Factors controlling the growth rate, carbon and oxygen isotope variation in modern calcite precipitation in a subtropical cave, Southwest China

Pu, Junbing; Wang, Aoyu; Shen, Lei; Yin, Jian‐Jun; Yuan, Daoxian; Zhao, Heping

doi:10.1016/j.jseaes.2015.12.010

Cited by 31 publications

(13 citation statements)

References 44 publications

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“…The growth rates of stalagmites are controlled by the cave air pCO 2 and water dripping rates. The stalagmite has the lowest growth rate during summer and the highest rate from fall to spring, which could have produced the variable Ba mass fractions in the stalagmite (Pu et al 2016). However, the constant Ba isotope compositions of the whole stalagmite profile indicate that the changes in the growth rates did not influence the Ba isotope compositions in the stalagmite.…”

Section: Barium Isotopes Of Calcium Carbonate Reference Materials Andmentioning

confidence: 99%

High‐Precision Barium Isotope Measurements of Carbonates by MC‐ICP‐MS

Zeng

Liu

et al. 2019

Geostandard Geoanalytic Res

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This study presents a high‐precision method to measure barium (Ba) isotope compositions of international carbonate reference materials and natural carbonates. Barium was purified using chromatographic columns filled with cation exchange resin (AG50W‐X12, 200–400 mesh). Barium isotopes were measured by MC‐ICP‐MS, using a 135Ba–136Ba double‐spike to correct mass‐dependent fractionation during purification and instrumental measurement. The precision and accuracy were monitored by measuring Ba isotope compositions of the reference material JCp‐1 (coral) and a synthetic solution obtained by mixing NIST SRM 3104a with other matrix elements. The mean δ137/134Ba values of JCp‐1 and the synthetic solution relative to NIST SRM 3104a were 0.21 ± 0.03‰ (2s, n = 16) and 0.02 ± 0.03‰ (2s, n = 6), respectively. Replicate measurements of NIST SRM 915b, COQ‐1, natural coral and stalagmite samples gave average δ137/134Ba values of 0.10 ± 0.04‰ (2s, n = 18), 0.08 ± 0.04‰ (2s, n = 20), 0.27 ± 0.04‰ (2s, n = 16) and 0.04 ± 0.03‰ (2s, n = 20), respectively. Barium mass fractions and Ba isotopes of subsamples drilled from one stalagmite profile were also measured. Although Ba mass fractions varied significantly along the profile, Ba isotope signatures were homogeneous, indicating that Ba isotope compositions of stalagmites could be a potential tool (in addition to Ba mass fractions) to constrain the source of Ba in carbonate rocks and minerals.

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Section: Barium Isotopes Of Calcium Carbonate Reference Materials Andmentioning

confidence: 99%

High‐Precision Barium Isotope Measurements of Carbonates by MC‐ICP‐MS

Zeng

Liu

et al. 2019

Geostandard Geoanalytic Res

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“…This correlates with lower pCO 2 during winter and spring and higher pCO 2 levels in summer, a feature that is in agreement with the general observation of lower calcite precipitation rates at higher pCO 2 in summer. During winter months, this pattern is reversed (e.g., Baldini et al, 2008;Cowen et al, 2013;Pu et al, 2016). , 2017) and saturation index are relatively constant, which explains the especially stable precipitation rates at this site (Fig.…”

Section: Implications For Speleothem Proxy Datamentioning

confidence: 88%

“…Compared to other caves worldwide, the BEC System displays relatively low cave air pCO 2 values (Spötl et al, 2005;Baldini et al, 2006;Banner et al, 2007;Cowan et al, 2013;Pla et al, 2016;Pu et al, 2016). Previous CO 2 mea- surements in Chamber 1, Chamber 2, and the Photographer's Chamber in Bunker Cave (Fig.…”

Section: Cave Air Co 2 Sourcesmentioning

confidence: 95%

Ventilation and cave air PCO2 in the Bunker-Emst Cave System (NW Germany): implications for speleothem proxy data

