Dynamics of CO2 in a karst catchment in the southwestern plateau, China

Wang, Shilu; Yeager, Kevin M.; Wan, Guojiang; Liu, Cong‐Qiang; Liu, Fang; Lü, Ying-Chun

doi:10.1007/s12665-014-3591-0

Cited by 13 publications

(24 citation statements)

References 71 publications

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“…Partial pressures of CO 2 in the surface lake water and emission flux of CO 2 at the lake water‐air interface showed clear seasonal patterns, according to the observations that have made with higher sampling frequency at more sampling sites in 2013 (Figure ) relative to the previous study (Wang et al, ). In summer and fall, the surface lake water was undersaturated with respect to atmospheric CO 2 owing to heavy consumption of CO 2 by algal photosynthesis.…”

Section: Resultssupporting

confidence: 63%

“…In winter and early spring, the lake water was supersaturated in CO 2 with high pCO 2 ranging from 1,000 to 2,000 μ atm and emitted more CO 2 into the atmosphere, acting as a carbon source (Figure ). In comparison, variations of pCO 2 displayed some irregular patterns in the previous observation that had a low sampling frequency (Wang et al, ). For example, exceptionally high pCO 2 of up to 5,000 μ atm occurred, and sometimes the lake water was under saturated in CO 2 in winter when the lake was vertically mixed (see Wang et al, ).…”

Section: Resultsmentioning

confidence: 55%

“…Direct, hydrological input of soil CO 2 is assumed to be an important source of lake CO 2 (Abril et al, ; Maberly et al, ; McDonald et al, ). On the other hand, dissolved IC (DIC, mainly HCO 3 − ) derived from catchments is thought to be a primary factor in sustaining CO 2 emissions in many lakes (Jones et al, ; Öquist et al, ; Wang et al, , ; Weyhenmeyer et al, ). These findings are in agreement with the results of a statistical analysis of more than 5,000 lakes reported by Marcé et al (), which showed that CO 2 supersaturation in lakes was directly related to carbonate weathering in catchments.…”

Section: Introductionmentioning

confidence: 99%

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Importance of Considered Organic Versus Inorganic Source of Carbon to Lakes for Calculating Net Effect on Landscape C Budgets

Wang

Yeager

et al. 2018

JGR Biogeosciences

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Lakes and reservoirs transform, emit, and bury carbon that is exported from land and are thus significant components of terrestrial carbon budgets. Their significance is often assessed by integrating these water bodies into terrestrial primary production. However, the transfer of inorganic carbon (IC) is likely a sticking point for these integrations because IC is not part of net ecosystem production. Here we integrated carbon evasion and organic carbon (OC) burial in a lake in the context of inorganic and OC cycling in a karst catchment from a system perspective. The lake emitted carbon dioxide (CO2) and buried OC at rates of 1.0 ± 0.2 and 0.9 ± 0.2 g C m−2 a−1, respectively, approximately equaling 13% and 11% of catchment net ecosystem production, respectively. These proportions represent significant influences on terrestrial carbon budgets, given an organic origin. However, catchment carbon export is dominated by IC that is derived from carbonates dissolved by soil CO2. Lake CO2 evasion accounts for less than 0.1% of soil CO2 efflux, suggesting little potential in significantly altering terrestrial carbon budgets. This comparison indicates the significance of aquatic CO2 evasion, requiring an adjustment of terrestrial carbon budgets to recognize their dependence on carbon origins. The significance may be overstated if inorganic origin is ignored. Our study suggests that a careful reassessment of the significance of CO2 evasion and OC burial in freshwater ecosystems to local and global carbon budgets, with full consideration of their sources, is necessary and pressing.

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Section: Resultssupporting

confidence: 63%

Section: Resultsmentioning

confidence: 55%

Section: Introductionmentioning

confidence: 99%

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Importance of Considered Organic Versus Inorganic Source of Carbon to Lakes for Calculating Net Effect on Landscape C Budgets

Wang

Yeager

et al. 2018

JGR Biogeosciences

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“…Furthermore, carbonate weathering can be enhanced by reacting with sulfuric acid. This acid may be produced naturally by the oxidation of sulfide minerals, or related to anthropogenic sources (Beaulieu et al, 2011;Li et al, 2008;Torres et al, 2014;Wang et al, 2015).…”

