水库水动力对水体富营养化影响

Influence of reservoir hydrodynamic on eutrophication of water body

当氮磷浓度达到富营养水平时,水动力条件(流量、流速和水位)可能成为制约因子,抑制水华发生。河道型深层出水的水库相对于湖泊型表层出水的水库,因为较大交换流量,较低营养盐浓度,保证了浮游植物和藻类较低的现存量。进一步研究水文条件(滞留时间、水位变化和水流运动)发现,保持较低的滞留时间、较高的水位和底层较低的流速,都有利于水库水体中营养盐和藻类的稀释,不利于浮游植物和藻类的生长,减缓水体富营养化进程。

When the concentration of nitrogen and phosphorus reaches the eutrophication level, hydrodynamic conditions （flow, flow rate, stage） may be the constraints, which will restrain the development of algal bloom. Comparing the reservoirs of river - type and draining off water from deep layer with that of lake - type and draining off water from shallow layer, the former reservoirs have a low biomass of phytoplankton and algae, because of the large traffic exchange and low concentration of nutrient. After further study on hydrological conditions （residence time, stage change, water flow motion）, the paper discovered that keeping short residence time, higher water level and lower water flow in bottom water layer is benefit to the dilution of concentration of nutrition and algae, is disbenenifit to the growth of phytoplankton and algae, witch slows down the eutrophication process.