长江口邻近陆架沉积物粒径变化趋势及动力成因  

Trend and Dynamic Cause of Sediment Transport on the Adjacent Continental Shelf of the Yangtze River Estuary

作　　者：杨云平[1,2] 李义天[2] 张明进[1] 刘万利[1] 樊咏阳[2] 

机构地区：[1]交通运输部天津水运工程科学研究所内河港航中心,天津300456 [2]武汉大学水资源与水电工程科学国家重点实验室,湖北武汉430072

出　　处：《海洋通报》2015年第2期138-145,共8页Marine Science Bulletin

基　　金：973计划项目(2010CB429002);国家自然科学基金(51209112)

摘　　要：基于长江口外邻近陆架近20年实测数据,分析了邻近陆架区域表层沉积物中值粒径、砂-泥分界线和泥质区变化规律,并探讨了自然机制和人类活动等对其影响。结果表明:1近期(2006-2010年)长江口邻近陆架区域沉积物中值粒径和砂、粉砂和粘土等值线分布格局较2006年以前未发生明显变化;2伴随流域入海泥沙量和海滨区悬沙浓度的减小,陆架区域表层沉积物中值颗粒表现为粗化趋势发展;3陆架区域砂-泥分界线2004-2007年在北侧(31°30′以北)无明显趋势,南侧(31°30′以南)为向口内移动,2008-2010年无论南侧还是北侧均为向口内移动,主要受长江径流枯水期,引起潮流水动力相对增强、悬沙浓度减小及苏北沿岸流等影响;4泥质区域为长江口沉积速率最大区域,由于入海泥沙和海滨区域悬沙浓度降低,三角洲侵蚀等环境下表现为减小趋势,因北槽深水航道整治工程的实施改变了南北槽分流比,南槽下泄径流水动力增加,使得泥质区位置存在南偏趋势。Based on the measured data in recent 20 years, the changing trend of the median grain size of the surface sediment, the sand-silt boundary and the argillaceous area on the adjacent continental shelf of the Yangtze River Estuary were analyzed thoroughly, and the effects of natural mechanism and human activities were discussed. The results showed that： 1 In recent years（2006-2010） the median grain size of sediment and the distribution pattern of grouped sediment in the adjacent continental shelf area to the Yangtze River Estuary did not change obviously compared with that before2006; 2 The medium-sized particles of the surface sediment in the continental shelf area displayed a coarsening trend with the decrease of sediment discharge from the basin and the drop of suspended sediment concentration in the shore area; 3In 2004-2007, the sand-silt boundary in the north part（north off 31°30′） of the continental shelf area did not show a clear moving trend, while that in the south part（south off 31°30′） moved inwards; In 2008-2010, the sand-silt boundaries both in the north and in the south parts of the continental shelf area moved inwards, the main reason ofwhich was that the dry season of the Yangtze River resulted in a relatively enhanced hydrodynamic force of the tides, a decreasing suspended sediment concentration and a flow along the banks in the Northern Jiangsu; 4 The maximum deposition rate is found at the argillaceous area in the Yangtze River Estuary, and it tended to shrink due to the drop of sediment discharge from the basin and the decrease of suspended sediment concentration in the shore area and erosion in the delta. Moreover, it tended to shift to the south at the same time because the implementation of the renovation project on the deep-water channel of the north passage changed the split ratio between the north and south passages with an increase in the power of the discharged runoff in the south passage.

关 键 词：表层沉积物 砂-泥分界线 泥质区 趋势及成因 邻近陆架 长江口 

分 类 号：P67[天文地球—海洋地质]