Relevant bibliographies by topics / Ca isotope

Academic literature on the topic 'Ca isotope'

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Published: 6 September 2023

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Journal articles on the topic "Ca isotope"

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Brown, Shaun T., Anirban Basu, Xin Ding, John N. Christensen, and Donald J. DePaolo. "Uranium isotope fractionation by abiotic reductive precipitation." Proceedings of the National Academy of Sciences 115, no. 35 (August 16, 2018): 8688–93. http://dx.doi.org/10.1073/pnas.1805234115.

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Significant uranium (U) isotope fractionation has been observed during abiotic reduction of aqueous U, counter to the expectation that uranium isotopes are only fractionated by bioassociated enzymatic reduction. In our experiments, aqueous U is removed from solution by reductive precipitation onto the surfaces of synthetic iron monosulfide. The magnitude of uranium isotopic fractionation increases with decreasing aqueous U removal rate and with increasing amounts of neutrally charged aqueous Ca–U–CO3 species. Our discovery means that abiotic U isotope fractionation likely occurs in any reducing environment with aqueous Ca ≥ 1 mM, and that the magnitude of isotopic fractionation changes in response to changes in aqueous major ion concentrations that affect U speciation. Our results have implications for the study of anoxia in the ancient oceans and other environments.
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Han, Guilin, Anton Eisenhauer, Jie Zeng, and Man Liu. "Calcium Biogeochemical Cycle in a Typical Karst Forest: Evidence from Calcium Isotope Compositions." Forests 12, no. 6 (May 25, 2021): 666. http://dx.doi.org/10.3390/f12060666.

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In order to better constrain calcium cycling in natural soil and in soil used for agriculture, we present the δ44/40Ca values measured in rainwater, groundwater, plants, soil, and bedrock samples from a representative karst forest in SW China. The δ44/40Ca values are found to differ by ≈3.0‰ in the karst forest ecosystem. The Ca isotope compositions and Ca contents of groundwater, rainwater, and bedrock suggest that the Ca of groundwater primarily originates from rainwater and bedrock. The δ44/40Ca values of plants are lower than that of soils, indicating the preferential uptake of light Ca isotopes by plants. The distribution of δ44/40Ca values in the soil profiles (increasing with soil depth) suggests that the recycling of crop-litter abundant with lighter Ca isotope has potential effects on soil Ca isotope composition. The soil Mg/Ca content ratio probably reflects the preferential plant uptake of Ca over Mg and the difference in soil maturity. Light Ca isotopes are more abundant in mature soils than nutrient-depleted soils. The relative abundance in the light Ca isotope (40Ca) is in the following order: farmland > burnt grassland > forests > grassland > shrubland. Our results further indicate that biological fractionation in a soil–plant system is a vital factor for Ca–geochemical transformations in soil surface systems.
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Antonelli, Michael A., Tushar Mittal, Anders McCarthy, Barbara Tripoli, James M. Watkins, and Donald J. DePaolo. "Ca isotopes record rapid crystal growth in volcanic and subvolcanic systems." Proceedings of the National Academy of Sciences 116, no. 41 (September 23, 2019): 20315–21. http://dx.doi.org/10.1073/pnas.1908921116.

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Kinetic calcium isotope effects can be used as growth-rate proxies for volcanic and subvolcanic minerals. Here, we analyze Ca isotopic compositions in experimental and natural samples and confirm that large kinetic effects (>2‰) can occur during magmatic plagioclase crystallization. Experiments confirm theoretical predictions that disequilibrium isotope effects depend mainly on the rates for crystal growth relative to liquid phase Ca diffusivity (R/D). Plagioclase phenocrysts from the 1915 Mount Lassen rhyodacite eruption, the ∼650-y-old Deadman Creek Dome eruption, and several mafic subvolcanic orbicules and plagioclase comb layers from Northern California have disequilibrium Ca isotopic compositions that suggest rapid crystal growth rates (>1 cm/y to 15 cm/y). The Ca isotope results, combined with complementary crystal-size distribution analyses, suggest that magmatic rejuvenation (and eruption) events, as reflected in crystal growth times, can be as short as ∼10−3 y. Although mafic systems are predicted to have shorter magmatic rejuvenation periods, we find similarly short timescales in both mafic and silicic systems. These results are consistent with a growing body of evidence suggesting that dominantly crystalline volcanic magma reservoirs can be rapidly reactivated by the injection of fresh magma prior to eruption. By focusing on a common mineral such as plagioclase, this approach can be applied across all major magmatic compositions, suggesting that Ca isotopes can be used as a tool for investigating the dynamics and timing of volcanic eruptions.
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Merrett, Deborah C., Christina Cheung, Christopher Meiklejohn, and Michael P. Richards. "Stable isotope analysis of human bone from Ganj Dareh, Iran, ca. 10,100 calBP." PLOS ONE 16, no. 3 (March 2, 2021): e0247569. http://dx.doi.org/10.1371/journal.pone.0247569.

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We report here on stable carbon, nitrogen, and sulfur isotope values from bone collagen of human (n = 20) and faunal (n = 11) remains from the Early Neolithic site of Ganj Dareh, Iran, dating to ca. 10,100 cal. BP. Our focus explores how isotope values of human bone vary by age and sex, and evaluates dietary practices at this site. It also provides a baseline for future studies of subsistence in the early Holocene Central Zagros Mountains, from the site with the first evidence for human ovicaprid management in the Near East. Human remains include individuals of all age groups for dietary reconstruction, as well two Ottoman intrusive burials for temporal and cultural comparison. All analyzed individuals exhibited δ13C and δ15N values consistent with a diet based heavily on C3 terrestrial sources. There is no statistically significant difference between the isotopic compositions of the two sexes, though males appear to show larger variations compared to females. Interesting patterns in the isotopic compositions of the subadults suggested weaning children may be fed with supplements with distinctive δ13C values. Significant difference in sulfur isotope values between humans and fauna could be the earliest evidence of transhumance and could identify one older adult male as a possible transhumant shepherd. Both Ottoman individuals had distinctively different δ13C, δ15N, and δ34S values compared to the Neolithic individuals. This is the first large scale analysis of human stable isotopes from the eastern end of the early Holocene Fertile Crescent. It provides a baseline for future intersite exploration of stable isotopes and insight into the lifeways, health, and processes of neolithisation associated with the origins of goat domestication at Ganj Dareh and the surrounding Central Zagros.
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Adloff, Markus, Andy Ridgwell, Fanny M. Monteiro, Ian J. Parkinson, Alexander J. Dickson, Philip A. E. Pogge von Strandmann, Matthew S. Fantle, and Sarah E. Greene. "Inclusion of a suite of weathering tracers in the cGENIE Earth system model – muffin release v.0.9.23." Geoscientific Model Development 14, no. 7 (July 5, 2021): 4187–223. http://dx.doi.org/10.5194/gmd-14-4187-2021.

