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Статті в журналах з теми "Ca isotopic measurements"
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Hillaire-Marcel, Claude, та Christiane Causse. "The Late Pleistocene Laurentide Glacier: Th/U Dating of its Major Fluctuations and δ18O Range of the Ice". Quaternary Research 32, № 2 (вересень 1989): 125–38. http://dx.doi.org/10.1016/0033-5894(89)90070-7.
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AbstractDirect information on the isotopic composition and timing of the now-vanished Laurentide glacier can be found in subglacial calcite or in early diagenetic concretions from glaciolacustrine deposits. Th/U isotopic measurements on early diagenetic concretions frome Lake Deschaillons varves (St. Lawrence Lowland, Québec) date the early Wisconsinan major ice advance at ca. 80,000 yr (isotopic stage 5a/4 transition). Significant retreat occurred at ca. 46,000 yr (isotopic stage 3) as indicated by Th/U isochrones on early diagenetic concretions from Lake Gayhurst varves in the Appalachian foothills of Québec. During the maximum extension of the ice, which is dated at ca. 22,000 yr by Th/U measurements on subglacial calcite at Cantley (northern margin of the St. Lawrence Lowland), δ18O values (vs PDB) ranging from −16/−19‰ (surficial ice) to ca. −30‰ (basal ice) are inferred for the Laurentide ice isotopic composition. Superimposition of two phases of carbonate precipitation does not prevent the establishment of their respective age and isotopic composition through correlation of independent parameters and calculation of mixing lines.
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Herbert, Timothy D., Rocio Caballero-Gill, and Joseph B. Novak. "A revised mid-Pliocene composite section centered on the M2 glacial event for ODP Site 846." Climate of the Past 17, no. 3 (June 23, 2021): 1385–94. http://dx.doi.org/10.5194/cp-17-1385-2021.
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Abstract. The composite section from ODP Site 846 has provided key data sets for Pliocene stable isotope and paleoclimatic time series. We document here apparent outliers in previously published data sets for stable isotopes and alkenone-derived sea surface temperature (SST) estimates in the Pliocene interval containing the M2 glaciation (ca. 3.290–3.3 Ma) by tying high-resolution core measurements to a continuous downhole conductivity log. We generate a revised sequence of new stable isotopic and alkenone measurements across the M2 event that correlate well to the revised splices of color reflectance and gamma ray attenuation porosity evaluator data from Site 846, and to a new composite section produced at equatorial Pacific ODP Site 850. A new composite splice for Site 846 is proposed, along with composite isotope and alkenone time series that should be integrated into revised Pliocene paleoclimatic stacks.
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Mennekes, David, Michael Rinderer, Stefan Seeger, and Natalie Orlowski. "Ecohydrological travel times derived from in situ stable water isotope measurements in trees during a semi-controlled pot experiment." Hydrology and Earth System Sciences 25, no. 8 (August 23, 2021): 4513–30. http://dx.doi.org/10.5194/hess-25-4513-2021.
