三峡水库泄水期香溪河库湾营养盐动态及干流逆向影响
Dynamic characteristics of nutrients in Xiangxi Bay and converse impact from mainstream in drainage period of the Three Gorges Reservoir
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摘要: 为了研究水库干流对支流库湾营养盐动态的影响，于2009年春季三峡水库汛前泄水期，通过监测分析了库湾水流特点及叶绿素a、总氮、总磷和溶解性硅酸盐的时空动态。研究发现：三峡水库汛前泄水期，库湾水体表现为分层异向流动，干流水体以异重流形式倒灌入库湾；特定的水流特性为泄水期库湾营养物质运移提供了水动力基础，水库干流对库湾营养盐的补给及水华暴发范围有明显逆向作用；受干流影响，氮和硅自河口至回水末端呈递减趋势，磷主要受上游来水影响，空间分布趋势与氮、硅相反；叶绿素a浓度峰值向上游移动，水华范围向上游收缩，河口处叶绿素a浓度的时间均值明显低于回水末端，表明三峡水库泄水期香溪河库湾下游水体水华受到干流逆向影响的抑制。Abstract: In order to study the impact of the main stream of the Three Gorges Reservoir（TGR） on dynamic characteristics of nutrients in Xiangxi Bay（XXB）,the flow features and chlorophyll a, total nitrogen(TN),total phosphorus(TP) as well as soluble silicate(D-Si) were continuously monitored to inquiry the temporal-spatial dynamics. During the TGR drainage period,the water flows of XXB could be mainly generalized as a densitystratified flow in different directions along depth and the water of main stream flow backward into the Bay in the form of density current. The particular flow of XXB during drainage period provides the hydrodynamic basis for the nutrient transport，and the converse effects of reservoir main stream play a significant role on the supply of nutrients for XXB. From the estuary to the end of the backwater zone, nitrogen and silicon diminished under the influence of the main stream，the spatial distribution of phosphorus was mainly affected by the upper reaches in contrast with nitrogen and silicon; the concentrations of chlorophyll a showed a rising trend from the estuary to the end of backwater zone，and the scope of water bloom contracted to upstream, which indicated that water bloom of XXB downstream was restricted by converse influence of main stream in the drainage period of the TGR.
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Key words:
- Three Gorges Reservoir /
- drainage period /
- nutrient /
- converse influence
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