Assessing the temporal evolution of dissolved inorganic carbon in waters exposed to atmospheric CO2(g): A laboratory approach

Abongwa, Pride T.; Atekwana, Estella A.

doi:10.1016/j.jhydrol.2013.09.045

Cited by 15 publications

(10 citation statements)

References 35 publications

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“…8‰ at 25 C in the HCO À 3 ÀCO 2 system; Mook et al, 1974). This interpretation and our results are consistent with mechanistic models of the isotopic response of DIC during evaporation (Abongwa and Atekwana, 2013;Dreybrodt and Deininger, 2014).…”

Section: Evaporation Experimentssupporting

confidence: 90%

“…Oxygen and carbon stable isotopic covariation has also been documented in evaporating Dead Sea brines (Stiller et al, 1985), degassing epithermal systems (Zheng, 1990) and laboratory experiments (Ufnar et al, 2008;Abongwa and Atekwana, 2013). Although several hydrological models incorporate evaporative effects in their isotopic determinations (Appelo, 2002;Cappa et al, 2003;Jones et al, 2005;Jones and Imbers, 2010), only one of these models explicitly addresses the coupled effects of evaporation on oxygen and carbon isotope fractionation (Deininger et al, 2012).…”

Section: Evaporation Experimentsmentioning

confidence: 99%

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Evaporation induced 18O and 13C enrichment in lake systems: A global perspective on hydrologic balance effects

Horton

Defliese

Tripati

et al. 2016

Quaternary Science Reviews

138

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a b s t r a c tGrowing pressure on sustainable water resource allocation in the context of global development and rapid environmental change demands rigorous knowledge of how regional water cycles change through time. One of the most attractive and widely utilized approaches for gaining this knowledge is the analysis of lake carbonate stable isotopic compositions. However, endogenic carbonate archives are sensitive to a variety of natural processes and conditions leaving isotopic datasets largely underdetermined. As a consequence, isotopic researchers are often required to assume values for multiple parameters, including temperature of carbonate formation or lake water d 18 O, in order to interpret changes in hydrologic conditions. Here, we review and analyze a global compilation of 57 lacustrine dual carbon and oxygen stable isotope records with a topical focus on the effects of shifting hydrologic balance on endogenic carbonate isotopic compositions.Through integration of multiple large datasets we show that lake carbonate d 18 O values and the lake waters from which they are derived are often shifted by >þ10‰ relative to source waters discharging into the lake. The global pattern of d 18 O and d 13 C covariation observed in >70% of the records studied and in several evaporation experiments demonstrates that isotopic fractionations associated with lake water evaporation cause the heavy carbon and oxygen isotope enrichments observed in most lakes and lake carbonate records. Modeled endogenic calcite compositions in isotopic equilibrium with lake source waters further demonstrate that evaporation effects can be extreme even in lake records where d 18 O and d 13 C covariation is absent. Aridisol pedogenic carbonates show similar isotopic responses to evaporation, and the relevance of evaporative modification to paleoclimatic and paleotopographic research using endogenic carbonate proxies are discussed.Recent advances in stable isotope research techniques present unprecedented opportunities to overcome the underdetermined nature of stable isotopic data through integration of multiple isotopic proxies, including dual element 13 C-excess values and clumped isotope temperature estimates. We demonstrate the utility of applying these multi-proxy approaches to the interpretation of paleohydroclimatic conditions in ancient lake systems. Understanding past, present, and future hydroclimatic systems is a global imperative. Significant progress should be expected as these modern research techniques become more widely applied and integrated with traditional stable isotopic proxies.

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Section: Evaporation Experimentssupporting

confidence: 90%

Section: Evaporation Experimentsmentioning

confidence: 99%

Evaporation induced 18O and 13C enrichment in lake systems: A global perspective on hydrologic balance effects

Horton

Defliese

Tripati

et al. 2016

Quaternary Science Reviews

138

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“…The trends in the TCO 2 versus δ 13 C DIC space are used to distinguish between the different processes and allow for the detection of combinations of different pathways. The Wiesent River data exhibit a negative slope and are consistent with model 1 by Abongwa and Atekwana () that assumes δ 13 C DIC enrichment during CO 2 degassing.…”

Section: Discussionmentioning

confidence: 99%

“…A similar linear correlation ( r 2 = 0.89) exists for the ratio of the average TCO 2 concentrations for each downstream sampling site to the average at the source in the scheme proposed recently by Abongwa and Atekwana () (Figure ). This scheme with five conceptual models was proposed to identify the chemical and isotope behaviour of DIC in solutions that interact with atmospheric CO 2 (g).…”

Section: Discussionmentioning

confidence: 99%

Spatial and temporal variations of pCO₂, dissolved inorganic carbon and stable isotopes along a temperate karstic watercourse

