High Strontium Content Research Articles

Coupling of X-ray fluorescence and Strontium isotopes to track brine influences in continental deposits: study of the Oligocene sediments in the Digne area (SE basin, France)

Deciphering past salt tectonics events is often difficult in orogenic domains. The southwestern Alpine foreland in France presents a long Mesozoic extensive salt tectonics history, inverted during the Cenozoic Alpine orogeny. Syn-orogenic Cenozoic salt-related deformations are rather difficult to identify because of the contemporaneous shortening experienced by the foreland. This study is based on sedimentologic and geochemical approaches (Sr concentration and 87 Sr/ 86 Sr ratio) of the Oligocene non-marine succession of St Geniez (Digne region, France. Oligocene salt influences are highlighted by (1) high strontium concentrations (>1000 ppm) in most of the series, (2) the occurrence of Halophyticgastropods and (3) the deposit of two gypsum beds. 87 Sr/ 86 Sr ratio measured in the limestones and the gypsum beds confirm a Triassic origin for the strontium, originating from the diapir of Sorine, located to the south-west for the first part of the series, and from the Authon Thrust, located to the north, for the upper part. Geochemical values also suggest the occurrence of two Triassic evaporite levels, one already known and attributed to the Carnian-Norian (Late Triassic) and one attributed to the Olenekian-Anisian (Ealy-Middle Triassic). These results support that combined use of field geology and geochemistry can provide information on erased past salt-tectonics.

Modification of Ti3C2Tx nanostructure with KH2PO4 and chitosan for effective removal of strontium from nuclear waste.

Nanostructure titanium carbide MXene (Ti3C2Tx) was modified with KH2PO4 and chitosan to effectively remove strontium from nuclear wastewater. Nuclear waste includes radionuclides of uranium, thorium, strontium, and cesium, which are classified depending on the concentration of radionuclides. Nuclear waste with a high strontium concentration is the production waste of radiopharmaceutical production centers. Ti3C2Tx was synthesized from Ti3AlC2 using HF40% and HF in situ (MILD-Ti3C2Tx) in 24h at 313.15 and 333.15K. Morphology, structure, and functional groups were investigated using the XRD, SEM, EDS, FTIR, and BET analyses. The Sr(II)'s adsorption capacity on Ti3C2Tx-HF and Ti3C2Tx-HF in situ was obtained as 61.9 and 253.5mgg-1, respectively (temperature, 298.15K; pH, 7.00; contact time, 180min; and Sr(II) concentration, 150mgl-1). Ti3C2Tx-HF in situ showed fourfold adsorption due to more hydroxyl functional groups and larger interlayer spacing. Ti3C2Tx was modified with KH2PO4 and chitosan to investigate the mechanism of change of Sr(II)'s adsorption capacity, which increased to 370 and 284mgg-1, respectively. The structural results of modified Ti3C2Tx showed that the surface functional groups increased when modified with chitosan. In addition, modification with KH2PO4, through encapsulating large amounts of KH2PO4 between Ti3C2Tx layers, increased the possibility of Sr(II) diffusion between layers and electrochemical interactions with hydroxyl groups, and thus, increased its adsorption. Some experiments were designed to investigate the effect of parameters like initial concentration of Sr(II), contact time, temperature, and pH solution, as well as modified- and unmodified-Ti3C2Tx on adsorbent. The results revealed that the adsorption process of Sr(II) with pristine and modified-Ti3C2Tx follows pseudo-second-order kinetics and Freundlich heterogeneous isotherm model. Freundlich model isotherm indicates the presence of various functional groups on the surface and between the pristine and modified Ti3C2Tx layers. Electrostatic reactions and intra-sphere complexation were the two dominant mechanisms of the adsorption process.

