an almost insoluble residue. 

Two case studies of acute intrusion of barium sulfate into the peritoneal space during barium enema examination of four men showed barium sulfate caused an acute inflammatory tissue response (Kay 1954 Yamamura et al. 1985), and in one case resulted in formation of a fibrous granuloma (Kay 1954). This is an extremely rare mode of entry and not of significant concern for individuals exposed at a hazardous waste site. Increased fluid accumulation in the intestinal lumen of rats was observed after intraperitoneal injection of barium chloride (Hardcastle et al. 1983b, 1985) however, this observation is not significant for individuals exposed at hazardous waste sites because of the route of exposure and because there has been no documentation of this effect occurring in humans following normal exposure routes. 

Food Chain Bioaccumulation. There is information that barium bioconcentrates in certain plants and aquatic organisms (Bowen 1966 Schroeder 1970). However, the extent to which plants bioconcentrate barium from soil or to which uptake occurs in terrestrial animals is not well characterized. Further studies on the bioconcentration of barium by plants and terrestrial animals and on the biomagnification of barium in terrestrial and aquatic food chains would be useful to better characterize the environmental fate of barium and define the importance of food chain accumulation as a source of human exposure. 

Einbroot HJ, Wobker F, Klippel HG. 1972. [Experimental studies on the accumulation and distribution of barium sulfate in the rat following inhalation], Int Arch Arbeitsmed 30 237-244. (German)... 

Sevoflurane is metabolized to compound A by carbon dioxide absorbers. It is nephrotoxic in rats, but nephrotoxicity in humans has not been proven. The accumulation of compound A is greatest with low fresh gas flows and barium hydroxide absorbers, both of which cause higher temperatures in the absorber. Current anesthetic practice is to use sodium hydroxide for carbon dioxide absorption, because it produces less compound A than barium hydroxide. 

Soluble barium compounds are absorbed by the lungs and gastrointestinal tract and small amounts are accumulated in the skeleton. The highest concentration of barium in the body is present in the lungs. Although some barium is excreted in the urine, it is reabsorbed by the renal tubules. It is primarily excreted in feces. 

FP-2 (iodine, cesium, rubidium, strontium, barium, europium, samarium)—are removed during the reduction step by extraction into the salt phase. There will be an accumulation of FP-2 fission products in the salt which is controlled by a continuous salt bleed. For 1000 kg of fuel, 2000 kg of salt are required. 

The barium content of human tissues is dependent on age. For example, in adults the liver contained barium levels of 4-20 mg kg dry matter, whereas in children the typical liver barium content was much higher, at 144 mg kg The majority of tissue barium is accumulated in the skeleton, with typical adult levels ranging from 16 to 95 mg kg dry matter. Very high barium contents were also determined in the prostate gland of children, with up to 1.3gkg dry matter in infants (Jaritz 1998). Other sources have described lower levels of barium in human tissues however... 

Once absorbed from the gastrointestinal tract, barium is accumulated predominantly into the skeleton (Bauer et al. 1956, Taylor et al. 1962, Bligh and Taylor 1963, Doman-ski etal. 1969, Dencker etal. 1976). In omnivorous humans, the apparent absorption of barium was determined as 25%,... 

Figure 7 Distribution of barium accumulation rates (units of mg cm per 1000 years) in the Pacific sediments. (After Bostrom K, Joensuu O, Moore C et al. (1973), Geochemistry of barium in pelagic sediments. Lithos 6 159-174.)...

Barium sulphate is also becoming a rather common scale, particularly in closed pulp mills. When it occurs, the problem of its formation is exbemely troublesome as it is a salt with very low solubility. Because barium sulphate is a salt of such low solubility, barium sulphate scale may form even if barium concenbation, relative to other cations, is low, particularly when concentration in the system of sulphate ions is high. Barium is dissolved from the wood in the digester. The sulphate ion comes into the system through additives such as alum, and high sulphate ion concenbation may develop as a result of accumulation of the sulphate ion from papermaker s alum (used in the rosin sizing process) or from sulphuric acid used for pH conbol. A particular problem is Barium sulphate deposition in the headbox of Kraft liner machines. 

The principal metal refined in a molten salt medium is aluminium. Something approaching 2% of the total aluminium produced is refined by a process based on the principle illustrated in Fig. 4.7. The density of the impure aluminium is increased by the addition of copper (25—30%) and that of a cryolite melt by the addition of barium fluoride so that three distinct layers, pure aluminium, melt and aluminium/copper, are formed in the cell. On electrolysis the aluminium is transferred from the anode of impure aluminium to the top layer while the major impurities (i) Na, Mg, Ca and Sr are oxidized from the anode pool to the melt but do not reduce at the cathode and therefore accumulate in the melt, and (ii) Fe, Si, Mn, Zn (and Cu) are oxidized less readily than aluminium and hence remain in the anode pool. The aluminium obtained is very pure, being in the range 99.99—99.999%. 

The accumulation of HBr during the oxidation produces a definite inhibition of the rate of oxidation. The effect is more than one of an increasing acidity, for, although other strong acids also inhibit the rate, the effect is largest for HBr and HCl 175). To minimize this inhibiting influence, the reaction may be carried out in the presence of a buffer such as barium carbonate or barium benzoate 176). In general, the presence of buffers in-... 

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