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Abstract. The metals strontium (Sr), lithium (Li), osmium (Os) and calcium (Ca), together with their isotopes, are important tracers of weathering and volcanism – primary processes which shape the long-term cycling of carbon and other biogeochemically important elements at the Earth's surface. Traditionally, because of their long residence times in the ocean, isotopic shifts in these four elements observed in the geologic record are almost exclusively interpreted with the aid of isotope-mixing, tracer-specific box models. However, such models may lack a mechanistic description of the links between the cycling of the four metals to other geochemically relevant elements, particularly carbon, or climate. Here we develop and evaluate an implementation of Sr, Li, Os and Ca isotope cycling in the Earth system model cGENIE. The model offers the possibility to study the dynamics of these metal systems alongside other more standard biogeochemical cycles, as well as their relationship with changing climate. We provide examples of how to apply this new model capability to investigate Sr, Li, Os and Ca isotope dynamics and responses to environmental change, for which we take the example of massive carbon release to the atmosphere.
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Martin, Jeremy E., Derek Vance, and Vincent Balter. "Magnesium stable isotope ecology using mammal tooth enamel." Proceedings of the National Academy of Sciences 112, no. 2 (December 22, 2014): 430–35. http://dx.doi.org/10.1073/pnas.1417792112.

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Geochemical inferences on ancient diet using bone and enamel apatite rely mainly on carbon isotope ratios (δ13C) and to a lesser extent on strontium/calcium (Sr/Ca) and barium/calcium (Ba/Ca) elemental ratios. Recent developments in nontraditional stable isotopes provide an unprecedented opportunity to use additional paleodietary proxies to disentangle complex diets such as omnivory. Of particular relevance for paleodietary reconstruction are metals present in large quantity in bone and enamel apatite, providing that biologically mediated fractionation processes are constrained. Calcium isotope ratios (δ44Ca) meet these criteria but exhibit complex ecological patterning. Stable magnesium isotope ratios (δ26Mg) also meet these criteria but a comprehensive understanding of its variability awaits new isotopic data. Here, 11 extant mammal species of known ecology from a single locality in equatorial Africa were sampled for tooth enamel and, together with vegetation and feces, analyzed for δ26Mg, δ13C, Sr/Ca, and Ba/Ca ratios. The results demonstrate that δ26Mg incorporated in tooth enamel becomes heavier from strict herbivores to omnivores/faunivores. Using data from experimentally raised sheep, we suggest that this26Mg enrichment up the trophic chain is due to a26Mg enrichment in muscle relative to bone. Notably, it is possible to distinguish omnivores from herbivores, using δ26Mg coupled to Ba/Ca ratios. The potential effects of metabolic and dietary changes on the enamel δ26Mg composition remain to be explored but, in the future, multiproxy approaches would permit a substantial refinement of dietary behaviors or enable accurate trophic reconstruction despite specimen-limited sampling, as is often the case for fossil assemblages.
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Mirosław-Grabowska, Joanna. "Isotope record of environmental changes at the Skaliska Basin during the Late Glacial and Holocene." Acta Palaeobotanica 53, no. 1 (June 1, 2013): 105–14. http://dx.doi.org/10.2478/acpa-2013-0008.

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ABSTRACT The results of isotopic investigations of the Skaliska Basin sediments are presented. Stable isotope analyses were done for authigenic carbonates from three profiles: W1 - Piotrowo-Ławniki, W2 - Sąkieły Małe, and W4 - Budzewo. The profiles contain carbonate silts at the bottom, then calcareous detritus gyttja and organic silts and peat at the top. Palynological data indicate that sediment were accumulated in the Skaliska Basin from the final phase of the Younger Dryas to the Subboreal period. The values δ18O change from ca −9.4 to −4.5‰, and δ13C values varies from −5.1 to +0.1‰. Such a large range of isotopic data reflects changing conditions in the basin during accumulation of deposits (different water levels, water temperatures, and bioproduction). Based on the results of stable isotope analyses of the carbonates, isotopic zones (Is) were defined and characterized for each profile. The results of isotopic analysis enabled reconstruction of varying environmental conditions connected with lake deepening and/or influx of water enriched in light isotopes, climatic warming, and increase of biological activity. The Late Glacial deposits are characterized by δ18O values of ca −6.5-6‰ and δ13C of ca −1‰. In the transitional time between the Late Glacial and the Holocene, δ18O systematically falls below −8‰, reflecting a substantial change in the isotopic composition of the lake water, likely caused by to inflow of melt water. During the Preboreal period the δ18O as well as the δ13C values systematically decrease and reach minima (−8.4-9.4‰ for δ18O and ca −3.5-4.7‰ for δ13C). At the beginning of the Boreal period, an increase of ca 2‰ in δ18O is noted and is associated with climatic warming. During the Atlantic period the varying trends in the δ18O record are likely connected with changing precipitation/evaporation ratios, causing changes in the isotope composition of the water. The fluctuations of the isotopic values in the upper parts of the successions probably point to shallowing of the lake due to sedimentary infill.
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Li, Chaofeng, Huiqian Wu, Xuance Wang, Zhuyin Chu, Youlian Li, and Jinghui Guo. "Determination of Lead Elemental Concentration and Isotopic Ratios in Coal Ash and Coal Fly Ash Reference Materials Using Isotope Dilution Thermal Ionization Mass Spectrometry." International Journal of Environmental Research and Public Health 16, no. 23 (November 28, 2019): 4772. http://dx.doi.org/10.3390/ijerph16234772.

