Journal articles on the topic '18-O isotope exchange'

sotope exchange of oxygen 18О2 with oxides NdMnO3+δ was investigated. The oxide was obtained from oxides Nd2O3 and Mn2O3 using a ceramic technology with annealing in air at 1400°C for 90 hours followed by cooling in a furnace. A planetary mill AGO-2 with a centrifugal factor of g = 60 was used for mechanical treatment of oxides. The study of isotope exchange was carried out by nuclear microanalysis. The concentration of the isotopes 18O and 16O in oxides was determined using a Van de Graaff accelerator and 18O(p, α)15N and 16O(d, p)17O* reactions at the energies of incident beams 762 and 900 keV. Isothermal annealing of powders was carried out in oxygen, enriched to 80% by the isotope 18O. It was established that the concentration of the isotope 18O in mechanically activated powders was several times higher than in the initial micropowder under the same conditions of annealing. The effect increased with increasing of mechanical activation time (30 - 300 s). The isotope exchange parameters connected with the processes at the boundaries of the particles of mechano-activated powder and within their volume were analyzed.

The kinetics of the isotope exchange between gaseous oxygen enriched with the 18O isotope and two LaMnO3+δ oxide samples – a nanopowder and a bulk nanocrystal – has been studied. The 18O isotope concentration has been measured by the acceleration nuclear microanalysis method. The coefficients of the volume and the nanograin boundary self-diffusion of oxygen have been evaluated at 500 °C. They are equal to 3.5·10 −20 and 1.5·10 −13 cm2/s, respectively.

The results of measurements of the bulk diffusion of tracer oxygen atoms in the oxides LnMnO3+δ (Ln = La, Nd, Sm) in the temperature range 400 – 750°С are presented. The measurements were carried out on micro-and nanopowders. Nanoscale powders were prepared by mechanical activation. A method based on the study of the kinetics of oxygen isotope exchange between the powder and gaseous oxygen enriched with 18O isotope was used to obtain data on the diffusion coefficients. The average concentration of 18O isotope in the powders was measured using NRA technique. The obtained diffusion coefficients lay in the range of 10-21 - 10-24 m2/s, the diffusion activation energy for all the oxides have been close to 1 eV. These results suggest that the migration of tracer oxygen in oxides LаMnO3+δ, NdMnO3+δ and SmMnO3+δ at low temperatures is realized via structural defects. As for the oxide LaMnO3+δ, its oxygen diffusion coefficients at low temperatures have been lower than the values extrapolated from high temperatures. Such behavior of diffusion properties has not been previously observed in other metal oxides. In this regard, the vacancy formation energy in the rare earth manganites has been supposed to increase with decreasing temperature.

To further validate the doubly labeled water method for measurement of CO2 production and energy expenditure in humans, we compared it with near-continuous respiratory gas exchange in nine healthy young adult males. Subjects were housed in a respiratory chamber for 4 days. Each received 2H2(18)O at either a low (n = 6) or a moderate (n = 3) isotope dose. Low and moderate doses produced initial 2H enrichments of 5 and 10 X 10(-3) atom percent excess, respectively, and initial 18O enrichments of 2 and 2.5 X 10(-2) atom percent excess, respectively. Total body water was calculated from isotope dilution in saliva collected at 4 and 5 h after the dose. CO2 production was calculated by the two-point method using the isotopic enrichments of urines collected just before each subject entered and left the chamber. Isotope enrichments relative to predose samples were measured by isotope ratio mass spectrometry. At low isotope dose, doubly labeled water overestimated average daily energy expenditure by 8 +/- 9% (SD) (range -7 to 22%). At moderate dose the difference was reduced to +4 +/- 5% (range 0-9%). The isotope elimination curves for 2H and 18O from serial urines collected from one of the subjects showed expected diurnal variations but were otherwise quite smooth. The overestimate may be due to approximations in the corrections for isotope fractionation and isotope dilution. An alternative approach to the corrections is presented that reduces the overestimate to 1%.

Abstract. At Thule Air Base on the coast of Baffin Bay (76.51∘ N, 68.74∘ W), we continuously measured water vapor isotopes (δ18O, δ2H) at a high frequency (1 s−1) from August 2017 through August 2019. Our resulting record, including derived deuterium excess (dxs) values, allows an analysis of isotopic–meteorological relationships at an unprecedented level of detail and duration for high Arctic Greenland. We examine isotopic variability across multiple temporal scales from daily to interannual, revealing that isotopic values at Thule are predominantly controlled by the sea ice extent in northern Baffin Bay and the synoptic flow pattern. This relationship can be identified through its expression in the following five interacting factors: (a) local air temperature, (b) local marine moisture availability, (c) the North Atlantic Oscillation (NAO), (d) surface wind regime, and (e) land-based evaporation and sublimation. Each factor's relative importance changes based on the temporal scale and in response to seasonal shifts in Thule's environment. Winter sea ice coverage forces distant sourcing of vapor that is isotopically light from fractionation during transport, while preventing isotopic exchange with local waters. Sea ice breakup in late spring triggers a rapid isotopic change at Thule as the newly open ocean supplies warmth and moisture that has ∼10 ‰ and ∼70 ‰ higher δ18O and δ2H values, respectively, and ∼10 ‰ lower dxs values. Sea ice retreat also leads to other environmental changes, such as sea breeze development, that radically alter the nature of relationships between isotopes and many meteorological variables in summer. On synoptic timescales, enhanced southerly flow promoted by negative NAO conditions produces higher δ18O and δ2H values and lower dxs values. Diel isotopic cycles are generally very small as a result of a moderated coastal climate and the counteracting isotopic effects of the sea breeze, local evaporation, and convection. Future losses in Baffin Bay's sea ice extent will likely shift mean annual isotopic compositions toward more summer-like values, and local glacial ice could potentially preserve isotopic evidence of past reductions. These findings highlight the influence that the local environment can have on isotope dynamics and the need for dedicated, multiseason monitoring to fully understand the controls on water vapor isotope variability.