Features of the Formation of Strontium Pollution of Drinking Groundwater and Associated Health Risks in the North-West of Russia

The purpose of this research was to determine the natural factors that contribute to maintaining the standard quality of fresh drinking groundwater in areas with high strontium content. Hazard index values for the consumption of water containing strontium were also calculated to assess the overall non-carcinogenic health risk from combined ingestion and dermal exposure. The results showed that the groundwater with strontium concentrations exceeding the maximum permissible concentrations had an increased correlation of strontium concentrations with total dissolved solids and celestite and gypsum saturation indices. A decrease in calcium content was recorded with a simultaneous increase in the concentration of magnesium and strontium. Reducing conditions in the aquifer were also favorable for the conservation of these waters. In waters of standard quality, all these factors did not appear, which indicates their formation in sediments with discretely located small inclusions of celestite and gypsum. These waters were characterized by a calcium bicarbonate composition, low total dissolved solids (TDS), and oxidizing conditions. Elevated radiocarbon contents indicate their relatively young age. In general, it was found that children in the study area are most vulnerable to risks. Fifty percent of wells supply drinking water that is unsafe for consumption. The water from about a third of the wells studied is dangerous for adults.

Source of inorganic components in the Middle Jurassic inertinite-rich coals of the Southern Ordos Basin, China: With emphasis on formation of Sr- and Ba-bearing minerals

The Middle Jurassic coal seams located in the southern Ordos Basin display notably high concentrations of barium (Ba) and strontium (Sr). To acquire a comprehensive understanding of the source and occurrence of the elevated contents of Ba- and Sr-bearing minerals and their formation mechanism in the coal, a suite of petrological, mineralogical, and geochemical analyses was conducted on the Middle Jurassic coals of the Gaojiapu mine (No. 4 Coal) from the Binchang mining area, using optical microscopy, field emission-scanning electron microscopy, X-ray diffraction, X-ray fluorescence, and inductively coupled plasma mass spectrometry. The results indicate that the No. 4 Coal is a high volatile B bituminous coal, which is characterized by low ash, medium sulfur, and high inertinite contents. The modes of occurrence of minerals identified in the coal, including calcite, dolomite, pyrite, quartz, kaolinite, anatase, barite, and celestine, indicate that the No. 4 Coal may have been subjected to multiple stages of solutions injection. Barium and Sr in the investigated coals are significantly enriched, exhibiting maximum values of 19738 μg/g and 9932 μg/g, respectively, while concentrations of other trace elements are generally depleted. Barite and celestine, generally coexisting with carbonate minerals, commonly occur as cell- and fracture-fillings. Furthermore, the strong correlation coefficients (r) for Ba vs. Ca + Mg and Sr vs. Ca + Mg (0.78 and 0.61, respectively) indicate that most barite and celestine have a close association with carbonate minerals of epigenetic origin. The highly elevated concentrations of Ba and Sr are thought to be primarily derived from solutions leaching barite deposits developed in the Qinling Orogenic Belt, which is located in the south of the Ordos Basin. When mapped spatially, the distributions of Ba and Sr concentrations are fan-shaped, decreasing from the NW to the SE of the mining area. Meteoric water containing dissolved CO2 induced partial dissolution of carbonate rocks, and during this process, selected metal ions (e.g., Ca2+, Mg2+, Al3+, Si2+, Fe2+, Ba2+, and Sr2+) were redistributed and subsequently migrated along fracture zones to the coal seam. The fracture systems and abundant cavities within inertinite in the coal provided sufficient space and conduits for solutions migration.

Synthesis and Antimicrobial Analysis of High Surface Area Strontium-Substituted Calcium Phosphate Nanostructures for Bone Regeneration.

