School of Karst Science/School of Geography and Environmental Sciences, Guizhou Normal University, 550001 Guiyang, People's Republic of China; The State Key Laboratory Incubation Base for Karst Mountain Ecology Environment of Guizhou Province, 550001 Guiyang, People's Republic of China.
School of Karst Science/School of Geography and Environmental Sciences, Guizhou Normal University, 550001 Guiyang, People's Republic of China; The State Key Laboratory Incubation Base for Karst Mountain Ecology Environment of Guizhou Province, 550001 Guiyang, People's Republic of China.
Sci Total Environ. 2023 Jul 10;881:163509. doi: 10.1016/j.scitotenv.2023.163509. Epub 2023 Apr 14.
Stalagmites are considered natural archives of climate proxies. However, under the combined effects of atmospheric circulation patterns, precipitation, and karst environments, drip hydrogeochemical processes can be coupled and linked to each other to control cave sediment record information. Therefore, the evolution of chemistry and factors controlling the isotopic composition of the dripwater during regional precipitation migration from the surface to caves need to be evaluated. In this study, hydrogeochemical characteristics and the isotopic composition of the dripwater in the Mahuang Cave in Guizhou Province, Southwest China, including stable isotope (δC) and trace element ratios, were monitored from August 2018 to December 2020. The results showed seasonal variations in the δC, Mg/Ca, and Sr/Ca values of the dripwater in dry and wet seasons under the control of water-gas-rock reactions, such as soil CO concentrations and carbonate rock dissolution. In addition, the five monitored dripwater points in the Mahuang Cave showed fast and slow seepage due to the complex cave fractures and stratigraphy, reflecting the effects of precipitation variations to different degrees. Indeed, the δC were more sensitive to the recharge changes from extreme precipitation and drought events. Therefore, dripwater δC is a reliable indicator of the recorded hydrological signal in the southwest monsoon region.
石笋被认为是气候代用指标的天然档案。然而，在大气环流模式、降水和喀斯特环境的综合影响下，滴水水文地球化学过程可以相互耦合和联系，从而控制洞穴沉积物记录的信息。因此，需要评估在地表到洞穴的区域降水迁移过程中，滴水化学演化以及控制同位素组成的因素。本研究对中国西南贵州省麻璜洞的滴水进行了连续监测，监测时间为 2018 年 8 月至 2020 年 12 月，监测内容包括稳定同位素（δC）和微量元素比值等水文地球化学特征和同位素组成。结果表明，在土壤 CO2浓度和碳酸盐岩溶解等水-气-岩反应的控制下，滴水在干湿季节的 δC、Mg/Ca 和 Sr/Ca 值存在季节性变化。此外，由于洞穴裂缝和地层的复杂性，麻璜洞的五个监测滴水点表现出快速和缓慢的渗流，这反映了降水变化的不同程度的影响。事实上，δC 对极端降水和干旱事件引起的补给变化更为敏感。因此，滴水 δC 是西南季风区记录水文信号的可靠指标。
