The impacts of the stratified density currents on supply pattern of main nutrients in Xiangxi River
分层异重流对香溪河库湾主要营养盐补给作用分析

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 Cl-; 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+, Cl-, K+, Ca2+, SO42- 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.