Research on Accumulation Mechanism of Freshwater Red Tide in a Dam Reservoir

一、观察了秋季寿人基水库库首Peridina的分布型和现存量的日变化。有三种分布模式：(A)白天在表层堆积；(B)夜间向下层扩散，形成溪流；(C)下层向下滑点附近扩散。Periddium的现存量以相似的增长速度逐日增加。由于生物是通过逆流输送的，生物量在一天中以24小时为周期周期性变化。这些结果表明赤潮在生长、进口和出口的平衡中发展和消散。II.测量了不同温度和光强条件下Periddium的游泳速度矢量。通过对获得的数据集进行分析，建立了预测Periddium群落垂直游动速度的数学模型。此外，利用水箱和假定水库水头的数学模型，对赤潮的积累和扩散过程进行了研究。考虑垂直游动响应的数学模型能较好地模拟生物的日变化。三、建立了模拟淡水赤潮蓄积机制的数学模型。用流体动力学模型预测进出口，用垂直游动模型预测垂直分布，用生态模型预测增长。该模型成功地模拟了寿仁集水库库首Peridina的时空分布。这些结果表明，淡水赤潮的堆积机制可以从工程的角度进行处理。

I.The diurnal change of distribution patterns and standing crop of Peridinium were observed at the head of Shourenji Dam Reservoir in autumn. There were three distribution patterns ; (a) accumulating at the surface in the day time ; (b) dispersing to lower layr and stream in the night ; (c) dispersing lower layr near the plunging point. The standing crop of Peridinium increased at similar rate of growth day by day. Since organisms were transported by the counter flow, The biomass periodically varied at 24 hours cycle in a day. These results show that the red tide develops and dissipates in the balance of growth, import and export.II.Swimming velocity vectors of Peridinium were measured under various temperature and light intensity conditions. Analyzing obtained data sets, we constructed a mathematical model that predicted the vertical swimming velocity of Peridinium community. Furthermore, using the water tank and the mathematical model that assuming the head of a water reservoir, we examined the accumulation and dispersion processes of red tide. The mathematical model including the vertical swimming responses could simulate the diurnal change of biomass.III.We developed the mathematical model that simulate the accumulation mechanism of freshwater red tide. It predicts the import and export using the fluid dynamics model, the vertical distribution using the vertical swimming model, and the growth using the ecological model. This model successfully simulated the temporal and spatial distribution of Peridinium at the head of Shourenji Dam Reservoir. These results suggested that accumulation mechanism of freshwater red tide could be treat in the term of engineering.