scholarly journals Reconstruction of drip-water δ<sup>18</sup>O based on calcite oxygen and clumped isotopes of speleothems from Bunker Cave (Germany)

2013 ◽  
Vol 9 (1) ◽  
pp. 377-391 ◽  
Author(s):  
T. Kluge ◽  
H. P. Affek ◽  
T. Marx ◽  
W. Aeschbach-Hertig ◽  
D. F. C. Riechelmann ◽  
...  
Keyword(s):  
Variation Method ◽  
Clumped Isotopes ◽  
New Approach ◽  
Drip Water ◽  
The Holocene ◽  
Water Composition ◽  
Kinetic Isotope ◽  
Cave Drip Water ◽  
Clumped Isotope ◽  
Kinetic Fractionation

Abstract. The geochemical signature of many speleothems used for reconstruction of past continental climates is affected by kinetic isotope fractionation. This limits quantitative paleoclimate reconstruction and, in cases where the kinetic fractionation varies with time, also affects relative paleoclimate interpretations. In carbonate archive research, clumped isotope thermometry is typically used as proxy for absolute temperatures. In the case of speleothems, however, clumped isotopes provide a sensitive indicator for disequilibrium effects. The extent of kinetic fractionation co-varies in Δ47 and δ18O so that it can be used to account for disequilibrium in δ18O and to extract the past drip-water composition. Here we apply this approach to stalagmites from Bunker Cave (Germany) and calculate drip-water δ18Ow values for the Eemian, MIS3, and the Holocene, relying on independent temperature estimates and accounting for disequilibrium. Applying the co-variation method to modern calcite precipitates yields drip-water δ18Ow values in agreement with modern cave drip-water δ18Ow of −7.9 ± 0.3‰, despite large and variable disequilibrium effects in both calcite δ18Oc and Δ47. Reconstructed paleo-drip-water δ18Ow values are lower during colder periods (e.g., MIS3: −8.6 ± 0.4‰ and the early Holocene at 11 ka: −9.7 ± 0.2‰) and show higher values during warmer climatic periods (e.g., the Eemian: −7.6 ± 0.2‰ and the Holocene Climatic Optimum: −7.2 ± 0.3‰). This new approach offers a unique possibility for quantitative climate reconstruction including the assessment of past hydrological conditions while accounting for disequilibrium effects.

scholarly journals Reconstruction of drip-water δ<sup>18</sup>O based on calcite oxygen and clumped isotopes of speleothems from Bunker Cave (Germany)

2012 ◽  
Vol 8 (4) ◽  
pp. 2853-2892 ◽  
Author(s):  
T. Kluge ◽  
H. P. Affek ◽  
T. Marx ◽  
W. Aeschbach-Hertig ◽  
D. F. C. Riechelmann ◽  
...  
Keyword(s):  
Variation Method ◽  
Clumped Isotopes ◽  
Drip Water ◽  
The Holocene ◽  
Mis 3 ◽  
Water Composition ◽  
Kinetic Isotope ◽  
Cave Drip Water ◽  
Clumped Isotope ◽  
Kinetic Fractionation

Abstract. The geochemical signature of many speleothems used for reconstruction of past continental climates is affected by kinetic isotope fractionation. This limits quantitative paleoclimate reconstruction and, in cases where the kinetic fractionation varies with time, also affects relative paleoclimate interpretations. In carbonate archive research, clumped isotope thermometry is typically used as proxy for absolute temperatures. In the case of speleothems, however, clumped isotopes provide a sensitive indicator for disequilibrium effects. The extent of kinetic fractionation co-varies in Δ47 and δ18O so that it can be used to account for disequilibrium in δ18O and to extract the past drip-water composition. Here we apply this approach to stalagmites from Bunker Cave (Germany) and calculate drip-water δ18Ow values for the Eemian, Marine Isotope Stage (MIS) 3, and the Holocene, relying on independent temperature estimates and accounting for disequilibrium. Applying the co-variation method to modern calcite precipitates yields drip-water δ18Ow values in agreement with modern cave drip-water δ18Ow of −7.9 ± 0.3‰, despite large and variable disequilibrium effects in both calcite δ18Oc and Δ47. Reconstructed paleo-drip-water δ18Ow values are lower during colder periods (e.g., MIS 3: −8.5 ± 0.4‰ and the early Holocene at 11 kyr: −9.3 ± 0.1‰) and show higher values during warmer climatic periods (e.g., the Eemian: −7.5 ± 0.2‰ and the Holocene Climatic Optimum: −7.2 ± 0.3‰). This new approach offers a unique possibility for quantitative climate reconstruction including the assessment of past hydrological conditions while accounting for disequilibrium effects.