Continuous microwave-assisted flow synthesis has been used as a simple, more efficient, and low-cost route to fabricate a range of nanosized (<100 nm) strontium-substituted calcium phosphates. In this study, fine nanopowder was synthesized via a continuous flow synthesis with microwave assistance from the solutions of calcium nitrate tetrahydrate (with strontium nitrate as Sr2+ ion source) and diammonium hydrogen phosphate at pH 10 with a time duration of 5 min. The morphological characterization of the obtained powder has been carried out by employing techniques such as transmission electron microscopy, X-ray diffraction, and Brunauer-Emmett-Teller surface area analysis. The chemical structural analysis to evaluate the surface properties was made by using X-ray photoelectron spectroscopy. Zeta potential analysis was performed to evaluate the colloidal stability of the particles. Antimicrobial studies were performed for all the compositions using four bacterial strains and an opportunistic human fungal pathogen Macrophomina phaseolina. It was found that the nanoproduct with high strontium content (15 wt% of strontium) showed pronounced antibacterial potential against M. luteus while it completely arrested the fungal growth after 48 h by all of its concentrations. Thus the synthesis strategy described herein facilitated the rapid production of nanosized Sr-substituted CaPs with excellent biological performance suitable for a bone replacement application.

FEATURES OF THE FORMATION OF HIGH STRONTIUM CONCENTRATIONS IN DRINKING GROUNDWATER NEAR THE SEA COAST

Estimates of strontium concentration factors in groundwater have been carried out in various regions of the world, however, as a rule, analyzes and interpretations were carried out for the entire set of hydrochemical data, without separating water samples with high and low strontium content. Therefore, correlations were often approximate. This study summarizes a new approach to the use of non-traditional tracers, including carbon and uranium isotopes, to study areas that are promising for drinking water supply. Water samples were divided into two clusters according to the content of strontium: 1) more than 7 mg/l, 2) less than 7 mg/l, and the goal was to understand the features of the formation of Sr concentrations for each cluster separately. It was found that in the samples of the first cluster there is a high correlation of Sr and total mineralization, along with a correlation of Sr with SO\(_{4}^{{2 - }}\), which may be due to high concentrations of Sr in carbonates with a high content of gypsum and celestite. The dedolomitization processes and the presence of reducing conditions in aquifers also have an effect. An increase in Sr concentrations due to upwelling of brackish water is not confirmed. In samples from the second cluster, low concentrations of Sr are associated with oxidative conditions in aquifers. No correlation was found between Sr and total mineralization due to low and discrete concentrations of gypsum and celestite in carbonates. There was no effect of dedolomitization. The upwelling of brackish water, on the contrary, can have a significant effect on the increase in Sr concentrations.

Features of a High Strontium Concentration in Drinking Groundwater near the Sea Coast

Features of a High Strontium Concentration in Drinking Groundwater near the Sea Coast

Time regularities of strontium concentration in drinking groundwater distant from the sea coast.

This paper confirms the regularities of the formation of increased concentrations of strontium (Sr) in fresh groundwater used for drinking water supply, depending on the time they are residen in the carbonate deposits of the aquifer. On average, every thousand years, the Sr concentration increases by 2.1-3.5mgL-1. In addition, high strontium content is positively correlated with altitude and well depth and negatively correlated with redox conditions in the aquifer. Large relief elevations are associated with the development of marginal moraine deposits from the Last Glacial Period composed predominantly of clay, which contributes to a decrease in water exchange. The high Sr content is associated with the dissolution of significant formations of celestite and strontianite, up to their ore occurrences. For this reason, the saturation indices (SIs) for celestite and strontianite correlate with TDS and rise to - 1.42 and 2.05, respectively. Low Sr values do not correlate with the residence time of groundwater in the aquifer or the depth of wells and tend to depressions in the relief, with a virtual absence of overlying sediments and positive Eh values, which indicates an active water exchange. The low level of Sr is associated with the dissolution of gypsum, calcite, and dolomite containing strontium as an impurity. This causes the SIs for gypsum, calcite, and dolomite to correlate with TDS, while for celestite and strontianite, the SI drops to - 5.02 and - 0.92, respectively. The established patterns make it possible to more reasonably choose places for the construction of water wells to obtain drinking water of standard quality.