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Abstract. Tree water uptake processes and ecohydrological travel times have gained more attention in recent ecohydrological studies. In situ measurement techniques for stable water isotopes offer great potential to investigate these processes but have not been applied much to tree xylem and soils so far. Here, we used in situ probes for stable water isotope measurements to monitor the isotopic signatures of soil and tree xylem water before and after two deuterium-labeled irrigation experiments. To show the potential of the method, we tested our measurement approach with 20-year-old trees of three different species (Pinus pinea, Alnus incana and Quercus suber). They were planted in large pots with homogeneous soil in order to have semi-controlled experimental conditions. Additional destructive sampling of soil and plant material allowed for a comparison between destructive (cryogenic vacuum extraction and direct water vapor equilibration) and in situ isotope measurements. Furthermore, isotope-tracer-based ecohydrological travel times were compared to travel times derived from sap flow measurements. The time to first arrival of the isotope tracer signals at 15 cm stem hight were ca. 17 h for all tree species and matched well with sap-flow-based travel times. However, at 150 cm stem height tracer-based travel times differed between tree species and ranged between 2.4 and 3.3 d. Sap-flow-based travel times at 150 cm stem hight were ca. 1.3 d longer than tracer-based travel times. The isotope signature of destructive and in situ isotope measurements differed notably, which suggests that the two types of techniques sampled water from different pools. In situ measurements of soil and xylem water were much more consistent between the three tree pots (on average standard deviations were smaller by 8.4 ‰ for δ2H and by 1.6 ‰ for δ18O for the in situ measurements) and also among the measurements from the same tree pot in comparison to the destructive methods (on average standard deviations were smaller by 7.8 ‰ and 1.6 ‰ for δ2H and δ18O, respectively). Our study demonstrates the potential of semi-controlled large-scale pot experiments and very frequent in situ isotope measurements for monitoring tree water uptake and ecohydrological travel times. It also shows that differences in sampling techniques or sensor types need to be considered when comparing results of different studies and within one study using different methods.
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Keller, Kathrin M., Sebastian Lienert, Anil Bozbiyik, Thomas F. Stocker, Olga V. Churakova (Sidorova), David C. Frank, Stefan Klesse, et al. "20th century changes in carbon isotopes and water-use efficiency: tree-ring-based evaluation of the CLM4.5 and LPX-Bern models." Biogeosciences 14, no. 10 (May 24, 2017): 2641–73. http://dx.doi.org/10.5194/bg-14-2641-2017.
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Abstract. Measurements of the stable carbon isotope ratio (δ13C) on annual tree rings offer new opportunities to evaluate mechanisms of variations in photosynthesis and stomatal conductance under changing CO2 and climate conditions, especially in conjunction with process-based biogeochemical model simulations. The isotopic discrimination is indicative of the ratio between the CO2 partial pressure in the intercellular cavities and the atmosphere (ci∕ca) and of the ratio of assimilation to stomatal conductance, termed intrinsic water-use efficiency (iWUE). We performed isotope-enabled simulations over the industrial period with the land biosphere module (CLM4.5) of the Community Earth System Model and the Land Surface Processes and Exchanges (LPX-Bern) dynamic global vegetation model. Results for C3 tree species show good agreement with a global compilation of δ13C measurements on leaves, though modeled 13C discrimination by C3 trees is smaller in arid regions than measured. A compilation of 76 tree-ring records, mainly from Europe, boreal Asia, and western North America, suggests on average small 20th century changes in isotopic discrimination and in ci∕ca and an increase in iWUE of about 27 % since 1900. LPX-Bern results match these century-scale reconstructions, supporting the idea that the physiology of stomata has evolved to optimize trade-offs between carbon gain by assimilation and water loss by transpiration. In contrast, CLM4.5 simulates an increase in discrimination and in turn a change in iWUE that is almost twice as large as that revealed by the tree-ring data. Factorial simulations show that these changes are mainly in response to rising atmospheric CO2. The results suggest that the downregulation of ci∕ca and of photosynthesis by nitrogen limitation is possibly too strong in the standard setup of CLM4.5 or that there may be problems associated with the implementation of conductance, assimilation, and related adjustment processes on long-term environmental changes.
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Leavitt, Steven W., та Robert M. Kalin. "A New Tree-Ring Width, δ13C and 14C Investigation of the Two Creeks Site". Radiocarbon 34, № 3 (1992): 792–97. http://dx.doi.org/10.1017/s0033822200064092.