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The rapid expansion of coal-fired power plants around the world has produced a huge volume of toxic elements associated with combustion residues such as coal fly ash (CFA) and coal ash (CA), which pose great threats to the global environment. It is therefore crucial for environmental science to monitor the migration and emission pathway of toxic elements such as CFA and CA. Lead isotopes have proved to be powerful tracers capable of dealing with this issue. Unfortunately, up to now, few high precision lead isotope data of CFA and CA certified reference materials (CRMs) determined by using the double spike technique have been reported. Hence, to facilitate the application of lead isotopes in environmental science, it is indispensable and urgent to determine a suite of high precision Pb isotope ratios and Pb elemental contents for CFA and CA CRMs. Here, we measured lead isotope ratios from four CFA and CA CRMs using thermal ionization mass spectrometry (TIMS) combined with the 204Pb–207Pb double spike method. Lead isotope ratios values of CRMs (GBW11124, GBW08401, GBW11125d, and JCFA-1) covered wide variation ranges from 17.993 to 19.228 for 206Pb/204Pb, from 15.513 to 15.675 for 207Pb/204Pb, and from 38.184 to 39.067 for 208Pb/204Pb. Lead isotope ratios of these CRMs, except for GBW11124, show good external reproducibility (2 RSD, n = 8), which is better than 0.05% for 206Pb/204Pb and 207Pb/204Pb, 0.07% for 208Pb/204Pb, 0.04% for 206Pb/207Pb, and 0.05% for 208Pb/206Pb. The Pb concentrations of these CRMs were determined using 207Pb single spike method. The reproducibility (1 RSD, n = 4) of Pb elemental content was <0.60%. This indicates the distribution of Pb elements in these CRMs is homogeneous. With the exception of GBW11124, the suite of CRMs can be used for determining CFA and CA matrix composition for quality control of Pb isotope analyses.
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Heydarizad, Mojtaba, and Rogert Sorí. "Application of Statistical Techniques to Study Stable Isotopes (18O and 2H) Characteristics of Precipitation in Iran (Southwest Asia)." Environmental Sciences Proceedings 8, no. 1 (June 1, 2021): 5. http://dx.doi.org/10.3390/ecas2021-10298.

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Various climatic and geographic parameters influence precipitation in Iran, which makes the interpretation of stable isotope signatures in precipitation very complicated. Thus, precipitation sampling stations for stable isotope analyses in Iran have been classified by cluster analysis (CA) into 10 clusters, based on their stable isotope characteristics. The classification of stations by CA also has a close correlation with the Koppen climatic zones across Iran. Finally, the stations in each cluster were plotted on the GMWL and EMMWL. This study shows that classifying precipitation sampling stations can simplify the interpretation of stable isotopes in the precipitation of regions with complicated climatic systems.
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Griffin, Ian J., and Steven A. Abrams. "Methodological considerations in measuring human calcium absorption: relevance to study the effects of inulin-type fructans." British Journal of Nutrition 93, S1 (April 2005): S105—S110. http://dx.doi.org/10.1079/bjn20041344.

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During the last 50 years, a variety of methods have been developed to estimate Ca absorption in man. Mass balances were initially used, but these were unable to accurately measure fractional Ca absorption because they cannot distinguish unabsorbed dietary Ca from endogenous faecal Ca excretion (excretion of previously absorbed Ca back into the gut). A number of isotopic methods have been developed that can measure true fractional Ca absorption, employing radioisotopes, stable isotopes, or both. Different methods involve collection of urine, faecal or plasma samples. Of the currently available methods, the dual isotope tracer method with a timed urine collection is probably the most precise and reliable. It is also relatively straightforward to carry out and avoids the need for a faecal collection. The purpose of the present paper is to discuss the general advantages and disadvantages of the different methods of Ca absorption. In addition, the limitations the different methods have in examining the possible effects of non-digestible oligosaccharides on Ca absorption will be discussed.
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Dissertations / Theses on the topic "Ca isotope"

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Chang, Veronica Tzu-Chun. "Mg and Ca isotope fractionation during CaCO₃ biomineralisation." Thesis, University of Oxford, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.269953.

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Thériault, Réginald J. "Evolution of the ca. 1.9 gallium Taltson magmatic zone, Northwest Territories: A neodymium isotope perspective." Thesis, University of Ottawa (Canada), 1990. http://hdl.handle.net/10393/5788.

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The Taltson magmatic zone is a north-trending belt of Early Proterozoic granitoids exposed over an area exceeding 18,000 km$\sp2$ in the Northwest Territories. Three petrologically and chronologically distinct intrusive suites comprise the Taltson zone. These are the 1986 Ma Deskenatlata suite, the 1955 to 1925 Ma Slave suite and the 1935 Ma Konth suite. The Deskenatlata suite is composed of a biotite-hornblende diorite to granite suite whose major and trace element chemistry supports derivation by arc magmatism. The Slave and Konth suites are leucocratic granitoids which contain numerous xenoliths of dominantly pelitic high grade paragneiss and display S-type granite mineralogy which commonly duplicates that of the pelitic gneisses. Bulk rock chemistry for the Konth suite is consistent with a homogeneous crustal magma source whereas the Slave suite is compositionally more heterogeneous. The Deskenatlata suite is considered as continental arc-derived granitoids resulting from eastward subduction of oceanic lithosphere beneath the Churchill Province. The Slave suite is regarded as the result of melting of various segments of heterogeneous Archean crust whereas the Konth may have evolved exclusively from melting of pelitic metasediments. (Abstract shortened by UMI.)
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MacDonald, Cody J. "Hydrothermal Circulation During Slip on the Mohave Wash Fault, ChemehueviMountains, SE CA: Oxygen Isotope Constraints." Ohio University / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1405810104.

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Feasby, Rebecca Susanne Godkin. "Stable isotope evidence for dietary patterns and environmental conditions at Tell Leilan, Syria, ca. 1900-2900 B.C." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp01/MQ28891.pdf.

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Marriott, Caedmon. "Lithium and calcium isotope fractionation and Li/Ca ratio incorporation into calcium carbonate as potential geochemical proxies." Thesis, University of Oxford, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.418477.

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Du, Vivier Alice Diana Charlotte. "Global evaluation of Os and Ca marine isotope stratigraphy and U-Pb geochronology of the OAE 2." Thesis, Durham University, 2014. http://etheses.dur.ac.uk/10649/.

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Oceanic anoxic events occur in response to significant climate perturbations. This study focuses on the late Cretaceous OAE 2, which occurred across the Cenomanian-Turonian boundary (CTB), ~93.9 Ma. Multiple isotope proxies have reviewed the implications of palaeocirculation, volcanism and climate change to assess the driving mechanism(s) associated with global anoxia. Utilising geochemistry and geochronology (Os, Ca and U-Pb) this study provides a greater understanding of palaeoclimate conditions and assesses the global extent of anoxia. Hitherto, analyses have focussed on sections in and around the proto-North Atlantic. Herein, high-resolution 187Os/188Os isotope stratigraphy from 8 globally representative sections is presented; Portland #1 core, Site 1260, Wunstorf, Vocontian Basin, Furlo, Site 530, Yezo Group, and Great Valley Sequence. The Re-Os system is sensitive to regional and global variation in seawater chemistry on the order of the residence time of Os due to ocean inputs: radiogenic Os from continental weathering and unradiogenic Os from hydrothermal inputs. The initial 187Os/188Os (Osi) profiles present a globally ubiquitous trend: radiogenic Os values are attenuated by unradiogenic Os for ~200 kyr, which then gradually return to radiogenic Os. Minor discrepancies illustrate the sensitivity of local water masses as a function of basin connectivity and global sea level; i.e., Portland, Great Valley Sequence and Yezo Group (temporally restricted basins) vs. Site 1260 and Site 530 (open ocean). Furthermore, a temporal framework is developed from existing ages (from the Western Interior, USA) and new U-Pb zircon geochronology (Yezo Group, Japan) to quantify the duration of OAE 2 and volcanic activity at the Caribbean LIP. Age models are applied and support the revision of the stratigraphic position of the OAE 2 onset and the CTB in the Yezo Group. The integration of the Western Interior and Pacific geochronology quantitatively verifies that the OAE 2 was globally synchronous occurring at ~94.4 Ma ± 0.15 Ma. In addition, marine δ44Ca records from 4 global OAE 2 sections are presented. The seawater mixing models reveal that δ44Ca values show no appreciable change to riverine or hydrothermal influx. Herein, I quantitatively demonstrate that fractionation is a parameter for δ44Ca isotopic variation at Portland and Pont d’Issole, which may be attributed to diagenetic reactions in the marl-rich lithology leading to site-specific fractionation. Therefore, marine δ44Ca profiles are different in each section as a function of varying fractionation factor. Ca isotope systematics are highly complex and so further work is crucial in order to develop our understanding of other parameters and to establish which, if any, is the most influential.
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Wogsland, Brittan Valhalla. "Organomineralization of Microbialites from Storr’s Lake, San Salvador Island, Bahamas: Calcium Stable Isotope Analysis using TIMS and a 42Ca-43Ca double spike." The Ohio State University, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=osu1587723502946554.

