^(137)Cs测年的东北兴凯湖现代沉积速率研究  

Sedimentation Rate in Lake Xingkai,Northeastern China,Based on^(137)Cs Dating

作　　者：廖东霞 郭海婷 吴孟孟 潘少明[1] LIAO DongXia;GUO HaiTing;WU MengMeng;PAN ShaoMing(School of Geography and Ocean Science,Nanjing University,Nanjing 210023,China)

机构地区：[1]南京大学地理与海洋科学学院,南京210023

出　　处：《沉积学报》2022年第6期1718-1727,共10页Acta Sedimentologica Sinica

基　　金：国家重点研发计划(2016YFA0600502);国家自然科学基金(41671466)。

摘　　要：对兴凯湖我国水域沉积物^(137)Cs比活度及通量空间分布进行了研究,利用^(137)Cs测年法建立年代框架,估算了兴凯湖的沉积速率,结合粒度C-M图分析了湖泊现代沉积环境。兴凯湖我国水域西岸白棱河河口区域^(137)Cs剖面形态区别于典型的^(137)Cs全球大气沉降模式,且^(137)Cs沉积通量高、平均^(137)Cs活度高,中部和东部区域^(137)Cs沉积通量低、平均^(137)Cs活度低;^(137)Cs沉积通量的空间分布主要受流域输入、水动力条件以及沉积物粒径的影响。兴凯湖沉积环境多表现为静水沉积,受特殊的风浪条件和泄洪闸等人类活动的影响,1963—2019年平均沉积速率空间分布上呈现西部高,中、东部低的特点,XKH-1、XKH-2和XKH-3柱样1963—2019年的平均沉积速率分别为0.143 cm/a、0.080 cm/a和0.036 cm/a。Lacustrine sedimentary records are very significant for gaining an understanding of basin erosion,since they reveal regional climatic and environmental changes and the influence of human activities.The^(137)Cs dating meth⁃od,which has been widely used since the early 1970s,has greatly promoted high-resolution studies of climate and en⁃vironmental changes recorded in lake sediments.Based on^(137)Cs dating and particle-size analysis for Lake Xingkai sed⁃iment cores,the distribution of^(137)Cs was investigated to calculate modern sedimentation rates and the reasons for the different rates.An inventory of^(137)Cs deposition was compiled for the sediment cores,and the modern sedimentary en⁃vironment of Lake Xingkai was analyzed using C–M diagrams.The main findings of the study were:(1)The estuary region of the Bailing River west of Xingkai Lake is under the dual influence of terrestrial input and sediment distur⁃bance,causing uniform and higher^(137)Cs concentrations in the upper part of the vertical profile.This differs from the typical^(137)Cs global atmospheric precipitation model.In Lake Xingkai the global^(137)Cs fallout peak(due to atmospheric nuclear weapons testing in other parts of the world in 1963)is smaller than in most lakes in northeastern China,main⁃ly influenced by the grain size of the sediment.(2)The deposition inventory and average activity of^(137)Cs in the Bailing River estuary region in western Lake Xingkai is higher than in the central area.Deposition in Lake Xingkai is affected by basin input,hydrodynamic conditions and sediment particle size.(3)The average sedimentation rates in⁃dicated in cores XKH-1,XKH-2 and XKH-3 are 0.143 cm/a,0.080 cm/a and 0.036 cm/a,respectively,from 1963 to 2019.Due to the influence of the particular wind/wave conditions and human activities(e.g.,release sluices),the regional sedimentation rate in central and eastern Lake Xingkai is lower than in the west.(4)The particle sizes in all cores from Lake Xingkai indicated by the C-M charts are located eithe

关 键 词：兴凯湖 ^(137)Cs 现代沉积速率 

分 类 号：K903[历史地理—人文地理学]