Повний текст джерелаАнотація:
We have made isotopic and dendrochronologic measurements on material collected from the Two Creeks site. Radiocarbon dating of outside wood of four logs yielded an average age of 11,760 ± 100 BP, in good agreement with results of Broecker and Farrand (1963) over 25 years ago. The range of 11,640 ± 160 to 11,900 ± 160 BP suggests a period of forest growth of 200–300 years, consistent with a ring-width chronology established by Kaiser (1987). Ring counting of five specimens gave a range of individual tree ages from 110 to 182 years, and width measurements indicate very low year-to-year variation in ring size. However, preliminary cross-dating of five samples produced a 202-year floating chronology. Stable-carbon isotope chronologies on cellulose from five-year ring groups show δ13C scatter among trees typical of that found within modern sites, with some matches of isotopic maxima and minima. Some downward δ13C trends may result from physiological response to rising lake levels (and/or cooling temperatures) at the site, which also produced very narrow rings in the outer ca. 50 ± 20 years.
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Dickinson, Dane, Samuel Bodé та Pascal Boeckx. "System for <i>δ</i><sup>13</sup>C–CO<sub>2</sub> and <i>x</i>CO<sub>2</sub> analysis of discrete gas samples by cavity ring-down spectroscopy". Atmospheric Measurement Techniques 10, № 11 (22 листопада 2017): 4507–19. http://dx.doi.org/10.5194/amt-10-4507-2017.
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Abstract. A method was devised for analysing small discrete gas samples (50 mL syringe) by cavity ring-down spectroscopy (CRDS). Measurements were accomplished by inletting 50 mL syringed samples into an isotopic-CO2 CRDS analyser (Picarro G2131-i) between baseline readings of a reference air standard, which produced sharp peaks in the CRDS data feed. A custom software script was developed to manage the measurement process and aggregate sample data in real time. The method was successfully tested with CO2 mole fractions (xCO2) ranging from < 0.1 to > 20 000 ppm and δ13C–CO2 values from −100 up to +30 000 ‰ in comparison to VPDB (Vienna Pee Dee Belemnite). Throughput was typically 10 samples h−1, with 13 h−1 possible under ideal conditions. The measurement failure rate in routine use was ca. 1 %. Calibration to correct for memory effects was performed with gravimetric gas standards ranging from 0.05 to 2109 ppm xCO2 and δ13C–CO2 levels varying from −27.3 to +21 740 ‰. Repeatability tests demonstrated that method precision for 50 mL samples was ca. 0.05 % in xCO2 and 0.15 ‰ in δ13C–CO2 for CO2 compositions from 300 to 2000 ppm with natural abundance 13C. Long-term method consistency was tested over a 9-month period, with results showing no systematic measurement drift over time. Standardised analysis of discrete gas samples expands the scope of application for isotopic-CO2 CRDS and enhances its potential for replacing conventional isotope ratio measurement techniques. Our method involves minimal set-up costs and can be readily implemented in Picarro G2131-i and G2201-i analysers or tailored for use with other CRDS instruments and trace gases.
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Bownes, Jessica M., Philippa L. Ascough, Gordon T. Cook, Iona Murray, and Clive Bonsall. "Using Stable Isotopes and a Bayesian Mixing Model (FRUITS) to Investigate Diet at the Early Neolithic Site of Carding Mill Bay, Scotland." Radiocarbon 59, no. 5 (October 2017): 1275–94. http://dx.doi.org/10.1017/rdc.2017.39.
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AbstractWe present δ13C, δ15N, and δ34S measurements on archaeological human and animal bone collagen samples from a shell midden dating to the Neolithic ca. 4000–3500 cal BC, together with measurements on modern fish and shellfish. These data were used in conjunction with the Bayesian mixing model, Food Reconstruction Using Isotopic Transferred Signals (FRUITS), to reconstruct human diet at the site. We demonstrate the importance of using a geographically appropriate faunal baseline in stable isotope paleodietary studies, and suggest that Neolithic individuals at this site consumed up to ca. 21% of dietary protein from marine resources, despite stable isotope ratios that imply a wholly terrestrial diet. This marine resource consumption does not significantly shift the radiocarbon (14C) dates of these individuals, so although we must consider the use of marine resources at the site, the chronology that has previously been established is secure. The δ13C and δ15N measurements from the archaeological herbivore bone collagen indicate that it is unlikely they ate plants enriched with fertilisers such as manure or seaweed. The δ34S values reveal a sea-spray effect; therefore, in this instance, δ34S cannot be used as a dietary indicator but can be used to demonstrate the likely locality of the fauna.
