龙感湖地区近3000年来的气候环境变迁

本文通过分析龙感湖沉积物中的色素、孢粉、硅藻研究结果，探讨该区近３０００年来环境气候波动特点，结果表明：３２００－２４００ａＢＰ，色素含量较高，与温度条件较好有关。该带孢粉浓度也最高，阔叶乔木绎种花粉丰富，湿生及水生植物经常出现。总体上为相对暖湿阶段，其中仍有凉湿波动。２４００－１６００ａＢＰ，具体分为两个阶段，前期约２４００－２０００ａＢＰ，ＣＤ、ＴＤ、Ｍｙｘ含量明显较低，水生、湿生草本减少，气

The Palaeoenvironm ental and Palaeoclimatic Changes of Longgan Lake since the Past 3000 Years

According to the contents and assemblages of pigments. diatom and sporex-pollen from the sediments core of Longgan lake, Anhui Province. this paper mainly deals with the climatic and environmental changes during the last 3000 years in Longgan Lake. The environment of this region changed as follows:During 3200- 2400aBP, the contents of CD, NC, TC were high, reflecting higher like productivity. The higher pigment value of Osc and Myx were relative to the temperature condition. moreover the abundance of vegetation, higher water temperature and lower turbidity could strengthen the competition of blue algae. Pollen concentration had the highest point comparing other stages, decious tree pollen was very abundant and also often occur other pollen of water and wet plants representing a relative warm and wet period with a cool - dry oscillation.During 2400 - 1600aBP, this period may be divided into two stages. In early period (about 2400- 2070aBP), the contents of CD,TC,Myx decreased obviously. some herbs such as Artemisia. Palygonum increased while other water and wet herbs decreased. indicating a cool-dry climate ; lately all the pigment percentages increased , indicating a higher temperature tend. Compared to first stages, the content of pigment at the stage was lower.inferring a tame cool and little wet climate.During 1600 - 1500 aBP, the lower pigment value of CD, TC,Osc and Myx showed that lake biomass reduced and the lake was extremely trophic. Meanwhile arboreal was in its valley period.During 1500- 1100 aBP, the contents of CD, TC. Myx increased obvlously. reflecting higher producidivity and a higher temperature tendency.1100 - 100 aBP, pigment percentage and pollen concentration decreased to its lowest point of the whole section. It indicate a cool and dry climate reflecting as Little Ice Age.100 aBP-present. the higher value of pigment of surface sediment may be related to the eutrophic status of the lake which maybe caused by the human activity.