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Horowitz, Michael (Michael Joshua) 1962. "Western South Atlantic holocene and glacial deepwater hydrography derived from benthic foraminiferal Cd/Ca and stable carbon isotope data." Thesis, Massachusetts Institute of Technology, 1999. http://hdl.handle.net/1721.1/69183.

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Thesis (S.M.)--Joint Program in Oceanography (Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences; and the Woods Hole Oceanographic Institution), 1999.
Includes bibliographical references (leaves 16-21).
Today, deep waters produced in the North Atlantic are exported through the western South Atlantic. Antarctic intermediate water (AAIW) also enters the Atlantic in this region. Circumpolar deep water (CDW) fills the depths below AAIW and above and below northern source waters. A depth transect of cores from 1567-3909 m water depth in the western South Atlantic are ideally located to monitor inter-ocean exchange of deep water, and variations in the relative strength of northern versus southern source water production. Last glacial maximum (LGM) Cd/Ca and 813C data indicate a nutrient-depleted intermediate-depth water mass. In the mid-depth western South Atlantic, a simple conversion of LGM 813C data suggests significantly less nutrient enrichment than LGM Cd/Ca ratios, but Cd/Ca and 613C data can be reconciled when plotted in CdW/ 13C space. Paired LGM Cd/Ca and S13C data from mid-depth cores suggest increasingly nutrient rich waters below 2000 m, but do not require an increase in Southern Ocean water contribution relative to today. Cd/Ca data suggest no glacial-interglacial change in the hydrography of the deepest waters of the region. To maintain relatively low Cd/Ca ratios (low nutrients) in the deepest western South Atlantic waters, and in CDW in general, during the LGM requires an increased supply of nutrient-depleted glacial North Atlantic intermediate water (GNAIW) and/or nutrient-depleted glacial Subantarctic surface waters to CDW to balance reduced NADW contribution to CDW. LGM Cd/Ca and 513C data suggest strong GNAIW influence in the western South Atlantic which in turn implies export of GNAIW from the Atlantic, and entrainment of GNAIW into the Antarctic Circumpolar current.
by Michael Horowitz.
S.M.
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Perez, Fernandez Andrea. "Etude expérimentale sur l'échange isotopique dans le système eau-roches carbonatées." Thesis, Toulouse 3, 2017. http://www.theses.fr/2017TOU30398.

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Les signatures isotopiques des minéraux carbonatés sont utilisées pour caractériser de nombreux processus géochimiques. Cette thèse a pour but de déterminer les vitesses auxquelles ces signatures isotopiques peuvent être altérées lors des interactions entre les fluides et les minéraux. A cette fin, une série d'études expérimentales a été conduite avec la dolomite (CaMg(CO3)2), la magnésite (MgCO3) et la calcite (CaCO3). On a mesuré l'évolution temporelle des compositions isotopiques de Ca et Mg pendant une série d'expériences de dissolution en réacteur fermé de la dolomite à des températures de 50°C à 126°C. A T < 120°C la composition isotopique du calcium dans la phase fluide est identique à celle de la dolomite initiale, mais au-delà de cette température, la signature isotopique du calcium dans le fluide (delta(44/42)Ca fluid) après 4 semaines était 0.6±0.1‰ plus lourde que l'originale. En revanche, le rapport delta(26/24)Mg du fluide reste égal à celui de la dolomite à toutes les températures étudiées. Ces résultats indiquent un double transfert de calcium vers et depuis la structure de la dolomite à T > 120°C. En outre, ces résultats suggèrent que la difficulté de la dolomite à précipiter à température ambiante doit être la conséquence de l'incapacité de Mg à s'incorporer dans la structure du minéral. Dans une autre étude on a conduit des expériences de dissolution de la magnésite à 25°C en solution aqueuses pour différents pH et pression de CO2. On a trouvé que la composition isotopique du fluide à proximité de l'équilibre chimique était différente de celle du solide, ce qui reflète un double transfert de Mg en direction et hors du minéral à température ambiante. Cependant, un seul mécanisme de fractionnement ne peut expliquer le comportement isotopique de Mg observé. La dernière partie de ce travail, consacrée au fractionnement isotopique du carbone dans le système calcite-eau, montre une évolution du fractionnement isotopique de cet élément vers le fractionnement isotopique à l'équilibre d'une durée d'une année après l'atteinte de l'équilibre chimique entre la calcite et l'eau. Les vitesses de rééquilibrage des isotopes de carbone sont ainsi quatre ordres de grandeurs plus lentes que la vitesse d'équilibrage de la calcite avec la solution. Ceci suggère que l'étape limitante dans le processus de rééquilibrage des isotopes du carbone est le transport de cet élément dans le cristal après l'échange isotopique à la surface de ce dernier. Les résultats de cette thèse indiquent que la signature isotopique de Mg, Ca et C des carbonates n'est pas invariante à l'échelle des temps géologiques et qu'elle peut être altérée durant l'interaction de ces minéraux avec l'eau. Ainsi, la préservation des signatures isotopiques des carbonates requiert d'une faible perméabilité des roches ou bien quelque mécanisme inhibant les échanges des métaux et du carbone à la surface des cristaux
The isotopic signatures of carbonate minerals have been applied to illuminate a plethora of natural geochemical processes. This thesis is aimed to assess the rates and or conditions at which such isotope signatures might be altered by fluid-mineral interaction through a series of systematic experimental studies performed with dolomite (CaMg(CO3)2) magnesite (MgCO3) and calcite (Ca-CO3). Ca and Mg isotopic compositions were measured as a function of time during closed-system stoichiometric dolomite dissolution experiments at 50 to 126°C. Although identical to that of the original dolomite at low temperatures, at temperatures >120 °C, the calcium isotopic signature of fluid phase (delta(44/42)Ca fluid) became 0.6±0.1‰ higher than that of the dissolving dolomite over a 4-week period. In contrast, the delta(26/24)Mg fluid, remained equal to that of the dolo-mite both at low and high temperatures. This set of experiments evidences the two-way transfer of calcium in and out of the dolomite structure at elevated temperatures. The results suggest that the inhability of dolomite to precipitate at these conditions is due to the difficulty of Mg to be reincorporated in the dolomite structure. In a follow-up study, magnesite was dissolved at 25°C in the presence of fluids with distinct pH and CO2 pressures. The isotopic compositions of the fluid differed from that of the solid at near-to chemical equilibrium indicating the two-way transfer of magnesium into this mineral at ambient temperatures. A single fractionation mechanism cannot explain the distinct Mg isotope behaviors observed. Further work on carbon isotope exchanges in the calcite water system shows a slow by steady evolution of the carbon isotopic composition towards the accepted equilibrium fractionation factor over the course of nearly year-long experiments after the system had attained bulk chemical equilibrium. Carbon isotope reequilibration rates were found to be approximately four orders of magnitude slower than that of bulk calcite dissolution, suggesting that the rate limiting step to the carbon isotope reequilibration process is the transport of carbon into and out of the bulk mineral after it has exchanged on the surface. The results of this thesis suggest that the Mg, Ca and C isotopic signatures in carbonate minerals are not invariant over geological time-frames and can be readily altered by water-mineral interaction. Such results indicate that the preservation of carbonate mineral signatures require low permeability rock formations or some inhibitory mechanism limiting metal and carbon exchange
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Bright, Jordon, and Jordon Bright. "Multi-Disciplinary Paleoenvironmental Context for the Integration of the Lower Colorado River Corridor, Bouse Formation, CA-AZ, USA, and Middle to Late Pleistocene Human Evolution, the Koora Plain, Southern Kenya." Diss., The University of Arizona, 2017. http://hdl.handle.net/10150/625880.

