Mineral waters, uranium

Helium occuis 11) in minerals of uranium and thorium, such as clevites. pitchblende, cnrnoiiie. niona/tie. and ako in beryl. 12> in mineral waters (I part lie per thousand of water, in some Iceland watersi. <3l in volcanic gjses. (4 i especially in certain natural gases ol the United Slates flic Hrs( discovery ol this kind was nude in Kansas. 

Uranium is a trace constituent in most ground waters. In typical aquifers with oxidizing ground water, uranium s concentration in solution appears to be limited by its abundance in source rocks. The uranium in ground water is removed from solution and deposited at a redox interface between sediments with reducing minerals and sediments without. In the resultant roll-front deposit, uranium is concentrated in the sediment, and its ground-water concentration remains low because of the low solubility of the uranium minerals that compose the deposit. Consequently, it is possible to have localized high concentrations of uranium in the earth s crust that are stable. 

In addition to HIE, the melts are probably enriched in volatiles, notably in water. Uranium, strontium, and lead may indeed be selectively enriched in water-rich melts/fluids (Gill, 1990 Keppler and Wyllie, 1990 Erenan et al., 1996 Keppler, 1995 You et al., 1996). This might account for the frequent occurrence of positive anomalies of strontium (and lead—not shown) on PM-normalized diagrams, and for the U/Th ratios systematically higher than PM values, both in whole rocks (Figures 16 and 17) and in acid-leached minerals (Figure 21). 

Sorption at natural pH of sea water. Elution with dilute mineral acids. Uranium capacity > 3600 ppm 119,125,144)... 

Uranium U(VI) minerals are most often products of the oxidation and weathering of nearby primary U(IV) ore minerals such as uraninite [U02(c)I and coffinite [USi04(c)l (cf. Pearcy et al. 1994). They also form by evaporative concentration of dissolved U(VI), particulary under arid conditions. Schoepite (/J-UOj 2H2O) is fairly soluble and, therefore, is a rare mineral, whereas carnotite K2(U02)2(V04)2j and tyuyamunite (Ca(U02)2(V04)2j, which have lower solubilities (particularly above pH 5) are the chief oxidized ore minerals of uranium. The plots in Figs. 13.5 and 13.6 indicate that uranyl minerals are least soluble in I0W-CO2 waters, and, therefore, are most likely to precipitate from such waters. This is con.sistent with the occurrence of carnotite and tyuyamunite in oxidized arid environments with poor. soil development (Chap. 7), such as in the calcrete deposits in Western Australia (cf. Mann 1974 Dall Aglio et al. 1974), and in the sandstone-hosted uranium deposits of the arid southwestern United States (cf. Hostetler and Carrels 1962 Nash et al. 1981). The... 

Formaldoxime has been applied in the determination of manganese in water [69,70], plants [69,71], silicate and carbonate minerals [72], uranium oxide [9], tin [73], and alkalies [74]. The formaldoxime method has been automated in the determination of manganese in water [75] and in silicate minerals [76]. The FIA technique has been applied in the analysis of natural waters [77] and silicates [78]. 

Arsenazo HI was applied in the determination of thorium in biological materials [103,104], natural waters [34,105,106], fertilizers [107], glass [108], silicate minerals [2,10,27,55,109], niobium and tantalum minerals [110], uranium minerals [3,18], manganese ores [19], lanthanide compounds [26,44], zirconium minerals [111], titanium concentrates [111], ilmenite and rutile [112]. Thorium was determined in waters with the use of the FIA technique [106]. 

One of the main components of the natural acitivity of mineral waters is gaseous radon. Other components of natural radioactivity of groundwaters are uranium and radium. Waters with an activity > 370 Bq 1 are considered to be radioactive mineral waters. 

Drinking water is primarily obtained from either surface supplies such as rivers and reservoirs or groundwater from wells. Groundwaters tend to have higher uranium concentrations than surface waters. This is due to the dissolution or solubilization of uranium from the underlying mineral structure. For this reason bottled mineral waters tend to have elevated levels of naturally occurring radionuclides, including uranium. 

The total daily ingestion of uranium can vary markedly due to the local concentration in drinking water or the consumption of mineral waters. The range of uranium concentrations in potable surface waters is 0.03-15 p,g/liter (0.4-185 mBq/liter) [19], and while public groundwater supplies are generally <10 JLg/liter (<125 mBq/liter), a few exceed 10(X) p,g/liter [20]. Because of the extreme variability in uranium concentration in potable waters, no global average has been adopted by the United Nations Scientific Committee for the Effects of Atomic Radiation (UNSCEAR). Mineral waters in three European nations have been reported to contain 0.04-70 xg U/liter (0.5-870 mBq/liter) [21]. 

A comprehensive study of uranium transfer from soil to plants, animals, and man in the food chain was published (Anke et al. 2009). The uranium content in vegetation in Germany was found to be much lower than in soil and the amount varied considerably between different types of soil and this was reflected in the concentration in plants and mineral waters. Table 3.5 shows the relative uranium content in flora in different types of soil (geological variation) in different geographical locations in Germany. 

A method for preconcentration and separation of ultra-trace amounts of uranium from aqueous samples (mineral water, rivers, wells, springs, and seawater) based on combining SPE with liquid-liquid microextraction was described (Dadfarnia et al. 2013). The water samples were filtered (0.45 pm) and acidified fo pH 2 wifh... 

In this study, the samples were digested with hydrochloric acid, rhodium was used as an internal standard, and uranium measurement was by ICPMS. In addition to an extensive survey of the uranium content in drinking water (tap water and bottled mineral water), many edible plants and other food products were also tested. The average uranium concentration in tap water in five regions of Germany was in the range of 0.28-2.4 pg L" with a maximum of 8.6 pg L". The range in the bottled mineral water samples varied from below the limit of detection (in this case, 0.015 pg L" ) to 24.5 pg L for one brand (Anke et al. 2009). 

Limits of detection (LODs) reached were 0.4 ng/1 of uranium and 2.8 ng/1 of thorium. The reproducibility of the LOV—MSFIA—ICP-MS was 1.7% expressed as relative standard deviation (RSD). Moreover, a high sensitivity, a wide working range, e.g. 0—200 pg/1 for both U and Th, and an injection frequency up to 9/h (depending on the sample volume) should be highlighted. Different water sample matrices (seawater, well water, freshwater, tap water and mineral water), a phosphogypsum sample with natural uranium and thorium content and a channel sediment reference material were satisfactorily analyzed with the proposed method. 

Dissolved Minerals. The most significant source of minerals for sustainable recovery may be ocean waters which contain nearly all the known elements in some degree of solution. Production of dissolved minerals from seawater is limited to fresh water, magnesium, magnesium compounds (qv), salt, bromine, and heavy water, ie, deuterium oxide. Considerable development of techniques for recovery of copper, gold, and uranium by solution or bacterial methods has been carried out in several countries for appHcation onshore. These methods are expected to be fully transferable to the marine environment (5). The potential for extraction of dissolved materials from naturally enriched sources, such as hydrothermal vents, may be high. 

Radon gas is formed in the process of radioactive decay of uranium. The distribution of naturally occurring radon follows the distribution of uranium in geological formations. Elevated levels have been observed in certain granite-type minerals. Residences built in these areas have the potential for elevated indoor concentrations of radon from radon gas entering through cracks and crevices and from outgassing from well water. 

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