中文摘要：

为了研究新安江水库过去环境变化和预测区域环境质量,选取了水库的3个代表性区域采集沉积物柱心,运用放射性核素计年技术、结合粒度变化特征,计算了水库建库以来的分段沉积速率,分析了沉积环境演化。研究发现,湖心区沉积柱在32 cm处存在明显的~（137）Cs识别峰,该峰时标为1964年。基于~（210）Pb CRS计年模型获得库区过去60年的沉积年代,32 cm处时标为1963年,与~（137）Cs计年结果一致;两者1964~2015年平均沉积速率均为0.23 g/（cm~2·a）。放射性核素计年与沉积事件研究表明,利用沉积物粒度变化指示的沉积事件能够为近代沉积计年提供可靠的依据;结合各点分段沉积速率,说明建库事件相较于大范围泄洪对沉积速率的影响更大。

英文摘要：

In order to study historical environmental change and forecast regional environmental quality of the Xin＇anjiang Reservoir in Zhejiang province,cores of lacustrine sediments collected from three representative zones of the reservoir have been studied for calculating the segmented sedimentation rates and analyzing evolution of the sedimentary environment of the Xin＇anjiang Reservoir since its establishment based on radionuclide dating and variation characteristics of grain-size in sediments. It is noticed that there is an obvious identifiable peak of ~（137）Cs at depth of 32 cm for core of sediments in the center of the reservoir,with time marker of 1964. This is identical to the time marker of 1963 which is obtained based on ~（210）Pb CRS dating model of core sediments depositedin the reservoir in past 60 years. From 1964 to 2015,the annual mean mass sedimentation rate is 0. 23g/（ cm~2·a）. The radionuclide dating and sedimentary event study show that the sedimentary events indicated by the variation of grain-sizes of sediments can provide reliable evidence for dating modern sediments.Combing with the segmented sedimentation rates of sediments in various sites of the reservoir,it is believed that the sedimentation rate of sediments was more strongly influenced by the reservoir building event than by the large-scale flood discharge.