AbstractWe report a study of whole-rock O–H–Sr–Nd isotopes of Ordovician igneous and metamorphic rocks exposed at different crustal palaeodepths along c. 750 km in the Sierras Pampeanas, NW Argentina. The isotope compositions preserved in the intermediate rocks (mostly tonalite) (average δ18O = +8.7 ± 0.5‰, δD = −73 ± 14‰, 87Sr/86Srt = 0.7088 ± 0.0001 and εNdt = −4.5 ± 0.6) show no major difference from those of most of the mafic rocks (average δ18O = +8 ± 0.8‰, δD = −84 ± 18‰, 87Sr/86Srt = 0.7082 ± 0.0016 and εNdt = −4 ± 1.1), suggesting that most of their magmas acquired their crustal characteristics in the mantle. The estimate of assimilation of crustal material (δ18O = +12.2 ± 1.7‰, δD = −89 ± 21‰, 87Sr/86Srt = 0.7146 ± 0.0034 and εNdt = −6.9 ± 0.7) by the tonalite is in most samples within the range 10–20%. Felsic magmas that reached upper crustal levels had isotope values (δ18O = +9.9 ± 1.5‰, δD= −76 ± 5‰, 87Sr/86Srt = 0.7067 ± 0.0010, εNdt = −3.5 ± 1.4) suggesting that they were not derived by fractionation of the contaminated intermediate magmas, but evolved from different magma batches. Some rocks of the arc, both igneous (mostly gabbro and tonalite) and metamorphic, underwent restricted interaction with meteoric fluids. Reported values of δ18O of magmatic zircons from the Famatinian arc rocks (+6 to +9‰) are comparable to our δ18O whole-rock data, indicating that pervasive oxygen isotope exchange in the lower crust was not a major process after zircon crystallization.

Abstract. Isotope labelling is a powerful tool to study elemental cycling within terrestrial ecosystems. Here we describe a new multi-isotope technique to label organic matter (OM). We exposed poplars (Populus deltoides x nigra) for 14 days to an atmosphere enriched in 13CO2 and depleted in 2H218O. After one week, the water-soluble leaf OM (δ13C = 1346 ± 162‰) and the leaf water were strongly labelled (δ18O = −63± 8‰, δ2H = −156 ± 15‰). The leaf water isotopic composition was between the atmospheric and stem water, indicating a considerable diffusion of vapour into the leaves (58–69%). The atomic ratios of the labels recovered (18O/13C, 2H/13C) were 2–4 times higher in leaves than in the stems and roots. This either indicates the synthesis of more condensed compounds (lignin vs. cellulose) in roots and stems, or be the result of O and H exchange and fractionation processes during transport and biosynthesis. We demonstrate that the three major OM elements (C, O, H) can be labelled and traced simultaneously within the plant. This approach could be of interdisciplinary interest for the fields of plant physiology, paleoclimatic reconstruction or soil science.

The surface and near-surface chemical composition of electroceramic materials often shows significant deviations from that of the bulk. In particular, layered materials, such as cation-ordered LnBaCo₂O_5+δ perovskites (Ln = lanthanide), undergo surface and sub-surface restructuring due to the segregation of the divalent alkaline-earth cation. These processes can take place during synthesis and processing steps (e.g. deposition, sintering or annealing), as well as at temperatures relevant for the operation of these materials as air electrodes in solid oxide fuel cells and electrolysers. Furthermore, the surface segregation in these double perovskites shows fast kinetics, starting at temperatures as low as 400 °C over short periods of time and leading to a decrease in the transition metal surface coverage exposed to the gas phase. In this work, we use a combination of stable isotope tracer labeling and surface-sensitive ion beam techniques to study the oxygen transport properties and their relationship with the surface chemistry in ordered LnBaCo₂O_5+δ perovskites. Time-of-Flight Secondary-Ion Mass Spectrometry (ToF-SIMS) combined with ¹⁸O isotope exchange was used to determine the oxygen tracer diffusion (D*) and surface exchange (k*) coefficients. Furthermore, Low Energy Ion Scattering (LEIS) was used for the analysis of the surface and near surface chemistry as it provides information from the first mono-atomic layer of the materials. In this way, we could relate the compositional modifications (e.g. cation segregation) taking place at the electrochemically-active surface during the exchange at high temperatures and the oxygen transport properties in double perovskite electrode materials to further our understanding of the mechanism of the surface exchange process.

Abstract. Isotope labelling is a powerful tool to study elemental cycling within terrestrial ecosystems. Here we describe a new multi-isotope technique to label organic matter (OM). We exposed poplars (Populus deltoides × nigra) for 14 days to an atmosphere enriched in 13CO2 and depleted in 2H218O. After 1 week, the water-soluble leaf OM (δ13C = 1346 ± 162‰) and the leaf water were strongly labelled (δ18O = −63 ± 8, δ2H = −156 ± 15‰). The leaf water isotopic composition was between the atmospheric and stem water, indicating a considerable back-diffusion of vapour into the leaves (58–69%) in the opposite direction to the net transpiration flow. The atomic ratios of the labels recovered (18O/13C, 2H/13C) were 2–4 times higher in leaves than in the stems and roots. This could be an indication of the synthesis of more condensed compounds in roots and stems (e.g. lignin vs. cellulose) or might be the result of O and H exchange and fractionation processes during phloem transport and biosynthesis. We demonstrate that the three major OM elements (C, O, H) can be labelled and traced simultaneously within the plant. This approach could be of interdisciplinary interest in the fields of plant physiology, palaeoclimatic reconstruction or soil science.

18 O isotope exchange measurements of photosystem II (PSII) in thylakoids from wild-type and mutant Synechocystis have been performed to investigate binding of substrate water to the high-affinity Mn 4 site in the oxygen-evolving complex (OEC). The mutants investigated were D1-D170H, a mutation of a direct ligand to the Mn 4 ion, and D1-D61N, a mutation in the second coordination sphere. The substrate water 18 O exchange rates for D61N were found to be 0.16±0.02 s −1 and 3.03±0.32 s −1 for the slow and fast phases of exchange, respectively, compared with 0.47±0.04 s −1 and 19.7±1.3 s −1 for the wild-type. The D1-D170H rates were found to be 0.70±0.16 s −1 and 24.4±4.6 s −1 and thus are almost within the error limits for the wild-type rates. The results from the D1-D170H mutant indicate that the high-affinity Mn 4 site does not directly bind to the substrate water molecule in slow exchange, but the binding of non-substrate water to this Mn ion cannot be excluded. The results from the D61N mutation show an interaction with both substrate water molecules, which could be an indication that D61 is involved in a hydrogen bonding network with the substrate water. Our results provide limitations as to where the two substrate water molecules bind in the OEC of PSII.

The doubly labeled water (2H2(18)O) method to assess energy expenditure in free-living conditions has been successfully validated against gas exchange measurements in lean healthy volunteers in both sedentary conditions and during sustained heavy exercise. However, no data are available on obese subjects. We therefore compared the 2H2(18)O method with indirect calorimetry (respiratory chamber) in 12 male subjects covering a wide range of body weight and composition (61-190 kg, 7-41% fat). Isotope pool sizes and elimination rates were calculated from 18O and 2H enrichments in baseline urine samples and in 7-h, 11.5-h, and daily postdose urine samples using the multipoint slope/intercept method. Results were corrected for isotopic fractionation. Mean 7-day energy expenditure in the respiratory chamber varied from 1,851 to 4,105 kcal/day. The doubly labeled water method tended to underestimate energy expenditure (-2.5 +/- 5.8%, not equal to 0, range -14 to +4%), with the larger underestimate observed in heavier and fatter subjects (r = -0.82 and -0.68, P less than 0.02, respectively). The underestimation in heavier subjects might be related to larger sequestration of deuterium during fat synthesis. In conclusion, the doubly labeled water method is a suitable and accurate method to measure energy expenditure in free-living conditions but might provide a slightly underestimated figure in fatter subjects.

