分层异重流对香溪河库湾主要营养盐补给作用分析

The impacts of the stratified density currents on supply pattern of main nutrients in Xiangxi River

为弄清分层异重流对三峡水库支流库湾主要营养盐的补给过程,通过分析2011年7月19日香溪河库湾常量离子、营养盐等监测数据,利用物质守恒规律,借用常量离子Cl-估算了分层异重流倒灌水量,计算了香溪河上游径流和水库干流倒灌对回水区氮、磷、硅负荷的贡献.研究表明:水库干流中的Na+、Cl-、K+、Ca2+、SO24-等离子浓度比香溪河上游径流高,在香溪河库湾中自河口至上游逐渐降低,Mg2+相反;SO24-、Cl-、Na+等离子空间分布差异显著,能够作为示踪离子;水库干流倒灌流量与上游径流流量比为12.59∶1;由长江干流倒灌输入的TN、TP、D-Si通量分别为54.97、3.53和221.90 t.d-1,香溪河上游径流输入通量依次为3.00、0.57和10.02 t.d-1;干流倒灌输入TN、TP、D-Si贡献率分别高达94.83%、86.13%和95.68%,沿河口逆向上游,干流倒灌对香溪河库湾营养盐的补给作用逐渐减小.

In order to investigate the impacts of the stratified density currents on input of main nutrients in tributary bays of the Three Gorges Reservoir, inorganic ion, nutrients and other parameters of Xiangxi Bay on July 19, 2011 were analyzed. According to the Law of the conservation of mass, the intrusion water volume from the mainstream of the Yangtze River was estimated by measuring concentration of constant ion C1 - ; and the contributions of nitrogen, phosphorus, silicon load from the upstream inflow of Xiangxi River and the mainstream of the Yangtze River were evaluated. The results show that the concentrations of Na＋ , C1- , K ＋ , Ca2＋ , SO4/2- and other ions of the Three Gorges Reservoir are higher than those in the inflow of Xiangxi River. These ions can therefore be used as tracers. The volume ratio between the mainstream and the upstream inflow is 12.59 ： 1. The fluxes of total nitrogen, total phosphorus and dissolved silicon from intrusions are 54.97, 3.53 and 221.90 t·d^-1, respectively, while the corresponding fluxes from the upstream inflow of Xiangxi River are 3.00, 0.57 and 10.02 t·d^-1 , respectively. The contribution rates of total nitrogen, total phosphorus and dissolved silicon from intrusions are 94.83% , 86.13% and 95.68% , respectively. The tendency decreases toward the end of the Xiangxi Bay along its longitudinal direction.