Using δ13C to reveal the importance of different water transport pathways in two nested karst basins, Southwest China

Hao, Zhipeng; Gao, Yang; Ma, Mengyao; Green, Sophie M.; Wang, Jing; Song, Xinshan; Dungait, Jennifer A. J.; Johnes, Penny J; Xiong, Bailian; Quine, Timothy A.; Sun, Xiaomin; Wen, Xuefa; He, Nianpeng

doi:10.1016/j.jhydrol.2019.01.070

Cited by 14 publications

(9 citation statements)

References 48 publications

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“…Additionally, roots which are mainly distributed in the 0-20 cm layers are more 12 C-depleted than leaves or twigs above (Hao et al, 2019), leading to higher δ 13 CSOC in rhizosphere soil than in surface soil. Another potential explanation is the continued decline of the δ 13 C of atmospheric CO2 since the industrial revolution (Cuntz, 2011), SOC formed later thus could inherit isotopically lighter C from overlying vegetation than that formed earlier.…”

Section: Vertical Variations Of Soc In Karst Regionsmentioning

confidence: 99%

“…The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper. (Du et al, 2014;Hao et al, 2019;Liu et al, 2020;Piao et al, 2001).…”

Section: Declaration Of Competing Interestmentioning

confidence: 99%

“…Detailed information about dominant plants overlying the four sampling sites and corresponding δ 13 C values of leaves (Fig. 2(b)) are referred to in previous publications (Du et al, 2014;Hao et al, 2019;Liu et al, 2020;Piao et al, 2001).…”

mentioning

confidence: 99%

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Vertical variations of soil carbon under different land uses in a karst critical zone observatory (CZO), SW China

Qin

et al. 2022

Geoderma

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Section: Vertical Variations Of Soc In Karst Regionsmentioning

confidence: 99%

Section: Declaration Of Competing Interestmentioning

confidence: 99%

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Vertical variations of soil carbon under different land uses in a karst critical zone observatory (CZO), SW China

Qin

et al. 2022

Geoderma

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“…We used the soil water and deep groundwater chemistry reported in Qin et al (2022) and Zhao et al (2018). The input rainfall has an average pH of 5.5, with average alkalinity, Ca, and δ 13 C at 50.0 μmol C/L, 250.0 μmol/L, and −12.5‰, respectively (Hao et al, 2019). The initial soil water has a pH of 7.5, and alkalinity, Ca, δ 13 C and δ 18 O at 3.5 × 10 −3 mol C/L, 2.0 × 10 −3 mol/L, −16.0‰ and −8.0‰, respectively.…”

Section: Tablementioning

confidence: 99%

Amplified Production and Export of Dissolved Inorganic Carbon During Hot and Wet Subtropical Monsoon

Wen,

Li,

Chen

et al. 2024

Water Resources Research

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Understanding the origins and processes of riverine dissolved inorganic carbon (DIC) is crucial for predicting the global carbon cycle with projected, more frequent climate extremes yet our knowledge has remained fragmented. Here we ask: How and how much do DIC production and export vary across space (shallow vs. deep, uphill vs. depression) and time (daily, seasonal, and annual)? How do the relative contributions of biogenic (soil respiration) and geogenic (carbonate weathering) sources differ under different temperature and hydrological conditions? We answer these questions using a catchment‐scale reactive transport model constrained by stream flow, stable water isotopes, stream DIC, and carbon isotope data from a headwater karstic catchment in southwest China in a subtropical monsoon climate. Results show climate seasonality regulates the timing of DIC production and export. In hot‐wet seasons, high temperature accelerates soil respiration and carbonate weathering (up to a factor of three) via elevating soil CO2 and carbonate solubility, whereas high discharge enhances export by two orders of magnitude compared to cold‐dry seasons. Carbonate weathering is driven more by soil CO2 than water flow. At the annual scale, 92.9% and 7.1% of DIC was produced in shallow and deep zone, respectively, whereas 64.5% and 35.5% of DIC was exported from shallow and deep zone, respectively. These results highlight the uniqueness of subtropical karst areas as synchronous reactors and transporters of DIC during the hot‐wet monsoon, contrasting the asynchronous production and export in other climate regions. A future hotter and wetter climate with more intensive storms in the region may further intensify DIC production and export, accentuating the potential of subtropical karst regions as global hot spots for carbon cycling.

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“…Variations in flow characteristics in these mediums with different hydraulic conductivities and storage capacities result in a marked spatiotemporal variability in hydrological processes. Under different wetness conditions, the sharp variations in hydrological connectivity between different landform units and between different mediums enhance the complexity of hydrological behaviours at the catchment scale (Hao et al, 2019). Specifically, the streamflow generation in intra‐event is still an unanswered question for karst catchment, due to the variable flow paths and mixing processes controlled by hydrological connectivity (Benischke, 2021; Berglund et al, 2019; Ford et al, 2019).…”

Section: Introductionmentioning

confidence: 99%

Intra‐event concentration–discharge relationships affected by hydrological connectivity in a karst catchment

Liu

Zhang

Chen

et al. 2023

Hydrological Processes

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Concentration-discharge (C-Q) relationship in streamflow provides insights into hydrological transport at the catchment scale. Changes in hydrological connectivity during runoff events often dominate flood and solute export in the karst catchment.However, only few studies have explored intra-event C-Q relationships and how they are affected by hydrological connectivity in karst catchment. In this study, we explored the intra-event C-Q relationships in underground channel flows by integrating solute concentration, discharge and modelled flow age in a 1.25 km 2 karst catchment in southwest China. We apply piecewise functions to characterize the C-Q relationships on rising and falling limbs of hydrograph. Geogenic solutes exhibited dilution C-Q patterns during the runoff event, which could be fitted by two power-law models with different coefficients on rising and falling limbs. Affected by the strong hydrological connectivity between surface and subsurface, hillslope and depression, a steeper C-Q slope on the rising limb indicated an exhaustible, proximal source, that is, groundwater. In contrast, the C-Q patterns of the soil enriched solutes changed from enrichment to dilution during the runoff event. The enrichment pattern occurring at the early of rising limb was caused by strong hydrological connectivity between the surface and subsurface, which indicated a distal and plentiful sources of soil water. Whilst the strong hydrological connectivity between hillslope and depression caused a dilution pattern at the latter of rising limb. On the falling limb of hydrograph, a dilution pattern implied that the small fractures could be another source zone of soil-enriched solutes in addition to soil layer in the depression. The C-Q behaviours of soil-enriched solutes can be fitted by a combination of a parabola model and a power law model for rising and falling limbs, respectively. The current study highlights the variations in intra-event C-Q relationships of different solutes affected by hydrological connectivity in the karst catchment. Which is crucial for assession of hydrochemical processes and fertilization management in this area.

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Using δ13C to reveal the importance of different water transport pathways in two nested karst basins, Southwest China

Cited by 14 publications

References 48 publications

Vertical variations of soil carbon under different land uses in a karst critical zone observatory (CZO), SW China

Vertical variations of soil carbon under different land uses in a karst critical zone observatory (CZO), SW China

Amplified Production and Export of Dissolved Inorganic Carbon During Hot and Wet Subtropical Monsoon

Intra‐event concentration–discharge relationships affected by hydrological connectivity in a karst catchment

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