Amorphous polymer-derived Si - C - N ceramics can be doped with different elements ( Al , B etc.) through various pre-ceramic polymer routes. Thus, controlling of the high temperature oxidation resistance can be achieved on an atomic level. An important factor for silica layer growth is oxygen diffusion in protective thermally grown layers. In order to get insight of the oxygen diffusion mechanism, analysis should include both, bulk and short-circuit diffusion. XRD measurements of oxidized Si - C - N and SiC revealed the possibility that oxide layers were fully crystallized and are composed of nano-sized cristobalite-like grains. Secondary ion mass spectrometry depth profile analysis after 18 O 2-16 O 2 isotope exchange experiments on oxidized SiC indicated that short-circuit diffusion is probably grain boundary diffusion of molecular oxygen.

Abstract. Stable isotopologues of CO2, such as 13CO2 and C18O16O, have been used to study the CO2 exchange between land and atmosphere. The advent of new measuring techniques has allowed near-continuous measurements of stable isotopes in the air. These measurements can be used with micrometeorological techniques, providing new tools to investigate the isotope exchange in ecosystems. The objectives of this study were to evaluate the use of the isotope flux ratio method (IFR) near the forest floor of a temperate deciduous forest and to study the temporal dynamics of δ18O of CO2 flux near the forest floor by comparing IFR estimates with estimates of δ18O of net soil CO2 flux provided by an analytical model. Mixing ratios of 12C16O2, 13CO2 and C16O18O were measured within and above a temperate deciduous forest, using the tunable diode laser spectroscopy technique. The half-hourly compositions of the CO2 flux near the forest floor (δ13CF and δ18OF) were compared with estimates provided by a modified Keeling plot technique (mKP) and by a Lagrangian dispersion analysis (WT analysis). The mKP and IFR δ18OF estimates showed good agreement (slope = 1.03 and correlation, R2 = 0.80). The δ13CF estimates from the two methods varied in a narrow range of −32.7 and −23.1 ‰; the mean (±SE) mKP and IFR δ13CF values were −27.5 ‰ (±0.2) and −27.3 ‰ (±0.1), respectively, and were statistically identical (p > 0.05). WT analysis and IFR δ18OF estimates showed better correlation (R2 = 0.37) when only turbulent periods (u* > 0.6 m s−1) were included in the analysis. The large data capture (~95 % of half-hour periods evaluated) for the IFR in comparison with mKP (27 %) shows that the former provides new opportunities for studying δ18O-CO2 flux dynamics within forest canopies. Values of δ18OF showed large temporal variation, with values ranging from −31.4 ‰ (DOY 208) to −11.2 ‰ (DOY 221). Precipitation events caused substantial variation (~8 ‰) in δ18OF over a period of approximately 24 h. A diel trend of δ18OF was observed, with more enriched values present during the daytime. Model simulations indicate that the activity of the carbon anhydrase enzyme was very variable during the evaluated period. These simulations indicate that more frequent sampling of δ18O of soil water could improve the estimates of δ18O of net soil CO2 flux.

Abstract. Stable isotopologues of CO2, such as 13CO2 and C18OO, have been used to study the CO2 exchange between land and atmosphere. The advent of new measuring techniques has allowed near-continuous measurements of stable isotopes in the air. These measurements can be used with micrometeorological techniques, providing new tools to investigate the isotope exchange in ecosystems. The objectives of this study were to evaluate the use of the isotope flux ratio method (IFR) near the forest floor of a temperate deciduous forest and to study the temporal dynamics of δ18O of CO2 flux near the forest floor by comparing IFR estimates with estimates of δ18O of net soil CO2 flux provided by an analytical model. Mixing ratios of 12C16O2, 13CO2 and C16O18O were measured within and above a temperate deciduous forest, using the tunable diode laser spectroscopy technique. The half-hourly compositions of the CO2 flux near the forest floor (δ13CF and δ18OF) were calculated by IFR and compared with estimates provided by a modified Keeling plot technique (mKP) and by a Lagrangian dispersion analysis (WT analysis). The mKP and IFR δ18OF estimates showed good agreement (slope = 1.03 and correlation, R2 = 0.80). The δ13CF estimates from the two methods varied in a narrow range of −32.7 and −23‰; the mean (± SE) mKP and IFR δ13CF values were −27.5‰ (±0.2) and −27.3‰ (±0.1), respectively, and were statistically identical (p>0.05). WT analysis and IFR δ18OF estimates showed better correlation (R2 = 0.37) when only turbulent periods (u*>0.6 m s−1) were included in the analysis. The large amount of data captured (~95 % of half-hour periods evaluated) for the IFR in comparison with mKP (27 %) shows that the former provides new opportunities for studying δ18OF dynamics within forest canopies. Values of δ18OF showed large temporal variation, with values ranging from −31.4‰ (DOY 208) to −11.2‰ (DOY 221). Precipitation events caused substantial variation (~8‰) in δ18OF over a period of approximately 24 h. A diel trend of δ18OF was observed, with more depleted values present during the daytime. Model simulations indicate that the activity of the carbonic anhydrase enzyme was quite variable during the evaluated period. These simulations indicate that more frequent sampling of δ18O of soil water could improve the estimates of δ18O of net soil CO2 flux.

Abstract. The analysis of the stable oxygen isotopes 18O and 16O has revolutionized paleoclimate research since the middle of the last century. Particularly, δ18O of ice cores from Greenland and Antarctica is used as a paleotemperature proxy, and δ18O of deep-sea sediments is used as a proxy for global ice volume. Important terrestrial archives to which δ18O as a paleoclimate proxy is successfully applied are speleothems, lake sediments, or tree rings. By contrast, δ18O applications to loess–paleosol sequences (LPSs) are scarce. Here we present a first continuous δ18O record (n=50) for the LPS Crvenka in Serbia, southeastern Europe, spanning the last glacial–interglacial cycle (since 145 ka). From a methodological point of view, we took advantage of a recently proposed paleoclimate/paleohydrological proxy based on bulk δ18O analyses of plant-derived lipids. The Crvenka δ18Obulk lipid values range between −10.2 ‰ and +23.0 ‰ and are systematically more positive in the interglacial and interstadial (paleo-)soils corresponding to marine oxygen-isotope stage (MIS) 1, 3, and 5, compared to the loess layers (MIS 2, 4, and 6). Our Crvenka δ18Obulk lipid record provides no evidence for the occurrence of interstadials and stadials comparable to the Dansgaard–Oeschger events known from the Greenland δ18Oice core records. Concerning the interpretation of our Crvenka δ18Obulk lipid record, plant-derived lipids such as fatty acids and alcohols are certainly strongly influenced by climatic factors such as temperature (via δ18Oprecipitation) and relative air humidity (via 18O enrichment of leaf water due to evapotranspiration). However, pool effects in the form of non-water-correlated lipids such as sterols or the input of root-derived lipids need to be considered, too. Similarly, the input of soil-microbial lipids and oxygen exchange reactions represent uncertainties challenging quantitative paleoclimate/paleohydrological reconstructions based on δ18Obulk lipid analyses from LPSs.

