太湖14000年以来古环境演变的湖泊记录

本文根据东西太湖短柱岩芯的沉积物的物理、化学、生物指标的综合分析,讨论了该区距今14ka来的古气候变化过程,结果表明14.3-13.3kaBP,太湖水位低,环境指标甚至表现为暴露特征,反映了气候干旱:13.3-12.4kaBP,为偏暖湿的过渡阶段;该孔柱270-280cm (11.5kaBP左右)各类指标均明显反映冷干特征,可能是YoungerDrays事件的记录,与我国东部其它地区有可比性;约10.9-10kaBP,这一时期是整个研究时段内一个较显著的温暖期。表现为还原沉积环境和水位相对较深;约10-7.2kaBP为冷暖交替的过渡带;7.2-5.737kaBP为暖湿气候;5.05kaBP多项分析指标发生突变,反映物源发生显著变化,可能存在沉积间断;表层沉积物则呈现现代环境的特征,西太湖藻类生长茂盛,偏氧化的沉积环境。目前湖泊生产力较高,富营养化程度高,表现为藻型湖泊特征;东太湖有机质来源以东太湖中生长较为茂盛的维管水生植物为主,目前湖泊生产力较低,富营养化程度低,表现为典型的草型湖泊特征。 

RECORD OF PALEOENVIRONMENTAL EVOLUTION OF TAIHU LAKE IN THE PAST 14000 YEARS

From the analysis of the magnetic susceptibility,TOC,TN,pigment,organic carbon isotope,HI,saturated hydrocarbon and ¹⁴C dating etc.of the sediment samples from cores of two boreholes in the Taihu lake,a knowledge of the evolution of paleoenvironment of the lake during the last 14ka is achieved.The results show that the lake has undergone the following stages:The Lake was at a low level,or even became exposed during 14.3-13.3kaBP,reflecting an arid climate.There existed a transitional stage during 13.3-12.4kaBP,the climate being slightly warm and wet.There are indications of a cold and dry climate around 11.5kaBP,probably corresponding to the Younger Drays event,comparable with other areas in east China.10.9-10kaBP is obviously a warm period with a reducing environment and relatively deep water.There was a alternation of cool and warm climate during 10-7.2kaBP.It was warm and wet during 7.2-5.737kaBP.Many climate indicators changed suddenly in 5.05kaBP,probably a reflection of change in material source and a sedimentation break.The uppermost surficial sediment shows features of a modern environment.The West Taihu Lake is of algae-type with high production and high eutrophication and is characterized by oxidation environment and flourishing algae.The East Taihu Lake is of macrophyte-type with low production and low eutrophication where the organic material mainly came from the exuberant aquatic vascular plants.