Section: Parameterization For Estimating Soil-rock Pcomentioning

confidence: 99%

Ecosystem controlled soil-rock pCO2 and carbonate weathering – Constraints by temperature and soil water content

et al. 2019

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A B S T R A C TCarbonate dissolution in soil-groundwater systems depends dominantly on pH, temperature and the saturation state of the solution with respect to abundant minerals. The pH of the solution is, in general, controlled by partial pressure of CO 2 (pCO 2 ) produced by ecosystem respiration, which is controlled by temperature and water availability. In order to better understand the control of land temperature on carbonate weathering, a database of published spring water hydrogeochemistry was built and analysed. Assuming that spring water is in equilibrium with the soil-water-rock-atmosphere, the soil pCO 2 can be back-calculated. Based on a database of spring water chemistry, the average soil-rock CO 2 was calculated by an inverse model framework and a strong relationship with temperature was observed. The identified relationship suggests a temperature control on carbonate weathering as a result of variations in soil-rock pCO 2 , which is itself controlled by ecosystem respiration processes. The findings are relevant for global scale analysis of carbonate weathering and carbon fluxes to the ocean, because concentration of weathering products from the soil-rock-system into the river system in humid, high temperature regions, are suggested to be larger than in low temperature regions. Furthermore, results suggest that, in specific spring samples, the hydrochemical evolution of rain water percolating through the soilrock complex can best be described by an open system with pCO 2 controlled by the ecosystem. Abundance of evaporites and pyrite sources influence significantly the chemistry of spring water and corrections must be taken into account in order to implement the inverse model framework presented in this study. Annual surface temperature and soil water content were identified as suitable variables to develop the parameterization of soil-rock pCO 2 , mechanistically consistent with soil respiration rate findings.

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“…After water samples were collected, concentrations of

{HCO}_{3}^{-}

were determined on site using HCl titration. DIC and

{CO}_{3}^{2 -}

concentrations and CO 2 partial pressures were calculated from

{HCO}_{3}^{-}

, pH, the reaction constants, and Henry's law constant for CO 2 (Wallin et al ; Wang et al ). For isotope analysis, water samples were filtered in the field through precombusted Whatman glass fiber filters (GF/F), collected in brown polyethylene bottles, and then spiked with saturated HgCl 2 solution to prevent microbial activity.…”

Section: Methodsmentioning

confidence: 99%

Carbon isotope fractionation in phytoplankton as a potential proxy for pH rather than for [CO₂(aq)]: Observations from a carbonate lake

Wang

Yeager

2016

Limnology & Oceanography

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The method of reconstructing paleoatmospheric CO2 levels using carbon isotope signatures of organic matter buried in sediments has been questioned due to the dubious foundation that carbon isotope fractionation during phytoplankton photosynthesis (εp) is controlled primarily by aquatic CO2 concentration ([CO2(aq)]). Consequently, what carbon isotope data from bulk sedimentary organic matter reflects is a puzzle. In this study, we determined the carbon isotope compositions of dissolved inorganic carbon and particulate organic carbon in a lake located in a carbonate area. Partial correlation analysis was employed to distinguish between direct and indirect factors in controlling εp. The results show that εp is more closely, and more steadily related with pH than with [CO2(aq)], which is in accordance with recent advances in our understanding of the physiology of carbon utilization by phytoplankton for CO2 and HCO3−. Therefore, we propose that carbon isotope fractionation in phytoplankton is more suitable as a proxy of pH than of [CO2(aq)]. One advantage of this amendment is that information on HCO3−, the main species of carbon uptake by phytoplankton, is likewise included. In the future, culture experiments aiming at revealing the relationship between pH and cellular carbon isotope signatures is necessary to construct a new isotope fractionation formula to couple the different effects of CO2 and HCO3−, which is of critical importance to improve the understanding of carbon isotope fractionation, and to more precisely model pH and CO2.

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Dynamics of CO2 in a karst catchment in the southwestern plateau, China

Cited by 13 publications

References 71 publications

Importance of Considered Organic Versus Inorganic Source of Carbon to Lakes for Calculating Net Effect on Landscape C Budgets

Importance of Considered Organic Versus Inorganic Source of Carbon to Lakes for Calculating Net Effect on Landscape C Budgets

Ecosystem controlled soil-rock pCO2 and carbonate weathering – Constraints by temperature and soil water content

Carbon isotope fractionation in phytoplankton as a potential proxy for pH rather than for [CO₂(aq)]: Observations from a carbonate lake

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Dynamics of CO2 in a karst catchment in the southwestern plateau, China

Cited by 13 publications

References 71 publications

Importance of Considered Organic Versus Inorganic Source of Carbon to Lakes for Calculating Net Effect on Landscape C Budgets

Importance of Considered Organic Versus Inorganic Source of Carbon to Lakes for Calculating Net Effect on Landscape C Budgets

Ecosystem controlled soil-rock pCO2 and carbonate weathering – Constraints by temperature and soil water content

Carbon isotope fractionation in phytoplankton as a potential proxy for pH rather than for [CO2(aq)]: Observations from a carbonate lake

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Carbon isotope fractionation in phytoplankton as a potential proxy for pH rather than for [CO₂(aq)]: Observations from a carbonate lake