Fractionation of clumped isotopes of CO2 during photosynthesis

2021 ◽  
Author(s):  
Getachew A. Adnew ◽  
Magdalena E.G. Hofmann ◽  
Thijs L. Pons ◽  
Gerbrand Koren ◽  
Martin Ziegler ◽  
...  
Keyword(s):  
Gas Exchange ◽  
Carbon Cycle ◽  
Isotope Composition ◽  
Diffusion Flux ◽  
Carbonic Anhydrase Activity ◽  
Clumped Isotopes ◽  
Photosynthetic Gas Exchange ◽  
O Isotope ◽  
Clumped Isotope ◽  
Kinetic Fractionation

&lt;p&gt;Stable isotope (&amp;#948;&lt;sup&gt;13&lt;/sup&gt;C and &amp;#948;&lt;sup&gt;18&lt;/sup&gt;O) and mole fraction measurements of CO&lt;sub&gt;2&lt;/sub&gt; are used to constrain the carbon cycle. However, the gross fluxes of the carbon cycle, especially photosynthesis and respiration, remain uncertain due to the challenging task of distinguishing individual flux terms from each other. The clumped isotope composition (&amp;#916;&lt;sub&gt;47&lt;/sub&gt;) of CO&lt;sub&gt;2&lt;/sub&gt; has been suggested as an additional tracer for gross CO&lt;sub&gt;2&lt;/sub&gt; fluxes since it depends mainly on temperature but not on the bulk isotopic composition of leaf, soil and surface water, unlike &amp;#948;&lt;sup&gt;18&lt;/sup&gt;O of CO&lt;sub&gt;2&lt;/sub&gt;.&lt;/p&gt;&lt;p&gt;In this study, we quantify the effect of photosynthetic gas exchange on &amp;#916;&lt;sub&gt;47&lt;/sub&gt; of CO&lt;sub&gt;2&lt;/sub&gt; using leaf cuvette experiments with two C&lt;sub&gt;3&lt;/sub&gt; and one C&lt;sub&gt;4&lt;/sub&gt; plants and discuss challenges and possible applications of clumped isotope measurements. The experimental results are supported by calculations with a leaf cuvette model. Our results demonstrate how the effect of gas exchange on &amp;#916;&lt;sub&gt;47&lt;/sub&gt; is controlled by CO&lt;sub&gt;2&lt;/sub&gt;-H&lt;sub&gt;2&lt;/sub&gt;O isotope exchange (using plants with different carbonic anhydrase activity), and kinetic fractionation as CO&lt;sub&gt;2&lt;/sub&gt; diffuses into and out of the leaf (using plants with different stomatal and mesophyll conductance). We experimentally confirm the previously suggested dependence of &amp;#916;&lt;sub&gt;47&lt;/sub&gt;&amp;#173;&amp;#173; on the stomatal conductance and back-diffusion flux.&lt;/p&gt;