In situ LIBS-XRF analysis as a combined approach to disclose the production technology of unique wall mirrors from Pompeii

It is assumed that the unique wall mirrors found at the Archaeological Park of Pompeii (PAP) are made of obsidian. To contribute to the knowledge of those archaeological artefacts, this work proposes in situ elemental analyses in collaboration with PAP seeking to determine, in a total no-destructive way, the composition and provenance of the main mirror preserved at the House of Gilded Cupids. Comparing the geochemical composition of this black glass with that of obsidian samples collected from the main Mediterranean sources, both X-ray fluorescence (XRF) and laser-induced breakdown spectroscopy (LIBS) confirmed an incompatible content of many key elements. LIBS in-depth analysis excluded the potential relation between the higher concentration of Ca and Mg and the presence of alteration products. In addition, XRF analysis missed the detection of Rb, Y, Zr and Nb, which are widely recognized as the elemental fingerprints of obsidian sources. Combined with the detection of a high content of strontium (500–700 ppm), the in situ elemental data proved that, rather than made of obsidian, the analysed mirror was handcrafted by the fusion of coastal sand. Waiting to extend this study to the other mirrors found at Pompeii, the results here presented indicate the history of these unique artefacts needs to be rewritten.

Study of ultrasound, initial concentration and electrode material on the electrochemical removal of selenium and strontium

Since high concentrations of selenium and strontium in water can potentially harm human health, various methods have been developed for their treatment. The objective of this paper was to validate previously published studies on the electrochemical removal of selenium and strontium, while also reducing the reactor operating time and using an ultrasound assisted process. After careful evaluation of the preliminary experiments, a combination of aluminum and iron electrodes was identified as the most suitable option for further investigation. The Design of Experiments approach was utilized to study the effects of ultrasound intensity (0%, 50%, 100%), operating time (2, 6, 10 minutes), applied current (2.5, 7.5, 12.5 A), and initial concentrations of selenium and strontium (1, 3, 5 mg L−1) on the sono-electrochemical removal of selenium and strontium from a synthetic solution. A modified ultrasonic bath, operating at 25 kHz, was used for all the experiments. The results showed that ultrasound and the initial selenium and strontium concentrations had no effect on the removal efficiency. The obtained reduced quadratic models predicted a removal efficiency of 93% for selenium and 34% for strontium under the optimal conditions, which included 10 minutes of operation and 12.5 A of current.

Is Australia weird? A cross-continental comparison of biological, geological and climatological features

Australia’s distinctive biogeography means that it is sometimes considered an ecologically unique continent with biological and abiotic features that are not comparable to those observed in the rest of the world. This leaves some researchers unclear as to whether findings from Australia apply to systems elsewhere (or vice-versa), which has consequences for the development of ecological theory and the application of ecological management principles. We analyzed 594,612 observations spanning 85 variables describing global climate, soil, geochemistry, plants, animals, and ecosystem function to test if Australia is broadly different to the other continents and compare how different each continent is from the global mean. We found significant differences between Australian and global means for none of 15 climate variables, only seven of 25 geochemistry variables, three of 16 soil variables, five of 12 plant trait variables, four of 11 animal variables, and one of five ecosystem function variables. Seven of these differences remained significant when we adjusted for multiple hypothesis testing: high soil pH, high soil concentrations of sodium and strontium, a high proportion of nitrogen-fixing plants, low plant leaf nitrogen concentration, low annual production rate to birth in mammals, and low marine productivity. Our analyses reveal numerous similarities between Australia and Africa and highlight dissimilarities between continents in the northern vs. southern hemispheres. Australia ranked the most distinctive continent for 26 variables, more often than Europe (15 variables), Africa (13 variables), Asia (12 variables each), South America (11 variables) or North America (8 variables). Australia was distinctive in a range of soil conditions and plant traits, and a few bird and mammal traits, tending to sit at a more extreme end of variation for some variables related to resource availability. However, combined analyses revealed that, overall, Australia is not significantly more different to the global mean than Africa, South America, or Europe. In conclusion, while Australia does have some unique and distinctive features, this is also true for each of the other continents, and the data do not support the idea that Australia is an overall outlier in its biotic or abiotic characteristics.

