The transmission of stable isotopes and elements/ions from the outside to the inside of a cave and their incorporation into drip water can involve numerous biogeochemical processes. To understand how the original signals of stable isotopes and elements/ions are modified by these processes, integrated studies of the interactions between vegetation, soil, epikarst, and caves are required. We conducted a multi-year monitoring study of the vegetation biomass, tree breast-height diameter, P-CO2 in soil air and cave air, delta C-13 in soil air, stable oxygen isotope in rainwater and drip water, and stable carbon isotope and elements/ions concentrations in drip water in Shawan Cave system, southwest China. The main results were as follows: (1) The evaporation effect weakened and the transpiration effect strengthened outsides the cave as vegetation improved, thus leading to a year-by-year increasing trend in the delta O-18 value of drip water. This indicates that changes in vegetation may have been another potential factor influencing the interannual variation of the delta O-18 value of drip water. (2) The CO2 concentration and delta C-13 value in soil air increased and decreased, respectively, with vegetation restoration, which caused the interannual variation in the dissolved inorganic carbon isotope (delta C-13(DIC)) value of drip water during the autumn and winter to exhibit a year-by-year decreasing trend. (3) The variations in the elements/ions concentrations of drip water were affected by vegetation uptake, vegetation transpiration, and water-rock interactions. It is inferred that the interannual variation in the elements/ions concentrations of drip water responded to vegetation restoration. (4) A conceptual model demonstrated that the three response modes of drip water delta O-18 value, delta C-13(DIC) value, and elements/ions to variations in vegetation. Overall, this study highlights the responses of the interannual changes in delta C-13(DIC), delta O-18, and elements/ions of drip water to vegetation restoration, which contributes critical insights into the paleoenvironmental interpretation of proxies of speleothems.
Publication name |
JOURNAL OF HYDROLOGY Volume: 590 Article Number: 125543 DOI: 10.1016/j.jhydrol.2020.125543 Published: NOV 2020 |
Author(s) |
Lyu, Yina; Luo, Weijun; Wang, Yanwei; Zeng, Guangneng; Cai, Xianli; Wang, Meifang; Chen, Jia; Yang, Kaiping; Weng, Xu; Cheng, Anyun; Zhang, Lin; Zhang, Runyu; Wang, Shijie |
Corresponding author(s) |
LUO Weijun luoweijun@vip.gyig.ac.cn Chinese Acad Sci, Inst Geochem, State Key Lab Environm Geochem, Guiyang 550081, Peoples R China. | View here for the details
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