Ocean strontium

Strontium is widely distributed in the earth s crust and oceans. Strontium is released into the atmosphere primarily as a result of natural sources, such as entrainment of dust particles and resuspension of soil. Radioactive strontium is released into the environment as a direct result of anthropogenic activities. Stable strontium can be neither created nor destroyed. However, strontium compounds may transform into other chemical compounds. Radioactive strontium is formed by nuclear reactions. Radioactive decay is the only mechanism for decreasing the concentration of radiostrontium. The half-life of 90Sr is 29 years. 

Brass, G. W. and Turekian. K. K. (1974). Strontium distribution in GEOSECS oceanic profiles. Earth Planet. Sci. Lett. 23,141-148. 

Courtois, C. and Clauer, N. (1980) Rare earth elements and strontium isotopes of polymetallic nodules from southeastern Pacific Ocean. Sedimentology, 27, 687-695. 

Palmer, M R. and Edmond, J.M. (1989) The strontium i.sotope budget of the modern ocean. Earth Planet. Sci. Lett., 92, 11-21. 

Palmer MR, Edmond JM (1989) The strontium isotope budget in the modem ocean. Earth Planet Sci Lett 92 11-26... 

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... 

For the nuclides studied (rubidium, cesium, strontium, bariun silver, cadmium, cerium, promethium, europium, and gadolinium) the distribution coefficients generally vary from about 10 ml/gm at solution-phase concentrations on the order of 10 mg-atom/ml to 10 and greater at concentrations on the order of 10 and less. These results are encouraging with regard to the sediment being able to provide a barrier to migration of nuclides away from a waste form and also appear to be reasonably consistent with related data for similar oceanic sediments and related clay minerals found within the continental United States. 

One should not conclude that trace analysis of water systems is a hopeless undertaking. It is possible to get results which are consistent and which seem to be reliable, but it does involve much effort and attention. One does not get satisfactory results without careful, critical appraisal of all conceivable variables involved. An example of the approach which is necessary is the recent work by Andersen in our laboratory on strontium and barium distribution in the Atlantic Ocean (I, 2). 

Bernstein, R.E., Betzer, PR., Feely, R.A., Byrne, R.H., Lamb, M.F. and Michaels, A.F. (1987) Acantharian fluxes and strontium to chlorinity ratios in the north Pacific Ocean. Science, 237,1490-1494. 

To begin the discussion, we will present briefly a view of the modern carbon cycle, with emphasis on processes, fluxes, reservoirs, and the "CO2 problem". In Chapter 4 we introduced this "problem" here it is developed further. We will then investigate the rock cycle and the sedimentary cycles of those elements most intimately involved with carbon. Weathering processes and source minerals, basalt-seawater reactions, and present-day sinks and oceanic balances of Ca, Mg, and C will be emphasized. The modern cycles of organic carbon, phosphorus, nitrogen, sulfur, and strontium are presented, and in Chapter 10 linked to those of Ca, Mg, and inorganic C. In conclusion in Chapter 10, aspects of the historical geochemistry of the carbon cycle are discussed, and tied to the evolution of Earth s surface environment. 

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.

Lowenstam H.A. (1961) Mineralogy, 180/160 ratios, and strontium and magnesium contents of recent and fossil brachiopods and their bearing on the history of the oceans. J. Geol. 69, 241-260. 

Manghnani M.H., Schlanger S.O. and Milholland P.D. (1980) Elastic properties related to depth of burial, strontium content and age, and diagenetic stage in pelagic carbonate sediments. In Bottom Interacting Ocean Acoustics (eds. W.A. Kupferman and F.D. Jensen), pp. . Plenum Press, New York. 

According to the latest estimates of Skinner [18], elements potentially recoverable from seawater are sodium, potassium, magnesium, calcium, strontium, chlorine, bromine, boron, and phosphorus because of their practically unlimited presence in the ocean. After improving respective technologies, recovery of the following elements is expected to become profitable as well lithium, rubidium, uranium, vanadium, and molybdenum. Additional profit can be gained since desalinated water will probably be obtained as a by-product. This could be important for countries with a very limited number of freshwater sources (e.g., Israel, Saudi Arabia). 

Tatsumoto M., Hedge C. E., and Engel A. E. J. (1965) Potassium, rubidium, strontium, thorium, uranium, and the ratio of strontium-87 to strontium-86 in oceanic tholeiitic... 

Few systematic Sr-Nd isotope studies have been performed on ocean island xenolith suites. Ducea et al. (2002) analyzed clinopyroxenes from plagioclase-spinel and spinel peridotites from Pali, (Oahu, Hawaii) and found relatively depleted strontium and neodymium isotope systematics that they interpret as representing their evolution as residues from the extraction of Pacific Ocean crust. Consistent with this is a 61 20Ma errorchron defined by the pyroxene separates that is within error of the 80-85 Ma age of Pacific lithosphere beneath Hawaii. 

A number of eclogites have both radiogenic neodymium isotopes and radiogenic strontium relative to bulk Earth. For these samples, some of the Sr/ Sr values exceed modem and Archean seawater compositions (see Chapter 6.17). Hence, in a subduction-type model, the radiogenic strontium isotopic composition of the eclogite protohth is not solely inherited from oceanic cmst but is likely to be a time-integrated response to Rb/Sr enrichment during hydrothermal alteration... 

B/Be, and strontium isotopes (Nicaragua lavas Reagan et al. (1994)) and with (oceanic Aleutian lavas George et al. (2003)) point to the isotopic composition of the sediment... 

Faure G. and Hurley P. M. (1963) The isotopic composition of strontium in oceanic and continental basalt application to the origin of igneous rocks. J. Petrol. 4, 31-50. 

The modem distribution of strontium isotopic ratios in basalts from both oceanic and continental regions is well documented (e.g., Hofmann, 1997 Chapter 2.03 Dickin, 1995), with the composition of the upper mantle today defined from analyses of N-MORBs ( Sr/ Sr = 0.7025 0.0005). Rubidium is one of the most incompatible elements during melting, and it is evident that... 

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