Effect of strontium loading on the structural and thermodynamic properties of Ca10-xSrx(PO4)6F2(x= 2, 4, 6, 8) solid solutions for radioactive waste immobilization

Fluorapatite is being contemplated as a potential host for the incorporation of fluoride bearing radioactive nuclear waste. Ca10(PO4)6F2 and Sr10(PO4)6F2 are two fluorapatites which are studied extensively for the purpose of radioactive waste immobilization. Here, in this work a series of solid solutions having compositions Ca10-xSrx(PO4)6F2(x = 2, 4, 6 and 8) were synthesized by solid state chemistry route. The detailed structural properties of these solid solutions were analysed by powder XRD, FTIR and Raman spectroscopy. Rietveld refinement was used to determine the structural changes as well as micro-structural strain in these compositions. At lower loading of Sr2+, there is a preference on site occupation of Sr2+ between two crystallographic Ca2+ sites as evidenced by Rietveld refinement. The calculated average strain values in the calcium rich compositions (x = 2 and 4) are higher than the strontium rich compositions (x = 6 and 8). Thermo-physical properties such as heat capacity and thermal expansion of Ca10-xSrx(PO4)6F2 (x = 2, 4, 6, 8) solid solutions were experimentally measured for the first time.Heat capacity values follow the usual solid solution behaviour. Electron beam irradiation studies show that these substituted solutions are resistant to phase degradation up to 1000 kGy as revealed by powder XRD. Moreover, combined FTIR, Raman and EPR studies confirmed that higher strontium content is detrimental to the fluorapatite through surface modification. This study further gives insight into design of better matrix in terms of 90Sr loading capacity and stability.

Strontium Ion-Functionalized Nano-Hydroxyapatite/Chitosan Composite Microspheres Promote Osteogenesis and Angiogenesis for Bone Regeneration

Critical-size bone defects are an important problem in clinical practice, which usually occurs in severe trauma, or tumor resection, and cannot heal completely and autonomously. Implantation of grafts is often required to promote the regeneration of critical-size bone defects. Metal ions play an important role in human health, as they affect the body's metabolism and the tissue function. Strontium ions (Sr2+) can promote osteogenesis and angiogenesis. Herein, we prepared nano-hydroxyapatite (nHA)/chitosan (CS) composite microspheres with a uniform particle size distribution and an extracellular matrix-like nanofiber structure using microfluidic technology and direct alkali-induced gelation. Strontium ions were stably added into the microspheres by using polydopamine (PDA) to chelate metal ions forming a bone repair material (nHA/CS@PDA-Sr) with good bioactivity. The coordination reaction of PDA can effectively control the release of strontium ions and avoid the negative effects caused by the high strontium concentration. Our in vitro experiments showed that the composite microspheres had good biocompatibility and that the PDA coating promotes cell adhesion. The slow release of strontium ions can effectively promote mesenchymal stem cells osteogenic differentiation and the vascularization of endothelial cells. In addition, we injected composite microspheres into cranial defects of rats to evaluate osseointegration in vivo. The results showed that nHA/CS@PDA-Sr could effectively promote bone regeneration in the defect area. This study demonstrates that composite microspheres stimulate bone repair providing a promising way for bone-defect regeneration.

