Stable Strontium Research Articles

Application of Stable Strontium Isotope Geochemistry and Fluid Inclusion Microthermometry to Studies of Dolomitization of the Deeply Buried Cambrian Carbonate Successions in West-Central Tarim Basin, NW China

Detailed petrographic, geochemical (O-C-Sr isotopes) and fluid inclusion studies of the deeply buried Cambrian carbonates in the West-central Tarim Basin revealed three types of crystalline dolomites (fine-crystalline, nonplanar-a(s), dolomite (RD1), fine- to medium-crystalline, planar-e(s) dolomite (RD2), and medium- to coarse-crystalline, nonplanar-a dolomite (RD3)), medium- to coarse-crystalline, nonplanar-a saddle dolomite cement (CD) and early and later-stage calcite cement. The occurrence of RD1 along low-amplitude stylolites points to link with pressure dissolution by which minor Mg ions were likely released for replacive dolomitization during early- to intermediate-burial seawater dolomitization. The increasing crystal sizes of RD2 and RD3 with irregular overgrowth rims suggests intense recrystallization and replacement upon the RD1 or remaining precursor limestones by dolomitizing fluids during late intermediate burial dolomitization. The overlap of δ18O, δ13C and 87Sr/86Sr values of RD1-RD3 and CD dolomite with coeval seawater values, suggests that the principal dolomitizing fluids that precipitated these dolomites was connate (Cambrian) seawater preserved in the host limestones/dolomites. Their high 87Sr/86Sr ratios suggest influx of radiogenic strontium into the Cambrian seawater. Two regimes of fluid flow are recognized in the study area: firstly, influx of magnesium-rich higher-temperature basinal brines along deep-seated faults/fractures, resulting in cementation by CD dolomite. Secondly, the incursion of meteoric waters, mixing with ascending higher-temperature basinal brines, and an increase in Ca2+/Mg2+ ratio in the fluids probably results in the precipitation of calcite cement in vugs and fractures.

Intra- and inter-individual variability of stable strontium isotope ratios in hard and soft body tissues of pigs.

Stable isotope analysis has become an indispensable tool for the identification of the flow of matter in ecological sciences. Stable strontium isotope ratios are used in several different scientific fields as markers for provenance, mobility, and migration. A crucial prerequisite for such studies is a reliable definition of local ranges and an estimation of expected isotopic variability. To study the local variability of stable strontium isotope ratios at a specific place, a farrow of ecologically and locally grown pigs was investigated and strontium was extracted from their hard tissues (tooth enamel, bones and bristles) as well as soft tissues (meat, organs and blood) via dry- and wet-ashing procedures and subsequent column separation. The 87 Sr/86 Sr ratio was then measured via TIMS (thermal ionization mass spectrometry). Reliable 87 Sr/86 Sr data was generated from all tissue types. Both intra- and inter-individual variability was high and tissue-specific patterns could be identified. High ranges occurred in sample types which were analyzed for animals of different age (pigs as well as piglets): teeth, parietal, mandible, femur, and leg muscle as well as in jaw muscle samples, which were only analyzed in adult pigs. Tooth enamel data showed a tooth-type-dependent pattern. We conclude that a time factor played a role for the observed variability, e.g. a shift in food supply. Furthermore, we presume that local range estimates from the literature only work for tissues which integrate all consumed components over a sufficient amount of time and average fluctuations which can be found in tissues with higher turnover rates.

Modifying Effect of Stable Strontium on Cell Death within the Conditions of Experiment

Modifying Effect of Stable Strontium on Cell Death within the Conditions of Experiment

Combining metal and nonmetal isotopic measurements in barite to identify mode of formation

