中文摘要：

对长江口泥质区Chjk01与E4站位的沉积物柱状样进行了210^Pb测年和粒度分析，结果显示Chjk01孔与E4孔的沉积年代分别为132年（1873-2005年）与41年（1962-2003年），平均沉积速率达2.8cm/a与3.5cm/a。高密度间隔（0.5-1.0cm）粒度分析达到了反映粒度季节性变化的高分辨尺度。两孔粉砂含量随深度基本保持不变，粘土与砂含量则互为消长。Chjk01孔沉积物粒度自1873年以来明显呈三段式变化，1873-1957年间的84年中粒度稳定地逐渐变粗、砂含量增加、粘土含量减少、分选变差；1957-1981年间的24年中粒度逐渐变细、粘土含量增加、砂含量减少、分选变好，在1970-1981年间的11年中粒度最细；1981-2005年间的24年中粒度总体变粗、砂含量波动式增大，但变化趋势不明显。E4孔在1962-2003年间的41年中，沉积粒度特征与Chjk01孔基本一致。1873年以来的132年期间长江口泥质区粒度变化的阶段性特征，主要与同时期长江水沙入海主泓位置，以及主汊道的分沙比阶段性演变相对应；长江口泥质区粒度长尺度的阶段性变化，对长江大通站（1950-2004年）水沙变化和东亚季风强度指数（1873-1995年）变化不敏感。因此，长江水沙入海主泓位置与两孔位置距离的变化是影响泥质区粗、细粒级含量相对变化的主控因素，掩盖了其他因素的影响。

英文摘要：

Sediment grain-size analysis and 210^Pb dating of two piston cores taken at station Chjk01 and E4 in the mud area off the Changjiang estuary were conducted. The 210^Pb dating of the two cores showed that the mean sedimentation rate of the cores of Chjk01 and E4 were 2.8cm/a and 3.5cm/a, respectively, in corresponding to the sedimentation duration of 132a （ 1873 - 2005） for core Chjk01 and 41a （ 1962 - 2003） for core E4. With sampling interval of 0.5 - 1.0cm the sediment grain size records with seasonal resolution were documented. The content of sand and clay varies in an opposite way, while the content of silt remains quite stable. Variation of grainsize parameters in core Chjk01 illustrated clearly a three-phasic changes since 1873：1 ） The grain size became gradually coarser and coarser since 1873 to 1957 with increasing mean size, sand content, and standard deviation and decreasing clay content; 2） The grain size became finer during 1957 - 1981 with decreased mean size, sand content and standard deviation, and decreased clay content. The finest part is the sediment in 1970 - 1981 ; 3） The grain size became coarser again during 1981 -2005 with fluctuatedly increased mean size and sand content. Variation of grain-size characteristics of core E4 during 1962 - 2003 was in an agreement with that of core Chjk01 in general. The three-phasic variation of grain size is generally in accordance with the phasic evolution of the mean stream channel in the Changjiang estuary since 1873 as the location of the Changjiang trunk stream to the sea was changed with the channel evolution, resulting in phasic change of the distance between the sampling stations and the location of the Changjiang mean stream to the sea. The variations of water and sediment discharge at the Datong Station in 1950-2004 and the Asian monsoon index in 1873 -1995 show little effect on variations of features of grain-size and its sensitive part. Therefore, the variation of distance between the location of the trunk stream of the Changjiang