Mineralogical features of gabbroic rocks from Mindyak mafic-ultramafic massif

The mineralogical features of several samples of gabbroids from the eastern part of the Mindyak mafic-ultramafic massif have been studied. The compositions of rock-forming and accessory minerals are given. The rocks underwent autometamorphic transformations with the replacement of the primary pyroxene-plagioclase association to amphibole and essentially sodium feldspar secondary assemblage. Typical accessory minerals are titanite, ilmenite, titanomagnetite, and apatite. The gabbroids of the massif cover a wide range of compositions from melanogabbro to diorites, also demonstrating significant variations in the contents of petrogenic oxides and trace elements. In terms of REE distribution, most of the studied samples of gabbroids are comparable to basalts of mid-ocean ridges, but often differ from them in high concentrations of strontium and some other rare elements. The gabbroids of the eastern part of the massif have U-Th mineralization in association with aggregates of xenomorphic zircon grains. The origin of these finds has not been established in the present study. Estimates of the PT conditions by the amphibole barometer show the presence of two maxima of values – 2.8–5.1 kbar and less than 2 kbar, which most likely fix two different stages in the formation of rocks – autometamorphism in the magma chamber during cooling and interaction with magmatic fluids (magnesian hornblende), and low-temperature (greenstone) transformations (actinolite).

Insights into the metamorphic history and origin of flake graphite mineralization at the Graphite Creek graphite deposit, Seward Peninsula, Alaska, USA

Graphite Creek is an unusual flake graphite deposit located on the Seward Peninsula, Alaska, USA. We present field observations, uranium-lead (U–Pb) monazite and titanite geochronology, carbon (C) and sulfur (S) stable isotope geochemistry, and graphite Raman spectroscopy data from this deposit that support a new model of flake graphite ore genesis in high-grade metamorphic environments. The Graphite Creek deposit is within the second sillimanite metamorphic zone of the Kigluaik Mountains gneiss dome. Flake graphite, hosted in sillimanite-gneiss and quartz-biotite paragneiss, occurs as disseminations and in sets of very high grade (up to 50 wt.% graphite), semi-massive to massive graphite lenses 0.2 to 1 m wide containing quartz, sillimanite, inclusions of garnet porphyroblasts, K-feldspar, and tourmaline. Restitic garnet, sillimanite, graphite, and biotite accumulations indicate a high degree of anatexis and melt loss. Strong yttrium depletion in monazite, high europium ratios (Eu/Eu*), and excursions of high strontium and thorium concentrations are consistent with biotite dehydration melting. Monazite and titanite U–Pb ages record peak metamorphism from ~ 97 to 92 million years ago (Ma) and a retrograde event at ~ 85 Ma. Raman spectroscopy confirms the presence of carbonaceous material and highly ordered, crystalline graphite. Graphite δ13CVPDB values of − 30 to − 12‰ and pyrrhotite δ34SVCDT values of − 14 to 10‰ are consistent with derivation from organic carbon and sulfur in sedimentary rocks, respectively. These data collectively suggest that formation of massive graphite lenses occurred approximately synchronously with high-temperature metamorphism and anatexis of a highly carbonaceous pelitic protolith. Melt extraction and fluid release associated with anatexis were likely crucial for concentrating graphite. High-temperature, graphitic migmatite sequences within high-strain shear zones may be favorable for the occurrence of high-grade flake graphite deposits.

Evaluation of Strontium Interference in Calcium Measurement Procedures and Content in Supplements as Measured by ICP-MS.

Bone health supplements containing strontium are available without prescription, however, the effects of strontium interference on clinical laboratory calcium measurement procedures are unknown. To evaluate strontium interference on total calcium measurements, plasma pools with exogenously added strontium were measured by 3 total calcium measurement procedures. For ionized calcium measurements, whole blood pools prepared with exogenously added strontium were measured by 2 ionized calcium measurement procedures. An inductively coupled plasma mass spectrometry assay (ICP-MS) was validated for research measurements of strontium content in commercially available supplements. Exogenous strontium addition to plasma caused positive bias for total calcium measurements. Strontium concentrations of 1.0 mg/dL (0.114 mmol/L), 2.5 mg/dL (0.284 mmol/L), and 5.0 mg/Dl (0.568 mmol/L) resulted in mean biases of 1.9% to 3.5%, 4.9% to 9.0%, and 10.8% to 19.2%, respectively, for total calcium measurement procedures. Biases for ionized calcium measurements were less than 4.5% for a strontium concentration of 5.0 mg/dL (0.568 mmol/L). An in-house-developed ICP-MS assay for strontium in commercially available supplements exhibited within-laboratory and within-run coefficients of variation of less than 3%, and a linear response was obtained over the assay analytical measurement range of 10 to 100 000 ng/mL (0.0001 to 1.141 mmol/L). Strontium recovery for the ICP-MS assay was 97.1% to 105.3%. The largest amount of strontium measured in dietary supplements was 395 mg in a 1054 mg tablet. Some dietary supplements contain larger amounts of strontium than indicated on the product label. High concentrations of strontium may cause significant interference for total calcium measurement procedures, but ionized calcium measurement procedures are not significantly affected.

