沉积学报2000，Vol.18Issue(3)：341-345,5.
洱海沉积物粒度记录与气候干湿变迁
Sediment Particle Sizes and the Dry- Humid Transformation of the Regional Climate in Erhai Lake
摘要
Abstract
As a main lodging of surface substances, lake sediments continuously and sensitively record information of re-gional climate and environment with annual to decadal resolution. The sediment core EH911208 - 3 - 5 with alength of 83cm was taken from deepwater location in Erhai Lake in 1991, using the sediment - water interface sampler specially designed by ourselves. The sediments were cut at intervals of 0.5～1.0cm and were measured forgrain sizes by the Scanning Photo Sedimentograph "Analysette 20" made in Germany. Based on accurate dating by137Cs and 210Pbex, the author reconstructs the dry - humid transformation history of the regional climate accordingto the vertical profile of sediment particle sizes, which provides a new effective way for recovering the century-scale climatic changes. The following conclusions are drawn: (1) General environmental significance of sediment grain size should not be applied mechanically in recon-structing palaeoclimate. Only after concretely analyzing all the factors which affect sediment grain size, can credi-ble conclusions be obtained during discussing different time - scales climate changes. (2) During long time- scale studies, lake level is the most important factor dominating sediment grain size.Sediments are finer during the humid period of high water level because coarse particles can not be transported tothe lake's deepwater part. On the contrary, during short time- scale studies within a given climate period, rainfallchange in the drainage basin becomes the key factor determining sediment grain size because the lake level is basi-cally constant. When rainfall is heavy, runoff flow is strong enough to bring coarse terrestrial particles to the sam-pling location, resulting in larger grain sizes. (3) The 15th century was the driest in the region of Lake Erhai during the past 640 years. There exist twotime - scales( 100 and 200 years) climatic quasi - periodical changes. From the end of the last century, the regionalclimate has been becoming drier and drier as a whole. At present, it is at the end of the dry period, so the regional climate will become humid in near future.关键词
沉积物粒度准周期变化干湿变迁洱海Key words
sediment grain size quasi - periodical changes dry- humid transformation Erhai Lake分类
资源环境引用本文复制引用
陈敬安,万国江,徐经意..洱海沉积物粒度记录与气候干湿变迁[J].沉积学报,2000,18(3):341-345,5.基金项目
国家自然科学基金(批准号：49894170)和中科院重大项目专题(KZ951-A1-402-06-04)资助项目 （批准号：49894170）
