| 摘要: |
| 根据卫星遥感图像和历史观测资料分析 ,莱州湾的高悬浮物浓度区基本在以黄河口为中心的北侧海域 ,而湾顶往往浓度低。 2 0 0 2年 8月针对莱州湾的底质类型、悬浮物粒径分布以及海流、盐度的航次调查资料显示 ,莱州湾的底质类型决定着其悬浮物的分布形态。距黄河口较近的区域底质粒级分布呈明显的双峰结构 ,即一个较粗的峰值和一个较细的峰值 ,而较细的峰值与水体中悬浮颗粒的粒径相近 ;距河口较远站位的底质分布则呈现单峰结构 ,并且底质的粒径较粗。因此 ,在一般潮流作用下 ,河口附近底部沉积物容易形成再悬浮 ,水体中悬浮物浓度较高 ;而距河口较远的区域底部沉积物再悬浮相对困难 ,水体中悬浮物浓度较低。本研究结果对莱州湾悬浮泥沙分布形态给出了合理的解释。 |
| 关键词: 莱州湾 黄河口 悬浮物 再悬浮 粒径 |
| DOI： |
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| 基金项目:国家863青年基金资助项目,2001AA616100号;国家重点基础研究发展规划资助项目,2002CB412504号 |
附件 |
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| DISTRIBUTION OF SUSPENDED MATTER AND ITS RELATIONSHIP WITH SEDIMENT PARTICLE SIZE IN LAIZHOU BAY |
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JIANG Wen-Sheng,WANG Hou-Jie
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1.Laboratory of Physical Oceanography, Institute of Physical Oceanography, Ocean University of China, Qingdao,266003;2.Institute of Estuarine and Coastal Studies, Ocean University of China, Qingdao 266003
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| Abstract: |
| Indicated by satellite images and historical investigations, the suspended matter in Laizhou Bay was mainly distributed in the area near old Huanghe (Yellow) River mouth (1976-1996), while in shallow coastal area the suspended matter concentration was relatively low. At first glance this may result from the sediment and water flux from the Huanghe River. However, the high suspended matter concentration zone continues to exist in the years after 1996 despite the facts that the end channel of the Huanghe River was shifted to the north, and that the water and sediment flux from the Huanghe River to the sea has been reduced sharply in recent years.
A cruise in the Laizhou Bay was carried out on August 27-28, 2002 to reveal the formation of this high-turbidity zone. During the survey 20 grid stations were covered in 54 hours and water samples were collected in the surface, middle and bottom layers at each station, together with the sea currents recorded in the same layers, as well as the sediment samples taken at the seabed. The YSI multi-parameter probe was used to get in situ temperature, salinity, and turbidity profile. The size distribution of the sediment was measured by Cilas 940 L Particle Size Analyzer and the size distribution of the suspended matter was tested with Beckman Coulter Multisizer 3 Particle Analyzer.
Observed surface and bottom turbidity distribution shows a high suspended concentration zone centered near the old Huanghe River mouth, which well matches the satellite images of this area during the same period. Although measurements were not taken at the same time, the horizontal pattern of the turbidity does not associate with the pattern of high current velocity or surface wind. This implies that the stable pattern of the turbidity may be dominated by the size distribution of sediment on the seabed.
On the size spectrum, the surface sediment size in the survey area is less than 100μm. Horizontal medium size distribution is similar to that of turbidity. In addition, in the area around the Huanghe River mouth, the sediment size is less than 16μm, which corresponds to the high turbidity zone. However, such correspondence does not exist between the medium size of the suspended particles and that of the sediment. The suspended particles and the sediment are different not only in medium size value but also in size spectrum. At the stations near the river mouth, sediment grain size spectrum is characterized by a bi-modal pattern. The fine peak is very close to the suspended sediment peak in water column. At the stations far from the river mouth, the spectrums are in a mono-modal pattern with the grain size coarser than that of the stations near the mouth. Therefore, the pattern of the turbidity distribution in the Laizhou Bay is a result of the resuspension, which is in turn dominated by the grain size of the sediment and hydrodynamic states. In the area near the Huanghe River mouth, the fine-grained fraction (<16μm) of the bottom sediment is more subject to be resuspended than that at stations far from the Huanghe River mouth. Consequently, the suspended particle concentration is high near the mouth and low far off the mouth.
The horizontal distribution of the salinity illustrates a lower salinity zone extending from new Huanghe River mouth to the center of the Laizhou Bay, which implies an influence of freshwater dilution from the river. But the monthly mean of the water flux was only 50 m3/s during the cruise, resulting in low sediment discharge to the sea. Therefore, the high concentration of suspended matter in the high-turbidity zone is mainly due to resuspension of the sediment. This is important for understanding the suspended matter transport in the Laizhou Bay. |
| Key words: Laizhou Bay Huanghe River mouth Suspended matter Resuspension Particle size |