Hydrogeochemistry and hydrobiology of technogenic reservoirs of mining territories of Eastern Transbaikalia

The chemical composition of the waters of quarry lakes formed as a result of the development of the Zavitinskoye lithium-beryllium deposit located in Eastern Transbaikalia (Russia) has been studied. The studied waters of the ore pits are fresh with a neutral and slightly alkaline reaction, mainly of the magnesium-calcium sulfate type. It was found that the quarry waters contain high concentrations of lithium (Li) and strontium (Sr), in isolated cases of arsenic (As). Low concentrations of other metals in man-made waters are due to the neutralizing effect of carbonates of host rocks and ores, but this does not make them environmentally safe. The content of trace elements in the waters of quarries relative to the background contents, as well as the standards of maximum permissible concentrations (MPC) of chemicals for the waters of water bodies of fishery importance and sanitary and hygienic indicators were determined. A distinctive feature of the studied quarry lakes, as well as other man-made reservoirs, is the low species diversity of zooplankton and macrophytes, which is mainly due to the small catchment area, the steepness of the shores, the absence of shallow waters and other factors.

Early dolomitization and subsequent hydrothermal modification of the middle Permian Qixia Formation carbonate in the northwest Sichuan Basin

High-quality dolomite reservoir are widely developed in Permian Qixia Formation in northwest Sichuan Basin. Understanding the genesis of dolomite is significant to predicting high-quality reservoir distribution. Based on the petrographical and geochemical characteristics, three types of dolomites and one type of dolomite cement were identified in the Qixia Formation in northwest Sichuan Basin: micritic to fine-crystalline dolomites (D1), medium-crystalline dolomite (D2), medium-to coarse-crystalline dolomite (D3) and saddle dolomite cement.Type D1 dolomites are characterized by micritic to fine-sized crystals, lamellar structure, generally dull to no luminescence, and relatively high strontium (Sr) concentrations. These characteristics suggest that type D1 dolomites were initially formed during the penecontemporaneous phase. The wide range of depleted δ18O values, slightly higher 87Sr/86Sr ratios and slightly positive europium (Eu) anomalies indicate that type-D1 dolomites were subsequently subjected to hydrothermal modification. Type D2 dolomite is characterized by unimodal middle-sized crystals and crystal texture dominated by nonplanar crystals. It usually occurs as thin or thick layers in the study area. The δ18O and δ13C values of type D2 dolomite generally fall within the estimated Middle Permian marine dolomite and show a significantly positive offset compared to those of coeval seawater. The 87Sr/86Sr ratios of type D2 dolomite are slightly higher than the coeval seawater. These features combined with the flat rare earth element (REE) profile and relatively high Sr concentrations (both are similar to the host limestone) indicate that type D2 dolomites first precipitated in the slightly evaporated Middle Permian seawater during the near-surface to shallow burial phase. Type D3 dolomites are mainly characterized by interlocking mosaic crystals with crystal sizes varying from 300 μm to 900 μm. It mainly occurs as patches in type D2 dolomites or as a thick layer sandwiched by type D2 dolomites. These features combined with its high 87Sr/86Sr ratios, δ18O depletion and positive Eu anomalies (which are very similar to those of the saddle dolomites) demonstrate that it is formed by hydrothermal recrystallization upon type D2 dolomites. Saddle dolomite generally occurs as the filling cement of pores, vugs, and fractures and is usually combined with matrix dolomite to form zebra dolomite and hydrothermal dolomite breccia. It has a curve crystal face, demonstrates wavy extinction under cross-polarization and red luminescence under a cathodoluminescence microscope. These features, together with the highest Th, most negative δ18O value and highest 87Sr/86Sr ratio compared to those of all types of dolomites in the study area as well as the positive Eu anomalies suggest that it should have been formed by hydrothermal fluid precipitation.Type D1 and type D3 dolomites are volumetrically minor and the pores are poorly developed. Saddle dolomite cemented and filled the pores and vugs of matrix dolomite, resulting in reservoir damage. Type D2 dolomites constitute the main body of high-quality reservoir in Qixia Formation. It precipitated in the slightly evaporated penesaline Middle Permian seawater during the near-surface to shallow burial phase. Potential high-quality reservoirs may occur in the shoal around the limited inter-shoal sea.

