摘要
通过对属都湖Esdr1孔沉积物粒度、磁化率等指标研究,利用137Cs建立年代标尺,结合文献和降水数据讨论了人类活动对湖泊沉积环境的影响。结果表明：17-14 cm（1958—1970年）沉积物中粗颗粒的砂含量和磁化率值急剧增加,分析应是20世纪50年代末流域大面积砍伐森林,强烈的水土流失所致;14-8 cm（1970—1988年）沉积物粒径变细,磁化率值降低,指示流域植被逐渐恢复,流域侵蚀减弱;8-0 cm（1988年至今）沉积物黏土含量升高、砂含量降低,应是湖泊出口处修建的水坝改变了湖泊水动力条件所致。
A sediment core Esdrl from Shudu lake was analyzed for grain size and magnetism. Accurate sediment chronology was established by ^137 Cs. By comparing the grain-size and magnetism proxies to document and precipitation data, we discussed the influence of disafforestation and dam on depositional environment. Both magnetic susceptibility and grain-size proxies increase remarkably at 17-14 cm（1958-1970） depth. Precipitation data reveal a decrease during this period. But county annals record that there was intense disafforestation from 1958 to 1963. Vegetation cover deterioration will lead to serious erosion in drainage area. More sand and silt transport to lake, which causes grain-size and magnetic susceptibility values to increase. Both precipitation and constructing dam affect lake sediment composition. The precipitation increased from 1988 to 2002. A dam was constructed at the lake outlet in 1988,which enlarged lake area. Finer sediments deposited with streamflow disappearance. Although precipitation slightly increased from 1988 to 2002 ,it is obvious that dam construction has more influence on lake sediment environment. It may be why grain size in Esdrl core became finer at 8-0 cm depth （1988-2002）.
出处
《海洋地质与第四纪地质》
CAS
CSCD
北大核心
2007年第5期115-120,共6页
Marine Geology & Quaternary Geology
基金
国家自然科学基金项目(40402015)
国家自然科学重点基金项目(40331003)
国家杰出青年基金项目(40625007)
关键词
湖泊沉积
粒度
磁化率
人类活动
沉积响应
lacustrine sediment
grain size
magnetic susceptibility
human activities
deposition
Shudu Lake
