Evaluation of Sediment Accumulation in Dianchi Lake Using 137Cs Dating
借助137Cs估算滇池沉积量

Based on the 137Cs activity and the specific geographical location of the Dianchi Basin, the 137Cs in the soil of Dianchi Basin and in the sediment of Dianchi Lake are derived from both the fallout of the world nuclear tests and that of China nuclear tests. Therefore, some sediment layers in special years, such as 1954, 1963, 1976 and 1986, can be identified by special distribution of 137Cs activity in the sediment cores. The mean annual accumulation mass of sediment per unit area (sediment accumulation rate) for a specific period can be calculated based on the accumulation mass of the various periods. The mean annual accumulations are diverse in different parts of the Dianchi Lake. But it is well agreed with the fact that sediment accumulation in the center of the lake is smaller than that of the lakeside. Then according to the shape of the lake, landforms of the lake basin, sources of sediment and other factors, Dianchi Lake is divided into five zones: central lake zone far from bank (I), central lake zone close to bank (II), western lake zone (III), eastern lake zone (IV) and southern lake zone (V). And using Geographic Information System (GIS), area of each zone is calculated. The total amounts of mean annual sediment accumulation of each zone for various periods is obtained by area of zone multiplying the sediment accumulation rate. The mean annual total amounts of sediment accumulations of the above five zones are 0.0572, 0.0925, 0.1249, 0.1095, and 0.0842 g/cm2a, respectively.