Carbon mass-balance modelling and carbon isotope exchange processes in dynamic caves

Frisia, Silvia; Fairchild, Ian J.; Fohlmeister, Jens; Miorandi, Renza; Spötl, Christoph; Borsato, Andrea

doi:10.1016/j.gca.2010.10.021

Cited by 185 publications

(159 citation statements)

References 60 publications

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“…Both gases, 222 Rn and CO2 follow the same pattern even when the source is different. These annual cycles are characterized by two outstanding moments related with the thermal relationship between outdoor and indoor air temperatures and responsible for the intensity of cave ventilation (Bourges et al, 2006;Frisia et al, 2011;Breecker et al, 2012). The cave is governed by a dynamic model, which combines diffusive and adevctive fluxes.…”

Section: Gaseous Recharge Of Rull Cavementioning

confidence: 99%

“…The estimations for other subterranean galleries reveal significant estimated outgassing daily fluxes of CO2 with different order of magnitude (e.g. 120 mol day -1 on average for the Hollow Ride cave (Kowalczk and Froelich, 2010), 2.34 to 11.71 kg day -1 for Grotta di Ernesto (Frisia et al, 2011) or 335 kg day -1 for Ojo Guareña karst system (FernandezCortes et al, 2015b)). …”

Section: The Role Of Rull Cave In the Soil-produced Co2 Redistributiomentioning

confidence: 99%

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Changes in the CO2 dynamics in near-surface cavities under a future warming scenario: Factors and evidence from the field and experimental findings

Pla

Cuezva

Garcia-Anton

et al. 2016

Science of The Total Environment

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This study is based in a field monitoring of a cave-soil-atmosphere system validated with laboratory experimentation. CO2 and 222 Rn dynamics in the cavity demonstrate the dependence on the climatic parameters, mainly on the differences between outdoor and indoor temperatures. Within the cave, the annual cycles are characterized by two outstanding moments: cave gaseous recharge and ventilation when cave acts as gaseous sink or source respectively. Relationship with soil above the cave exists permanently. Soil temperature and moisture are responsible for CO2 production at different time scales.Soil CO2 in Rull site reaches values higher than 3000 ppm in April-May, which falls to nearly 1000 ppm during the summer time. Due to CO 2 diffusion, maximum values in the cave are reached in the warmest months and are in accordance to soil CO2 values. Within the cave, maximum CO2 concentration is, in average, 3470 ppm while minimum is 623 ppm. Cave temperature and relative humidity remain quite stable with mean values of 16.1 ºC and 97.9% respectively. To describe field findings, CO2 production and diffusion experiments are developed related to soil behaviour. Results show that soil CO2 production increases as soil temperature and moisture increase according to a calculated logarithmic equation until water content in soil exceeds the saturation values. In addition, CO2 diffusion in Rull soil is reduced around 60% when water content in soil increases from 0 to 30%. Soil-produced CO2 reaches Rull cave, by diffusion. We estimate 57 kg of emitted CO2 from the cave to the atmosphere in an annual cycle, considering a volume of 9915 m 3 . Finally, projections of future climate in the study site confirm a general tendency for annual-mean conditions to be warmer and drier, which will directly affect soil CO2 production. Under this situation, Rull cave will experience changes in the stored and then exchanged annual amount of CO2.

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Section: Gaseous Recharge Of Rull Cavementioning

confidence: 99%

Section: The Role Of Rull Cave In the Soil-produced Co2 Redistributiomentioning

confidence: 99%

Changes in the CO2 dynamics in near-surface cavities under a future warming scenario: Factors and evidence from the field and experimental findings

Pla

Cuezva

Garcia-Anton

et al. 2016

Science of The Total Environment

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“…The next step is to separate the last two known influences: the host rock contribution and in-cave fractionation. Numerous cave-monitoring studies have demonstrated that fractionation in caves is kinetic rather than equilibrium in nature (Spötl et al, 2005;Frisia et al, 2011;Tremaine et al, 2011), thus precluding the use of equilibrium factors when estimating the fractionation effect. Therefore, we use the measured d 13 C of stalagmite LR06-B1 and initial d 13 C of soil-water DIC to further differentiate between host rock C contribution and fractionation effects inside the cave.…”

Section: Host Rock Contribution To Dcfmentioning

confidence: 99%

Hydrological control of the dead carbon fraction in a Holocene tropical speleothem