Barite (BaSO4) is a highly stable and widely-distributed mineral found in magmatic, metamorphic, and sedimentary rocks of all ages, as well as in soils, aerosol dust, and extraterrestrial material. Barite can form in a variety of settings in the oceans (hydrothermal deposits, cold seeps, water column, or within sediments) and on the continents (soils, sulfidic springs and in the subsurface) when (1) two fluids mix – one containing barium and another containing sulfate, (2) sulfur is oxidized forming sulfate in a barium containing solution, or (3) barium or sulfate is concentrated in microenvironments where either sulfate or barium are already present. Hydrologic and biologic processes can therefore play key roles in the formation of barite and affect its geochemical composition. Characteristics of barite from various modern settings are identified here to serve as analogs for ancient systems, summarizing previous work and adding new details from the pelagic marine, hydrothermal, cold seep and continental setting. Radiogenic strontium in barite clearly identifies the source(s) of fluid forming barite with the most radiogenic values measured in continental sulfidic spring settings associated with a deep fluid component that interacts with ancient crustal rocks. Sulfur and oxygen isotopes can distinguish between sources of sulfate and identify settings where the influence of (bio)chemical processes such as sulfate reduction is prominent. There are no unique stable strontium isotopic signatures for barite formed in any of the settings investigated here, but Holocene coretop marine pelagic barite appears to have a constant offset from seawater of approximately −0.53‰ in coretop samples in contrast to the wide range of values in barite precipitated in other settings. Stable strontium mass dependent fractionation could be useful in understanding post-depositional and diagenetic processes such as authigenic precipitation and recrystallization.

Provenance analysis of human cremations by 87Sr/86Sr isotopic ratios: migration into an Iron Age mining region in North-Rhine Westphalia

The Siegerland (North-Rhine Westphalia, FRG) is famous for its early mining industry and ore exploitation. The archaeological context of cremated burials as well as grave goods indicate parallels to today's Wetterau (Hesse), suggesting migration into the Siegerland. After morphological examination of the cremations augmented by a histological age-at-death determination, provenance analysis by use of stable strontium isotope analysis was carried out. 60 individuals from the burial mound at Netphen-Deuz in the Siegerland were available for anthropological examination. The 87Sr/86Sr isotopic ratio was measured in 29 dentine and 15 bone samples. At least 19 individuals exhibited a non-local isotopic signal which was compatible with a provenance from the Wetterau region. Since 87Sr/86Sr isotopic ratios in the bioapatite are thermally stable, provenance analysis of cremated finds is thus possible, whereby a testable archaeological hypothesis is prerequisite. Histological examination of cremated bones proved indispensable for the age-at-death estimation.

Weathering processes, catchment geology and river management impacts on radiogenic (87Sr/86Sr) and stable (δ88/86Sr) strontium isotope compositions of Canadian boreal rivers

Radiogenic (87Sr/86Sr) and stable (δ88/86Sr) strontium isotope compositions spanning a calendar year are reported for rivers from across subarctic Canada that drain contrasting lithologies ranging from Precambrian bedrock (Koksoak, Great Whale and La Grande rivers of Northern Quebec) to carbonate and clastic Phanerozoic sedimentary rocks of the Western Interior Platform (Nelson River, of central and western Canada). The 87Sr/86Sr isotopic compositions of the river waters reflect the underlying geology, with rivers draining the Precambrian Shield having higher 87Sr/86Sr ratios (0.727–0.734) than the Phanerozoic dominated Nelson River (0.713). The stable strontium isotope values (δ88/86Sr) range from 0.26 to 0.39‰, with the values for the Nelson River overlapping those of the other three. Rivers that have not been developed for hydroelectric power show a seasonal variation in the 87Sr/86Sr ratios, whereas those that have been diverted or dammed show little or no seasonal variation due to increased residence time of their water in hydroelectric reservoirs. The three rivers from Northern Quebec show discrete ranges in their 87Sr/86Sr and δ88/86Sr isotope compositions that correlate with the Ca/Sr and Na/Sr ratios of the river water. These correlations are interpreted to reflect differential chemical weathering of felsic versus mafic source rocks and/or of surficial sediment vs bedrock sources.

A synergetic biomineralization strategy for immobilizing strontium during calcification of the coccolithophore Emiliania huxleyi.

The coccolithophore species Emiliania huxleyi has one of the most global distributions in the modern oceans. They are characteristically covered with calcite scales called coccoliths. In this study, stable strontium immobilization during the calcification process was investigated to indirectly assess a proposed bioremediation approach for removing Sr2+ contamination from marine environments. Results indicate that E. huxleyi has high Sr2+ tolerance and removal efficiency in response to Sr2+ stress ranging from 5.6 to 105.6ppm. Sr2+ immobilization during E. huxleyi calcification indicates a concentration-dependent synergistic mechanism. At lower concentrations of Sr2+ (25.6ppm), Sr2+ is incorporated into coccoliths through competitive supply between Sr2+ and Ca2+. In addition, calcite productivity decreases with increased Sr2+ removal efficiency due to crystallographic transformation of coccoliths from hydrated calcite into aragonite at 55.6ppm Sr2+. Further formation of strontianite at 105.6ppm Sr2+ is due to precipitation of Sr2+ on the edge of the rims and radial arrays of the coccoliths. Our study implies that coccolithophores are capable of significant removal of Sr2+ from the marine environment.

