Analytical Methods

Heuser, Alexander; Schmitt, Anne‐Désirée; Gussone, Nikolaus; Wombacher, Frank

doi:10.1007/978-3-540-68953-9_2

Cited by 11 publications

(6 citation statements)

References 192 publications

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“…Independent measurements of NIST SRM 1486 standards yielded a mean value of: −1.047 ± 0.13‰ 2 SD (n = 101). These values are the same as those measured in the same laboratory at LGLTPE 12,24,30,[32][33][34][52][53][54][55] and agree well with previously published values from other laboratories 31,[57][58][59] .…”

Section: Methodssupporting

confidence: 91%

Calcium isotopic ecology of Turkana Basin hominins

et al. 2020

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Diet is a major driver of hominin evolution, but most of the geochemical evidence relies on carbon isotopes (δ 13 C). Here, we report enamel stable calcium isotope (δ 44/42 Ca) values against δ 13 C values for several hominins and co-existing primates in the Turkana Basin area, circa 4 to 2 Ma. Australopithecus anamensis clusters with mammal browsers, Kenyanthropus platyops is distinct from A. anamensis in foraging into more open environments and the coexisting Theropithecus brumpti encompasses both the grazer and omnivore/carnivore domains. Early Homo is remarkable for its wide distribution in δ 44/42 Ca values, possibly reflecting omnivorous and opportunistic preferences. Paranthropus boisei is uniquely distributed in the δ 13 C versus δ 44/42 Ca iso-space being distinct from all other hominins from the Turkana Basin area as well as from the co-existing Theropithecus oswaldi. Several hypotheses are explored to discuss the unique δ 44/42 Ca values of Paranthropus boisei including significant differences observed with δ 44/42 Ca values recently reported for P. robustus from South Africa, questioning the monophyly of this genus.

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Section: Methodssupporting

confidence: 91%

Calcium isotopic ecology of Turkana Basin hominins

et al. 2020

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“…Note, that δ 44/42 Ca are a factor of ∼2 smaller than δ 44/40 Ca values, a notation often reported in previous work. δ 44/42 Ca can be converted to δ 44/40 Ca by multiplying by 2.05 (see Heuser et al, 2016).…”

Section: Methodsmentioning

confidence: 99%

Calcium Isotopes in Human Urine as a Diagnostic Tool for Bone Loss: Additional Evidence for Time Delays in Bone Response to Experimental Bed Rest

et al. 2019

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The calcium (Ca) isotopic composition in urine during bed rest has been demonstrated to be systematically light, indicating a negative bone mineral balance (i.e., bone loss). Here we present new Ca isotope data on urine during the “nutritional countermeasures” (NUC) bed rest study. We analyzed the Ca isotopic composition of 24 h pooled urine samples from seven healthy male subjects during baseline data collection (BDC), head-down-tilt bed rest and recovery. Additionally, we analyzed urine from two follow-up examinations after the regeneration phase. We observed a change in Ca isotopic composition during the bed rest phase, indicative of bone loss with a time delay of 10 to 21 days. We also observe that the Ca isotopic composition of urine is strongly dependent on the individual Ca metabolism and varies between subjects. We relate this individuality in Ca metabolism to differences in the amounts of Ca being recycled in the kidneys. Previous studies have shown that the more Ca is reabsorbed in the kidneys the more enriched the urine becomes in heavy isotopes of calcium. The Ca isotopic composition of urine is thus modified by more than one process and cannot be used in a straightforward manner to monitor net bone mineral balance. To overcome this problem, we propose a new baseline approach for using Ca isotopes, which effectively cancels out the effects of individual renal Ca reabsorption. This allows us to detect bone loss in patients without ambiguity by combining measurements of the Ca isotopic composition of urine and daily Ca excretion rate and comparing these to data collected on healthy individuals with a normal steady-state bone balance.

