摘要
利用放射性核素210Pb、137Cs及241 Am测年方法,确定上级湖表层沉积物的年龄、沉积速率及其变化,分析湖泊沉积速率变化与自然环境演化、人类活动(尤其是修筑堤坝等水利工程)之间的关系,为合理开发利用湖泊资源、保护生态环境提供理论依据。137Cs测年结果表明,沉积柱芯中137 Cs 1964年时标不明显,不存在1975年、1986年时标;利用241 Am及210Pbex辅助计年,确定质量深度6.37g.cm-2处为1964年,至表层的平均沉积速率为0.135g.cm-2.a-1。利用210PbexCRS模式计算出每个样品深度所对应的年代,与历史资料较吻合。210PbexCRS计年结果显示,自1859年以来上级湖的沉积速率不稳定,以二级坝建成使用的1960年为界,划分为建坝前平均沉积速率低及建坝后沉积速率上升两个大的时段。上级湖沉积速率的变化与流域旱、涝变化及人类活动有关。
Using radioactive nuclides 210 Pb,137 Cs and 241 Am dating methods, to make sure that the age and sedimentation rate change of surface sediment of higher-up lake, analyze the connection between lake sedimentation rate changes and natural environment evolution, human activities （especially the construction of dams and other water conservancy projeets）, offering the theory basis to utilize lake resources and protect the ecological environment reasonably. The result of 137 Cs dating shows that 137 Cs time mark of 1964 was not obvious and time marks of 1975 and 1986 did not exist in DS sediment core. With the assist of 241Arn and 210pbex dating,it was made sure that the age at mass depth of 6. 37 g.cm-2 was 1964 and the average sedimentation rate from the mass depth to surface of DS core was 0. 135 g.cm-2· a-1. The ages of the samples calculated by 210pbex modal were agreed with historical information. The result of 210 Pbex CRS dating showed that sedimentation rate of higher-up lake had changed since 1859. The deposition process of higher-up lake can be divided into two periods by 1960 when Erji dam constructed. The average sedimentation rate was slow before 1960 and relatively fast after then. The sedimentation rate changes of higher-up lake were related with dry or flood weather and human activities of the drainage basin.
出处
《地理与地理信息科学》
CSCD
北大核心
2012年第5期90-94,共5页
Geography and Geo-Information Science
基金
国家自然科学基金面上项目(41173094)
国家自然科学基金重点项目(41030751)
江苏高校优势学科建设工程资助项目
枣庄市科学技术发展计划项目(200818-2)
