采用脉冲振幅调制(PAM)技术，对同一浓度金属离子Hg2+、Cd2+、Cu2+、Zn2+对斜生栅藻、蛋白核小球藻、普通小球藻的抑制作用进行了测定研究。通过对3种藻叶绿素a PSⅡ系统各荧光参数的测定，以抑制率和重金属响应时间为分析参考依据，确定蛋白核小球藻为4种重金属的敏感藻种。3种不同藻对4种重金属的敏感度为：蛋白核小球藻>斜生栅藻>普通小球藻，4种重金属对蛋白核小球藻的急性毒性大小为：Hg2+>Cu2+>Cd2+>Zn2+。与传统的藻类生长抑制实验相比，该敏感藻种筛选方法具有简便、快速的优点。

The inhibitions of scenedesmus obliquus, chlorella pyrenoidosa and chlorella vulgaris stressed by the same concentration of Hg2+, Cd2+, Cu2+, Zn2+ are investigated with pulse amplitute modulation (PAM) technology.The chlorophyll-a fluorescence parameters of PSⅡ system are measured and the inhibition rates and response times of three kinds of algals offer reference for the sensitive microalgal species. From the results, chlorella pyrenoidosa is determines as a sensitive microalgal species to Hg2+, Cd2+, Cu2+, Zn2+. The sensitivity of three microalgals can be expressed as chlorella pyrenoidosa>scenedesmus obliquus>chlorella vulgaris.The toxicity results of four kinds of heavy metal ions can be expressed as Hg2+>Cu2+>Cd2+>Zn2+. Compared to algal growth inhibition experiment, this new method for a sensitive microalgal specie selection is simple and rapid.