Strontium in seawater

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. 

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... 

Stoll H. M. and Schrag D. P. (1998) Effects of Quaternary sea level cycles on strontium in seawater. Geochim. Cosmochim. Acto 62(7), 1107-1118. 

Peterman Z. E., Hedge C. E., and Tourtelot H. A. (1970) Isotopic composition of strontium in seawater throughout Phanerozoic time. Geochim. Cosmochim. Acta 34, 105-120. 

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. 

Krosshaven et al. [64] used scintillation spectrometry employing germanium detectors to measure 137 caesium and strontium in coastal seawaters. 

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

Figure 9.23. Oceanic cycles of strontium and sulfur. Sr fluxes are in units of 109 moles y 1 S fluxes are in units of 1012 moles y1. The imbalance for S suggests storage of S042" in seawater.

Veizer J. (1989) Strontium isotopes in seawater through time. In Annual Reviews Earth and Planet. Sci. 17 (ed. G.W. Weatherill), pp. 141-167. Annual Reviews Inc., Palo Alto, California. 

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. 

Strontium isotope ratios and abundances in samples from the oceanic crust may be used to determine the complete chemical mass balance of strontium exchange between seawater and basalt, including the loss of basaltic strontium to hydrothermal solutions, and uptake of basaltic or seawater strontium from hydrothermal solutions. A mass balance of this exchange can be made in four steps, (i) The relative amount of basaltic and seawater strontium in altered basalt can be determined from the measured Sr/ Sr of an altered sample as a (linear) mixture of strontium from the two end members, the (contemporaneous) seawater and basalt, (ii) The inventory of the basaltic and seawater strontium in an altered sample (in mg/kg) may then be determined from the above ratio of seawater and basalt in the sample and the total strontium abundance measured for this sample, (iii) Seawater strontium addition to the basalt is given directly by the seawater strontium inventory calculated in Step (ii). (iv) The determination of flux of basaltic strontium in or out of an altered sample is more complicated because it has to be related to the original inventory of strontium. It is determined as the difference between the original basaltic inventory and the basaltic strontium present in the altered sample. 

Since the Precambrian, the Sr/ Sr of seawater has fluctuated between —0.7070 and —0.7092 as the result of variations in the relative rates of input of Sr-enriched strontium from continental weathering and Sr-depleted strontium from mantle sources. Fluids in sedimentary basins containing Paleozoic strata typically have Sr/ Sr ratios in excess of seawater values that are contemporaneous or coeval with the deposi-tional age of the current host sediment. This is well illustrated by the data of Connolly et al. (1990) for the Alberta Basin, Canada. The enrichment is due to the release of strontium attending the alteration of silicates. Due to the significant increase of Sr/ Sr in seawater since the Jurassic, some formation waters in Cenozoic sedimentary basins actually have Sr/ Sr ratios lower than those of contemporaneous seawater due to the addition of strontium dissolved from older and deeper sedimentary sources... 

The first neodymium-isotopic analyses aimed at characterizing the oceans closely followed the initial development of neodymium isotopes as a chronometer and tracer (Richard et al., 1976 DePaolo and Wasserburg, 1976a O Nions et al., 1977). O Nions et al. (1978) was the first to report neodymium (along with lead and strontium) isotopes in manganese nodules and hydrothermal sediments. They confirmed the distinction between continental and mantle provenances of lead in hydrogenous and hydrothermal manganese sediments, respectively. Consistent with the previous studies, they found that strontium in these deposits is derived from seawater. All of the neodymium-isotope ratios in their samples from the Pacific were similar and lower than the bulk... 

The most striking aspect of the Cenozoic strontium record is the nearly monotonic, and relatively rapid rise in seawater Sr/ Sr ratio during the last 40 Myr, as compared to the small... 

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