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Sangster, D. F., P. M. Outridge, and W. J. Davis. "Stable lead isotope characteristics of lead ore deposits of environmental significance." Environmental Reviews 8, no. 2 (February 1, 2000): 115–47. http://dx.doi.org/10.1139/a00-008.
Повний текст джерелаАнотація:
Stable Pb isotopes are increasingly used in environmental science as tracers of natural and anthropogenic Pb sources. This review provides a summary of the recent geological literature concerning Pb isotopes in global Pb ore deposits. The isotopic characteristics of 151 Pb deposits, including 78 20th-century producing mines, have been summarized using the 204Pb-based ratios common to geological science and the 206Pb- and 207Pb-based ratios (i.e., excluding 204Pb) more often employed in environmental studies. A number of current mines, including those exploiting several Australian, Scandinavian, and U.S.A. deposits, have extreme isotopic compositions that provide unique signatures. However, a majority of mines (and unproductive deposits) fall within a relatively narrow range:206Pb/207Pb of 1.15-1.22 and 208Pb/207Pb of 2.42-2.50. In some contexts, unequivocal identification of a source exhibiting one of these common signatures would be difficult, especially with the relatively low precision (ca. 0.2-0.5% RSD) of quadrupole inductively coupled plasma - mass spectrometry (ICP-MS) which has been the most common instrument for environmental Pb isotope measurements. In settings with disparate industrial and natural Pb signatures (i.e., sources withisotopic ratios differing by about 2% or more), ICP-MS precision is adequate for source discrimination. Statistical analyses suggested that while 204Pb is critical for identifying a small proportion of environmental Pb sources, about 86% of the source discrimination power is due to the 206Pb, 207Pb, and 208Pb isotopes. Thus, the requisite analytical precision, rather than a lack of 204Pb data, is the most critical issue with respect to unequivocal identification of Pb sources in most cases. Several factors, especially the increasing dominance of recycling in global Pb production and the international transportation of ore concentrate and refined Pb, may cause unpredictable changes in the isotopic signatures of industrial sources,with a long-term trend towards homogenization. More frequent,comprehensive, and high-precision isotopic characterization of possible point and non-point Pb emitters such as gasoline, smelters, and battery-recycling plants, together with increased efforts to document the origin of constituent leads in industrial sources, would help to address these concerns.Key words: lead isotopes; lead pollution; source identification; lead ore deposits.
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Rodgers, P., C. Soulsby, S. Waldron, and D. Tetzlaff. "Using stable isotope tracers to assess hydrological flow paths, residence times and landscape influences in a nested mesoscale catchment." Hydrology and Earth System Sciences 9, no. 3 (July 22, 2005): 139–55. http://dx.doi.org/10.5194/hess-9-139-2005.
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Abstract. δ18O measurements in precipitation and stream waters were used to investigate hydrological flow paths and residence times at nested spatial scales in the mesoscale (233 km2) River Feugh catchment in the northeast of Scotland over the 2001-2002 hydrological year. Precipitation δ18O exhibited strong seasonal variation, which although significantly damped within the catchment, was reflected in stream water at six sampling sites. This allowed δ18O variations to be used to infer the relative influence of soil-derived storm flows with a seasonally variable isotopic signature, and groundwater of apparently more constant isotopic composition. Periodic regression analysis was then used to examine the sub-catchment difference using an exponential flow model to provide indicative estimates of mean stream water residence times, which varied between approximately 3 and 14 months. This showed that the effects of increasing scale on estimated mean stream water residence time was minimal beyond that of the smallest (ca. 1 km2) headwater catchment scale. Instead, the interaction of catchment soil cover and topography appeared to be the dominant controlling influence. Where sub-catchments had extensive peat coverage, responsive hydrological pathways produced seasonally variable δ18O signatures in runoff with short mean residence times (ca. 3 months). In contrast, areas dominated by steeper slopes, more freely draining soils and larger groundwater storage in shallow valley-bottom aquifers, deeper flow paths allow for more effective mixing and damping of δ18O indicating longer residence times (>12 months). These insights from δ18O measurements extend the hydrological understanding of the Feugh catchment gained from previous geochemical tracer studies, and demonstrate the utility of isotope tracers in investigating the interaction of hydrological processes and catchment characteristics at larger spatial scales.
