Research On The Geochemical Characteristics, Hydrogen And Oxygen Stable Isotope Migration Characteristics Of Drip Water In Yangkou Cave, Chongqing, China

Global climate change is always a significant issue which has gotten a comprehensive attention and research over the world, among all the problems, global warming is the one that attracts people’s attention most, because global warming can result in a series of cological and environmental issues, and threaten society’s safety, people’s existence and sustainable development. The reasons that contribute to global warming involve in many aspects in which the major factors are those two:one is people’s producing activities and the influence that the modern construction make on climate, the other one comes from the natural force majeure. But the climate change situation we face now is not only a status of spontaneous change of earth’s climate system around its period, but a result of adding the influence made by human activities. Dealing with global climate change needs to control the quantity of human activities, at the same time, we should have a deep understanding about the changing rules of earth’s climate system itself, both of those two are important. And reinforcing the study on geologic climate is an important way to understand the changing rules of earth’s climate system.In this thesis, a continuous monitoring program was executed in Yangkou cave in Jinfo Mountain, Chongqing. This paper investigated the variable characteristics and climatic significance of atmospheric precipitation-stable isotope of hydrogen oxygen and drip water in cave; Combining the intensity of ENSO with monsoon index, the author analyzed the effect that the general circulation of atmosphere have on the composition of table isotope of hydrogen oxygen in atmospheric precipitation of southwest monsoon region of China; In addition, we also analyzed microelement’s content and the variable characteristics of its specific value, then discussed the responding mechanism that those microelement have on modern environment. The paper provided paleoclimate reconstruction with a theoretical basis by using those indexes and we draw these conclusions as follows:1. The atmospheric precipitation and cave drip δD and δ18O both showed an overall trend that exhausted in summer and enriched in winter, which was influenced by the seasonal difference of the source of precipitation, outside the Yangkou cave. But under the effect of the adjustment function given by overlying rock-soil bed in cave, the range of seasonal variation of δD and δ18O in Yangkou cave was much less than the range of seasonal variation of precipitation, and had an obvious lag compared to precipitation. The δD and δ18O of cave drip water got a big difference in seasonal variation than atmospheric precipitation, which could be affected by the pipeline’s growth in crack of overlying rock bed in cave、the thickness of covering layer、residence time of karstic water、migration path before the becoming of cave drip、the altitude and rate of dripping of cave drip sites、 the distance from cave drip sites to cave, and so on.2. The precipitation δ18 of the Yangkou cave stand got a negative correlation with the amount of precipitation and temperature, presented amount the effect to rainfull and negative correlation with temperature. As a whole, the cave drip water δ18O had a negative correlation with the rainfull, but showed a feature of diversification in the relationship with temperature: there was no correlation between the cave drip δ18O of monitoring points 1#、 2#、5#、 6# and water temperatures cave temperature; the cave drip δ18O of monitoring point 3# got a positive correlation with water temperature and cave temperature, and correlation index were 0.4055 and 0.3545 respectively; The complex relationship with temperperature maybe used by the differece seasonal change of sites. Compared to the monitoring point 3#, the index of monitoring point 4# got a converse relation with water temperature and cave temperature, and correlation index were-0.3746 and-0.4449. The diversification of the correlation of temperature did be relevant to the difference of seasonal variation of δ18O of every monitoring sites.3. The 8D and δ18O of drip water both showed the succession and variability over the precipitation. But as a whole, the seasonal variation of those two cave drips wasn’t obvious enough, and the possibility of using the stalagmite in that cave to rebuild paleoclimate which was done by seasonal resolution was slim. But the drip water 8D and δ18O inherited the native information of atmospheric precipitation so that the cave drip δ18O of stalagmite in the cave could be used to rebuild the paleoclimatic change of a long time scale about 10 years or more.4. General circulation of atmosphere had a great influence on precipitation of monsoon region in southern China where Yangkou cave was located, so the composition of stable hydrogen and oxygen isotopes of atmospheric precipitation in this place had a positive relationship with ENSO. When El Nino worked, the force of subtropical anticyclone in western pacific was powerful, the monsoon index in western Pacific was high, which caused a relatively heavy value of stable hydrogen and oxygen isotopes of atmospheric precipitation in southern China; when La Nina worked, southeast trades got strengthened, the index of Indian Ocean monsoon became high, and stable isotope of precipitation got light.Besides what had been talked, the analysis of excess deuterium (d) showed that the difference of different season and source of water vapour was the major reason that contributed to the obvious seasonal difference of the composition of stable hydrogen and oxygen isotopes in atmospheric precipitation of this place.5. The content of cave drip Ca2+、Mg2+、 Sr2+in Yangkou cave got a certain feature of seasonal variation, showing a feature of high index in rainy season and low index in dry season. The cave drip Mg/Ca、Sr/Ca got a feature of high index in dry season and low index in rainy season by analyzing the monitoring point from 1# to 6# one by one, and element ratio of the cave drip in Ynagkou cave was controlled basicly by atmospheric precipitation, which could reflect the change of precipitation outside the world.