干流倒灌异重流对香溪河库湾营养盐的补给作用

三峡水库蓄水以来,其支流库湾每年均暴发严重的春季水华.为研究三峡水库支流营养盐受干流的逆向影响,于2010年对三峡水库库首区域最大的支流香溪河库湾水流特点及总氮、总磷的时空动态分布进行了详细监测.研究发现库湾水体表现为分层异向流动,存在明显的倒灌异重流现象,分别以表、中、底3种形式倒灌入香溪河库湾;特定的水流特性为库湾营养物质的运输提供了水动力基础,香溪河河口处由干流倒灌输入总氮、总磷的平均瞬时通量分别为501.92 g.s-1、48.17 g.s-1,在2010年干流倒灌输入香溪河库湾的总氮、总磷污染负荷分别占总量的43.4%、21.5%.结果表明,倒灌输入的总氮、总磷占有很大的比例,同时加强三峡水库支流及干流上游流域污染控制才是有效控制支流水华发生的根本途径.

Effects of Intrusions from Three Gorges Reservoir on Nutrient Supply to Xiangxi Bay

Frequent spring blooms have been observed in tributary bays of Three Gorges Reservoir (TGR) since its initial filling. In order to study Three Gorges Reservoir of nutrients by the River tributaries reverse effect, a well-designed field monitoring plan was conducted. The results show: there are significant intrusions from Three Gorges Reservoir to Xiangxi Bay to the surface, middle and bottom with three forms of intrusion respectively. The unique flow characteristics provide a hydrodynamic background of nutrient distributions of Xiangxi Bay. The average instantaneous fluxes of the input TN and TP of the intrusions from the confluence were 501.92 g ·s^-1 and 48.17 g ·s^-1, respectively; TN and TP loads originated from intrusions accounted for 43.4% and 21.5%, respectively to total amount in the whole year. The study shows that intrusion of the total nitrogen input, a large proportion of total phosphorus, and reducing the pollution loads of tributaries and upper reach basin of Three Gorges Reservoir is the fundamental way to eradicate algal blooms.