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Carignan, Jean, Damien Cardinal, Anton Eisenhauer, Albert Galy, Mark Rehkamper, Frank Wombacher, and Nathalie Vigier. "A Reflection on Mg, Cd, Ca, Li and Si Isotopic Measurements and Related Reference Materials." Geostandards and Geoanalytical Research 28, no. 1 (May 2004): 139–48. http://dx.doi.org/10.1111/j.1751-908x.2004.tb01050.x.
Повний текст джерелаКниги з теми "Ca isotopic measurements"
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M, Imamura, and United States. National Aeronautics and Space Administration., eds. Measurements of proton-induced production cross sections for ³⁶Cl from Ca and K. [Washington, DC: National Aeronautics and Space Administration, 1998.
Знайти повний текст джерелаЧастини книг з теми "Ca isotopic measurements"
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Leavitt, Steven W., and John Roden. "Isotope Dendrochronology: Historical Perspective." In Stable Isotopes in Tree Rings, 3–20. Cham: Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-030-92698-4_1.
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AbstractAlthough the fields of dendrochronology and light stable-isotope mass spectrometry emerged at different times in the first half of the 20th Century, their convergence with the earliest measurements of isotope composition of tree rings is now ca. 70 years old. Much of the early stable isotope analysis (including on wood) explored natural variation of isotopes in the environment, but those researchers making the measurements were already contemplating the role of the isotope composition of the source substrates (e.g., water and CO2), biochemical fractionation, and environment as contributors to final tree-ring isotope values. Growing interest in tree-ring isotopes was heavily motivated by paleoclimate or paleoatmosphere reconstruction, but this new field rapidly developed to generate greatly improved mechanistic understanding along with expanded applications to physiology, ecology, pollution, and more. This chapter primarily charts the historical progression in tree-ring C-H-O isotope studies over those seven decades, but it also identifies potential productive emerging and future directions.
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Cernusak, Lucas A., and Nerea Ubierna. "Carbon Isotope Effects in Relation to CO2 Assimilation by Tree Canopies." In Stable Isotopes in Tree Rings, 291–310. Cham: Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-030-92698-4_9.