Riechelmann¹,

Breitenbach²,

Schröder‐Ritzrau³

et al. 2019

JCKS

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Cave air pCO 2 (carbon dioxide partial pressure) is, along with drip rate, one of the most important factors controlling speleothem carbonate precipitation. As a consequence, pCO 2 has an indirect but important control on speleothem proxy data (e.g., elemental concentrations, isotopic values). The CO 2 concentration of cave air depends on CO 2 source(s) and productivity, CO 2 transport through the epikarst and karst zone, and cave air ventilation. To assess ventilation patterns in the Bunker-Emst Cave (BEC) System, we monitored the pCO 2 value approximately 100 m from the lower entrance (Bunker Cave) at bi-hourly resolution between April 2012 and February 2014. The two entrances of the BEC system were artificially opened between 1860-1863 (Emst Cave) and 1926 (Bunker Cave). Near-atmospheric minimum pCO 2 dynamics of 408 ppmv are measured in winter, and up to 811 ppmv are recorded in summer. Outside air contributes the highest proportion to cave air CO 2 , while soil, and possibly also ground air, provide a far smaller proportion throughout the whole year. Cave air pCO 2 correlates positively with the temperature difference between surface and cave air during summer and negatively in winter, with no clear pattern for spring and autumn. Dynamic ventilation is driven by temperature and resulting density differences between cave and surface air. In summer, warm atmospheric air is entrained through the upper cave entrance where it cools. With increasing density, the cooled air flows toward the lower entrance. In winter, this pattern is reversed, due to cold, atmospheric air entering the cave via the lower entrance, while relatively warm cave air rises and exits the cave via the upper entrance. The situation is further modulated by preferential south-southwestern winds that point directly on both cave entrances. Thus, cave ventilation is frequently disturbed, especially during periods with higher wind speed. Modern ventilation of the BEC system-induced by artificially openings-is not a direct analogue for pre-1860 ventilation conditions. The artificial change of ventilation resulted in a strong increase of δ 13 C speleothem values. Prior to the cave opening in 1860, Holocene δ 13 C speleothem values were significantly lower, probably related to limited ventilation due to the lack of significant connections between the surface and cave. Reduced ventilation led to significantly higher pCO 2 values, minimal CO 2 degassing from drip water and low kinetic isotope fractionation. Both modern and fossil speleothem precipitation rates are driven by water supply and carbonate saturation, and not by cave air pCO 2 . Today, pCO 2 variability is too small to affect carbonate precipitation rates and the same is likely true for pCO 2 variability prior to artificial opening of the cave. Thus, fossil speleothems from BEC System are likely more sensitive to temperature and infiltration dynamics. The Bunker-Emst Cave System, therefore, represents different ventilation patterns and their influence on speleothem proxy data in an exemplary ...

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“…if large number of water samples are needed). SIc is often calculated using some software for geochemical modelling such as PHREEQC (Caboi et al, 1993;Cooper et al, 2002;Dreybrodt et al, 2011;Kanduč et al, 2012;Yan et al, 2016) or WATEQ4F (Edmunds et al, 1987;Mcdonald et al, 2007;Panda et al, 2017) or WATSPEC (Liu et al, 2007;Yang et al, 2012;Pu et al, 2015). Calculation can also be done directly in spreadsheet software using the equations of SIc presented by Langelier (1936).…”

Section: Introductionmentioning

confidence: 99%

SIc–Abacus: An in–situ tool for estimating SIc and Pco2 in the context of carbonate karst

Peyraube

Lastennet

Denis

et al. 2019

Journal of Hydrology

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This article aims to provide an on the spot, handy field tool that can be used in estimating the Saturation Index with respect to calcite in karst aquifers in a limestone context. It relies on an abacus that gives the SIc by using measured pH and bicarbonate concentration as coordinates. The analytical expressions of the carbonate equilibrium equations are derived in order to calculate SIc from values that can be measured on field. Using these established relationships, we propose an Abacus built from the SIc=f(Pco 2 eq) reference frame, hence called SIc-Abacus. Accuracy of SIc calculation is also discussed. SIc is calculated with values measured considering uncertainty coming from pH (±0.05 pH units), temperature (±0.1 °C), bicarbonate and calcium concentrations (±2.5 mg/L and ±2 mg/L). This gives, for each sample, a range of possible SIc values of ±0.060 pH units (for a bicarbonate concentration close to 300 mg/L). The effect on SIc range of possible values given by bicarbonate and calcium uncertainties is about 10 times lower than the effect brought by pH uncertainty. Also, bicarbonate and calcium concentration can be estimated from electrical conductivity leading to a possible range of SIc value of ±0.087 pH units. In both cases, the range of possible values of SIc varies according to the bicarbonate concentration. Using Cussac and Lascaux sites, an evaluation was done. Results show the goodness of fit (R 2 =0.96) between the calculated SIc from measured pH, bicarbonate and calcium concentration and the estimated SIc values generated from the SIc-Abacus. Apart from calculating SIc, another method which is an alternative use of the generated SIc equation focused on obtaining pH using parameters such as electrical conductivity and dissolved CO 2 measurements is presented. The study shows that SIc-Abacus can be a new in-situ tool for karst aquifer surveys. It can facilitate in making a swift decision that tackles carbonate karst issues (e.g. when selecting sites or in deciding if extensive monitoring should be performed or not based from a specific objective).

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Factors controlling the growth rate, carbon and oxygen isotope variation in modern calcite precipitation in a subtropical cave, Southwest China

Cited by 31 publications

References 44 publications

High‐Precision Barium Isotope Measurements of Carbonates by MC‐ICP‐MS

High‐Precision Barium Isotope Measurements of Carbonates by MC‐ICP‐MS

Ventilation and cave air PCO2 in the Bunker-Emst Cave System (NW Germany): implications for speleothem proxy data

SIc–Abacus: An in–situ tool for estimating SIc and Pco2 in the context of carbonate karst

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