Depth-Dependent isotope dynamics in karst reservoirs: Multi-Decadal monitoring insights from French caves

IF 5.9 1区地球科学 Q1 ENGINEERING, CIVIL

Journal of Hydrology Pub Date : 2025-03-06 DOI:10.1016/j.jhydrol.2025.133028

Jian Zhang , Dominique Genty , François Bourges , Bénédicte Minster , Edouard Régnier , Ludovic Devaux , Stéphane Bujan , Ting-Yong Li

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引用次数: 0

Abstract

Understanding the stable oxygen isotope (δ¹⁸O/δD) compositions in rainwater and cave drip water within karst systems is essential for past climatic reconstructions all over the world. However, the relationship between cave drip water isotopes and upper karst infiltrated water and reservoirs remains unclear. Over twenty years, we monitored eight caves in France, from North to South: Arcy-sur-Cure, Villars, Cussac, Pech-Merle, Chauvet, Orgnac, Niaux, and Clamouse, collecting 3,000 dripping water samples from 32 drip points to measure δ¹⁸O and δD isotopes. As already observed in many cave sites, the isotopic composition of drip waters shows temporal stability with a Coefficient of Variation (CV) below 7 %, suggesting effective rainfall mixing during infiltration period. However, putting all these data on cave vertical cross sections, we observed subtle decreasing gradients in the averaged dripping δ¹⁸O values. For the first time in a multi-cave study, a clear logarithmic decrease of δ¹⁸O and δD with depth is found. Deeper sites show more negative isotopic values, especially in shallower zones (<50 m). In order to better understand these gradients, we used the hydrologic KarstFor model which revealed the importance of overflow mechanisms and of evapotranspiration (ETP) in driving this depth-dependent isotopic effect. These findings emphasize the significance of incorporating depth-dependent reservoir dynamics when analyzing isotopes in cave environments, advocating for a nuanced understanding of karst hydrological processes in affecting stalagmite δ¹⁸O.

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来源期刊

Journal of Hydrology 地学-地球科学综合

CiteScore

11.00

自引率

12.50%

发文量

1309

审稿时长

7.5 months

期刊介绍： The Journal of Hydrology publishes original research papers and comprehensive reviews in all the subfields of the hydrological sciences including water based management and policy issues that impact on economics and society. These comprise, but are not limited to the physical, chemical, biogeochemical, stochastic and systems aspects of surface and groundwater hydrology, hydrometeorology and hydrogeology. Relevant topics incorporating the insights and methodologies of disciplines such as climatology, water resource systems, hydraulics, agrohydrology, geomorphology, soil science, instrumentation and remote sensing, civil and environmental engineering are included. Social science perspectives on hydrological problems such as resource and ecological economics, environmental sociology, psychology and behavioural science, management and policy analysis are also invited. Multi-and interdisciplinary analyses of hydrological problems are within scope. The science published in the Journal of Hydrology is relevant to catchment scales rather than exclusively to a local scale or site.