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AbstractThe carbon atoms deposited in tree rings originate from the CO2 in the atmosphere to which the tree’s canopy is exposed. Thus, the first control on the stable carbon-isotope composition of tree rings is by δ13C of atmospheric CO2. There has been an inter-annual trend of decreasing δ13C of atmospheric CO2 over the past two centuries as a result of combustion of fossil fuels and land-use change. Atmospheric CO2 is, for the most part, well mixed, but the sub-canopy air space can become depleted in 13C due to inputs from soil and plant respiration when turbulent exchange with the troposphere is hindered, for example by a high leaf area index at night. This is less likely to occur during daytime when turbulence is higher and photosynthesis takes place. Discrimination against 13C (∆13C) occurs upon assimilation of atmospheric CO2 by C3 photosynthesis. Trees using the C3 photosynthetic pathway comprise the overwhelming majority of all trees. The primary control on the extent of discrimination during C3 photosynthesis is the drawdown in CO2 concentration from the air outside the leaf to the site of carboxylation in the chloroplast. Part of this drawdown is captured by ci/ca, that is, the ratio of intercellular to ambient CO2 concentrations. The ci/ca represents the balance between the CO2 supply by stomata and its demand by photosynthesis. It can be related to water-use efficiency, the amount of CO2 taken up by photosynthesis for a given amount of water loss to the atmosphere, assuming a given evaporative demand. To predict time-averaged ci/ca from wood ∆13C, a simplified, linear model can be employed. In this linear model, the slope is determined by $$\overline{b }$$ b ¯ , the effective enzymatic discrimination. The value of $$\overline{b }$$ b ¯ can be estimated by comparing wood ∆13C to representative measurements of ci/ca. The $$\overline{b }$$ b ¯ was originally estimated from observations of leaf tissue to have a value of 27‰. We compiled data for woody stem tissue here, and our analysis suggests that a lower $$\overline{b }$$ b ¯ should be used in the simplified model for wood ($$\overline{b }$$ b ¯ = 25.5‰) than for leaves ($$\overline{b }$$ b ¯ = 27‰). This is also consistent with widespread observations that woody tissues are enriched in 13C compared to leaves.
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Criss, Robert E. "Isotope Hydrology." In Principles of Stable Isotope Distribution. Oxford University Press, 1999. http://dx.doi.org/10.1093/oso/9780195117752.003.0005.
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No substance exemplifies the principles of isotope distribution better than water. Water is practically ubiquitous at the Earth’s surface, where it undergoes phase transitions, interacts with minerals and the atmosphere, and participates in complex metabolic processes essential to life. The isotopes of hydrogen and oxygen undergo large fractionations during these processes, providing a multiple isotopic tracer record of diverse phenomena. In the hydrologic cycle, hydrogen and oxygen isotope ratios provide conservative tracers, uniquely intrinsic to the water molecule, that elucidate the origin, phase transitions, and transport of H2O. In particular, the isotope data associated with these processes are amenable to theoretical modeling using the laws of physical chemistry. The characteristics of the principal reservoirs of natural waters on Earth are provided in the following sections. The distinct characters of these different reservoirs are very clearly shown on graphs where the δD values are plotted against those of δ18O. The oceans constitute 97.25% of the hydrosphere, cover 70% of the Earth’s surface to a mean depth of 3.8 km, and have an enormous total volume of 1.37 × 109 km3. This large reservoir has strikingly uniform isotopic concentrations, with almost all samples having δ18O = 0 ± 1 and δD = 0 ± 5 per mil relative to SMOW (Craig and Gordon, 1965). Values outside these ranges are almost invariably confined to surface waters that have salinities that differ from the normal value of 3.5 wt. %. These varations are generally attributable to evaporation, formation of sea ice, or addition of meteoric precipitation that may occur by direct rainfall, by river inflow, or by melting of icebergs. The latter effect was clearly documented by Epstein and Mayeda (1953) in the surface waters of the North Atlantic, where the isotopic variations were strongly correlated with variations in salinity. In detail, the deep waters of different ocean basins have distinct values of δ18O and salinity. Thus, the δ18O values of deep waters from the North Atlantic (ca. +0.05‰), Pacific (-0.15‰), and Antarctic (-0.40‰) oceans are distinct, and careful measurements can be used to infer details of oceanic circulation patterns (Craig and Gordon, 1965).
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Koehler, Héloïse, Fabio Wegmüller, Benjamin Audiard, Patrick Auguste, Jean-Jacques Bahain, Hervé Bocherens, Simon Diemer, et al. "The Middle Paleolithic Occupations of Mutzig-Rain (Alsace, France)." In Tübingen Publications in Prehistory. Kerns Verlag, 2021. http://dx.doi.org/10.51315/9783935751353.006.