Abstract. We used the recently developed commercially available Delta Ray isotope ratio infrared spectrometer (IRIS) to continuously measure the CO2 concentration c and its isotopic composition δ13C and δ18O in a managed beech forest in central Germany. Our objectives are (a) to characterize the Delta Ray IRIS and evaluate its internal calibration procedure and (b) to quantify the seasonal variability of c, δ13C, δ18O and the isotopic composition of nighttime net ecosystem CO2 exchange (respiration) Reco13C and Reco18O derived from Keeling plot intercepts. The analyzer's minimal Allan deviation (as a measure of precision) was below 0.01 ppm for the CO2 concentration and below 0.03 ‰ for both δ values. The potential accuracy (defined as the 1σ deviation from the respective linear regression that was used for calibration) was approximately 0.45 ppm for c, 0.24 ‰ for 13C and 0.3 ‰ for 18O. For repeated measurements of a target gas in the field, the long-term standard deviation from the mean was 0.3 ppm for c and below 0.3 ‰ for both δ values. We used measurements of nine different inlet heights to evaluate the isotopic compositions of nighttime net ecosystem CO2 exchange Reco13C and Reco18O in a 3-month measurement campaign in a beech forest in autumn 2015. During this period, an early snow and frost event occurred, coinciding with a change in the observed characteristics of both Reco13C and Reco18O. Before the first snow, Reco13C correlated significantly (p < 10−4) with time-lagged net radiation Rn, a driver of photosynthesis and photosynthetic discrimination against 13C. This correlation became insignificant (p > 0.1) for the period after the first snow, indicating a decoupling of δ13C of respiration from recent assimilates. For 18O, we measured a decrease of 30 ‰ within 10 days in Reco18O after the snow event, potentially reflecting the influence of 18O depleted snow on soil moisture. This decrease was 10 times larger than the corresponding decrease in δ18O in ambient CO2 (below 3 ‰) and took 3 times longer to recover (3 weeks vs. 1 week). In summary, we conclude that (1) the new Delta Ray IRIS with its internal calibration procedure provides an opportunity to precisely and accurately measure c, δ13C and δ18O at field sites and (2) even short snow or frost events might have strong effects on the isotopic composition (in particular 18O) of CO2 exchange on an ecosystem scale.

Abstract. The continuous in situ measurement of δ18O in atmospheric CO2 opens a new door to differentiating between CO2 source and sink components with high temporal resolution. Continuous 13C–CO2 measurement systems have already been commercially available for some time, but until now, only few instruments have been able to provide a continuous measurement of the oxygen isotope ratio in CO2. Besides precise 13C/12C observations, the Fourier transform infrared (FTIR) spectrometer is also able to measure the 18O / 16O ratio in CO2, but the precision and accuracy of the measurements have not yet been evaluated. Here we present a first analysis of δ18O-CO2 (and δ13C-CO2) measurements with the FTIR analyser in Heidelberg. We used Allan deviation to determine the repeatability of δ18O-CO2 measurements and found that it decreases from 0.25‰ for 10 min averages to about 0.1‰ after 2 h and remains at that value up to 24 h. We evaluated the measurement precision over a 10-month period (intermediate measurement precision) using daily working gas measurements and found that our spectrometer measured δ18O-CO2 to better than 0.3‰ at a temporal resolution of less than 10 min. The compatibility of our FTIR-spectrometric measurements to isotope-ratio mass-spectrometric (IRMS) measurements was determined by comparing FTIR measurements of cylinder gases and ambient air with IRMS measurements of flask samples, filled with gases of the same cylinders or collected from the same ambient air intake. Two-sample t tests revealed that, at the 0.01 significance level, the FTIR and the IRMS measurements do not differ significantly from each other and are thus compatible. We describe two weekly episodes of ambient air measurements, one in winter and one in summer, and discuss what potential insights and new challenges combined highly resolved CO2, δ13C-CO2 and δ18O-CO2 records may provide in terms of better understanding regional scale continental carbon exchange processes.

Abstract. The continuous in-situ measurement of δ18O in atmospheric CO2 opens a new door to differentiating between CO2 source and sink components with high temporal resolution. Continuous 13C-CO2 measurement systems have been commercially available already for some time, but until now, only few instruments have been able to provide a continuous measurement of the oxygen isotope ratio in CO2. Besides precise 13C/12C observations, the Fourier Transform InfraRed (FTIR) spectrometer also measures the 18O/16O ratio of CO2, but the precision and accuracy of the measurements has not been evaluated yet. Here we present a first analysis of δ18O-CO2 (and δ13C-CO2) measurements with the FTIR in Heidelberg. We find that our spectrometer measures 18O in CO2 with a reproducibility of better than 0.3‰ at a temporal resolution of less than 10 min, as determined from surveillance gas measurements over a period of ten months. An Allan deviation test shows that the δ18O repeatability reaches 0.15‰ for half-hourly means. The compatibility of our spectroscopic measurements was determined by comparing FTIR measurements of calibration gases and ambient air to mass-spectrometric measurements of flask samples, filled with the cylinder gases or episodically collected over a diurnal cycle (event). We found that direct cylinder gas measurements agree to 0.01 ± 0.04‰ (mean and standard deviation) for δ13C-CO2 and 0.01 ± 0.11‰ for δ18O. Two weekly episodes of recent ambient air measurements, one in winter and one in summer, are discussed in view of the question, which potential insights and new challenges combined highly resolved δ18O-CO2 and δ13C-CO2 records may provide in terms of better understanding regional scale continental carbon exchange processes.