Farmed calcite δ18O, δ13C, and Δ47 at Ascunsă cave, Romania

2021 ◽  
Author(s):  
Virgil Dragusin ◽  
Vasile Ersek ◽  
Alvaro Fernandez ◽  
Roxana Ionete ◽  
Andreea Iordache ◽  
...  
Keyword(s):  
Air Temperature ◽  
Saturation Index ◽  
Isotope Effects ◽  
Monitoring Program ◽  
Drip Water ◽  
Water Ph ◽  
Calcite Saturation ◽  
Calcite Deposition ◽  
Clumped Isotope ◽  
Kinetic Fractionation

&lt;p&gt;Ascuns&amp;#259; cave (Romania) is the subject of a monitoring program since 2012. While the cave air temperature was very stable around 7&amp;#176;C for most of the time, it experienced in 2019 a 3&amp;#176;C rise, and remained high until the present.&lt;/p&gt;&lt;p&gt;We present here &amp;#948;&lt;sup&gt;18&lt;/sup&gt;O, &amp;#948;&lt;sup&gt;13&lt;/sup&gt;C, and clumped isotope results from calcite farmed at two drip points inside the cave (POM X and POM 2). POM X has a slower drip rate than POM 2 and deposits calcite more continuously. Calcite deposition has been shown to depend on cave air CO&lt;sub&gt;2&lt;/sub&gt; concentration, which controls the drip water pH and, further, the calcite saturation index.&lt;/p&gt;&lt;p&gt;In 2019, &amp;#948;&lt;sup&gt;18&lt;/sup&gt;O values at both sites quickly shifted to lower values as a response to the increase in temperature. At POM X, values were situated between approximately -7.2&amp;#8240; and -7.6&amp;#8240; before this transition, whereas in 2019 they shifted to -7.8&amp;#8240; - -8.0&amp;#8240;. At POM 2, where values were generally lower, they shifted from -7.5&amp;#8240; to -7.8&amp;#8240; to -8.0&amp;#8240;.&lt;/p&gt;&lt;p&gt;Clumped isotope temperature estimates mostly agree, within measurement error, with measured cave temperature. This agreement is notable given that strong offsets are commonly observed in mid-latitude caves, reflecting kinetic fractionation effects. However, intervals with deviations from cave temperature are also observed, suggesting variations in isotopic disequilibrium conditions with time.&lt;/p&gt;&lt;p&gt;Here we will discuss these isotope changes in relation to cave air temperature and CO&lt;sub&gt;2&lt;/sub&gt; concentration, drip water isotope values and elemental chemistry, as well as in relation to drip rates, in order to improve our understanding of calcite precipitation and isotope effects in caves.&lt;/p&gt;

Cave drip water solutes in south-eastern Australia: Constraining sources, sinks and processes

2019 ◽  
Vol 651 ◽  
pp. 2175-2186 ◽  
Author(s):  
Carol V. Tadros ◽  
Pauline C. Treble ◽  
Andy Baker ◽  
Stuart Hankin ◽  
Regina Roach
Keyword(s):  
Drip Water ◽  
South Eastern ◽  
Cave Drip Water ◽  
Eastern Australia ◽  
South Eastern Australia

scholarly journals Cave Drip Water-Related Samples as a Natural Environment for Aromatic Hydrocarbon-Degrading Bacteria

2019 ◽  
Vol 7 (2) ◽  
pp. 33 ◽  
Author(s):  
Eric Marques ◽  
Gislaine Silva ◽  
João Dias ◽  
Eduardo Gross ◽  
Moara Costa ◽  
...  
Keyword(s):  
Aromatic Hydrocarbon ◽  
Microbial Communities ◽  
16S Rdna ◽  
Aromatic Compounds ◽  
Denaturing Gradient Gel Electrophoresis ◽  
Amplicon Sequencing ◽  
Drip Water ◽  
Rdna Sequencing ◽  
Degrading Bacteria ◽  
Cave Drip Water

