Seasonal variations of cave dripwater hydrogeochemical parameters and δ13CDIC in the subtropical monsoon region and links to regional hydroclimate

Heng Zhang; Zhongfa Zhou; Hui Dong; Lihui Yan; Shengjun Ding; Jing Huang; Xiaohuan Gong; Dan Su

doi:10.1016/j.scitotenv.2023.163509

Seasonal variations of cave dripwater hydrogeochemical parameters and δ¹³C_DIC in the subtropical monsoon region and links to regional hydroclimate

Sci Total Environ. 2023 Jul 10:881:163509. doi: 10.1016/j.scitotenv.2023.163509. Epub 2023 Apr 14.

Authors

Heng Zhang¹, Zhongfa Zhou², Hui Dong¹, Lihui Yan¹, Shengjun Ding¹, Jing Huang¹, Xiaohuan Gong¹, Dan Su¹

Affiliations

¹ 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.
² 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. Electronic address: fa6897@gznu.edu.cn.

PMID: 37062310
DOI: 10.1016/j.scitotenv.2023.163509

Abstract

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 (δ¹³C_DIC) and trace element ratios, were monitored from August 2018 to December 2020. The results showed seasonal variations in the δ¹³C_DIC, 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 CO₂ 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 δ¹³C_DIC were more sensitive to the recharge changes from extreme precipitation and drought events. Therefore, dripwater δ¹³C_DIC is a reliable indicator of the recorded hydrological signal in the southwest monsoon region.

Keywords: Climate response; Dripwater hydrogeochemistry; Hydrological type; Mahuang Cave; δ(13)C(DIC).