中文摘要：

沉降运动是悬浮物主要运动形式之一,是影响营养盐内源释放的主要运动过程,研究悬浮物沉降速度对湖泊富营养化的研究具有重要意义.为了解浅水湖泊悬浮物的沉降特征,以太湖梅梁湾为例,采用声学多普勒流速仪,光学后向散射浊度仪以及风速风向仪在梅梁湾进行了连续9 d的野外观测.采用扩散沉降平衡的方法计算小风速情况下悬浮物的沉降速度,并对沉降速度与垂向流速、风速、悬浮物浓度的关系进行分析.结果表明悬浮物平均沉降速度为0.0785 mm/s,表层垂向流速和悬浮物浓度对悬浮物沉降速度变化起主要作用;而在底层,风速、垂向流速、悬浮物浓度都对悬浮物运动有重要影响,具体表现为风速〉1.5 m/s时,垂向流速紊动增大,悬浮物因起悬而浓度较大,并且沉降速度波动较大;风速〈1.5 m/s时,垂向流速基本向下且流速较小,沉降速度也较小.本文揭示了大型浅水湖泊悬浮物的动态沉降特征,为今后太湖污染物的输移、水环境数学模型和湖泊富营养化的深入研究奠定了必要的基础.

英文摘要：

Suspended solid settlement is one of the main transport forms, and plays an important role in lake nutrient release. Thus, study on suspended solid settling velocity is significant to understand the eutrophication. To study the suspended solid settling velocity, this paper takes Lake Taihu as an example. Field 9 days-in situ observations were conducted in Meiliang Bay using Acoustic Doppler Velocity, Optical Backscatter Sensor and PH- Ⅱ Handheld weather stations. The suspended solid settling velocity was estimated by the balance of settling and diffusive flux, and we analyzed the relationship among wind speed, vertical velocity, suspended solid concentration （SSC） and settling velocity. The results were obtained： （1） the mean settling velocity is 0.0785 ram/s; （2） the vertical velocity and SSC has a great effect on sediment transport in the surface layer; （3） in the bed layer, the relationship among settling velocity, vertical velocity and SSC shows that when the wind speed was higher than 1.5 m/s, the vertical velocity with large fluctuations and high SSC and the settling velocity were slower; when the wind speed was lower than 1.5 m/s, the vertical velocity was slower and the SSC was small, but settling velocity was quicker, which means the more SSC the quicker settling velocity. It reve＇,ds the characteristics of suspended solid settlement in large shallow lakes, which is the necessary foundation further study of pollutants transport, water environnlental mathematic and eutrophication.