Restricted contact with the external environment has allowed the development of microbial communities adapted to the oligotrophy of caves. However, nutrients can be transported to caves by drip water and affect the microbial communities inside the cave. To evaluate the influence of aromatic compounds carried by drip water on the microbial community, two limestone caves were selected in Brazil. Drip-water-saturated and unsaturated sediment, and dripping water itself, were collected from each cave and bacterial 16S rDNA amplicon sequencing and denaturing gradient gel electrophoresis (DGGE) of naphthalene dioxygenase (ndo) genes were performed. Energy-dispersive X-ray spectroscopy (EDX) and atomic absorption spectroscopy (AAS) were performed to evaluate inorganic nutrients, and GC was performed to estimate aromatic compounds in the samples. The high frequency of Sphingomonadaceae in drip water samples indicates the presence of aromatic hydrocarbon-degrading bacteria. This finding was consistent with the detection of naphthalene and acenaphthene and the presence of ndo genes in drip-water-related samples. The aromatic compounds, aromatic hydrocarbon-degrading bacteria and 16S rDNA sequencing indicate that aromatic compounds may be one of the sources of energy and carbon to the system and the drip-water-associated bacterial community contains several potentially aromatic hydrocarbon-degrading bacteria. To the best of our knowledge, this is the first work to present compelling evidence for the presence of aromatic hydrocarbon-degrading bacteria in cave drip water.

scholarly journals The Influences of Hydrology on the Radiogenic and Stable Carbon Isotope Composition of Cave Drip Water, Grotta di Ernesto (Italy)

Radiocarbon ◽  
2010 ◽  
Vol 52 (4) ◽  
pp. 1529-1544 ◽  
Author(s):  
J Fohlmeister ◽  
A Schröder-Ritzrau ◽  
C Spötl ◽  
S Frisia ◽  
R Miorandi ◽  
...  
Keyword(s):  
Soil Carbon ◽  
Water Cycle ◽  
Isotope Composition ◽  
Stable Carbon Isotope ◽  
Carbon Dynamics ◽  
Calcite Dissolution ◽  
Drip Water ◽  
Soil Carbon Dynamics ◽  
Ne Italy ◽  
Cave Drip Water

14C and δ13C values of C-containing species in cave drip waters are mainly controlled by the C isotope composition of karst rock and soil air, as well as by soil carbon dynamics, in particular the amount of soil CO2 in the unsaturated soil zone and the process of calcite dissolution. Here, we investigate soil carbon dynamics by analyzing the 14C activity and δ13C values of C dissolved in cave drip water. Monthly over a 2-yr period, we collected drip water from 2 drip sites, one fast and one relatively slow, within the shallow Grotta di Ernesto Cave (NE Italy). The 14C data reveal a pronounced annual cycle. In contrast, the δ13C values do not show an annual pattern and only small interannual variability compared to the δ13C values of soil waters. The annual 14C drip-water cycle is a function of drip-rate variability, soil moisture, and ultimately hydrology.

Clumped Isotope Paleothermometry: Principles, Applications, and Challenges

2012 ◽  
Vol 18 ◽  
pp. 101-114 ◽  
Author(s):  
Hagit P. Affek
Keyword(s):  
Isotope Composition ◽  
Isotope Analysis ◽  
Atomic Scale ◽  
Clumped Isotopes ◽  
Temperature Dependent ◽  
Deep Time ◽  
Diagenetic Alteration ◽  
Carbonate Formation ◽  
Rare Isotopes ◽  
Clumped Isotope

Clumped isotopes geochemistry measures the thermodynamic preference of two heavy, rare, isotopes to bind with each other. This preference is temperature dependent, and is more pronounced at low temperatures. Carbonate clumped isotope values are independent of the carbonate δ13C and δ18O, making them independent of the carbon or oxygen composition of the solution from which the carbonate precipitated. At equilibrium, it is therefore a direct proxy for the temperature in which the carbonate mineral formed. In most cases, carbonate clumped isotopes record the temperature of carbonate formation, irrespective of the mineral form (calcite, aragonite, or bioapatite) or the organism making it. The carbonate formation temperatures obtained from carbonate clumped isotope analysis can be used in conjunction with the δ18O of the same carbonate, to constrain the oxygen isotope composition of the water from which the carbonate has precipitated. There are, however, cases of deviation from thermodynamic equilibrium, where both clumped and oxygen isotopes are offset from the expected values. Such carbonates must be characterized and calibrated separately. For deep-time applications, special care must be paid to the preservation of the original signal, in particular with respect to diagenetic alteration associated with atomic scale diffusion that may be undetectable by common tests for diagenesis.