PECULIARITIES OF THE REGULATION OF THE IMMUNE SYSTEM IN CHILDREN RESIDING IN CONDITIONS OF STRONTIUM GEOCHEMICAL PROVINCE

There was made a study of the features of apoptosis in children drinking potable water with an increased content of stable strontium of natural origin. The percentage of non-standard samples of strontium content in the water on the observation territory was 16.7%, which corresponded to the exceedance of the maximum permissible concentration of strontium in drinking water at the level of 1.2 MPC (up to 8.4 mg/l). In children living in the strontium geochemical province, the blood content of strontium (0.1 mg/dm3) was established statistically significant higher (p = 0.02) in comparison with the results obtained from children living in the territory of relative sanitary and hygienic well-being (0.028 mg/dm3). There was made an estimation of parameters of the dependence between the concentration of strontium in drinking water and the concentration of strontium in the blood was estimated, there was obtained a reliable dependence (b0 = 0.04, b1 = 0.012, R2 = 0.44, F = 310, p = 0.00001) of the increase in the blood content of strontium by the 1.3 times relative to the reference level from the concentration of strontium in water. In the exposure range of 7.84 ± 0.62 mg/L per 1 mg/L increase in strontium in water, its concentration in the blood was established to increase by 0.012 mg/dm3. In children living in the strontium geochemical province (1.5-0.8 times) by the method of flow cytometry, there were established to statistically significant decline the (relative and absolute values) number of CD95+ lymphocytes (p = 0.04-0.001) by 3.8 times, the expression of p53, bcl-2, Bax and the amount of Annexin V-FITC+PI- cells dying via the path of apoptosis, as well as the content of Annexin V-FITC+PI+ cells, dying via necrosis was statistically significantly (p = 0.001) elevated, in comparison with the control group. The obtained results prove the prolonged excessive effect on the children’s organism of stable strontium supplied with drinking water to lead to changes in the functioning of the immune system, characterized by a violation of the regulation of cell death - inhibition of apoptosis and activation of necrosis. The ranges of values of strontium in the blood corresponding to the ranges at the level of 0.1 [0.04-0.11] mg/dm3 are given in the ranges of apoptotic regulation (relative content,%): CD95+ - 17.50 [15.48; 22.03], p53 - 0.53 [0.22; 0.98], bcl-2 0.24 [0.21; 0.36], bax = 5.66 [4.67; 7.84], AnnexinV-FITC+PI- cells: 0.67 [0.56; 0.88], AnnexinV-FITC+ PI+ cells: 10.58 [9.54; 16.11]. The indices of apoptotic regulation of CD95+, p53, bcl-2, Annexin V-FITC+ PI- are recommended to be used as indices of early disorders of the immune status, and also for the monitoring the effectiveness of preventive measures in the territories of strontium geochemical provinces.

Stable strontium isotopic heterogeneity in the solar system from double-spike data

Strontium isotopic anomalies in meteorites are important in assessing nucleosynthetic sources to, and measuring the timing of, early solar system processes. However, conventional use of a constant 88Sr/86Sr value in correcting for instrumental mass fractionation during analysis renders measurements ambiguous and removes information on mass-dependent fractionation variations. From double-spike techniques we obtain data for the four stable strontium isotopes free of this ambiguity, and report measurements from a range of meteoritic, lunar and terrestrial materials. The Earth, Moon, basaltic eucrites and feldspars from angrites (differentiated samples) follow a single mass-dependent fractionation line and have a common nucleosynthetic origin in terms of their strontium isotopes. In contrast, bulk rock CI, CV3, CM and CO chondrite samples serve to define another mass-dependent fractionation line, displaced by 94 ± 28 ppm to heavier 84Sr/86Sr and/or 88Sr/86Sr ratios than that for the differentiated samples. Our Sr-isotopic data are consistent with a primary contrast in early solar system composition between an outer zone of primitive, mostly undifferentiated, materials and an inner zone of (almost entirely) differentiated materials that accumulated to form the terrestrial planets.