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Since the seminal works of Wegener and Darwin the notion that things evolve, and the how and the why of it, has generated intense debate. The surface of the Earth, and the creatures that live on it, are not static entities. Landscapes evolve. Organisms evolve. Understanding the how and the why requires a firm understanding of a myriad of interdependent and complex variables such as (but not limited to) climate, ecology, and tectonics. Unravelling the complexities though which landscapes and ecosystems evolve requires a broad interdisciplinary approach, where multiple investigative tools are simultaneously brought to bear on a given question. The study of old lake sediments, or paleolimnology, is a marquee example of a powerful interdisciplinary methodology that has been used extensively in reconstructing the Earth's past. This work showcases two examples where the discipline of paleolimnology advances our understanding of evolution on a landscape scale and on a human scale. In the southwestern United States, a record of the processes involved during the late Miocene and early Pliocene (~ 5 Ma) evolution of a major continental river drainage - the Colorado River – is partially preserved along the southern border of Arizona and California as the enigmatic Bouse Formation. And in southern Kenya, nearly 170 meters of lake and wetland sediments that have accumulated in the Koora Plain preserve a one-million-year long record of the environmental conditions against which our species, Homo sapiens, evolved. My research allows me to conclude that the depositional environment of the Bouse Formation was lacustrine; a fully marine interpretation that has been previously proposed is untenable. I also demonstrate that over the past 1.0 Ma, Homo sapiens in southern Kenya evolved against a backdrop of increasing regional aridity.
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Books on the topic "Ca isotope"

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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.

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Lachniet, Matthew S., and Juan Pablo Bernal-Uruchurtu. AD 550–600 Collapse at Teotihuacan. Oxford University Press, 2017. http://dx.doi.org/10.1093/oso/9780199329199.003.0006.

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We analyze a 2400-year rainfall reconstruction from an ultra-high-resolution absolutely-dated stalagmite (JX-6) from southwestern Mexico (Lachniet et al., 2012). Oxygen isotope variations correlate strongly to rainfall amount in the Mexico City area since 1870 CE, and for the wider southwestern Mexico region since 1948, allowing us to quantitatively reconstruct rainfall variability for the Basin of Mexico and Sierra Madre del Sur for the past 2400 years. Because oxygen isotopes integrate rainfall variations over broad geographic regions, our data suggest substantial variations in Mesoamerican monsoon strength over the past two millennia. As a result of low age uncertainties (≤ 11 yr), our stalagmite paleoclimate reconstruction allows us to place robust ages on past rainfall variations with a resolution an order of magnitude more precise than archeological dates associated with societal change. We relate our new rainfall reconstruction to the sequence of events at Teotihuacan (Millon, 1967; Cowgill, 2015a) and to other pre-Colombian civilizations in Mesoamerica. We observe a centuries long drying trend that culminated in peak drought conditions in ca. 750 CE related to a weakening monsoon, which may have been a stressor on Mesoamerican societies. Teotihuacan is an ideal location to test for links between climate change and society, because it was located in a semi-arid highland valley with limited permanent water sources, which relied upon spring fed irrigation to ensure a reliable maize harvest (Sanders, 1977). The city of Teotihuacan was one of the largest Mesoamerican cities, which apparently reached population sizes of 80,000 to 100,000 inhabitants by AD 300 (Cowgill, 1997; 2015a). Following the “Great Fire”, which dates approximately to AD 550, population decreased to lower levels and many buildings were abandoned (Cowgill, 2015). Because of the apparent reliance on rainwater capture (Linn é, 2003) and spring-fed agriculture in the Teotihuacan valley to ensure food security and drinking water, food production and domestic water supplies should have been sensitive to rainfall variations that recharge the surficial aquifer that sustained spring discharge prior recent groundwater extraction.
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Griffith, Elizabeth, Weiqi Yao, and Adina Paytan. Pelagic Barite: Tracer of Ocean Productivity and a Recorder of Isotopic Compositions of Seawater S, o, Sr, Ca and Ba. Cambridge University Press, 2021.

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Griffith, Elizabeth, Weiqi Yao, and Adina Paytan. Pelagic Barite: Tracer of Ocean Productivity and a Recorder of Isotopic Compositions of Seawater S, o, Sr, Ca and Ba. Cambridge University Press, 2020.