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The Paleolithic site of Mutzig, discovered by chance in 1992 (Sainty 1992), has been the focus of several excavations since 2009. Located in Alsace (Bas-Rhin, France), it is presently one of only a handful of sites reliably attributed to the Middle Paleolithic in this area, thus providing rare evidence for a zone still relatively unknown for Early Prehistoric remains. The excellent preservation of the remains and the long stratigraphic sequence, with 6 to 8 in situ archaeological levels, make Mutzig a potential reference site for environmental and behavioral analyses for the Middle Paleolithic of the region. At least four archaeological levels contain burnt elements, and one level features a hearth structure. Taken together, the archaeological material, which is abundant in each of the different layers, forms an assemblage of more than 3000 faunal remains and more than 1500 lithic artifacts. Analyses of this site provide valuable insights into the environment and Neandertal ways of life in Alsace. We provide here only general results, with more detailed descriptions of the lithic and faunal remains presented in Diemer (this volume) and Sévêque (this volume). The faunal remains recovered from the human occupations in Levels 5 and 7 reflect the same relatively cold steppe-like environmental context and include reindeer, woolly mammoth, steppe horse, steppe bison and woolly rhinoceros. Small vertebrates also indicate a cold climate, though not related to the Pleniglacial. Confirmed isotopic data, from oxygen and carbon isotope measurements of horse and mammoth teeth, indicate temperatures lower than those of today and an open environment. Levels 9 and 10, however, tend to reveal a more temperate climate. The available OSL and ESR/U-series dates place the Mutzig occupations within the Early Weichselian Glacial (MIS 5, ca. 90,000 BP), an attribution which biometric analyses and the large and small fauna record tend to corroborate (Koehler et al. 2016a).
Тези доповідей конференцій з теми "Ca isotopic measurements"
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Haldar, Utpalendu, Roberta L. Rudnick, and Ramananda Chakrabarti. "The evolution of K/Ca in the upper continental crust constrained from Ca isotopic measurements of glacial diamictites." In Goldschmidt2022. France: European Association of Geochemistry, 2022. http://dx.doi.org/10.46427/gold2022.9038.
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Hashimoto, Y., K. Minamino, D. Nagamoto, S. Hasegawa, Tetuso Iguchi, and Kenichi Watanabe. "Measurement of isotope ratio of Ca[sup +] ions in a linear Paul Trap." In 4TH INTERNATIONAL CONFERENCE ON LASER PROBING—LAP 2008. AIP, 2009. http://dx.doi.org/10.1063/1.3115607.
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Tong, William G., Ken Weed, and Zhiqiang Wu. "Doppler-free nonlinear laser spectroscopy for isotope analysis and hyperfine structure measurement." In OSA Annual Meeting. Washington, D.C.: Optica Publishing Group, 1992. http://dx.doi.org/10.1364/oam.1992.mkk5.
Повний текст джерелаАнотація:
Hyperfine structure measurement by a high-resolution laser spectroscopic method based on optical phase conjugation by nonlinear wave mixing is presented by using different atomizers, including analytical flames and low-pressure dc discharge plasmas. Isotope solutions can be conveniently introduced to a flame atomizer such as an air-acetylene flame. When a demountable discharge plasma atomizer (1–10 Torr) is used, pressure broadening is also minimized and Doppler broadening is cancelled. Unlike many other nonlinear methods, these Doppler-free nonlinear wave mixing methods (e.g., degenerate four-wave mixing) offer easy optical alignment and excellent detection sensitivity (parts-per-billion or better) and require very low laser power levels (e.g., nanojoules for excimer-pumped or Nd:YAG-pumped dye lasers). One can also use low-power cw lasers such as argon-ion-pumped single-frequency ring dye lasers. Theoretical isotope/hyperfine-structure profiles can be calculated by using simple quadratic Lorentzian profiles and can then be matched with the experimental spectra for many elements such as Ba, Ca, Na, Mn, and Li. By using “transient” coherent-grating based signal generated by vectorial optical phase conjugation, certain lines of a fine structure could be selectively probed, and hence, simpler Doppler-free fine structures could be measured.