中文摘要：

通过对长江下游镇扬段的牛轭湖—内江的泥沙、水质、光强、藻类等进行现场监测和数据分析,探讨了内江悬浮泥沙对水下光强的衰减规律以及对藻类生长的影响。结果表明：内江水体中存在80%以上的粒径小于75μm的微细悬浮颗粒,其中不易沉降的粘土颗粒占到20%～50%左右,枯水期平均含量为40 mg/L,丰水期平均含量为70 mg/L,而藻细胞生物总量基本都在100万个/L以内,其中绿藻、硅藻为优势种。数据分析表明：泥沙对水下光强的衰减遵循指数函数衰减规律,光衰减系数与泥沙含量呈较好的线性相关性,内江的优势种绿藻、硅藻的生物量与泥沙含量呈显著的指数相关。认为,泥沙通过衰减光强间接地抑制藻类繁殖,这一抑制作用可以由泥沙含量和藻细胞密度之间的关系进行定量。

英文摘要：

A field survey was carried out in Neijiang that is an oxbow lake located within the Zhenjiang-Yangzhou segment in the lower reach of Yangtze River.Sediment concentrations,water transparency,underwater light intensity,algae species and biomass in the oxbow lake were monitored periodically.The observed data were analyzed.Results show that fine suspended particulate matters with the granular size less than 75 μm can constitute more than 80% of the total suspended sediment load in the lake;among which,clay grains account for 20%-50% of the fine suspended sediment.The mean values of sediment concentration in the lake are 40mg/L and 70mg/L for low and high water period,respectively.The gross algae biomass is basically within 100×104 cell/L and dominated by green algae species.The light attenuation resulting from the suspended sediment load in the lake obeys the exponential law,and the relationship of green algae biomass and sediment concentration is also exponential.The diffuse attenuation coefficient appears to be linearly correlated to the sediment concentration.We thus conclude that the suspended sediment can inhibit the algae reproduction process through indirectly declining the underwater light intensity.Such an inhibition can be quantified by the relationship of algae cell density and sediment concentration.