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Book chapters on the topic "Ca isotope"

1

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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Jin, Meng, and Dong Feng. "Non-traditional Stable Isotope Geochemistry of Seep Deposits." In South China Sea Seeps, 171–87. Singapore: Springer Nature Singapore, 2023. http://dx.doi.org/10.1007/978-981-99-1494-4_10.

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AbstractNon-traditional stable isotope geochemistry is a useful tool for revealing element migration, transformation and circulation in geological processes. A series of biogeochemical processes result in special and variable sedimentary environments in seep systems. Many elements are impacted and involved in different biogeochemical processes in seep systems, especially the formation of authigenic minerals, making seep deposits archives for studying elemental and isotopic behaviors in natural environments. Iron (Fe) and molybdenum (Mo) are involved in the formation of pyrite, and magnesium (Mg) and calcium (Ca) are closely related to the precipitation of authigenic carbonate. Research on the Fe, Mo, Mg and Ca isotopic compositions of different seep deposits from the South China Sea has been conducted in recent years. Preliminary studies have provided new insights into the mechanisms of isotopic fractionation and element cycling during early diagenesis. In this chapter, we provide an overview of the current understanding of the Fe, Mo, Mg and Ca isotope geochemistry of seep deposits from the South China Sea, targeting authigenic minerals, sediments and pore fluids.
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Schmitt, Anne-Désirée. "Earth-Surface Ca Isotopic Fractionations." In Calcium Stable Isotope Geochemistry, 145–72. Berlin, Heidelberg: Springer Berlin Heidelberg, 2016. http://dx.doi.org/10.1007/978-3-540-68953-9_5.

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Heuser, Alexander. "Biomedical Application of Ca Stable Isotopes." In Calcium Stable Isotope Geochemistry, 247–60. Berlin, Heidelberg: Springer Berlin Heidelberg, 2016. http://dx.doi.org/10.1007/978-3-540-68953-9_8.

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Tipper, Edward T., Anne-Désirée Schmitt, and Nikolaus Gussone. "Global Ca Cycles: Coupling of Continental and Oceanic Processes." In Calcium Stable Isotope Geochemistry, 173–222. Berlin, Heidelberg: Springer Berlin Heidelberg, 2016. http://dx.doi.org/10.1007/978-3-540-68953-9_6.

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Köhler-Langes, Florian. "Probing the Isotope Shift: $$\varDelta g=g({}^{40}\mathrm{Ca}^{17+})-g(^{48}\mathrm{Ca}^{17+})$$ Δ g = g ( 40 Ca 17 + ) - g ( 48 Ca 17 + )." In The Electron Mass and Calcium Isotope Shifts, 135–45. Cham: Springer International Publishing, 2017. http://dx.doi.org/10.1007/978-3-319-50877-1_6.

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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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Jung, Kyunghun, Yuta Yamamoto, and Shuichi Hasegawa. "Development of multiple laser frequency control system for Ca+ isotope ion cooling." In TCP 2014, 39–51. Cham: Springer International Publishing, 2015. http://dx.doi.org/10.1007/978-3-319-61588-2_5.

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Kuhn, A. J., J. Bauch, and W. H. Schröder. "Monitoring uptake and contents of Mg, Ca and K in Norway spruce as influenced by pH and Al, using microprobe analysis and stable isotope labelling." In Nutrient Uptake and Cycling in Forest Ecosystems, 135–50. Dordrecht: Springer Netherlands, 1995. http://dx.doi.org/10.1007/978-94-011-0455-5_15.

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Pfahler, V., J. Adu-Gyamfi, A. Watzinger, and F. Tamburini. "Modifications and Issues During Purification." In Oxygen Isotopes of Inorganic Phosphate in Environmental Samples, 45–49. Cham: Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-030-97497-8_4.

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AbstractDepending on the extract, it is necessary to modify the purification protocol slightly. Each sample is different and despite a thorough testing of the purification protocol, issues might occur. The three modifications suggested include (1) adjustments in pH, (2) magnesium ammonium phosphate (MAP) precipitation and (3) reductions, prior to A1, of cations like iron (Fe), silica (Si) and calcium (Ca) which could cause interferences during the purification process. Some of the major issues often encountered are (1) no APM precipitation due to the presence of high carbonate concentrations, (2) the presence of high organic matter that requires additional steps in the protocol, (3) crystals not dissolving and (4) discoloration of solution.
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Conference papers on the topic "Ca isotope"

1

Nelson, Claire, Andrew Jacobson, Gabriella D. Kitch, and Tobias Weisenberger. "Ca-O bonding controls the Ca isotope geochemistry of hydrothermal zeolites from Iceland." In Goldschmidt2021. France: European Association of Geochemistry, 2021. http://dx.doi.org/10.7185/gold2021.7694.

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Sun, Jian, Xiangkun Zhu, Nick Belshaw, Gideon Henderson, Wei Chen, Jindrich Kynicky, Anna Doroshkevich, et al. "Application of Ca isotope systematics in studies of carbonatites." In Goldschmidt2021. France: European Association of Geochemistry, 2021. http://dx.doi.org/10.7185/gold2021.4361.

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Shirayama, Shimpey, Takefumi Mikatsura, Hiroaki Ueda, and Chikara Konagai. "Laser system for isotope separation." In OE/LASE '90, 14-19 Jan., Los Angeles, CA, edited by Petras V. Avizonis, Charles Freed, Jin J. Kim, and Frank K. Tittel. SPIE, 1990. http://dx.doi.org/10.1117/12.18497.

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Nelson, Claire, Andrew Jacobson, and Tobias Björn Weisenberger. "Ca Isotope Study of Hyaloclastite Weathering in the Icelandic Highlands." In Goldschmidt2020. Geochemical Society, 2020. http://dx.doi.org/10.46427/gold2020.1907.

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Drummond, Margaret G., Arianna C. Camarena, Arianna C. Camarena, Barry Hibbs, Barry Hibbs, Lillian E. Alwood, Lillian E. Alwood, Johnathan Alexander, and Johnathan Alexander. "ISOTOPE HYDROLOGY AND HYDROCHEMISTRY OF THE UPPER LOS ANGELES RIVER, CA." In GSA Connects 2022 meeting in Denver, Colorado. Geological Society of America, 2022. http://dx.doi.org/10.1130/abs/2022am-382527.

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Gibson, Timothy M., Peter W. Crockford, Thi Hao Bui, Sarah Wörndle-Quoëx, and Galen P. Halverson. "TECTONOSTRATIGRAPHY AND RADIOGENIC ISOTOPE CHEMOSTRATIGRAPHY OF THE CA. 1 GA BYLOT SUPERGROUP." In GSA Annual Meeting in Seattle, Washington, USA - 2017. Geological Society of America, 2017. http://dx.doi.org/10.1130/abs/2017am-296363.