Abstract. Palaeoatmospheric records of carbon dioxide and its stable carbon isotope composition (δ13C) obtained from polar ice cores provide important constraints on the natural variability of the carbon cycle. However, the measurements are both analytically challenging and time-consuming; thus only data exist from a limited number of sampling sites and time periods. Additional analytical resources with high analytical precision and throughput are thus desirable to extend the existing datasets. Moreover, consistent measurements derived by independent laboratories and a variety of analytical systems help to further increase confidence in the global CO2 palaeo-reconstructions. Here, we describe our new set-up for simultaneous measurements of atmospheric CO2 mixing ratios and atmospheric δ13C and δ18O-CO2 in air extracted from ice core samples. The centrepiece of the system is a newly designed needle cracker for the mechanical release of air entrapped in ice core samples of 8–13 g operated at −45 °C. The small sample size allows for high resolution and replicate sampling schemes. In our method, CO2 is cryogenically and chromatographically separated from the bulk air and its isotopic composition subsequently determined by continuous flow isotope ratio mass spectrometry (IRMS). In combination with thermal conductivity measurement of the bulk air, the CO2 mixing ratio is calculated. The analytical precision determined from standard air sample measurements over ice is ±1.9 ppm for CO2 and ±0.09 ‰ for δ13C. In a laboratory intercomparison study with CSIRO (Aspendale, Australia), good agreement between CO2 and δ13C results is found for Law Dome ice core samples. Replicate analysis of these samples resulted in a pooled standard deviation of 2.0 ppm for CO2 and 0.11 ‰ for δ13C. These numbers are good, though they are rather conservative estimates of the overall analytical precision achieved for single ice sample measurements. Facilitated by the small sample requirement, replicate measurements are feasible, allowing the method precision to be improved potentially. Further, new analytical approaches are introduced for the accurate correction of the procedural blank and for a consistent detection of measurement outliers, which is based on δ18O-CO2 and the exchange of oxygen between CO2 and the surrounding ice (H2O).

Abstract. Stable water isotopes (δ18O) obtained from snow and ice samples of polar regions are used to reconstruct past climate variability, but heat and mass transport processes can affect the isotopic composition. Here we present an experimental study on the effect of airflow on the snow isotopic composition through a snow pack in controlled laboratory conditions. The influence of isothermal and controlled temperature gradient conditions on the δ18O content in the snow and interstitial water vapour is elucidated. The observed disequilibrium between snow and vapour isotopes led to the exchange of isotopes between snow and vapour under non-equilibrium processes, significantly changing the δ18O content of the snow. The type of metamorphism of the snow had a significant influence on this process. These findings are pertinent to the interpretation of the records of stable isotopes of water from ice cores. These laboratory measurements suggest that a highly resolved climate history is relevant for the interpretation of the snow isotopic composition in the field.

Background Desflurane, enflurane and isoflurane can be degraded to carbon monoxide (CO) by carbon dioxide absorbents, whereas sevoflurane and halothane form negligible amounts of CO. Carbon monoxide formation is greater with drier absorbent, and with barium hydroxide, than with soda lime. The mechanism, role of absorbent composition and water, and anesthetic structures determining CO formation are unknown. This investigation examined sequential steps in anesthetic degradation to CO. Methods Carbon monoxide formation from anesthetics and desiccated barium hydroxide lime or soda lime was determined at equimole and equiMAC concentrations. Carbon monoxide formation from deuterium-substituted anesthetics was also quantified. Proton abstraction from anesthetics by strong base was determined by deuterium isotope exchange. A reactive chemical intermediate was trapped and identified by gas chromatography-mass spectrometry. The source of the oxygen in CO was identified by 18O incorporation. Results Desflurane,enflurane,andisoflurane(difluoromethylethyl ethers), but not sevoflurane (monofluoromethyl ether), methoxyflurane (methy-ethyl ether), or halothane (alkane) were degraded to CO. The amount of CO formed was desflurane &gt; or = enflurane &gt; isoflurane at equiMAC and enflurane &gt; desflurane &gt; isoflurane at equimole concentrations. Proton abstraction from the difluoromethoxy carbon was greater with potassium than with sodium hydroxide, but unmeasurable with barium hydroxide. Carbon monoxide formation was correlated (r = 0.95-1.00) with difluoromethoxy (enflurane &gt; desflurane &gt; isoflurane &gt; or = methoxyflurane = sevoflurane = 0) but not ethyl carbon proton abstraction. Deuterium substitution on enflurane and desflurane diminished CO formation. Chemical trapping showed formation of a difluorocarbene intermediate from enflurane and desflurane. Incorporation of H2(18)O in barium hydroxide lime resulted in C18O formation from unlabeled enflurane and desflurane. Conclusions A difluoromethoxy group is a structural requirement for haloether degradation to CO. Results are consistent with initial base-catalyzed difluoromethoxy proton abstraction (potassium &gt; sodium hydroxide, thus greater CO formation with barium hydroxide lime vs. soda lime) forming a carbanion (reprotonated by water to regenerate the anesthetic, hence requirements for relatively dry absorbent), carbanion decomposition to a difluorocarbene, and subsequent difluorocarbene reaction to form CO.

Abstract. To trace NO3– sources and assess NO3– dynamics in the salinized rivers and estuaries, three rivers (HH River, CB River and JY River) and two estuaries (HH Estuary and CJ Estuary) along the Bohai Bay (China) have been selected to determine DIN and δ15N and δ18O-NO3–. Upstream of the HH River NO3– was removed 30.9 ± 22.1% by aerobic denitrification, resulting from effects of the floodgate: limiting water exchange with downstream and prolonging water residence time to remove NO3–. Downstream of the HH River NO3– was removed 2.5 ± 13.3% by NO3– turnover processes. Conversely, NO3– was increased 36.6 ± 25.2% by external N source addition in the CB River and 34.6 ± 35.1% by in-stream nitrification in the JY River, respectively. The HH and CY Estuaries behaved mostly conservative excluding the sewage input in the CJ Estuary. Hydrodynamics in estuaries have been changed by the ongoing reclamation projects, aggravating the estuaries losing the attenuation function of NO3–.

Abstract. To trace NO3− sources and assess NO3− dynamics in salinized rivers and estuaries, three rivers (Haihe River: HH River, Chaobaixin River: CB River and Jiyun River: JY River) and two estuaries (HH Estuary and CJ Estuary) along the Bohai Bay (China) have been selected to determine dissolved inorganic nitrogen (DIN: NH4+, NO2− and NO3−. Upstream of the HH River, NO3− was removed 30.9 ± 22.1% by denitrification, resulting from effects of the floodgate: limiting water exchange with downstream and prolonging water residence time to remove NO3−. Downstream of the HH River NO3− was removed 2.5 ± 13.3% by NO3− turnover processes. Conversely, NO3− was increased 36.6 ± 25.2% by external N source addition in the CB River and 34.6 ± 35.1% by in-stream nitrification in the JY River. The HH and CY Estuaries behaved mostly conservatively excluding the sewage input in the CJ Estuary. Hydrodynamics in estuaries has been changed by the ongoing reclamation projects, aggravating the loss of the attenuation function of NO3− in the estuary.

