Migration strontium

Production. MetaUic strontium was first successfully produced by the electrolysis of fused strontium chloride. Although many attempts were made to develop this process, the deposited metal has a tendency to migrate into the fused electrolyte and the method was not satisfactory. A more effective early method was that described in Reference r5. Strontium oxide is reduced thermally with aluminum according to the following reaction ... 

The chemical identities of the fission products determine their subsequent redistribution, those elements which are in the gaseous state at the temperature of the operation migrating to the cooler exterior of the fuel rods, and die less voltile elements undergoing incorporation in the fuel rod in solid solution. Thus caesium and iodine migrate to the gas fill which sunounds the fuel rod, and elements such as the rare earths and zirconium are accommodated in solid solution in UO2 without significant migration along the fuel rod radius. Strontium and barium oxidize to form separate islands which can be seen under the microscope. 

Price, T. D., J. H. Burton, and R. A. Bentley (2002), The characterization of biologically available strontium isotopes ratios for the study of prehistoric migrations, Archaeometry 44(1), 117-135. 

The interconnect material is in contact with both electrodes at elevated temperatures, so chemical compatibility with other fuel cell components is important. Although, direct reaction of lanthanum chromite based materials with other components is typically not a major problem [2], reaction between calcium-doped lanthanum chromite and YSZ has been observed [20-24], but can be minimized by application of an interlayer to prevent calcium migration [25], Strontium doping, rather than calcium doping, tends to improve the resistance to reaction [26], but reaction can occur with strontium doping, especially if SrCr04 forms on the interconnect [27],... 

Bentley, R.A., Price, T.D., Liming, J., Gronenborn, D., Wahl, J. and Fullager, P.D. (2002). Prehistoric migration in Europe strontium isotope analysis of early Neolithic skeletons. Current Anthropology 43 799-804. 

Evans, J.A., Chenery, C.A. and Fitzpatrick, A.P. (2006). Bronze Age childhood migration of individuals near Stonhenge, revealed by strontium and oxygen isotope tooth enamel analysis. Archaeometry 48 309-321. 

Price, T.D., Grupe, G. and Schroter, P. (1994). Reconstruction of migration patterns in the Bell Beaker period by stable strontium isotope analysis. Applied Geochemistry 9 413-417. 

Studies are being conducted by the Pacific Northwest National Laboratory (PNNL) to investigate the use of clinoptilolite as an in situ permeable barrier to strontium (Sr °) migration in groundwater at the site referred to as the 100-N area of the Hanford Site. This technology uses clinoptilolite to absorb radioactive Sr ° from groundwater. 

The work that was performed in this set of experiments was an extension of work performed by Inoue and Kaufman (7). In the previous work, the migration of strontium in glauconite was modeled using conditions of local equilibrium for flows up to 6.3 kilometers per year (72 cm/hr). The differences between the predicted and experimental results in the experiments performed by Inoue and Kaufman may be due to the existence of non-equilibrium behavior. 

Strontium-85 with SrCl2 carrier was added to an aliquot of the calcium-strontium solution to form a radioactive solution with l X 10 M Sr. At the start of an experiment, a small quantity (20 p ) of the radioactive solution was injected into the solution stream above the glauconite column and the column was eluted with solution until all the radioactive strontium had moved through the column. The eluent was collected in fractions and each fraction was analyzed to determine the migration characteristics of the strontium in the column. 

The relative migration rate of the peak concentration of strontium at a solution flow rate of 0.1 mL per minute was used to calculate the equilibrium fractionation of strontium between glauconite and solution. It was determined that at equilibrium 0.958 of the strontium would be adsorbed by the glauconite and 0.042 of the strontium would be in solution (mobile phase). 

The F, G, and zone length input parameters to the ARDISC model were varied to fit the strontium migration data at a flow rate of 2 mL per minute. 

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. 

The case of Srcl8C6(PFO)2 complexes differs, as the PFO" counterions are amphiphilic in nature and their carboxylate head coordinates to strontium, while their perfluoroalkyl chain cannot and do not attract each other, thus preventing selfaggregation of the complexes. The affinity of these fluorinated chains for C02 contributes to solubilize the strontium complexes. As a result, the Srcl8C6(PFO)2 complexes sitting at the interface are "diluted", while the others migrated from the interface to SC-C02 40 % are found at more than 8 A from the interface, and can thus be considered as "extracted" at 305 K. 

Model Fitting to Mixing-Cell Data Multiple-site kinetic models have been used to describe pesticide and herbicide movement in soils (15,16,17), cesium migration in columns (18), and strontium migration in a sandy aquifer over a twenty-year time period (1L). The results of the selective extraction procedures in all experiments discussed here suggest that a multi-site model should provide a better fit of the data than a single-site model. This hypothesis is supported by the variances in Table I, with the possible exception of selenium. 

Predicted rates of the radioelement transport through sediment were found to depend strongly on HLW compositions. Compositions of HLW that are high in HEDTA/EDTA concentrations resulted in 30 to 40 times faster migration rates for americium and strontium. Neptunium and plutonium migration rates increased by factors of 6 to 40 by changing HLW from dilute/noncomplexed to concentrated/complexed compositions. 

Effective Migration Coefficients of Chloride, Cesium, and Strontium Ions in Bentonites from the Sajobabony Deposit (Table 3.1)... 

Torstenfelt B. (1985b) Migration of the fission products strontium, technetium, iodine and cesium in clay. Radiochim. Acta 39, 97-104. 

The place of origin of prehistoric people can also be determined. The isotopic proveniencing of human remains, using ratios of strontium isotopes, has been employed in archaeology for approximately 20 years. Strontium isotope analyses have been used successfully in a number of studies. The basic principle involves comparison of isotope ratios in human tooth enamel with local levels in bone or other materials. Because isotopic ratios vary geographically, values in human teeth (marking place of birth) that differ from the local ratio (place of death) indicate migration. This method of analysis is described in more detail in Chap. 8, Provenience and Provenance. 

Hodell, David A., Rhonda L. Quinn, Mark Brenner, and George Kamenov. 2004. Spatial variation of strontium isotopes ( Sr/ Sr) in the Maya region a tool for tracking ancient human migration. Journal of Archaeological Science 31 585-601. 

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