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Novikov, Dmitry A., Aleksandr N. Pyryaev, Anatoly V. Chernykh, Fedor F. Dultsev, and Anna F. Sukhorukova. "The first results of integrated isotope-hydrogeochemical studies of natural waters in the Novosibirsk urban agglomeration." In Недропользование. Горное дело. Направления и технологии поиска, разведки и разработки месторождений полезных ископаемых. Экономика. Геоэкология. Федеральное государственное бюджетное учреждение науки Институт нефтегазовой геологии и геофизики им. А.А. Трофимука Сибирского отделения Российской академии наук, 2020. http://dx.doi.org/10.18303/b978-5-4262-0102-6-2020-018.

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The first results obtained in the integrated isotope-hydrogeochemical studies of natural waters in the Novosibirsk urban agglomeration are reported. The features of hydrogeological structure defined the existing hydraulic interconnection between water-bearing complexes of quaternary sediments, upper Devonian - lower Carboniferous rocks and upper Paleozoic granites. According to chemical composition, 25 types of water were distinguished, with the prevalence of HCO3 Mg-Ca, HCO3 Na-Mg-Ca and SO4 -HCO3 Na-Mg-Ca with TDS within the range from 127 to 1848 mg/l.
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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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Messa, Cole, Kenneth Sims, Sean Scott, and Mark Clementz. "Stable Ca Isotope Fractionation in Cenozoic Marine Mammals: Beyond Biomineralization & Trophic Positioning." In Goldschmidt2021. France: European Association of Geochemistry, 2021. http://dx.doi.org/10.7185/gold2021.7273.

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Mills, Jennifer V., Holly A. Barnhart, Donald J. DePaolo, and Laura N. Lammers. "Ca Isotope and Trace Element Evidence for Non-Monomer Impurity Incorporation during Calcite Growth." In Goldschmidt2020. Geochemical Society, 2020. http://dx.doi.org/10.46427/gold2020.1810.

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Reports on the topic "Ca isotope"

1

Reid, M. S., X. Wang, N. Utting, and C. Jiang. Comparison of water chemistry of hydraulic-fracturing flowback water from two geological locations at the Duvernay Formation, Alberta, Canada. Natural Resources Canada/CMSS/Information Management, 2021. http://dx.doi.org/10.4095/329276.

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We analyzed and compared the water chemistry between 17 Fox Creek region samples, each from a different well, and 23 Three Hills region samples from a single well. Overall, the two regions were similar in chemical composition but showed small differences in some lower abundance dissolved elements. Additionally, we investigated changes in water chemistry of FPW over time from a single well. The majority of water quality parameters and water chemistry remained constant over the 7-month sampling time. Major ion chemistry showed increasing concentrations of Ca and Mg, and a decreasing concentration of SO4. Several trace elements also showed small trends of both increasing and decreasing concentrations over time. There was a strong correlation between Ca and Mg concentrations in both the Fox Creek region samples and Three Hills region samples, which is an indication of the mixing of formation water. However, the correlation between B and Sr was different among two region samples, which is likely due to the delayed mixing of formation water with the fracturing fluids during the flowback at different time periods of post fracturing. Likewise, Fox Creek region samples showed correlations between concentrations of Cl and Ca, Na and Ca, and Na and Mg, but these correlations were not seen in the Three Hills region samples. Geochemical modeling demonstrates that there are potential scales formed in the flowback water, but most of the minerals are still in the dissolution state in the formation. Stable isotopic analysis confirmed the mixing of injection water and the formation water.
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Regis, D., and M. Sanborn-Barrie. Delimiting the extent of 'Boothia terrane' crust, Nunavut: new U-Pb geochronological results. Natural Resources Canada/CMSS/Information Management, 2022. http://dx.doi.org/10.4095/330703.

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The Boothia Peninsula - Somerset Island region of north-central Nunavut is a frontier region (70-74°N, 94°W) long considered as part of Rae craton. Recent field mapping and acquisition of isotopic (U-Pb, Sm-Nd) data as part of the GEM-2 Boothia-Somerset project allowed this region's exposed Precambrian bedrock to be better characterized with respect to petrology and litho-geochemistry, and to be more extensively and more precisely time-calibrated. The discovery of unique, possibly exotic, basement characterized by a ca. 2.55-2.51 Ga TTG suite overlain by ca. 2.5 Ga metasedimentary rocks, cut by 2.49- 2.48 Ga plutons, are all atypical components of the Archean Rae crust. This new knowledge and the hint of similar 'Boothia terrane' crust south of Boothia Peninsula (Ryan et al., 2009), east of the Queen Maud block (Davis et al., 2014) in central Nunavut, and in northernmost Saskatchewan (Cloutier et al., 2021), raised the possibility this terrane may extend &amp;gt;1600 km across north-central Canada. During the foundational year of GEM-GeoNorth, the extent of Boothia terrane crust was explored through legacy samples collected during the 2012 GEM Frontiers' transect across mainland Nunavut. As part of this new study, field descriptions, photographic records and legacy samples were examined, and new U-Pb zircon geochronology was acquired. The new data and knowledge were used to: i) identify new components of Boothia terrane on the mainland southwest of Boothia Peninsula; ii) further distinguish this crust from that of Rae affinity; and iii) better constrain the depositional age of Sherman Group metasedimentary rocks.
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Shenker, Moshe, Paul R. Bloom, Abraham Shaviv, Adina Paytan, Barbara J. Cade-Menun, Yona Chen, and Jorge Tarchitzky. Fate of Phosphorus Originated from Treated Wastewater and Biosolids in Soils: Speciation, Transport, and Accumulation. United States Department of Agriculture, June 2011. http://dx.doi.org/10.32747/2011.7697103.bard.