Abstract. Siliceous sponge spicules constitute an important siliceous component of lacustrine sediments, together with widespread diatom frustules. In contrast to diatom frustules, siliceous spicules are formed in sponges in an enzymatic way. Previous attempts to use their oxygen isotopic signature (δ18Osilica) as a paleoenvironmental proxy have led to contradictory conclusions. These attempts demonstrated the need to further assess whether sponges form their silica in oxygen isotopic equilibrium with water. For this reason, we measured the δ18O signature of sponge spicules from a single freshwater species (Metania spinata) grown on natural and artificial supports over nine months in a small Brazilian pond (Lagoa Verde, northwestern Minas Gerais). The δ18Osilica values were obtained using the infrared (IR) laser-heating fluorination technique following a controlled isotopic exchange (CIE). The δ18O values (δ18Owater) and temperature of the pond water were periodically measured and reconstructed over the course of the sponge growth. Assuming that silica may form continuously in the spicules, temperature and δ18Owater values over the months of growth were weighted using a sponge growth coefficient previously established for Metania spinata. The δ18Osilica values of sponges grown simultaneously and on similar substrates were scattered. No relationships were observed between the Δ18Osilica-water and water temperature when the reconstructed values were considered. Conversely, a positive correlation was obtained, with a coefficient of 0.3‰ °C–1 (R2 = 0.63), when δ18Owater values and water temperature at the time of sample collection were considered. Such a positive temperature coefficient clearly indicates that the freshwater sponge Metania spinata does not form its siliceous spicules in oxygen isotopic equilibrium with the pond water. Instead, one or several biologically controlled kinetic fractionation mechanisms may be in play during the various steps of silica formation. Our results suggest that the latest precipitation gives its δ18O imprint to the entire spicules assemblage. The amplitude of the apparent fractionations increases with temperature, but other controlling parameters, such as dissolved Si concentration and nutrient availability, co-varying with temperature may intervene. These results prevent the use of δ18Osilica values from the spongillites of northwestern Minas Gerais as a direct proxy for past δ18Owater and/or temperature changes.

The Daugava or Zapadnaya (Western) Dvina River belongs to the Baltic Sea basin. The length of the river is 1,005 km with a drainage area of 87,900 km². It crosses three countries: Russia (323 km and 18,500 km²), Belarus (328 km and 33,100 km²) and Latvia (352 km and 24,700 km²). Water samples were collected at three points with the following coordinates: Kraslava, Daugavpils, and Riga and distance from the river mouth 320, 255, and 20 km respectively. Discharge measurements by use of acoustic Doppler current profiler (ADCP) from a moving boat were also performed in the locations indicated above. Nitrates were extracted from water samples using the ‘ion-exchange resin method’, which involves extracting NO₃^- from freshwater and converting it into solid silver nitrate, which is then analysed for ¹⁵N/¹⁴N and ¹⁸O/¹⁶O ratios by IRMS. Prior to passing water through an anion-exchange resin precipitation of O-bearing contaminants (mainly sulphate and phosphate) with barium chloride was carried out. The δ¹⁵N_NO3 values of riverine samples varied from 7.1 to 8.6 ‰ in Kraslava, from 7.2 to 8.3 ‰ in Daugavpils, and from 8.1 to 9.0 ‰ in Riga and displayed significant differences between the three sampling points.

AbstractIt has been well known that the influxing meteoric water can hydrothermally lower oxygen and hydrogen isotopes of rocks and/or minerals during continental magmatic or metamorphic processes in certain appropriate cases. Its opposite, however, is not implicitly true and needs independent testing. In terms of a novel procedure recently proposed for dealing with thermodynamic re-equilibration of oxygen isotopes between constituent minerals and water from fossil hydrothermal systems, the initial oxygen isotopes of water ($${\updelta }^{18}{\text{O}}_{\text{W}}^{\text{i}}$$ δ 18 O W i ) are theoretically inverted from the early Cretaceous post-collisional granitoids and Triassic gneissic country rock across the Dabie orogen in central-eastern China. Despite ancient meteoric waters with low $${\updelta }^{18}{\text{O}}_{\text{W}}^{\text{i}}$$ δ 18 O W i value down to − 11.01 ± 0.43‰ (one standard deviation, 1SD), oxygen isotopes of hydrothermally altered rock-forming minerals from a granitoid were unexpectedly but concurrently lowered by an evolved magmatic water with mildly high $${\updelta }^{18}{\text{O}}_{\text{W}}^{\text{i}}$$ δ 18 O W i value of 2.81 ± 0.05‰ at 375 °C with a water/rock (W/R)c ratio of 1.78 ± 0.20 for the closed system. The lifetime of fossil hydrothermal systems studied herein is kinetically constrained to no more than 1.2 million years (Myr) via surface-reaction oxygen exchange in the late-stage of continental magmatism or metamorphism. Thereby, caution should be paid when lowered oxygen isotopes of hydrothermally altered rocks and/or minerals were intuitively and/or empirically inferred from the external infiltration of the purely meteoric water with a low $${\updelta }^{18}{\text{O}}_{\text{W}}^{\text{i}}$$ δ 18 O W i value alone.

ABSTRACT While the external infiltration of water has been identified from modern geothermal and/or fossil hydrothermal systems through stable isotopes, the physicochemical boundary conditions like the initial oxygen isotopes of water $( {{\rm \delta }^{ 18}{\rm O}_{\rm W}^{\rm i} } ) $ and rock as well as alteration temperature were implicitly presumed or empirically estimated by the conventional forward modelling. In terms of a novel procedure proposed to deal with partial re-equilibration of oxygen isotopes between constituent minerals and water, the externally infiltrated meteoric and magmatic water are theoretically inverted from the early Cretaceous post-collisional granitoid and intruded Triassic gneissic country rock across the Dabie orogen in central-eastern China. The meteoric water with a $ {{\rm \delta }^{ 18}{\rm O}_{\rm W}^{\rm i} } $ value of −11.01 ‰ was externally infiltrated with a granitoid and thermodynamically re-equilibrated with rock-forming minerals at 140°C with a minimum water/rock (W/R)o ratio around 1.10 for an open system. The lifetime of this meteoric hydrothermal system is kinetically constrained less than 0.7 million years (Myr) via modelling of surface reaction oxygen exchange. A gneissic country rock, however, was externally infiltrated by a magmatic water with $ {{\rm \delta }^{ 18}{\rm O}_{\rm W}^{\rm i} } $ value of 4.21 ‰ at 340°C with a (W/R)o ratio of 1.23, and this magmatic hydrothermal system could last no more than 12 thousand years (Kyr) to rapidly re-equilibrate with rock-forming minerals. Nevertheless, the external infiltration of water can be theoretically inverted with oxygen isotopes of re-equilibrated rock-forming minerals, and the ancient hydrothermal systems driven by magmatism or metamorphism within continental orogens worldwide can be reliably quantified.