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“…(2003) and Heuser et al. (2016). The latter value was used to recalculate the values relative to seawater:

{\delta }^{44/40}{\mathrm{C}\mathrm{a}}_{\mathrm{s}\mathrm{a}\mathrm{m}\mathrm{p}\mathrm{l}\mathrm{e}/\mathrm{s}\mathrm{w}}={\delta }^{44/40}{\mathrm{C}\mathrm{a}}_{\mathrm{s}\mathrm{a}\mathrm{m}\mathrm{p}\mathrm{l}\mathrm{e}/\mathrm{S}\mathrm{R}\mathrm{M}915a}-1.88

…”

Section: Methodsmentioning

confidence: 96%

“…The highest value was chosen as the external reproducibility (i.e., 0.11 ‰) in this study. The accuracy of our measurements was explored through the measurements of an internal Atlantic seawater standard (1.90 ‰ ± 0.11, 2SD, N = 12) during the same period of time, which matches the reported value of 1.88 ‰ by Hippler et al (2003) and Heuser et al (2016). The latter value was used to recalculate the values relative to seawater:…”

Section: Calcium Isotope (δ 44/40 Ca) Measurementsmentioning

confidence: 92%

The Calcium Isotope (δ^44/40Ca) Record Through Environmental Changes: Insights From the Late Triassic

Kovács

Demangel

Baldermann

et al. 2022

Geochem Geophys Geosyst

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The stable calcium (Ca) isotopic composition of marine carbonate archives (δ 44/40 Ca) was proposed to be an important palaeo-environmental and palaeo-oceanographic proxy, mainly because of the linkage between the Ca and C geochemical cycles. The continental weathering of Ca bearing carbonates and silicates is the main source of Ca to the ocean, while authigenic, biogenic and diagenetic carbonate precipitation in the marine realm is the main Ca sink (DePaolo, 2004). The global Ca fluxes play a key control on the CO 2 level in the atmosphere and on the related oceanic-atmospheric system as well as on climate regulation throughout the geological record (Fantle & Tipper, 2014;Gussone et al., 2020). Variations in the Ca isotopic composition of marine carbonate archives through time, that is, as a consequence of Ca mineral weathering, carbonate precipitation and subse-Abstract Calcium isotopes (δ 44/40 Ca) are particularly useful in palaeo-environmental studies due to the key role of carbonate minerals in continental weathering and their formation in seawater. The calcium isotope ratio can provide hints on past changes in the calcium fluxes, environmental shifts, ecological factors and alternatively diagenesis of carbonate rocks. The investigation of the Late Triassic calcium isotope record offers a great opportunity to evaluate such factors in a time interval that witnessed important environmental and ecological turnovers, such as the first appearance of calcareous nannoplankton, ocean acidification and periods of elevated extinction rates. In this study, we present a δ 44/40 Ca data set from the upper Norian (Upper Triassic) through the lower Hettangian (Lower Jurassic) interval. The isotope records reveal two globally significant signals: a ∼ 0.20‰ decrease through the early Rhaetian (Upper Triassic) and a small, negative (∼0.14‰) excursion corresponding to the emplacement of the Central Atlantic Magmatic Province, at the end of the Triassic. The possible explanations for these signals are changes in the isotopic ratio of the continental calcium influx to the ocean due to the high chemical weathering rate of carbonates and possibly ocean acidification, respectively. The considerable (∼0.15-0.30‰) offset in δ 44/40 Ca between study areas is likely the combined result of local differences in lithology and early marine diagenesis. The major evolutionary step represented by the first occurrence of calcareous nannoplankton did not have at this time a determining role on the calcium isotopic signature of the marine carbonates.Plain Language Summary During Earth's history, profound environmental changes happened, which are recorded in geological samples and accessible through proxy methods. We measured Late Triassic carbonates for their Ca isotopic composition. The Late Triassic witnessed important environmental and ecological turnovers, such as the first appearance of calcareous nannoplankton, mass extinction and ocean acidification associated with CO 2 emission from a large volcanic province. These multiple events help...

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Analytical Methods

Cited by 11 publications

References 192 publications

Calcium isotopic ecology of Turkana Basin hominins

Calcium isotopic ecology of Turkana Basin hominins

Calcium Isotopes in Human Urine as a Diagnostic Tool for Bone Loss: Additional Evidence for Time Delays in Bone Response to Experimental Bed Rest

The Calcium Isotope (δ^44/40Ca) Record Through Environmental Changes: Insights From the Late Triassic

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Analytical Methods

Cited by 11 publications

References 192 publications

Calcium isotopic ecology of Turkana Basin hominins

Calcium isotopic ecology of Turkana Basin hominins

Calcium Isotopes in Human Urine as a Diagnostic Tool for Bone Loss: Additional Evidence for Time Delays in Bone Response to Experimental Bed Rest

The Calcium Isotope (δ44/40Ca) Record Through Environmental Changes: Insights From the Late Triassic

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The Calcium Isotope (δ^44/40Ca) Record Through Environmental Changes: Insights From the Late Triassic