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Beneficial use of reclaimed wastewater (RW) and biosolids (BS) in soils is accompanied by large input of sewage-originated P. Prolonged application may result in P accumulation up to levelsBeneficial use of reclaimed wastewater (RW) and biosolids (BS) in soils is accompanied by large input of sewage-originated P. Prolonged application may result in P accumulation up to levels that impair plant nutrition, increase P loss, and promote eutrophication in downstream waters. This study aims to shed light on the RW- and BS-P forms in soils and to follow the processes that determine P reactivity, solubility, availability, and loss in RW and BS treated soils. The Technion group used sequential P extraction combined with measuring stable oxygen isotopic composition in phosphate (δ18OP) and with 31P-NMR studies to probe P speciation and transformations in soils irrigated with RW or fresh water (FW). The application of the δ18OP method to probe inorganic P (Pi) speciation and transformations in soils was developed through collaboration between the Technion and the UCSC groups. The method was used to trace Pi in water-, NaHCO3-, NaOH-, and HCl- P fractions in a calcareous clay soil (Acre, Israel) irrigated with RW or FW. The δ18OP signature changes during a month of incubation indicated biogeochemical processes. The water soluble Pi (WSPi) was affected by enzymatic activity yielding isotopic equilibrium with the water molecules in the soil solution. Further it interacted rapidly with the NaHCO3-Pi. The more stable Pi pools also exhibited isotopic alterations in the first two weeks after P application, likely related to microbial activity. Isotopic depletion which could result from organic P (PO) mineralization was followed by enrichment which may result from biologic discrimination in the uptake. Similar transformations were observed in both soils although transformations related to biological activity were more pronounced in the soil treated with RW. Specific P compounds were identified by the Technion group, using solution-state 31P-NMR in wastewater and in soil P extracts from Acre soils irrigated by RW and FW. Few identified PO compounds (e.g., D-glucose-6-phosphate) indicated coupled transformations of P and C in the wastewater. The RW soil retained higher P content, mainly in the labile fractions, but lower labile PO, than the FW soil; this and the fact that P species in the various soil extracts of the RW soil appear independent of P species in the RW are attributed to enhanced biological activity and P recycling in the RW soil. Consistent with that, both soils retained very similar P species in the soil pools. The HUJ group tested P stabilization to maximize the environmental safe application rates and the agronomic beneficial use of BS. Sequential P extraction indicated that the most reactive BS-P forms: WSP, membrane-P, and NaHCO3-P, were effectively stabilized by ferrous sulfate (FeSul), calcium oxide (CaO), or aluminum sulfate (alum). After applying the stabilized BS, or fresh BS (FBS), FBS compost (BSC), or P fertilizer (KH2PO4) to an alluvial soil, P availability was probed during 100 days of incubation. A plant-based bioassay indicated that P availability followed the order KH2PO4 >> alum-BS > BSC ≥ FBS > CaO-BS >> FeSul-BS. The WSPi concentration in soil increased following FBS or BSC application, and P mineralization further increased it during incubation. In contrast, the chemically stabilized BS reduced WSPi concentrations relative to the untreated soil. It was concluded that the chemically stabilized BS effectively controlled WSPi in the soil while still supplying P to support plant growth. Using the sequential extraction procedure the persistence of P availability in BS treated soils was shown to be of a long-term nature. 15 years after the last BS application to MN soils that were annually amended for 20 years by heavy rates of BS, about 25% of the added BS-P was found in the labile fractions. The UMN group further probed soil-P speciation in these soils by bulk and micro X-ray absorption near edge structure (XANES). This newly developed method was shown to be a powerful tool for P speciation in soils. In a control soil (no BS added), 54% of the total P was PO and it was mostly identified as phytic acid; 15% was identified as brushite and 26% as strengite. A corn crop BS amended soil included mostly P-Fe-peat complex, variscite and Al-P-peat complex but no Ca-P while in a BS-grass soil octacalcium phosphate was identified and o-phosphorylethanolamine or phytic acid was shown to dominate the PO fraction that impair plant nutrition, increase P loss, and promote eutrophication in downstream waters. This study aims to shed light on the RW- and BS-P forms in soils and to follow the processes that determine P reactivity, solubility, availability, and loss in RW and BS treated soils. The Technion group used sequential P extraction combined with measuring stable oxygen isotopic composition in phosphate (δ18OP) and with 31P-NMR studies to probe P speciation and transformations in soils irrigated with RW or fresh water (FW). The application of the δ18OP method to probe inorganic P (Pi) speciation and transformations in soils was developed through collaboration between the Technion and the UCSC groups. The method was used to trace Pi in water-, NaHCO3-, NaOH-, and HCl- P fractions in a calcareous clay soil (Acre, Israel) irrigated with RW or FW. The δ18OP signature changes during a month of incubation indicated biogeochemical processes. The water soluble Pi (WSPi) was affected by enzymatic activity yielding isotopic equilibrium with the water molecules in the soil solution. Further it interacted rapidly with the NaHCO3-Pi. The more stable Pi pools also exhibited isotopic alterations in the first two weeks after P application, likely related to microbial activity. Isotopic depletion which could result from organic P (PO) mineralization was followed by enrichment which may result from biologic discrimination in the uptake. Similar transformations were observed in both soils although transformations related to biological activity were more pronounced in the soil treated with RW. Specific P compounds were identified by the Technion group, using solution-state 31P-NMR in wastewater and in soil P extracts from Acre soils irrigated by RW and FW. Few identified PO compounds (e.g., D-glucose-6-phosphate) indicated coupled transformations of P and C in the wastewater. The RW soil retained higher P content, mainly in the labile fractions, but lower labile PO, than the FW soil; this and the fact that P species in the various soil extracts of the RW soil appear independent of P species in the RW are attributed to enhanced biological activity and P recycling in the RW soil. Consistent with that, both soils retained very similar P species in the soil pools. The HUJ group tested P stabilization to maximize the environmental safe application rates and the agronomic beneficial use of BS. Sequential P extraction indicated that the most reactive BS-P forms: WSP, membrane-P, and NaHCO3-P, were effectively stabilized by ferrous sulfate (FeSul), calcium oxide (CaO), or aluminum sulfate (alum). After applying the stabilized BS, or fresh BS (FBS), FBS compost (BSC), or P fertilizer (KH2PO4) to an alluvial soil, P availability was probed during 100 days of incubation. A plant-based bioassay indicated that P availability followed the order KH2PO4 >> alum-BS > BSC ≥ FBS > CaO-BS >> FeSul-BS. The WSPi concentration in soil increased following FBS or BSC application, and P mineralization further increased it during incubation. In contrast, the chemically stabilized BS reduced WSPi concentrations relative to the untreated soil. It was concluded that the chemically stabilized BS effectively controlled WSPi in the soil while still supplying P to support plant growth. Using the sequential extraction procedure the persistence of P availability in BS treated soils was shown to be of a long-term nature. 15 years after the last BS application to MN soils that were annually amended for 20 years by heavy rates of BS, about 25% of the added BS-P was found in the labile fractions. The UMN group further probed soil-P speciation in these soils by bulk and micro X-ray absorption near edge structure (XANES). This newly developed method was shown to be a powerful tool for P speciation in soils. In a control soil (no BS added), 54% of the total P was PO and it was mostly identified as phytic acid; 15% was identified as brushite and 26% as strengite. A corn crop BS amended soil included mostly P-Fe-peat complex, variscite and Al-P-peat complex but no Ca-P while in a BS-grass soil octacalcium phosphate was identified and o-phosphorylethanolamine or phytic acid was shown to dominate the PO fraction.
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You might also be interested in the extended bibliographies on the topic 'Ca isotope' for particular source types:
Journal articles Dissertations / Theses
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