巴丹吉林沙漠及其南缘地区的水化学和环境同位素特征与环境演变

The Badain Jaran Desert lies on the Alashan Plateau in western Inner Mongolia. Because of huge dunes, permanent lakes and on the northern fringe of the Asian summer monsoon, the Badain Jaran Desert has been drawing attentions of many experts. And they have made great progress in dune’s geomorphology, botany in desert, paleoclimate change and other study areas. We analyzed environmental isotope and ion chemistry in lakes and groundwater of the desert and southeastern area, and collected some other evidences from 14C dating, fossils and archeology. According to chemical analysis, we discuss the difference spatial character of ion chemistry and environmental isotope in lakes and groundwater of the desert and adjacent. Contrasting with ion chemistry and isotope results in other arid area, we argue origin of groundwater and lakes in the desert area, and get a preliminary understanding of desert lakes’ evolution during Holocene. Some main conclusions were drawn as follows: 1. It has a obvious difference in hydrophysical parameters between lakes and groundwater in the desert and margin. 2. The results of ion analysis show that Na+ and Cl- are dominant in most lakes of the desert. Meanwhile, Na+ 、Cl- and HCO3- are dominant in groundwater of the desert and adjacent, and alsoMg2+、Ca2+、and NO3- have more percentage than in lakes. 3. Owing to different solubilities, the conten of main ions in water varies with the content of TDS. Whereas the content of TDS is over 100 g/L, the content of SO42-、HCO3-、Mg2+and Ca2+ in lakes descend. 4. The result of isotope analyzing indicate the lakes and groundwater in southeast desert have a similar vaporing trend with the groundwater in the southeast margin of the desert. It imply there would have some kind of contact between groundwater in margin and lakes of southeast desert. 5. Contrasting with isotope results of groundwater in other arid area, it show that the groundwater in the desert and Yabulai area should be phreatic water which have a low water table. Therefore, we conclude that the groundwater in southeast part of the desert and southern margin mainly are recharged by precipitation of local abundant rainfall and groundwater of low mountain of southern area. 6. And all of these evidences, which are different from salinity, the content of CO32- and geological data, show that the bigger northern lake group and southeastern lake group in the desert have different groundwater replenishing system because a fold belt lie between of the two group lakes and obstruct them in landform. and HCO3- 7. The 14C dating results of fossil and lacustrine deposits show that there maybe have a wider range of shoreline during early and middle Holocene than today. 8. By the discovery and study of some pieces of pottery and fine stoneware, we preliminary conclude that there maybe have some certain amount of early human activities in the Badain Jaran Desert.