Seawater strontium concentration

Figure 1.49. Change of the strontium content and Sr/ Sr ratio of Kuroko anhydrite during the deposition and dissolution due to the mixing of hot ascending solution and cold solution (normal seawater) (Shikazono et al., 1983). R mixing ratio (in weight) = S.W./(S.W.+H.S.) in which S.W. and H.S. are seawater and hydrothermal solution, respectively. Open triangle Fukazawa deposits. Solid triangle Hanawa deposits. Open square Wanibuchi deposits. Solid square Shakanai deposits. Concentration of Ca, Sr " " and SO of H.S. are assumed to be 1,(XX) ppm, 1 ppm, and 10 mol/kg H2O, respectively. Concentrations of Ca, Sr " and SO of S.W. are taken to be 412 ppm, 8 ppm, and 2,712 ppm. Temperatures of H.S. and S.W. are assumed to be 350°C and 5°C (Shikazono et al., 1983).

Robertson [ 57 ] has measured the adsorption of zinc, caesium, strontium, antimony, indium, iron, silver, copper, cobalt, rubidium, scandium, and uranium onto glass and polyethylene containers. Radioactive forms of these elements were added to samples of seawater, the samples were adjusted to the original pH of 8.0, and aliquots were poured into polyethylene bottles, Pyrex-glass bottles and polyethylene bottles contained 1 ml concentrated hydrochloric acid to bring the pH to about 1.5. Adsorption on the containers was observed for storage periods of up to 75 d with the use of a Nal(Tl) well crystal. Negligible adsorption on all containers was registered for zinc, caesium, strontium, and... 

Polarography has also been applied to the determination of potassium in seawater [535]. The sample (1 ml) is heated to 70 °C and treated with 0.1 M sodium tetraphenylborate (1 ml). The precipitated potassium tetraphenylborate is filtered off, washed with 1% acetic acid, and dissolved in 5 ml acetone. This solution is treated with 3 ml 0.1 M thallium nitrate and 1.25 ml 2M sodium hydroxide, and the precipitate of thallium tetraphenylborate is filtered off. The filtrate is made up to 25 ml, and after de-aeration with nitrogen, unconsumed thallium is determined polarographically. There is no interference from 60 mg sodium, 0.2 mg calcium or magnesium, 20 pg barium, or 2.5 pg strontium. Standard eviations at concentrations of 375, 750, and 1125 pg potassium per ml were 26.4, 26.9, and 30.5, respectively. Results agreed with those obtained by flame photometry. 

Carr [562] has studied the effects of salinity on the determination of strontium in seawater by atomic absorption spectrometry using an air-acetylene flame. Using solutions containing 7.5 mg/1 strontium and between 5 and 14% sodium chloride, he demonstrated a decrease in absorption with increasing sodium chloride concentration. To overcome this effect a standard additions procedure is recommended. 

Average Concentrations of Rubidium, Strontium and Barium in Seawater (3)... 

The distribution coefficients determined for strontium (at U c) and for barium (at ll C for 3 0 < -log < U.5 and at for all other values of -log Ci) are summarized in Figure 2. Due to the relatively high concentration of strontium in seawater (and hence the relatively high concentration initially in the clay-phase) only limited data for strontium were obtained. The distribution coefficients which were obtained appear to behave similarly to the respective coefficients for barium but are somewhat smaller in magnitude. For solution-phase concentrations on the order of 10"3 mg-atom/ml, the barium coefficients appear to be between 10 and 100 ml/gm, and for solution-phase concentrations on the order of 10 ", the barium coefficients appear to be on the order of 10, as was expected. Furthermore, the coefficients for both strontium and barium are generally consistent with the corresponding data obtained for similar oceanic sediments and related clay minerals found within the continental United States (6,758 13) The... 

Ordinary anion and cation ion-exchange resins are of limited use for the analytical concentration of trace elements from water, because of their lack of selectivity. This is especially so with strong electrolytes such as seawater. In this case the major ions sodium, magnesium, calcium and strontium, are retained preferentially. However, the recent advent of commercial chelating resins based mainly on iminodiacetic acid-substituted cross-linked polystyrene, makes it possible to concentrate trace elements from waters. In consequence, a number of researchers have used chelating resins for trace-metal preconcentration from seawater and natural waters. 

An example of a process such as this is one where strontium is recovered and concentrated from the mixtures in which it is present together with a large excess of sodium and a considerable amount of calcium, natural brines, and concentrates of seawater treatment. 

Strontium is widely used in ferrous and nonferrous metallurgy as a deacidifier and as an antifrictional material for producing glasses and some special optic materials. It exists in seawater at a concentration of 8 mg/L. 

Figure 13 Concentrations of alkali earth metals at different stages of the cascade process in the course of strontium recovery from seawater (see text).

Selective separation of strontium from calcium at significant SrCl2 concentration levels up to 2 g/L was obtained with KB-4 carboxylic add exchanger employed in a Higgins-type contactor [246]. The pilot unit for strontium recovery from seawater in the closed (and practically waste-free) processing scheme was constructed in the Okhotsk Sea region (Sakhalin power station). The data obtained with the new pilot plant have shown that several components will be recovered simultaneously from seawater. The unit is estimated to produce more than 150 kg of SrCOj, more than 5000 kg of KNOj, and about 2 kg of RbNOj [15]. However, recovery of strontium is still uneconomical. Its cost is expected to become comparable to that of strontium produced from traditional, land-based sources. 

The number of publications involved with the recovery of rubidium from seawater is very limited. Most of the work in this field is by Russian scientists, who have proposed several schemes for the combined recovery of rubidium, strontium, and potassium with natural zeolites [15, 19, 250-253, 257]. A number of inorganic sorbents with high selectivity toward rubidium were also synthesized for the recovery of rubidium from natural hydromineral sources, including seawater. Ferrocyanides of the transition-metal ions were shown to exhibit the best properties for this purpose [258, 259]. Mordenite (another natural zeolite) has recently been proposed for selective recovery of rubidium from natural hydromineral sources as well [260]. A review of the properties of inorganic sorbents applicable for the recovery of rubidium from hydromineral sources has been published [261]. Studies of rubidium recovery fix>m seawater [15, 19, 250-253] have shown that the final processing of rubidium concentrates, especially the selective separation of Rb -K mixtures remains the major problem. A report was recently published showing that this problem can be successfully solved by countercurrent ion exchange on phenolic resins [262]. 

In addition to magnesium, at least trace amounts of many components present in seawater can be incorporated into marine carbonates. Concentrations range from trace (e.g., heavy metals), to minor (e.g., strontium), to major (e.g., magnesium, see previous discussion). This means that there is potentially a large amount of information that can be obtained from the study of carbonate mineral composition. This type of... 

Fig. 16. Comparison of (a) sodium (b) potassium (c) calcium (d) magnesium (e) strontium (f) boron and (g) bromide concentrations, respectively, of mine brine samples with an evaporating seawater and Louisiana formation waters (dotted outline) from Collins (1975).

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