岱海^(14)C测年的现代碳库效应研究  

MODERN RESERVOIR AGE FOR ^(14)C DATING IN DAIHAI LAKE

作　　者：吴艳宏[1] 王苏民[1] 周力平[2] 孙照斌[1] 

机构地区：[1]中国科学院南京地理与湖泊研究所,南京210008 [2]北京大学地理学院地表过程分析与模拟教育部重点实验室,北京100871

出　　处：《第四纪研究》2007年第4期507-510,共4页Quaternary Sciences

基　　金：国家自然科学重点基金项目(批准号:90411017)资助

摘　　要：碳库效应的复杂性是影响建立湖泊沉积物高精度年代序列的一大障碍。本项研究通过我国内蒙古半干旱区封闭湖泊表层沉积物、湖水、现生沉水植物狐尾藻、现生鲤鱼鱼骨和湖岸表层土壤等一系列样品的14C年代测定,表明现代岱海确实存在碳库效应。碳库效应年龄因湖水盐度在湖区的不均而有所变化,岱海西部湖区弓坝河径流补给量大,湖水盐度较东部稍低,碳库效应年龄也略小于东部湖区。表层沉积物中有机质包含浮游生物和沉水植物的混合信息,因而其碳库效应年龄较沉水植物年龄轻,岱海湖心表层沉积物碳库效应年龄在2000a左右。这一碳库效应年龄较通过沉积钻孔14C年龄线性回归获得的年龄偏大,可能的原因是在时间序列上碳库效应并非恒定。Reservoir effect on ^14C dating is a common problem in marine and lacustrine sediments. Our knowledge of reservoir ages, either modern or ancient, is still very limited. We present here a series of ^14C ages of lake surface sediments, lake water, submerged aquatic plant （Myriophyllum）, fish （Cyprinus carpio） bone, and surface soil samples from the Daihai Lake, which is a closed lake located in semi-arid area of Inner Mongolia, China, in order to evaluate the modern reservoir age. Our results confirm that in the Daihai Lake, modern reservoir effect does exist in surface lake sediments, lake water, soil, submerged aquatic plant and even in the fish bones. The modern reservoir age varies with salinity in different parts of the lake. In western part of the lake, which is fed by more fresh water from the Gongba River, the salinity is a little lower than in the eastern part. The reservoir age there is younger than that in eastern part correspondingly. The reservoir age of the surface lake sediments is younger than that of submerged aquatic plant because of the organic matter＇in lake sediments which is a mixture of plankton and submerged plants. The reservoir age of the surface lake sediments from the center of the Daihai Lake is estimated to be ca. 2000a. This reservoir age is significantly older than those in some recent literatures which were obtained using linear extrapolation method. A possible explanation for the discrepancy is that the reservoir effect is temporally variable.

关 键 词：^14C测年 碳库效应 湖泊沉积物 岱海 

分 类 号：P343.3[天文地球—水文科学] P597[天文地球—地球物理学]