Geldern

Schulte

Mäder

et al. 2015

Hydrological Processes

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This study investigated CO2 degassing and related carbon isotope fractionation effects in the Wiesent River that drains a catchment in the karst terrain of the Franconian Alb, Southern Germany. The river was investigated by physico‐chemical and stable isotope analyses of water and dissolved inorganic carbon during all seasons along 65‐km long downstream transects between source and mouth. Calculated pCO2 values at the source were 21 400 ± 2400 µatm. The pCO2 rapidly decreased in the river water and dropped to an average of 1240 ± 330 µatm near the mouth. About 90% of this decrease occurred within the first 6 km of the river. The river was supersaturated with respect to CO2 over its entire course and must have acted as a continuous year‐round CO2 source to the atmosphere. The average CO2 flux from the karst river was estimated with 450 mmol m−2 day−1 with higher fluxes up to 5680 mmol m−2 day−1 at the source. At the source, δ13CDIC values showed no seasonal variations with an average of −14.2 ± 0.2‰. This indicated that groundwater retained high pCO2 mainly from soil CO2. The contribution of soil CO2 to dissolved inorganic carbon was estimated at 65% to 72%. The downstream CO2 loss caused a positive shift in δ13CDIC values of 2‰ between source and mouth because of the preferential loss of the 12C isotope during degassing. Considering the findings of this study and the fact that carbonate lithology covers a significant part of the earth's surface, CO2 evasion from karst regions might contribute notably to the annual carbon dioxide release from global freshwater systems. Copyright © 2015 John Wiley & Sons, Ltd.

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“…At the LTP Creek, the samples show no relationship between C t /C 0 versus δ 13 C DIC because the DIC remains nearly constant (Figure h). Our interpretation of the DIC‐δ 13 C DIC evolution in the DIC‐δ 13 C space is consistent with the mechanical models that suggest that this relationship is ascribed to CO 2(g) loss from solutions (Abongwa and Atekwana, ). The change in δ 13 C DIC composition in the water during the outgassing of CO 2(g) depends on the rate of loss and the amount of excess CO 2(aq) that is present in the water at the source, and then at any time during flow by the amount lost (Figure g and h).…”

Section: Discussionmentioning

confidence: 99%

Dissolved inorganic carbon evolution in neutral discharge from mine tailings piles

Ali

Atekwana

2016

Hydrological Processes

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We measured the concentrations of dissolved inorganic carbon (DIC) and major ions and the stable carbon isotope ratios of DIC (δ13CDIC) in two creeks discharging from carbonate‐rich sulphide‐containing mine tailings piles. Our aim was to assess downstream carbon evolution of the tailings discharge as it interacted with the atmosphere. The discharge had pH of 6.5–8.1 and was saturated with respect to carbonates. Over the reach of one creek, the DIC concentrations decreased by 1.1 mmol C/l and δ13CDIC increased by ~4.0‰ 200 m from the seep source. The decrease in the DIC concentrations was concomitant with decreases in the partial pressure of CO2(aq) because of the loss of excess CO2(aq) from the discharge. The corresponding enrichment in the δ13CDIC is because of kinetic isotope fractionation accompanying the loss of CO2(g). Over the reach of the other creek, there was no significant decrease in the DIC concentrations or notable changes in the δ13CDIC. The insignificant change in the DIC concentrations and the δ13CDIC is because the first water sample was collected 160 m away from the discharge seep, not accessible during this research. In this case, most of the excess CO2(aq) was lost before our first sampling station. Our results indicate that neutral discharges from tailings piles quickly lose excess CO2(aq) to the atmosphere and the DIC becomes enrich in 13C. We suggest that a significant amount of carbon cycling in neutral discharges from tailings piles occur close to the locations where the discharge seeps to the surface. Copyright © 2015 John Wiley & Sons, Ltd.

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Assessing the temporal evolution of dissolved inorganic carbon in waters exposed to atmospheric CO2(g): A laboratory approach

Cited by 15 publications

References 35 publications

Evaporation induced 18O and 13C enrichment in lake systems: A global perspective on hydrologic balance effects

Evaporation induced 18O and 13C enrichment in lake systems: A global perspective on hydrologic balance effects

Spatial and temporal variations of pCO₂, dissolved inorganic carbon and stable isotopes along a temperate karstic watercourse

Dissolved inorganic carbon evolution in neutral discharge from mine tailings piles

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Assessing the temporal evolution of dissolved inorganic carbon in waters exposed to atmospheric CO2(g): A laboratory approach

Cited by 15 publications

References 35 publications

Evaporation induced 18O and 13C enrichment in lake systems: A global perspective on hydrologic balance effects

Evaporation induced 18O and 13C enrichment in lake systems: A global perspective on hydrologic balance effects

Spatial and temporal variations of pCO2, dissolved inorganic carbon and stable isotopes along a temperate karstic watercourse

Dissolved inorganic carbon evolution in neutral discharge from mine tailings piles

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Product

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Spatial and temporal variations of pCO₂, dissolved inorganic carbon and stable isotopes along a temperate karstic watercourse