Impacts Of Hydrodynamic Conditions On Growth And Space Distribution Of Diatom

With the water storage in the three gorges reservoir area, hydrological conditions of secondary tributary changed greatly, such as flow velocity slowed extremely, water disturbance weakened and diatom bloom broken out many times in spring. And there is a growing trend in the change of hydrological conditions. Many literatures had determined the influence of a single factor from hydrodynamic conditions on algae growth. However, there were not many more literatures about the synthesis influence of hydrodynamic conditions and other typical factors, such as light, nutrient salt, water depth and etc., on diatom growth.In order to resolve the problem of diatom bloom of the secondary tributary in three gorges reservoir, based on the hydrological conditions, light intensity and nutrient level in the high-frequency time of diatom, design the device simulating the water flow and growing environment of the secondary tributary backwater area in three gorges reservoir area. Turbulent dissipation rate and flow velocity are the characteristic parameters of hydrological conditions. To research the impact on growth and spatial distribution, come from turbulent dissipation rate, light intensity, nutrient level and water depth on diatom. To research the growth impact on diatom, come from light intensity, nutrient level on diatom. The following conclusions:1) In the experiments of turbulent dissipation rate coupling typical factors, the effects of light intensity are the most prominent, followed by turbulent dissipation rate and nutrient level, the depth of water is minimal impact. And when turbulent dissipation rate is 4.80×10^-4 m2/ s3, light intensity is 2000 lx, nutrient level is TN?1.00?/TP?0.05? mg/L, depth of water is 10 cm, it is the best for diatom.2) Analysis of turbulent dissipation rate coupling typical factors on the impact of the spatial distribution of diatom, it is concluded the vertical distribution of specific growth rate of diatom and TP in the water. With the turbulent dissipation rate increasing, the diatom will float. Especially, when is the turbulent dissipation rate at 4.8 × 10^-4 m²/s³, the specific growth rate of diatom at the water surface. But, when the turbulent dissipation rate is higher than 25.73 × 10^-4 m²/s³, the diatom biomass and the specific growth rate of diatom will be inhibited. And the impact between turbulent dissipation rate and spatial distribution is significant on diatom.3) In the experiments of flow velocity coupling typical factors, the nutrient level is the most prominent, followed by light intensity, and the least is velocity conditions. And when flow velocity is 0.10 m/s, light intensity is 2500 lx, nutrient level is TN?1.50?/TP?0.10? mg/L, it is the best for diatom.