高分辨湖泊沉积和孢粉记录对气候、水文变化的响应

High-resolution Records of Lacustrine Sedimentology and Palynology Responding to Changes in Climate and Hydrology

通过对长江中游网湖钻孔高精度分层样品(1.5年/样品)的沉积学和孢粉学研究,试图揭示过去百年网湖在由开放到封闭体系变化中,沉积孢粉与气候、水文动力变化的过程及其相互关系。相关分析和低频滤波分析,反映出沉积物和孢粉的变化对流域降水和长江流量的敏感响应。在过去130年中的多雨洪水年份,湖泊受长江倒灌影响,沉积物以黏土细颗粒为主,并接受长江上中游孢粉的沉积;而在少雨枯水年份中,以源于流域的粉砂粗颗粒沉积为主,湖泊水域和周边湿地的水生孢粉大量沉积。时间序列的频谱分析显示了沉积物中值粒径、乔灌木和水生花粉、降水和流量都具有3～4年和9～11年周期变化。网湖的沉积孢粉与水动力关系为利用湖泊孢粉沉积记录重建过去湖泊环境、认识湖泊水系通江与封闭的水动力变化提供科学依据。

This paper studied high-resolution sedimentary pollen sequence（1.5 yr/e） of Wanghu Lake,in the middle reach of Yangtze River,and analyzed the relationships of changes in pollen types and contents,sediment granularity,and climate-hydrology features during the past hundred years when the lake turned from an open water system into closed basin.Correlation analysis for time series of pollen,granularity,catchment precipitation and river discharge,showed that significant linear relationships with 95% confidence level.Major pollen types showed a 27%-40% synchronous changes with time series of granularity and precipitation during the past 130 years,and a 47%-57% synchronous changes with time series of granularity and river discharge before the mid-1960’s when the lake naturally connected with Yangtze River,suggesting pollen deposition controlled by sediments and catchment precipitation.The author found synchronous changes among sedimentary granularity and pollen with precipitation and river discharge which all experienced 3-4 years and 9-11 years cycles in the time series,suggesting sedimentation responding to climate changes.This study may provide scientific basis to reconstruct past environmental changes using sediment and pollen records,and to understand bio-sedimentology dynamics in the lake sediments.