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对沉积物柱样1,2的137Cs和210Pb定年分析,这两个样品137Cs最大蓄积峰值出现的年份分别为1963年和1986年。利用沉积物中137Cs蓄积峰,计算沉积物的深度沉积速率分别为0.153 1 cm·a-1、0.153 8 cm·a-1,计算出的质量堆积速率分别为0.048 4 g·a-1·cm-2、0.048 2 g·a-1·cm-2。210Pb计算出的两个柱样的沉积速率分别为0.052 0 g·a-1·cm-2,0.051 4 g·a-1·cm-2,137Cs和210Pb计算出的沉积速率,结果较为一致。由此可见,利用137Cs和210Pb综合定年,相互印证,可以消除一些偶然因素带来的定年偏差,进而较准确地计算湖泊沉积速率,这对研究青海湖近现代环境变化具有一定的现实意义。
The 137Cs and 210Pb dating of sediment-like samples 1 and 2 showed that the maximum accumulation peak of 137Cs in these two samples appeared in 1963 and 1986, respectively. The 137Cs accumulation peak in the sediment was used to calculate the depth sediment deposition rates of 0.153 1 cm · a-1 and 1 · 053 8 cm · a-1, respectively. The calculated mass accumulation rates were 0.048 4 g · a-1 · cm -2,0.048 2 g · a-1 · cm-2.210Pb calculated the deposition rate of the two column samples were 0.052 0 g · a -1 · cm -2,0.051 4 g · a -1 · cm- 2,137Cs and 210Pb calculated deposition rate, the results are more consistent. Therefore, the comprehensive dating of 137Cs and 210Pb confirms each other, which can eliminate the discrepancy of years caused by some accidental factors, and then calculate the lakes sedimentation rate more accurately. This is of practical significance for studying the recent environmental changes in Qinghai Lake.