水体浊度变化影响下的河口溶解氧系统动力学模型及应用

Dissolved oxygen dynamics model and its application in estuary subject to turbidity variability

考虑河口水体浊度变化对水下光照条件的影响,建立了河口溶解氧系统动力学模型。模型包含光合作用、呼吸作用、大气复氧过程、生化需氧量及氮质需氧量5个过程。在光合作用子模型中通过考虑光衰减系数对浊度的响应关系,实现了关于水体浊度变化对河口溶解氧的影响效应分析。基于野外实地监测数据的对比分析,明确了不同光衰减系数-浊度模型的差异,探讨了二者为对数关系时拟合效果最优的合理性。对黄河口不同季节溶解氧模拟结果表明,日变化呈现单峰单谷的波动状态。浊度的增加将通过降低透光度影响到水体溶解氧水平。不同季节浊度扰动对溶解氧的影响有显著差异。水体溶解氧对温度变化最敏感,风速和BOD衰减速率常数次之,对盐度和水深变化不敏感。

To determine the effect of turbidity variation on dissolved oxygen in estuarine areas, a system dynamics model of dissolved oxygen has been developed. It offers us a closer insight to the effect of turbidi- ty on underwater light climate, sequentially the photosynthetic yield. The one-dimension model comprises five parts： re-aeration, biochemical oxygen demand, nitrogenous oxygen demand, photosynthesis and respira- tion of the phytoplankton. According to the comparison, it is revealed that the model including logarithmic relationship between light attenuation coefficient and turbidity is the best one. The did dissolved oxygen dy- namics show that fluctuation changes with single peak-valley type. Turbidity is an important factor which controls the DO dynamics in the estuary and varies inversely with DO. There are significant differences in the responses of DO to turbidity disturbances at each season. Temperature is the most sensitive parameter followed by wind speed and BOD decay rate coefficient.