Griffiths

Fohlmeister

Drysdale

et al. 2012

Quaternary Geochronology

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a b s t r a c tOver the past decade, a number of speleothem studies have used radiocarbon ( 14 C) to address a range of palaeoclimate problems. These have included the use of the bomb pulse 14 C to anchor chronologies over the last 60 years, the combination of U-Th and 14 C measurements to improve the radiocarbon agecalibration curve, and linking atmospheric 14 C variations with climate change. An issue with a number of these studies is how to constrain, or interpret, variations in the amount of radioactively dead carbon (i.e. the dead carbon fraction, or DCF) that reduces radiocarbon concentrations in speleothems. In this study, we use 14 C, stable-isotopes, and trace-elements in a U-Th dated speleothem from Flores, Indonesia, to examine DCF variations and their relationship with above-cave climate over the late Holocene and modern era. A strong association between the DCF and hydrologically-controlled proxy data suggests that more dead carbon was being delivered to the speleothem during periods of higher cave recharge (i.e. lower d 18 O, d 13 C and Mg/Ca values), and hence stronger summer monsoon. To explore this relationship, we used a geochemical soil-karst model coupled with 14 C measurements through the bomb pulse to disentangle the dominant components governing DCF variability in the speleothem. We find that the DCF is primarily controlled by limestone dissolution associated with changes in open-versus closed-system conditions, rather than kinetic fractionation and/or variations in the age spectrum of soil organic matter above the cave. Therefore, we infer that periods of higher rainfall resulted in a higher DCF because the system was in a more closed state, which inhibited carbon isotope exchange between the karst water dissolved inorganic carbon and soil-gas CO 2 , and ultimately led to a greater contribution of dead carbon from the bedrock.Published by Elsevier B.V.

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“…While much work has been done to understand the physical and chemical controls on speleothem carbon isotope ratios (e.g. Hendy, 1971;Genty et al, 2001;Mickler et al, 2004;Sp€ otl et al, 2005;Fairchild et al, 2006;Dreybrodt, 2008;Frisia et al, 2011), the basic conceptual model of the sources of speleothem carbon which suggests that it is derived from two main sources e soil CO 2 and carbonate bedrock e has remained largely unchanged.…”

Section: Introductionmentioning

confidence: 99%

Radiocarbon evidence for decomposition of aged organic matter in the vadose zone as the main source of speleothem carbon

Noronha

Johnson

Southon

et al. 2015

Quaternary Science Reviews

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a b s t r a c tSeveral recent studies have used records of the radiocarbon ( 14 C) bomb peak in speleothems to inversely model the soil a 14 CO 2 and the age distribution of soil organic material (SOM) above caves, in part to investigate the potential of speleothems as sensitive records of past SOM dynamics. The results of these modeling studies have suggested that soil CO 2 at karst sites is derived primarily from the decomposition of SOM with turnover times on the order of decades to centuries. This result is in stark contrast with observations of soil a 14 CO 2 at non-karst sites, which indicate that soil CO 2 is derived primarily from root respiration and decomposition of SOM with much shorter turnover times. This discrepancy suggests that SOM in karst settings may have a very different age distribution than sites that have been studied previously and/or that soil CO 2 is not the main source of speleothem carbon. To help resolve this discrepancy, we present an improved inverse model which we use to estimate the age of CO 2 above several caves. We also present results from a detailed case study of soil carbon dynamics at Heshang Cave, China. This work demonstrates that SOM in karst sites may be much older than SOM in non-karst soils that have been studied previously, but that CO 2 produced in the shallow soil zone is unlikely to be the main source of speleothem carbon. A review of the literature suggests that the most likely explanation for the aforementioned discrepancy is that decomposition of down-washed SOM in the vadose zone is the dominant source of speleothem carbon.

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Carbon mass-balance modelling and carbon isotope exchange processes in dynamic caves

Cited by 185 publications

References 60 publications

Changes in the CO2 dynamics in near-surface cavities under a future warming scenario: Factors and evidence from the field and experimental findings

Changes in the CO2 dynamics in near-surface cavities under a future warming scenario: Factors and evidence from the field and experimental findings

Hydrological control of the dead carbon fraction in a Holocene tropical speleothem

Radiocarbon evidence for decomposition of aged organic matter in the vadose zone as the main source of speleothem carbon

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