长江口动水絮凝沉降与拦门沙淤积的关系

THE RELATIONSHIP BETWEEN FLOCCULATING SETTLEMENT IN FLOWING WATER AND DEPOSITION IN THE CHANGJIANG RIVER ESTUARY MOUTH BAR AREA

根据1982年4月－1983年3月长江口南槽3个站位全年逐月大潮的水化学成分、悬沙粒度与粘土矿物资料，1984－1992年在环形水槽中获得的近百个组次的动水絮凝沉降试验研究资料，以及长江口细颗粒泥沙、浮泥与底质研究成果，对拦门沙形成过程及其机理进行综合研究。结果表明，长江口拦门沙为最年轻的活动三角洲，汛期集中输水输沙与台湾暖流同期相遇，为动水絮凝沉降最强和浮泥最为发育时期；涨潮期当盐度为（9－13）x10－3时，伊利石、高岭石在盐水楔顶部发生动水絮凝沉降，而落潮期当盐度在（19—24）X10－3时，蒙脱石在盐水楔尾部发生动水絮凝沉降，揭示了拦门沙水平淤积的基本规律；半月周期的浮泥透镜体所残积的中、粗粉沙形成钻孔中常见的透镜体与薄层理，则揭示了拦门沙的垂直加积的基本规律，为拦门沙综合治理与深水航道的开发利用提供科学依据。

Based on the water chemical components, the suspended grain size and clayminerals data in the Changjiang River Estuary South Channel, every springtide fromApril, 1983 to March, 1984, and about a hundred flocculating settlement test dataon flowing water, which were undertaken in the circle water channel from 1984 to1992, and the results of study on the fine sediments, fluid mud and bottom. sedim-ents, the formingprocess and mechanism of mouth bar were comprehensively studied.It was shown that the mouth bar is the youngest active delta in the ChangjiangRiver Estuary during the flood season, while the area where the Changjiang runoffand Taiwan warm current meet off the Changjiang Estuary was the strongest floccu-lating settlement and most active fluid mud development. The illites and kaolinitesare flocculated and deposited at the salt water wedgehead where the water salinityis about 9 X 10-3-13 X 10-3 during flood time and the montmorillionites are floc-cu1ated and deposited in the salt water wedgetail where the water salinity is aboutl9 X 10-3-24 X 10-3 during the ebb time, which show the essential regularities ofthe horizontal deposition in the mouth bar area. The fluid mud lens which growsand declines in a semi-month cycle produces a coarse and medium silt relic lens and.beddings, which show the essential regularities of vertica1 ccumuItion in ChngjingRiver Estury mouth bar are. The above findings provide the scientific base for thecomprehensive mangement and deep waterway desingand uses of mouth bar.