结合粒度和^(137)Cs对小流域水库沉积物的定年——以黔中喀斯特地区克酬水库为例  

Dating by sediment grain size and ^(137)Cs in small reservoir:a case study of Kechou reservoir, in Karst area of central Guizhou Province

作　　者：王文博[1] 蔡运龙[1] 王红亚[1] 

机构地区：[1]北京大学资源与环境地理系地表过程分析与模拟教育部重点实验室,北京100871

出　　处：《湖泊科学》2008年第3期306-314,共9页Journal of Lake Sciences

基　　金：国家自然科学基金重点项目(40335046)资助

摘　　要：对取自黔中喀斯特地区克酬水库32cm长沉积物柱样进行137Cs比活度以及粒度测定,结合气象站点降雨数据进行比对分析,对沉积物不同层位的年代进行了划分,并以此结合质量深度推算了1960-2004年间该水库的沉积速率.结合实例分析了137Cs沉降、运移和沉积,改进了仅依靠137Cs峰值定年方法,认为在流域面积较小、137Cs比活度测试绝对数值较小的流域,降水和其他条件造成的土壤侵蚀程度差异可能是造成土壤中137Cs进入湖泊沉积物多少的更主要原因,并表现为沉积物中137Cs不同层位的差异.A 32cm long sediment-core was sampled from Kechou reservoir located in Karst area of central Guizhou Province. According to study on grain size pattern and ^137Cs dating in the profile, comparing with precipitation records, we determined the sediment ages in different depth of this core. Using the cumulative mass depth, we also calculated the deposit rates in different stages from 1960 to 2004. We improved the traditional ^137Cs dating method which only relied on the position of peaks in profile. By analyzing the ^137Cs depositing transportation and sedimentation, we found that the absolute values of ^137Cs in the certain small catchment often appear in the low level. We believe that the soil erosion, which was caused by precipitation and other reasons, should intensively affect the amount of ^137Cs depositing from soil to the sediment in reservoir. That should be the main reason of different pattern of ^137Cs distributions in the sediment-core.

关 键 词：^137Cs定年 喀斯特小流域 水库沉积物 粒度 

分 类 号：P343.3[天文地球—水文科学]