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High-resolution carbon and oxygen isotope records in stalagmites provide significant information for quantitative paleo-reconstructions of past temperature and precipitation. This paper describes results of isotopic analysis of dissolved inorganic carbon (DIC) in Panlong Cave water (from drips and shallow pools). Cave water was sampled monthly throughout 2012 and analyzed for δC composition. The values of δC in drip water were in the range of −10.42 to −16.07 ‰, while the values of δC in pool water were in the range of −1.88 to −6.94 ‰. Dissolved inorganic carbon isotope records showed a gradual stepwise negative excursion from January to August, and a gradual stepwise positive excursion from September to December. δC in cave water showed remarkable seasonal variations, which were negative excursion from 2 to 5 ‰ in rainy season than in dry season. A negative δC excursion in summer was not the result of vegetation types, which was contributed to enhance root respiration and decomposition of soil organic matter. A correlation between δC values of perennial drip water and pool water samples with air temperature and precipitation amount suggests that these negative excursions were caused by increasing air temperature during rainy season. Negative excursions in δC values of seasonal drip water were correlated with monthly precipitation, caused by the influx of soil organic matter into the cave. Hence, this paper provides an important framework and an empirical basis for reconstructing temperature from stalagmites and drip water in this region. [ABSTRACT FROM AUTHOR]

The simulation and monitoring of environmental proxies in cave systems is of great significance for understanding the controlling factors of stalagmite geochemistry and for further analysing the signal transmission process and mechanism in cave systems. In this study, we collected samples from three drip points in Liangfeng Cave from 2015 to 2020, Guilin City, Southwest China. The δ13C DIC values, total alkalinity and modern calcite deposition rates at the drip points in the cave were measured during the monitoring period. Comparison of these data with atmospheric temperature and rainfall data from the study area revealed that (1) the δ13C DIC and total alkalinity values of cave drip water show a seasonal pattern involving low values that increase in summer and autumn and high values that decrease in winter and spring, which is synchronized with the changes in the regional rainfall and temperature. (2) The modern calcite deposition rate also shows characteristics of significant seasonal variation. In addition, modern calcite deposition rate of drip water (site LF-4) decreased year by year. On an interannual time scale, the recharge regime of this drip water is likely to be the main control on the modern calcite deposition rate. (3) The δ13C DIC values of the drip water in Liangfeng Cave (well ventilated) are generally higher than those of another cave (weakly ventilated) in the study area for winter and spring. The cave ventilation effect leads to a higher δ13C DIC value in the drip water during times of low cave pCO 2. (4) Because Liangfeng Cave is a well-ventilated cave, the drip water could record the seasonal regional climatology variation. Observations from the well-ventilated Liangfeng Cave provide a reference point for the interpretation of regional climatology signals from speleothem proxy records. • The long-term monitoring study was performed in well ventilation Cave, Guilin, SW China. • Total alkalinity, δ13C DIC , drip rate and calcite deposition rate show obvious seasonal variation. • Ventilation significantly effect on the δ13C DIC values of cave drip water during winter and spring. [ABSTRACT FROM AUTHOR]