Abstract
The Tibetan Plateau (TP), including its surrounding mountain ranges, represents the largest store of ice outside the polar regions. It hosts numerous lakes as well as the head waters of major Asian rivers, on which billions of people depend, and it is particularly sensitive to climate change. The moisture transport to the TP is controlled by the Indian and Pacific monsoon and the Westerlies. Understanding the evolution of the interaction of these circulation systems requires studies on climate archives in different spatial and temporal contexts. The objective of this study is to learn more about the interannual variability of precipitation patterns across the TP and how different hydrologic systems react to different climatic factors. Aragonite shells of the aquatic gastropod Radix, which is widely distributed in the region, may represent suitable archives for inferring hydrologic and climatic signals in particularly high resolution. Therefore, sclerochronological studies of δ18O and δ13C ratios in Radix shells from seven lakes were conducted, each representing a different hydrologic and climatic setting, on a transect from the Pamirs across the TP. The shell patterns exhibit an increasing influence of precipitation and a decreasing influence of evaporation on the isotope compositions from west to east. δ18O values of shells from lakes on the eastern and central TP (Donggi Cona, Yamdrok Yumco, Tarab Co) mirror monsoon signals, indicated by more negative values and higher variabilities compared to the more western lakes (Karakul, Bangong/Nyak, Manasarovar). In Yadang Co, located on the central southern TP, the monsoon rains did not reach the lake in the sampling year, although it is located in a region which is usually affected by monsoon circulation. The δ18O values are used to differentiate the annual hydrological cycle into ice cover period, melt water period, precipitation period and evaporation period. δ13C compositions in the shells particularly depend on specific habitats, which vary in biological productivity and in carbon sources. δ18O and δ13C patterns show a positive covariance in shells originating from large closed basins. The results show that Radix shells mirror general climatic differences between the seven lake regions. These differences reflect both regional and local climate signals in sub-seasonal resolution, without noticeable dependence on the particular lake system.
| Original language | English |
|---|---|
| Pages (from-to) | 282-298 |
| Number of pages | 17 |
| Journal | Quaternary International |
| Volume | 290-291 |
| DOIs | |
| Publication status | Published - 2013 |
Bibliographical note
Funding Information:We are grateful to Parm Viktor von Oheimb (University of Giessen, Germany) who assisted in field work, to Franziska Slotta and Matthias Friebel (both FU Berlin, Germany) for assistance in sample processing, to Elke Heyde (FU Berlin) for hydrogeochemical analyses, to Sylvia Pinkerneil who assisted in geochemical analytical work (GFZ, Potsdam, Germany), to Alexandra Oppelt who assisted in field work and contributed geochemical analytical work (formerly FU Berlin), to Jan Evers (FU Berlin) who produced Fig. 1 , to Norm Catto for English proof reading and to two anonymous reviewers who helped to improve the manuscript. The research was funded by the Deutsche Forschungsgemeinschaft (German Science Foundation) within Priority Program 1372, Tibetan Plateau: Formation – Climate – Ecosystems. The field work was also partially supported by the National Science Foundation of China (no. 40871096 , grant to H. C. Zhang).