The Characteristic And Environmental Significance Of Stable Istope Of Karst Spring And Drip Water In Chongqing Furong Cave

Chongqing Furong cave, as the only cave listed in the world natural heritage preservation, is attractive to many experts and scholars because of its rich sediment. Since2005, Southwest University started scientific research on Furong cave. Among the previous research findings, the scholars prefer to study on the transfer of anion and cation in drip water and carbon isotope in Chongqing Furong cave, while merely there are deep studies on stable isotope like hydrogen and oxygen. Based on two and half year monitoring research on the hydrogen and oxygen stable isotope of overlapping spring, drip water and pond water in Furong cave, the accounts for the seasonal changes stability of drip water δ18O and unobvious response to external environment in Furong Cave will be discussed in this essay, which contributes to understand better the environmental information of δ18O the secondary carbonate presents. The results are as follows:When compared with karst spring, the environment of the internal water body is more stable with smaller changes of temperature and moisture in one yea and higher co2concentration in the air which presents seasonal changes. In the hydro-chemistry monitoring, the synchronization change of anion of drip water is also the evidence for the integrity of cave environment, but the different ranges of data and unsynchronized drip velocity in each site is the evidence for the complication of drip water channel. In general, the internal environment of Furong cave is stable but different, which provides research background for stable isotope analysis.The monitoring result of hydrogen and oxygen isotope of karst spring reveals that the yearly change of its data value is less than that of the rainfall monitoring site nearby with more negative value of isotope. In the span of monitoring, there is irregular change in each season. In October,2011, δ18O value is the minimum while d value is the minimum in October,2010. The reason is that the main source of karst spring is the rainfall in summer and the response always delays, and only the information of intensive rainfall can be captured in short period of time. The less negative δ18O and d value is due to the continuous evaporation of light isotope in the water body.Regarding drip water, the analysis of LMWL also proves the source is precipitation and the similarity of drip water δ18O and8D value to those of karst spring also proves the same source of the both. In changing trend, the hydrogen and oxygen isotope of internal water body is very stable and it cannot capture the seasonal change information. The linear relationship model of δ18O value of drip water, external temperature and moisture and internal environment information cannot scientifically explain the reason. By the overall analysis, adjustment capacity of aeration zone overlapping the cave has been found. It is of great significance to hydrogen and oxygen isotope value of drip water. The δ18O value of drip water present yearly moving mean the preliminary explain is δ18O mean value is the reflection of rainfall in summer at present.In contemporary China, the research of hydrogen and oxygen stable isotope in speleology field is focused on whether there is the signal distortion in its source and during transferring process. However, no regional relationship has been established. The result in this essay can combine with other caves in monsoon region in China to test that whether the established atmospheric circulation model based on hydrogen and oxygen stable isotope of modern drip water in certain region is reliable. Finally, it is discovered that the response mechanism to atmospheric circulation differs in caves in different regions.