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The hidden buffering: How carbonate geology and sediments suppress CO2 emissions from reservoirs.

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Title:	The hidden buffering: How carbonate geology and sediments suppress CO2 emissions from reservoirs.
Authors:	Hu, Xuan¹ (AUTHOR), Wang, Wanfa¹ (AUTHOR) wfwang@gzu.edu.cn, Lu, Xixi² (AUTHOR), Qi, Hongkai³ (AUTHOR), Kumar, Amit⁴ (AUTHOR), He, Dengming¹ (AUTHOR), Tu, Shijun¹ (AUTHOR), Bao, Yufei⁵ (AUTHOR), Zeng, Jie¹ (AUTHOR), Wu, Qixin¹ (AUTHOR), Xia, Hao⁶ (AUTHOR), Wang, Yuchun⁵ (AUTHOR), Li, Si-Liang⁷ (AUTHOR)
Source:	Journal of Hydrology. Aug2026, Vol. 675, pN.PAG-N.PAG. 1p.
Subjects:	Sediments, Geology, Carbon emissions, Buffer solutions, Carbon cycle, Lakes
Abstract:	• Carbonate buffering suppresses CO 2 production and emissions in cascade reservoirs. • High suspended sediment concentrations amplify carbonate buffering in plateau reservoirs. • Carbonate-dominated reservoirs with high suspended sediment reduce CO 2 emissions globally. • Incorporating geological and sedimentary contexts improves reservoir carbon budget estimates. Research on carbon cycling in Qinghai–Tibet Plateau rivers has attracted considerable attention. However, the role of carbonate buffering in regulating carbon dioxide (CO 2) dynamics within cascade reservoirs remains poorly understood, particularly in plateau regions characterized by carbonate-rich geology and high suspended sediment concentration (SSC). In carbonate-enriched sediments, carbonate buffering prolongs the equilibration timescales of both partial pressure of CO 2 (p CO 2) and stable isotopic composition of dissolved inorganic carbon (δ13C DIC) with the atmosphere by ∼10-fold and ∼100-fold, respectively, compared to non-buffered scenarios. Over extended timescales, water-carbonate interactions effectively limit the evasion of metabolically produced CO 2 in cascade reservoirs of the Lancang River, reducing CO 2 emissions flux (F CO2) by 24.4%. This buffering effect is particularly pronounced in the hypolimnion, where increased carbonate dissolution occurs, and remains sustained in the outflows. Globally, carbonate-dominated reservoirs with high SSC exhibit 82% lower F CO2 than those with low SSC, demonstrating that suspended sediments critically amplify carbonate buffering's suppression of CO 2 emissions. These findings highlight the necessity of incorporating coupled geological and sedimentary processes into global carbon budgets and climate assessments, particularly in high-altitude regions. [ABSTRACT FROM AUTHOR]
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Database:	Engineering Source

Description
Abstract:	• Carbonate buffering suppresses CO 2 production and emissions in cascade reservoirs. • High suspended sediment concentrations amplify carbonate buffering in plateau reservoirs. • Carbonate-dominated reservoirs with high suspended sediment reduce CO 2 emissions globally. • Incorporating geological and sedimentary contexts improves reservoir carbon budget estimates. Research on carbon cycling in Qinghai–Tibet Plateau rivers has attracted considerable attention. However, the role of carbonate buffering in regulating carbon dioxide (CO 2) dynamics within cascade reservoirs remains poorly understood, particularly in plateau regions characterized by carbonate-rich geology and high suspended sediment concentration (SSC). In carbonate-enriched sediments, carbonate buffering prolongs the equilibration timescales of both partial pressure of CO 2 (p CO 2) and stable isotopic composition of dissolved inorganic carbon (δ13C DIC) with the atmosphere by ∼10-fold and ∼100-fold, respectively, compared to non-buffered scenarios. Over extended timescales, water-carbonate interactions effectively limit the evasion of metabolically produced CO 2 in cascade reservoirs of the Lancang River, reducing CO 2 emissions flux (F CO2) by 24.4%. This buffering effect is particularly pronounced in the hypolimnion, where increased carbonate dissolution occurs, and remains sustained in the outflows. Globally, carbonate-dominated reservoirs with high SSC exhibit 82% lower F CO2 than those with low SSC, demonstrating that suspended sediments critically amplify carbonate buffering's suppression of CO 2 emissions. These findings highlight the necessity of incorporating coupled geological and sedimentary processes into global carbon budgets and climate assessments, particularly in high-altitude regions. [ABSTRACT FROM AUTHOR]
ISSN:	00221694
DOI:	10.1016/j.jhydrol.2026.135646