The Climatic And Environmental Evolution Since The Holocene Reflected By The Lake Sediment Records In Haolaihure In Inner Mongolia, China

The climatic and environmental evolution since the Holocene is a very important research field in the past researches of the global change. This research can contribute to better predict the trend of climatic and environmental evolution in the future. Understanding the evolution law of the global climate and environment since the Holocene, you need to obtain the reliable climatic and environmental records with high resolution from the different climate sensitive areas. The monsoon's boundary zone in North China is very sensitive to the climatic and environmental changes, so the lake sediments there are the ideal materials to study the climatic and environmental evolution.Through field survey and investigation, and according to the former relative research results, this paper selected the Haolaihure ancient lake as the research objects located in the monsoon's boundary zone in North China. Through conducting the AMS14C dating of the lake sediments in different layers and carbon pool correction of the AMS14C dating results combining with the optically stimulated luminescence dating and the characteristics of the profile sediments, this paper established the precise time scale of this profile. Then, the process of climatic and environmental evolution of Haolaihure since the Holocene has been reconstructed by utilizing the diatom records and pollen records in the profile sediments respectively. At last, through the comprehensive analysis of the process of climatic and environmental evolution revealed by the diatom records and pollen records, the climatic and environmental evolution of Haolaihure since the Holocene has been divided into the following stages:â… (12.08-11.50 cal. ka B.P.). The climate was cold and dry, and the environmental conditions were not suitable for the growth and reproduction of biological.â…¡(11.50-8.97cal. ka B.P.) The temperature increased, but the climate was still relatively cool, with obvious cold and hot fluctuation. The effective humidity was still low, and the climate was dry.â…¢(8.97-6.71 cal. ka B.P.). The climate was still slightly cool and dry; but the drought degree eased compared with the previous stage.â…£(6.71-5.85 cal. ka B.P.). The climate began to be warmer and wetter, and the environmental conditions were better.â…¤(5.85-2.89 cal. ka B.P.). Generally, the climate was warm and humid. There were only small amplitude fluctuations of dry in the medium-term. The environmental conditions were very suitable for the growth and reproduction of biological. VI(2.89-0.24 cal. ka B.P.). The climate was mainly cool and slightly dry. The lake became shallower gradually and finally dried up and disappeared in about 0.24 cal. Ka B.P.The process of climatic and environmental evolution above of Haolaihure is consistent with the former study results of the relative areas in general trend. It showed the cold and dry period before the Holocene, the early Holocene fluctuation and warming period, the mid-Holocene climatic optimum, and the late Holocene cooling period. This indicates that they were influenced by the common background of the global climate. But with regard to the beginning and ending time of all the stages, and combination of water and heat in different periods of every stage, there were some differences in the study results between the different areas and different scholars. These differences were probably caused by different factors, such as the different atmospheric circulation conditions and climatic conditions in various areas, the different sensitivity of the environmental index, the differences of sampling time resolution or the dating error, and so on, which are looking forward to further study in the future.