scholarly journals Semi-arid zone caves: Evaporation and hydrological controls on δ18O drip water composition and implications for speleothem paleoclimate reconstructions

2016 ◽  
Vol 131 ◽  
pp. 285-301 ◽  
Author(s):  
Monika Markowska ◽  
Andy Baker ◽  
Martin S. Andersen ◽  
Catherine N. Jex ◽  
Mark O. Cuthbert ◽  
...  
Keyword(s):  
Arid Zone ◽  
Drip Water ◽  
Water Composition ◽  
Paleoclimate Reconstructions ◽  
Semi Arid

Dating cave drip water by tritium

2010 ◽  
Vol 394 (3-4) ◽  
pp. 396-406 ◽  
Author(s):  
T. Kluge ◽  
D.F.C. Riechelmann ◽  
M. Wieser ◽  
C. Spötl ◽  
J. Sültenfuß ◽  
...  
Keyword(s):  
Drip Water ◽  
Cave Drip Water

scholarly journals Kinetic isotope effects of <sup>12</sup>CH<sub>3</sub>D  + OH and <sup>13</sup>CH<sub>3</sub>D  + OH from 278 to 313 K

2016 ◽  
Vol 16 (7) ◽  
pp. 4439-4449 ◽  
Author(s):  
L. M. T. Joelsson ◽  
J. A. Schmidt ◽  
E. J. K. Nilsson ◽  
T. Blunier ◽  
D. W. T. Griffith ◽  
...  
Keyword(s):  
Isotope Effects ◽  
Kinetic Isotope Effects ◽  
State Theory ◽  
Atmospheric Methane ◽  
Isotopic Signatures ◽  
Budget Analysis ◽  
Kinetic Isotope ◽  
Methane Budget ◽  
Source Signal ◽  
Clumped Isotope

Abstract. Methane is the second most important long-lived greenhouse gas and plays a central role in the chemistry of the Earth's atmosphere. Nonetheless there are significant uncertainties in its source budget. Analysis of the isotopic composition of atmospheric methane, including the doubly substituted species 13CH3D, offers new insight into the methane budget as the sources and sinks have distinct isotopic signatures. The most important sink of atmospheric methane is oxidation by OH in the troposphere, which accounts for around 84 % of all methane removal. Here we present experimentally derived methane + OH kinetic isotope effects and their temperature dependence over the range of 278 to 313 K for CH3D and 13CH3D; the latter is reported here for the first time. We find kCH4/kCH3D = 1.31 ± 0.01 and kCH4/k13CH3D = 1.34 ± 0.03 at room temperature, implying that the methane + OH kinetic isotope effect is multiplicative such that (kCH4/k13CH4)(kCH4/kCH3D) = kCH4/k13CH3D, within the experimental uncertainty, given the literature value of kCH4/k13CH4 = 1.0039 ± 0.0002. In addition, the kinetic isotope effects were characterized using transition state theory with tunneling corrections. Good agreement between the experimental, quantum chemical, and available literature values was obtained. Based on the results we conclude that the OH reaction (the main sink of methane) at steady state can produce an atmospheric clumped isotope signal (Δ(13CH3D) = ln([CH4][13CH3D]/[13CH4][CH3D])) of 0.02 ± 0.02. This implies that the bulk tropospheric Δ(13CH3D) reflects the source signal with relatively small adjustment due to the sink signal (i.e., mainly OH oxidation).

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