长江口及邻近海域现代沉积速率及其对长江入海泥沙去向的指示意义  

Sedimentation Rates and Its Indication to Distribution of Yangtze Sediment Supply around the Yangtze (Changjiang) River Estuary and Its Adjacent Area, China

作　　者：王昕[1,2] 石学法[2] 王国庆[3] 乔淑卿[2] 刘涛[2] 

机构地区：[1]鲁东大学地理与规划学院,山东烟台264025 [2]海洋沉积与环境地质国家海洋局重点实验室,国家海洋局第一海洋研究所,山东青岛266061 [3]中国地质大学地球科学学院,湖北武汉430074

出　　处：《地球科学（中国地质大学学报）》2013年第4期763-775,共13页Earth Science-Journal of China University of Geosciences

基　　金：海洋公益性行业科研专项(No.200805063);中国科学院海洋地质与环境重点实验室开放基金(No.MGE2012KG09);国家自然科学基金项目(No.41076023);海上试验场建设技术研究和原型设计(No.200905024)

摘　　要：对长江口及附近海域的16根重力柱样进行了210Pb沉积速率测试,结合以往成果,揭示了该区现代沉积速率分布格局,对其控制因素以及其对认识长江入海泥沙去向的指示意义进行了探讨.沉积速率最高值分布在南支口外、杭州湾口群岛北部的前三角洲地区,最高可达6.3m/a,总体上在3cm/a以上;次高值分布在杭州湾北部,约1.7～3.0cm/a,南部略低,约0.4～1.0cm/a;长江口水下负地形北部海域存在小片沉积速率较高的区域,最高值达2.58cm/a;低值主要分布在苏北辐射沙洲、过渡沉积区以及浅海陆架的大片区域,基本保持在1cm/a以下.研究表明,长江泥沙出口门后主要在水下三角洲地区进行了堆积,其次有相当部分在涨潮流顶托下进入杭州湾,进入杭州湾南部的泥沙又在落潮流作用下经杭州湾南侧向舟山海域方向输运;长江入海物质向外海的扩散基本被控制在123°E以西,苏北辐射沙洲、过渡沉积区以及浅海陆架的大片区域缺乏现代长江物质供应;长江悬浮泥沙对研究区东北部陆架区影响较小,废黄河口被侵蚀物质和黄海悬浮物质为其较高沉积速率的主要贡献者.Based on 210 Pb data of 16 gravity core samples and from the previous study, the spatial pattern of sedimentation rates and its indication to distribution of Yangtze sediment supply in the Yangtze River estuary and its adjacent area were examined. The high accumulation rates were observed at the subaqueous delta off the south branch with the maximum value of 6. 3 cm/a, generally above 3 cm/a. The second highest values distribute on the Hangzhou bay, about 1.7--3.0 cm/a in north and much lower in south （0. 4--1.0 cm/a）. Relative higher sedimentation rates, about 2.58 cm/a, appear in the northwest of study area. The radial sand ridges along the north Jiangsu coastal line, delta-shelf transitional zone and continental shelf were characterized by low sedimentation rates （~1 cm/a）, due to the strong hydrodynamic setting and lack of modern Changjiang material sup- ply. As revealed by this study, a large amount of Yangtze sediment load is deposited around the subaqueous delta and the north Hangzhou Bay. The dispersion of modern Yangtze sediment to East China Sea is constrained to the west of 123~E. The rela- tively high sedimentation rate in north continental area is mainly contributed by sediment eroded from the abandoned Yellowdelta and suspended materials transported by Yellow Sea longshore currents.

关 键 词：长江水下三角洲 210Pb 沉积速率 输沙 海洋学 

分 类 号：X141[环境科学与工程—环境科学]