松花湖沉积物^137Cs和^210Pb分布及沉积速率

Vertical Distribution of ^(137)Cs and ^(210)Pb and Sedimentation Rate in Songhua Lake

松花湖沉积物柱心中存在3个明显的137Cs蓄积峰,分别是37 cm处的1964年蓄积峰、27 cm处的1971年蓄积峰和23 cm处的1975年蓄积峰。利用137Cs核素1964年和1975年对应蓄积峰计算的沉积速率分别为0.86 cm/a和0.71 cm/a。采用210Pb计年的常量初始浓度模式(CIC)计算的平均沉积速率为0.71 cm/a,两者估算的沉积速率吻合。松花湖1964—1975年间的沉积速率明显高于1975—2006年间的沉积速率。137Cs和210Pb计年方法的结合有助于提高沉积速率估算的准确性。

Three distinct ^137Cs peaks formed at 1964, 1971 and 1975, respectively, are recognized in the sediment core of Songhua Lake. Using ^137Cs depths recorded in 1964 and 1975 as the datum levels, the sedimentation rate are calculated to be 0.86 cm/a and 0.71 cm/a, respectively. The average sedimentation rate is 0.71 cm/a calculated by CIC model of ^210Pb dating, which showed a good agreement with the result calculated by the ^137Cs. The sedimentation rate from 1964 to 1975 is higher than those from 1975 to 2006 in Songhua Lake. The combination of ^137Cs and ^210pb dating is meaningful in improving the estimating accuracy of the sedimentation rates.