В соединениях, кристаллизующихся в структурном типе пирохлора (пр. гр. симм. Fd3m) общей формулы А2В2X6X’, на месте катионов A могут находиться двух- или трёхзарядные ионы, на месте B – четырёх- или пятизарядные ионы. В большом количестве работ рассматриваются вопросы формирования таких структур в зависимости от природы и размеров катионов A и B, мало внимания уделяется определению температурных интервалов их устойчивости. Поэтому целью данной работы являлось исследование термолиза твердых растворов замещения H2Sb2–xVxO6·nH2Oв интервале температур 25–700 °С, определение влияния природы катиона B (Sb, V) на устойчивость структуры типа пирохлора при нагревании.Твердые растворы замещения были получены методом соосаждения. В качестве объектов исследования выбраны образцы H2Sb2–xVxO6·nH2O, содержащие по данным элементного анализа 0; 5 (x = 0.10); 15 (x = 0.30); 20 (x = 0.40); 24 (x = 0.48) ат.% ванадия. С помощью метода ИК-спектроскопии анализировали изменение протонгидратной подрешетки в образцах, содержащих различное количество V+5. Рентгенофазовый и термогравиметрический анализ образцов позволил смоделировать процесс термолиза и определить состав фаз на каждой стадии.Показано, что при температурах 25–400 °С происходит удаление протонсодержащих группировок из гексагональных каналов структуры типа пирохлора. Увеличение количества ионов V+5 в твердых растворах изменяет энергию связи протонов с ионами кислорода [BO3]–-октаэдра, что приводит к смещению границ стадий: ионы оксония и молекулы воды удаляются при более высоких температурах, а гидроксид-ионы при более низких температурах. Повышениетемпературы выше 500 °С приводит к разрушению структуры по причине удаления кислорода из [BO3]–-октаэдров.Предложена модель заполнения атомами кристаллографических позиций структуры типа пирохлора для фаз, которые образуются при термолизе H2Sb2–xVxO6·nH2O при температурах 25–400 °С.Установлены структурные формулы твердых растворов - (H3O)Sb2-xVxO5(OH)·nH2O, где 0 < x≤ 0.48, 0 <n≤ 1.1. Показано, что на температурные интервалы стадий термолиза влияет энергия связи протонов с ионами кислорода [BO3]–-октаэдров, где B = V, Sb, формирующих каркас структуры. При этом в рамках структуры типа пирохлора исследуемые твердые растворы устойчивы до 400 °С. ЛИТЕРАТУРА Subramanian M. A., Aravamudan G., Rao G. V. S. Oxide pyrochlores — A review. Progress in Solid State Chemistry. 1983;15(2): 55–143. DOI: https://doi.org/10.1016/0079-6786(83)90001-8 Krasnov A. G., Piir I. V., Koroleva M. S., Sekushin N. A., Ryabkov Y. I., Piskaykina M. M., Sadykov V. A., Sadovskaya E. M., Pelipenko V. V., Eremeev N. F. The conductivity and ionic transport of doped bismuth titanate pyrochlore Bi1.6МxTi2O7–d (М– Mg, Sc, Cu). Solid State Ionics. 2017;302: 118–125. DOI: https://doi.org/10.1016/j.ssi.2016.12.019 Cherednichenko L. A., Moroz Ya. A. Catalytic properties of heteropolytungstates with 3d elementsand their thermolysis products. Kinetics and Catalysis. 2018;59(5): 572–577. DOI: https://doi.org/10.1134/S0023158418050038 Krasnov A. G., Kabanov A. A., Kabanova N. A., Piir I. V., Shein I. R. Ab initio modeling of oxygen ionmigration in non-stoichiometric bismuth titanate pyrochlore Bi1.5Ti2O6.25. Solid State Ionics. 2019;335: 135–141. DOI: https://doi.org/10.1016/j.ssi.2019.02.023 Farlenkov A. S., Khodimchuk A. V., Eremin V. A., Tropin E. S., Fetisov A. V., Shevyrev N. A., Leonidov I. I., Ananyev M. V. Oxygen isotope exchange in doped lanthanum zirconates. Journal of Solid State Chemistry. 2018;268: 45–54. DOI: https://doi.org/10.1016/j.jssc.2018.08.022 Rejith R. S., Thomas J. K., Solomon S. Structural, optical and impedance spectroscopic characterizations of RE2Zr2O7 (RE = La, Y) ceramics. Solid State Ionics. 2018;323: 112–122. DOI: https://doi.org/10.1016/j.ssi.2018.05.025 Егорышева А. В., Эллерт О. Г., Гайтко О. М., Берсенева А. А., Максимов Ю. В., Дудкина Т. Д. Магнитные свойства твердых растворов со структурой типа пирохлора Pr2-xFe1+xSbO7, Bi2–xLnxFeSbO7 (Ln = La, Pr). Неорганические материалы. 2016;52(10): 1106–1115. DOI: https://doi.org/10.7868/S0002337X16100079 Rau J. G., Gingras M. J. P. Frustrated quantum rare-earth pyrochlores. Annual Review of Condensed Matter Physics. 2019;10(1): 357-386. DOI: https://doi.org/10.1146/annurev-conmatphys-022317-110520 Ломанова Н. А., Томкович М. В., Соколов В. В., Уголков В. Л. Формирование и термическое поведение нанокристаллического Bi2Ti2O7. Журнал общей химии. 2018;88(12): 1937–1942. DOI: https://doi.org/10.1134/S0044460X18120016 Liu X., Huang L., Wu X., Wang Z., Dong G., Wang C., Liu Y., Wang L. Bi2Zr2O7 nanoparticles synthesized by soft-templated sol-gel methods for visiblelight-driven catalytic degradation of tetracycline. Chemosphere. 2018;210: 424–432. DOI: https://doi.org/10.1016/j.chemosphere.2018.07.040 Weller M. T., Hughes R. W., Rooke J., Knee Ch. S., Reading J. The pyrochlore family – a potential panacea for the frustrated perovskite chemist. Dalton Transactions. 2004;19: 3032–3041. DOI: https://doi.org/10.1039/B401787K Knop O., Brisse F., Meads R. E., Brainbridge J. Pyrochlores. IV. Crystallographic and mossbauer studies of A2FeSbO7 pyrochlores. Canadian Journal of Chemistry. 1968;46: 3829–3832. DOI: https://doi.org/10.1139/v68-635 Sadykov V. A., Koroleva M. S., Piir I. V., Chezhina N. V., Korolev D. A., Skriabin P. I., Krasnov A. V., Sadovskaya E. M., Eremeev N. F., Nekipelov S. V., Sivkov V. N. Structural and transport properties of doped bismuth titanates and niobates. Solid State Ionics. 