Chemical Stability of La 1-X Sr x Mn0.8Ni0.2O3-δ x={0.1 to 0.5} Cathode Compositions with 8YSZ at High Temperature

Ni-added LSM compositions (La 1-x Sr x Mn0.8Ni0.2O3 with x={0.1 to 0.5}) and YSZ mixtures (50/50 wt%) were used for evaluating their chemical stability at high temperature (1300oC). Ni-added LSM raw powders were fabricated by using a glycine route. X-ray diffraction was used to quantify and identify crystallographic phases. DC four-probe measurement was used for electrical characterization. Results show that Ni-addition at the B-site of LSM structure is effective for suppressing the secondary phase formation, particularly La2Zr2O7, when strontium content is between 0.1≤x≤0.2. Electrical conductivity was about 100 S cm-1 within the chemically stable strontium content range. Therefore, it is expected that suppression of La2Zr2O7 formation at high temperature could improve SOFC performance, especially during long time operation, thus supporting the co-sintering of a whole SOFC ceramic stack at high temperature.

Effect of calcite precipitation on stable strontium isotopic compositions: Insights from riverine and pool waters in a karst cave

Radiogenic and stable Sr isotope ratios (87Sr/86Sr, δ88/86Sr) serve as potential tracers for evaluation of weathering sources and associated physicochemical processes in terrestrial environments. Despite carbonate weathering sourcing two-thirds of the total continental Sr flux to the ocean, however, few attempts have been aimed at studying stable Sr isotope fractionation in carbonate-dominated aquifers. Here we present a monthly-resolved monitoring dataset of major ion concentrations and Sr isotope ratios for karst riverine and pool waters at the Luofang Cave in the Central China to understand the potential controls responsible for water δ88/86Sr compositions under various climatic conditions. With the exception of some pool waters in the dry period, significantly heavier δ88/86Sr were detected in the riverine and pool waters (0.20‰ to 0.42‰) compared to bedrock δ88/86Sr (0.24‰ to 0.28‰), which can't be interpreted solely by lithology. A sequential leaching experiment of the local soils suggests limited stable Sr isotope fractionation during incongruent silicate mineral dissolution. Local plant utilization and biological activity in the soil overlying the cave are possible processes for causing the observed heavier δ88/86Sr in cave water. However, air partial pressure of CO2 in cave, monitoring water pH, and Sr isotopic mass balance calculations suggest that plant utilization is unlikely to be the primary control on the heavier water δ88/86Sr. On the other hand, significant stable Sr isotope fractionation was found between the cave dripping waters and calcite precipitates, and the Δ88/86Srcar-aq was estimated to be −0.15‰±0.07‰ (2SD). Precipitation of secondary calcites might be a potential process responsible for the heavier δ88/86Sr in the waters. The negative correlation between δ88/86Sr and Sr/Na ratios in the cave waters is consistent with a scenario of preferential incorporation of the light Sr isotope by solid phase. Furthermore, by combining the calcite saturation states and water pH, our results suggest that calcite precipitation is the most likely process controlling δ88/86Sr compositions in cave water. We demonstrate that secondary calcite precipitation in carbonate-dominated catchments could be important in controlling the riverine water δ88/86Sr compositions.

Adsorption of 133Cs and 87Sr on pumice tuff: A comparative study between powder and intact solid phase

This study examines the use of intact samples as an alternative to powder in conventional batch sorption studies to determine the distribution coefficient (Kd). Stable cesium (133Cs) and strontium (87Sr) were used under specified geochemical conditions to compare the Kd values of powder and block pumice tuff samples. The aim of the study was to infer any Kd difference under laboratory and field conditions. Kd values for block samples were found to be less than one order of magnitude lower than powder materials for both Cs and Sr on fresh tuff, and more than one order of magnitude lower in oxidized tuff. Destruction of micropores in oxidized tuff was estimated to be mainly responsible for reducing Kd values in oxidized tuff. However, approximately one order of magnitude difference in Kd values indicates that homogenously prepared intact samples can be used for sorption coefficient measurement at closer to in situ conditions. Pore size distribution analysis using mercury intrusion porosimetry revealed that lower Kd values on block samples result from lower surface area available as sorption sites due to inaccessible closed pores in the intact solid.

