会仙喀斯特湿地沉积物的沉积速率

Deposition Rate of Sediment in Huixian Karst Wetland

为了研究会仙喀斯特湿地沉积物的沉积速率,在会仙喀斯特湿地设置了4个采样点,于2018年12月10日,根据实际采样条件,在各采样点采集了不同深度的沉积物样品,测定沉积物岩芯中^(210)Pb的比活度值并分析其垂直分布规律;利用^(210)Pb计年常用模型中的恒定通量恒定沉积模型,计算得到会仙湿地沉积物的沉积速率。研究结果表明,会仙湿地沉积物中的过剩^(210)Pb的比活度值为1.73~48.69 Bq/kg,随着沉积物深度的增加,4个采样点沉积物岩芯中的过剩^(210)Pb比活度值波动较大但总体上在减小;利用^(210)Pb计年的恒定通量恒定沉积模型,计算得到采样点3(木林沙)和采样点4(竹红江)沉积物的平均沉积速率分别为0.81 cm/a和0.67 cm/a。

In order to study distribution of ^(210)Pb in the sediment and the deposition rate of sediment,four sampling sites were set in Huixian karst wetland.According to the actual situation,the sediment samples at different depths were collected on December 10,2018,and the specific activity of ^(210)Pb in sediment cores and its vertical distribution were investigated.Using the constant flux constant sedimentation model,which was commonly used in ^(210)Pb dating model,the deposition rate of sediments in Huixian karst wetland was calculated.The results showed that the specific activity values of the excess ^(210)Pb in the sediments in Huixian wetland were 1.73-48.69 Bq/kg.With the sediment depth increased,the specific activity values of the excess ^(210)Pb in the sediment cores from the four sampling sites fluctuated greatly,but the specific activity values of the excess ^(210)Pb decreased in general.The average deposition rates of sediment cores at sampling site 3(Mulinsha)and sampling site 4(Zhuhongjiang)were 0.81 cm/a and 0.67 cm/a,respectively through the ^(210)Pb age constant flux constant sedimentation model.In recent years,with the global warming and the increasing pressure of population growth,the Guilin Huixian wetland might be affected by the external environment or human activities more severely,resulting in the increase of deposition rate in this area.