Flow turbulence has been widely accepted as one of the essential factors affecting phytoplankton growth. In this study, laboratory cultures of Microcystis aeruginosa in beakers were carried out under different turbulent conditions to identify the quantitative relationship between the algal growth rate and the turbulent intensity. The turbulent intensity (represented by energy dissipation rate, ε) was simulated with the software FLUENT. Daily measurement of the two parameters (algal biomass and chlorophyll-a concentration) was carried out during the experimental period to represent the algal growth rate. Meanwhile, the rates of photosynthetic oxygen evolution and chlorophyll fluorescence intensity were calculated to investigate the photosynthetic efficiency. The results indicated that the growth rate of Microcystis aeruginosa became higher in the turbulent environment than in the still water environment under the designed experimental conditions. The peak growth rate of Microcystis aeruginosa occurred when ε was 6.44 × 10⁻² m²/s³, over which the rate declined, probably due to unfavorable impacts of strong turbulence. In comparison, the maximum rate of photosynthetic oxygen evolution occurred when ε was 0.19 m²/s³. Based on the findings of this study, an exponential function was proposed in order to incorporate the effect of flow turbulence into the existing algal growth models, which usually just consider the impacts of nutrient availability, illumination, and temperature.

中文翻译：

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湍流对藻类生长的定量影响的实验研究

湍流被广泛认为是影响浮游植物生长的重要因素之一。在这项研究中，在不同的湍流条件下对烧杯中的铜绿微囊藻进行实验室培养，以鉴定藻类生长速率和湍流强度之间的定量关系。用软件FLUENT模拟了湍流强度（用能量耗散率ε表示）。在实验期间每天测量两个参数（藻类生物量和叶绿素-a浓度）以代表藻类的生长速率。同时，计算了光合氧的释放速率和叶绿素荧光强度，以研究光合效率。结果表明，在设计的实验条件下，铜绿微囊藻在湍流环境中的水位高于静水环境。铜绿微囊藻的峰值生长速率出现在ε为6.44×10 ^-2 m ² / s ^3时，该速率下降，这可能是由于强湍流的不利影响。相比之下，当ε为0.19 m ² / s ³时，发生了最大的光合氧气释放速率。。根据这项研究的结果，提出了一个指数函数，以便将湍流的影响纳入现有的藻类生长模型中，该模型通常仅考虑营养物可利用性，光照和温度的影响。