A sequential determination of 90Sr and 210Po in food samples.

The latest EU Council Regulation 2016/52/Euratom updates the emergency limits on radionuclides in foods including 210Po and 90Sr, two of the most important radionuclides for radiological dose from the ingestion pathway. A novel and straightforward method has been developed for sequential determination of 90Sr and 210Po in food samples using ultra low-level liquid scintillation counting and alpha-particle spectrometry. For 90Sr analysis, the method makes use of stable strontium as yield tracer, and 210Po is determined through self-deposition using 209Po as a yield tracer. The quantification limit for this method is 25.0 and 2.0Bqkg-1 for 90Sr and 210Po, respectively. The proposed radiochemical separation can be completed within 2days for a batch of 12 samples. The radiochemical procedure was validated by its application for the measurement of IAEA certified reference materials, and through participation in a national intercomparison exercise. Results are also presented in seafood from the Mediterranean coast.

Phytoremediation of strontium contaminated soil by Sorghum bicolor (L.) Moench and soil microbial community-level physiological profiles (CLPPs)

Phytoremediation of strontium contaminated soil by Sorghum bicolor (L.) Moench was investigated, and the soil microbial community-level physiological profiles (CLPPs) were examined. The growth and the stable strontium (88Sr) accumulations of the energy crop S. bicolor grown on the Sr-spiked soil at the level of 0, 50, 100, 200, and 400mg/kg soil were characterized through pot soil system after the entire growth period (140days). Correspondingly, the available content of strontium in soil extracted by Mehlich III extraction solution reached 42.0, 71.9, 151.8, and 242.2mg/kg, respectively. The Sr-polluted soil microbial community was assessed by a Biolog Eco-plate method. The results showed that the spiked Sr significantly increased the height and the stem biomass weight of the plant. Sr contents in roots, stems, and leaves of the sorghum increased linearly (R 2>0.95) with the elevation of the Sr-spiked level in soil. The average Sr concentration in roots, stems, and leaves reached 68.9, 61.3, and 132.6mg/kg dry weight (DW) under Sr-spiked 400mg/kg soil, respectively. Sr content in tissues decreased in the order of leaves > roots > stems. The bioconcentration factor (BCF; Sr contents in shoots to soil) values of S. bicolor in soil system was lower than 1 (0.21∼0.39) whether based on the spiked Sr level or on the available Sr level in soil. The transfer factor (TF; Sr contents in shoots to roots) values of S. bicolor in soil system usually is higher than 1 or near to 1 (0.92∼1.29). TF values increased while BCF values decreased as the soil Sr increased. The Biolog Eco-plate assay showed that Sr at the spiked level of 400mg/kg soil enhanced the soil microbial diversity and activity.

Strontium concentration, radiogenic (87Sr/86Sr) and stable (δ88Sr) strontium isotope systematics in a controlled feeding study

ABSTRACTTranshumance and palaeodiet are two central themes in archaeology and using chemical analysis of bones and teeth to reconstruct trends and patterns in diet and mobility has become a cornerstone of bioarchaeology. This study has investigated strontium concentration ([Sr]), radiogenic (87Sr/86Sr) and stable strontium (δ88Sr) isotope systematics in a controlled feeding experiment on domestic pigs designed to simulate terrestrial versus marine protein consumption. The results of the radiogenic (87Sr/86Sr) analysis offer a validation of the strontium isotope methodology. The study confirms that the radiogenic strontium isotope composition of dental enamel does represent the radiogenic strontium isotope composition of the diet. The results of the δ88Sr analysis have revealed a distinct shift of 0.322 ± 0.060 ‰ towards isotopically light Sr with trophic level. The magnitude of this shift is consistent with the predictions from the analogous shift observed in calcium isotopes. This is the first time that trophic level fractionation in δ88Sr has been identified in a controlled setting. Although still in its infancy, δ88Sr analysis has great potential to inform on trophic level systematics, to investigate dietary trends in early life and is potentially useful in examining diagenetic alteration.

