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The stable isotopic composition of meteoric precipitation is an important component of global and regional water cycle research. Stable isotope data can help reconstruct paleoclimate related to ice cores, lake sediments, and stalagmites. We investigated the daily variation in isotopic composition of meteoric precipitation from 2008 to 2012 in the Guilin region of China. δ18O of meteoric precipitation ranged from −14.21 to +2.38 ‰, with an average value of −5.78 ‰ (Vienna Standard Mean Ocean Water; VSMOW). Meteoric precipitation in the summer half-year (May through October) increased, with a relatively low δ18O value of −8.04 ‰ (VSMOW; average of 261 groups) and −56.03 ‰ (VSMOW) of average δD, accounting for 67.6 % of the total annual meteoric precipitation. Meteoric precipitation in the winter half-year (November through April) decreased, with a relatively high δ18O value of −2.89 ‰ (average of 210 groups) and −9.23 ‰ of average δD, accounting for 32.4 % of total meteoric precipitation. The local meteoric water line (LMWL) equation in Guilin area has local climate characteristics. By combining environmental isotope data of precipitation using a backwards trajectory, water vapor sources of the meteoric precipitation in Guilin area are inferred and traced. Our results show that the isotopic composition of meteoric water vapor sources in Guilin area are related to monsoon type, source of precipitation cloud masses, and precipitation properties. The isotopic composition of meteoric precipitation in the summer half-year (May through October) was mainly affected by the summer monsoon or summer typhoons, namely controlled by water vapor source from the Bay of Bengal and the South China sea, and the second the West Pacific, and the δ18O value of meteoric precipitation was strongly negative. There was a significant negative correlation between the δ18O values of meteoric precipitation and the amount of precipitation and temperature in the summer half-year. The amount effect of the meteoric precipitation often concealed the temperature effect. The isotopic composition of meteoric precipitation in the winter season or winter half-year was affected by the water vapor source of the warm moist air masses from the West Pacific and continental cold air masses from the Siberia–Mongolia/winter monsoon or local evaporation vapor circulation, and the δ18O value of meteoric precipitation was relatively positive, and indicated that the water vapor of meteoric precipitation along the water vapor trajectory was affected by the evaporation as well as the local water vapor evaporation. The research results have showed that different sources of water vapor has a significant influence on the δ18O variation of meteoric precipitation, therefore, analysis of δ18O in the meteoric precipitation, especially its seasonal variation characteristics of analysis, can conversely reveal the water vapor sources of local meteoric precipitation.

The time sequence of paleoclimatic changes from 245.2 to 147.9 ka B.P. has been established by high precision U-series dating by Thermal Ionization Mass Spectrometry and the analysis of the oxygen isotopes from a stalagmite of Shuinan Cave in Guilin. The oxygen isotope pattern is divided into three main intervals. The top part of the stalagmite (interval C) displays mainly relatively heavy oxygen isotopes, mostly −7 to −5‰VPDB, but at a depth of 86.5 cm below the top, there is a sharp change to values lighter than −8 ‰. This boundary, dated at 192.6 ±3.9 ka B.P. is correlated with the boundary between marine oxygen isotope stages 6 and 7. The underlying interval B has δ18O values consistently between −7.5 and −8.5‰ until 271 cm depth when there is a sharp rise in δ18O values towards values as heavy as −5‰. The upper position of this change is dated at 242.5±6.4 ka B.P. and is correlated with the boundary between marine isotope stages 7 and 8. Carbon isotope values lie between −8.5 and −11‰ and are not uniquely high or low in the three intervals, but also show rapid changes at the boundaries between intervals in the same sense as the shifts in δ18O. The pronounced shifts in δ18O are attributed to changes in the paleo-monsoon intensity which reflect major reorganizations of the climate system, but some regional characteristics are also present. The results are also consistent with previous studies of climate proxies from loess-palaesol sequences in northern China. These characteristics show that paleo-climate evolution since the late stage of the middle Pleistocene Epoch in the Guilin area not only follows the global characteristics, but also has the strong district or regional patterns.

A high-resolution climate record from 163.00 kaBP to 113.80 kaBP has been obtained through TIMS-U series dating and carbon and oxygen isotope analysis of the three large stalagmites from two caves in the south of Guizhou Province, China. The record of the oxygen isotopes from the stalagmites reveals that the undulation characteristics between the cooling event of the glacial period and the warming event of the interglacial period in the research area can compare well to those of ice cores, lake sediments, loess and deep sea sediments on the scale of ten-thousand years or millennium time scale. The climate undulation provided by the record of the stalagmites has a coherence with the global changes and a tele-connection to the paleoclimate changes in the north polar region. Our results suggest that the direct dynamics of paleo-monsoon circulation changes reflected in the record of the stalagmites might be caused by changes of the global ice volume, and in turn related to various factors, including the solar radiation strength at the mid-latitudes in the Northern Hemisphere, the southern extension of the ice-rafted event in the North Atlantic, and changes of the equatorial Pacific sea surface temperature at the low-latitudes. Using δ 18 O values, we have calculated the temperatures and the results show that the temperature difference between the penultimate glacial period (with an average temperature of 8.1℃, and a minimum temperature range from 0.65℃ to −1.43℃ at stage 6) and the last interglacial period (with an average temperature of 18.24℃ at sub-stage 5e ) was about 10℃. This temperature difference from the record of the stalagmites corresponds in general to the record temperature variation (about 10℃) of measured ice cores. The climate records from the three stalagmites in the two caves have shown that the circulation strength of the Asian summer monsoon and the winter monsoon in the penultimate glacial period and the last interglacial period had a clear change. With the TIMS-U series method, termination II of the penultimate glacial period has been precisely dated at an age of (129.28±1.10) kaBP for the three stalagmites in the south of Guizhou Province, China. This borderline age represents the beginning of the last interglacial period or the boundary between the Middle Pleistocene and the Late Pleistocene, and corresponds to the beginning age of the last interglacial period shown by the ice cores and in the SPECMAP curve of the marine oxygen isotopes. The chronology determination of termination II is not only of stratigraphic and chronological significance, but also lays an important foundation for discussing the short time scales of climate oscillation and rapidly changing events of paleoclimate in the circulation region of the East Asian monsoon.