| 长江河口水下三角洲210Pb分布特征及其沉积速率 |
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| 引用本文： | 张瑞,潘少明,汪亚平,高建华.长江河口水下三角洲210Pb分布特征及其沉积速率[J].沉积学报,2009,27(4):704-713. |
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| 作者姓名： | 张瑞 潘少明 汪亚平 高建华 |
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| 作者单位： | 南京大学海岸与海岛开发教育部重点实验室 南京 210093 |
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| 基金项目： | 国家重点基础研究发展规划(973计划)，国家自然科学基金 |
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| 摘 要： | 通过对长江水下三角洲采集的十个沉积物柱状样中的放射性核素210Pb分析得知，长江水下三角洲表层210Pb放射性比度在2.15~4.22 dpm·g-1之间，210Pb沉降通量在1.50~11.21 dpm·cm-2 yr-1之间，过剩210Pb总量在>48.29~>361.68 dpm·cm-2之间；210Pb沉降通量以及过剩210Pb总量均高于理论值，这表明在沉积物中存在210Pb的净输入和聚集。由210Pb放射性比度剖面所反映的沉积速率可知长江水下三角洲泥质沉积区沉积速率介于1.36~4.11 cm·yr-1之间；总体上呈现近岸沉积速率较低，沿31°N纬线向20 m等深线沉积速率升高的趋势，从122°15′E到122°30′E范围为长江水下三角洲的泥质沉积物堆积中心，其平均沉积速率为3.51 cm·yr-1。
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| 关 键 词： | 沉积速率 沉积通量 过剩210Pb总量 长江口 水下三角洲 |
| 收稿时间： | 1900-01-01 |
Sedimentation Rates and Characteristics of Radionuclide 210Pb at the Subaqueous Delta in Changjiang Estuary |
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| ZHANG Rui,PAN Shao-ming,WANG Ya-ping,GAO Jian-hua.Sedimentation Rates and Characteristics of Radionuclide 210Pb at the Subaqueous Delta in Changjiang Estuary[J].Acta Sedimentologica Sinica,2009,27(4):704-713. |
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| Authors: | ZHANG Rui PAN Shao-ming WANG Ya-ping GAO Jian-hua |
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| Institution: | Key Laboratory of Coast and Island Development, Nanjing University, Nanjing 210093 |
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| Abstract: | The 10 sediment cores were collected from subaqueous delta of Changjiang estuary in April 2006, using the gravity coring equipment. The length of the cores varied from 100 to 160cm. Following visual inspection for geological parameters and photography of the cores, they were subsampled at 2 cm intervals for the entire length of the cores. Profiles of 210Pb measured in 10 sediment cores were analyzed to elucidate the sediment rates as well as the characteristics of 210Pb. 210Pb (via 210Po) was determined by α spectrometry. Distribution of sedimentation rates reveals that during the last 100 years, the derived sedimentation rates vary from 1.36 to 4.11 cm·yr 1, and generally increase seaward the 20m isobaths. In addition, the region from 122°15′E to 122°30′E, i.e. from cores SC05 to SC11, is considered as the mud depocenter in Changjiang estuary, with the mean sediment rates of 3.51cm·yr 1. This pattern could coincide with the dispersal of Changjiang River derived sediments, with influence by the current and tidal systems. The 210Pb activities of the surfacial sediment vary from 2.15 to 4.22dpm·g 1, and 210Pb deposition fluxes from 1.50 to 11.21dpm·cm 2·yr 1, as well as excess 210Pb inventories between >48.29 and >361.68dpm·cm 2, respectively. The excess 210Pb inventories appear to be higher than the theoretical inventory at the subaqueous delta of Changjiang estuary. It is indicated that besides the atmospheric 210Pb fallout, the fluvial inputs could play an important role, whilst the much riverine sediment discharges may be scavenged and deposited at the subaqueous delta of Changjiang estuary. |
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