Isotope pattern deconvolution of different sources of stable strontium isotopes in natural systems

Isotope pattern deconvolution (IPD) allows for the determination of the fraction to which natural sources form the isotopic composition of a samples from the corresponding isotope pattern.

Study of iron, zinc, stable strontium, and lithium contents in biological fluids and tissues in an experiment simulating space flight conditions

Atomic emission spectral analysis with inductively coupled argon plasma was used to measure contents of iron, zinc, stable strontium, and lithium in blood serum and its ultrafiltered fraction, as well as the level of their excretion in 24-h urine and hair, in a ground-based experiment simulating space flight conditions. The monitoring of iron levels of serum and its ultrafiltered fraction has shown a proper balance between the indicated parameters at all stages of the experiment. The iron forms bound to protein carriers were identified only in blood serum. The study in the conditions of the experiment has shown the dependence of blood serum zinc content on the nutritional status. The level of stable strontium excretion with 24-h urine can serve as a biological indicator of changes in its homeostasis. The experimental conditions have not been found to affect the form of serum lithium; i.e., lithium was invariably present in the ionized state and its content remained equal to the amount of ultrafiltered lithium in all blood samples investigated in all experimental periods.

Encapsulation of Strontium Ranelate in Poly(Lactic Acid) Matrix

Osteoporosis is a disease characterized with reduced density and quality of bone. Novel treatment strategies have been developed with the aim to inhibit excessive bone resorption and to increase bone formation. Strontium ranelate (SrRan), a novel orally active agent consisting of two atoms of stable strontium and the organic moiety ranelic acid, has proven drug ability to increase not only the bone mass but also mechanical properties. Despite the advantages it has been shown that systemic administration of SrRan can cause such side effects as diarrhea, hypersensitivity and myocardial infarction. Microencapsulation of SrRan could overcome the possible side effects from the systemic drug use as well as to increase its efficiency by local delivery of drug right to the affected bone site. Thus in the current research an attempt was made to prepare and characterize poly (lactic acid)/srontium ranelate microcapsules and to evaluate the drug interaction with the polymer during the microparticle formation.

Mesoporous manganese oxides prepared by sol-gel method: Synthesis, characterization and sorption properties towards strontium ions

Radionuclides of strontium 85,90Sr are one of the main components of low active liquid radioactive wastes. In present work mesoporous manganese oxides were synthesized by non-template sol-gel method and their sorption properties towards strontium 85Sr ions from model aqueous solutions were studied. Influence of phase composition and parameters of porous structure of manganese oxide sorbents on their sorption and selective properties towards radioactive 85Sr ions was established. The samples of manganese oxide prepared with hydrogen peroxide and calcined at 200–400°C were characterized by the highest values of sorption capacity and distribution coefficient of approximately 200–220mgg−1 and (0.72–3.67)×105cm3g−1 respectively. It was shown that the presence of 0.1M NaCl solution practically doesn’t influence on removal efficiency of stable strontium ions and leads to decreasing distribution coefficient on a decimal order. In case of the presence of 0.05M CaCl2 solution falling strontium removal efficiency was observed for all synthesized sorbents regardless of the properties of reducing reagent and its calcination temperature. Sorption characteristics in this case significantly decreased and amounted to 12–18mgg−1 for sorption capacity and (1.1–8.7)×102cm3g−1 for distribution coefficient.

Regulation of apoptotic signal by strontium in immunocytes

Exposure to heavy metals can initiate the development of negative effects in different organs and systems, including the immune system, and can be manifested as dysfunction of receptor systems and intracellular signaling. The participation of stable strontium (Sr2+) in the regulation of apoptotic signals in immunocompetent cells was analyzed. Various mechanisms of strontium-induced modulation of the apoptotic lymphocyte reaction were described, and the formation of intracellular signal transduction involving Sr2+ was defined. The flow cytometry method was used to study changes in membrane and intracellular markers of apoptosis in children who consumed drinking water with the elevated levels of strontium. It was shown that the content of strontium in blood in the range of 0.0129–0.173 mg/dm3 affected different ways of apoptosis regulation (CD95-, p53-, and TNF-induced apoptosis) and their integration sites, thereby reducing the transmission of apoptotic signal in immunocompetent cells, and formed an alternative pathway of the cell elimination based on the mechanism of necrosis.