为探寻汉江中下游早春硅藻水华频繁暴发的原因，于2010年早春硅藻水华暴发的前期，对取自汉江的原水样，从水流速度、光照强度和水体温度3个方面研究了水华硅藻——汉斯冠盘藻（Stephanodiscus hantzschii）的生物学特性。研究结果表明：在试验设定的流速范围内（0～0.5m/s），汉江水华硅藻生长状况良好，在2℃环境条件下长势较好；15μE/(m²·s）和25 μE/(m²·s）两组光强条件下培养的冠盘藻密度没有显著性差异，表明春季汉江流速偏低和适宜的气候条件是汉江早春硅藻水华频繁暴发的主要诱发因子；汉江水体中的营养盐浓度足以满足硅藻快速增殖的需要而形成水华，显示了汉江近年来污染负荷较重。

To explore the causes of early-spring diatom bloom in the middle and lower reaches of Hanjiang River, we took unamended water sample from Hanjiang River before the diatom bloom in the early spring of 2010 to study the biological characteristics of Stephanodiscus hantzschii in terms of water velocity, illumination intensity and water temperature. The results indicated that Stephanodiscus hantzschii adapted well to water velocity of 0-0.5 m/s, and could grow well in the water temperature of 2-15℃, especially in 2℃. There was no significant difference in the diatom growth abundance when the illumination intensity is of 15 and 25 μE/(m2·s). It’s concluded that low water velocity and suitable climate are main incentives of diatom bloom outbreak in early spring. It’s also pointed out that the eutrophication is becoming serious as  nutrients concentration in the Hanjiang River could meet with the demand of water bloom outbreak.