2018;315: 33–39. DOI: https://doi.org/10.1016/j.ssi.2017.12.008 Егорышева А. В., Попова Е. Ф., Тюрин А. В., Хорошилов А. В., Гайтко О. М., Светогоров Р. Д. Сложные танталаты РЗЭ с пирохлороподобной структурой: синтез, структура и термические свойства. Журнал неорганической химии. 2019;64(11):1154–1165. DOI: https://doi.org/10.1134/S0044457X19110059 McCauley R. A. Structural characteristics of pyrochlore formation. Journal of Applied Physics. 1980;51(1): 290–294. DOI: https://doi.org/10.1063/1.327368 Лупицкая Ю. А., Бурмистров В. А. Фазообразование в системе K2CO3–Sb2O3–WO3 при нагревании. Журнал неорганической химии. 2011; 56 (2): 329–331. Режим доступа: https://www.elibrary.ru/download/elibrary_15599328_91286141.pdf Piir I. V., Koroleva M. S., Korolev D. A., Chezina N. V., Semenov V. G., Panchuk V. V. Bismuth iron titanate pyrochlores: Thermostability, structure and properties. Journal of Solid State Chemistry. 2013;204: 245–250. DOI: https://doi.org/10.1016/j.jssc.2013.05.031 Лупицкая Ю. А., Калганов Д. А., Клюева М. В. Образование cоединений в системе Ag2O-Sb2O3-MoO3 при нагревании. Неорганические материалы. 2018;54(3): 252–256. DOI: https://doi.org/10.7868/S0002337X18030053 Lomakin M. S., Proskurina O. V., Danilovich D. P., Panchuk V. V., Semenov V. G., Gusarov V. V. Hydrothermal synthesis, phase formation and crystal chemistry of the pyrochlore/Bi2WO6 and pyrochlore/a-Fe2O3 composites in the Bi2O3–Fe2O3–WO3 system. Journal of Solid State Chemistry. 2019. DOI: https://doi.org/10.1016/j.jssc.2019.121064 Yang J., Han Y., Shahid M., Pan W., Zhao M., Wu W., Wan C. A promising material for thermal barrier coating: Pyrochlore-related compound Sm2FeTaO7. Scripta Materialia. 2018;149: 49–52. DOI: https://doi.org/10.1016/j.scriptamat.2018.02.005 Коваленко Л. Ю., Бурмистров В. А., Лупицкая Ю. А., Ковалев И. Н., Галимов Д. М. Синтез твёрдых растворов H2Sb2–xVxO6·nH2O со структурой типа пирохлора. Бутлеровские сообщения. 2018;55(8): 24–30. ROI: jbc-01/jbc-01/18-55-8-24 Коваленко Л. Ю., Бурмистров В. А. Диэлектрическая релаксация и протонная проводимость полисурьмяной кислоты, допированной ионами ванадия. Конденсированные среды и межфазные границы. 2019;21(2): 204–214. DOI: https://doi.org/10.17308/kcmf.2019.21/758 Трофимов В. Г., Шейнкман А. И., Клещев Г. В. О пятиокиси сурьмы в кристаллическом состоянии. Журнал структурной химии. 1973;14(2): 275–279. Коваленко Л. Ю., Ярошенко Ф. А., Бурмистров В. А., Исаева Т. Н., Галимов Д. М. Термолизгидрата пентаоксида сурьмы. Неорганические материалы. 2019;55(6): 628–634. DOI: https://doi.org/10.1134/S0002337X19060083 Chen J., Chen Z., Zhang X., Li X., Yu L., Li. D. Antimony oxide hydrate (Sb2O5·3H2O) as a simple and high effi cient photocatalyst for oxidation of benzene. Applied Catalysis B: Environmental. 2018;210: 379–385. DOI: https://doi.org/10.1016/j.apcatb.2017.04.004 Kovalenko L. Yu., Burmistrov V. A., Lupitskaya Yu. A., Yaroshenko F. A., Filonenko E. M., Bulaeva E. A. Ion exchange of H+/Na+ in polyantimonic acid, doped with vanadium ions. Pure and Applied Chemistry. 2019. DOI: https://doi.org/10.1515/pac-2019-0112 Юхневич Г. В. Успехи в применении ИК-спектроскопии для характеристики ОН-связей. Успехи химии. 1963;32(11): 1397–1423. DOI: https://doi.org/10.1070/RC1963v032n11ABEH001370 Тарасова Н. А., Анимица И. Е. Влияние природы галогена на локальную структуру и интеркалацию воды в оксигалогенидах Ba2InO3X (X = F, Cl, Br). Оптика и спектроскопия. 2018;124(2): 167–170. DOI: https://doi.org/10.21883/OS.2018.02.45518.171-17 Дерягин Б. В., Чураев Н. В., Овчаренко Ф. Д., Тарасевич Ю. И., Букин В. А., Сарвазян А. П., Харакоз Д. П., Саушкин В. В. Вода в дисперсных системах. М.: Химия; 1989. 288 с. Ферапонтов Н. Б., Вдовина С. Н., Гагарин А. Н., Струсовская Н. Л., Токмачев М. Г. Свойства воды в гелях гидрофильных полимеров. Конденсированные среды и межфазные границы. 2011; 13(2): 208–214. Режим доступа: http://www.kcmf.vsu.ru/resources/t_13_2_2011_015.pdf Frenkel L. S. Nuclear magnetic resonance method for determining the moisture holding capacity of cation exchange resins as a function of temperature. Analytical Chemistry. 1973;45(8): 1570–1571. DOI: https://doi.org/10.1021/ac60330a052 Карговский А. В. Водные кластеры: структуры и оптические колебательные спектры. Известия вузов. Прикладная нелинейная динамика. 2006;14(5): 110–119. DOI: https://doi.org/10.18500/0869-6632-2006-14-5-110-119 Eisenberg D., Kauzmann W. The structure and properties of water. Oxford: Oxford University Press; 1969. 296 p. Yu T., Zhang H., Cao H., Zheng G. Understanding the enhanced removal of Bi(III) using modifi ed crystalline antimonic acids: creation of a transitional pyrochlore-type structure and the Sb(V)-Bi(III) interaction behaviors. Chemical Engineering Journal. 2019;360: 313–324. DOI: https://doi.org/10.1016/j.cej.2018.11.209 Nakamoto K. Infrared and raman spectra of inorganic and coordination compounds: Part A: Theory and applications inorganic chemistry (Sixth ed.). New York: John Wiley & Sons; 2009. 419 p. DOI: https://doi.org/10.1002/9780470405840 Birchall T., Sleight A. W. Oxidation states in vanadium antimonate (“VSbO4”). Inorganic Chemistry. 1976;15(4): 868–870. DOI: https://doi.org/10.1021/ic50158a026 Guerrero-Pérez M. O. V-containing mixed oxide catalysts for reduction–oxidation-based reactions with environmental applications: A short review. Catalysts. 2018;8(11): 564. DOI: https://doi.org/10.3390/catal8110564 Котов В. Ю., Ярославцев А. Б. Протонная подвижность в неорганических гидратах кислот и кислых солей. Известия Академии наук. Серия химическая. 2002;4: 515–528. Полинг Л. Природа химической связи. М.:Ленинград: Госхимиздат; 1947. 116 с.