^(210)Pb和^(137)Cs法对比研究武汉东湖现代沉积速率

A comparative study on recent sedimentation rates in Lake Donghu, Wuhanwith ^(210)Pb and ^(137)Cs dating techniques

对采自东湖 站和 站的沉积物采用210Pb和137Cs相结合的方法测定沉积速率,210Pb法测出东湖 站和 站的沉积速率为8.73mm/a和6.90mm/a,137Cs测出东湖 站和 站的沉积速率为7.4mm/a和5.8mm/a.分析了两种方法测定结果差异产生的原因,并与以往的研究相对比,探讨东湖沉积速率空间分布的规律性,沉积速率变化与人类活动的关系、沉积速率与扰动的关系.

Two undisturbed sediment cores at 90 cm and 150 cm at the StationⅠ and Ⅱ in Lake Donghu, Wuhan, were collected respectively. Environmental ()^(210)Pb and ()^(137)Cs dating techniques were applied to determine recent sedimentation rates. The results showed that: (1)The recent sedimentation rates of sediment at StationⅠandⅡdetermined by ()^(210)Pb are 8.7 mm/a and 6.9 mm/a. While the recent sedimentation rates determined by ()^(137)Cs are 7.4 mm/a and 5.8 mm/a. After contrasting ()^(210)Pb and ()^(137)Cs dating techniques, this paper figured that: (1)()^(137)Cs dating technique was more reliable. ((2) The) recent sedimentation rates gradually decreased from Station Ⅰto Station Ⅱdue to the differences of substance supply and sedimentary environments. (3) The recent sedimentation rates from 1964 to 1975 were greatest, and it decreased from 1964 to 2002, which were both possibly attributed to human activities. (4) The sediment at Station Ⅰand Station Ⅱwas disturbed by biodisturbance and mechanic disturbance.