Exposure to multiple metals and diabetes mellitus risk in dong ethnicity in China: from the China multi-ethnic cohort study.

Metals play an important role in the development of diabetes mellitus (DM). The association of metals with diabetes among the Dong ethnicity in China remains poorly understood. The current study aimed to evaluate the association of single metal exposure and multi-metal co-exposure with DM risk. Urinary concentrations of arsenic, cadmium, chromium, copper, iron, lead, manganese, mercury, molybdenum, nickel, strontium, vanadium, and zinc were measured using inductively coupled plasma-mass spectrometry (ICP-MS) among 4479 Dong ethnic participants aged 30-79years from the China Multi-Ethnic Cohort (CMEC) study. Based on tertiles, the metal exposure can be divided into three groups: low, middle, and high exposure. Multivariate logistic regression models and principal component analysis were performed to determine exposure to single-metal and multi-metal co-exposure in relation to DM. A decrease in risk of DM was associated with iron (OR = 0.78, 95% CI: 0.61-1.00 and 0.68, 0.53-0.88 for the middle and high vs. low) and strontium (OR = 0.87, 95% CI: 0.69-1.12 and 0.67, 0.51-0.86 for the middle and high vs. low), respectively. A principal component 3 (PC3) characterized by iron and strontium showed an inverse association with DM. A principal component 4 (PC4) characterized by manganese and lead positively associated with DM. Exposure to high concentrations of urinary iron and strontium may reduce the risk of diabetes mellitus. This study revealed an increase in the risk of diabetes mellitus by co-exposure to high concentrations of urinary manganese and lead.

Methane-rich thermal and mineral waters of the Avachinsky Depression, Kamchatka

Wells up to 3000 m deep at the foot of the active volcanoes Koryaksky and Avachinsky within the Avachinsky Depression revealed a basin of saline waters (up to 22 g/l), methane-rich gas (CH4 up to 75 vol% in dry gas) with a temperature up to about 70 °C in the western part of the explored area (Ketkino Field) and colder ones - to the east, closer to the Pacific coast. This article presents data on the chemical composition including trace elements, and isotopic compositions of these waters that include δD and δ18O of waters, 87Sr/86Sr of the dissolved Sr, 3He/4He, δ13C of CH4 and CO2 in gases, and δ34S of the dissolved H2S and SO4. The composition of the waters is sodium chloride, with very low contents of sulfate and magnesium in waters of the western section of the basin, high calcium (up to 960 ppm), and unusually high concentrations of strontium (up to 54 ppm). The N2/Ar ratio is generally 2–3 times higher than in the air, i.e. non-atmospheric nitrogen is present. A distinctive geochemical feature of the basin is the significant difference between δ13C–CH4 and 87Sr/86Sr in the thermal Ketkino fluids comparing to colder fluids of other parts of the basin, despite the practically identical composition of waters and gases. Possible scenarios of water-rock interaction responsible for the chemical composition of waters are discussed.