目前环境监测中多采用单一指标的监测方法，对污染物质共同作用产生的环境危害监测较少。以叶绿素a含量和光能转化效率为指标，研究Hg（汞)和DBP(邻苯二甲酸二丁酯）单一及联合胁迫下的毒性作用。结果表明：Hg, DBP单一作用及联合胁迫对四尾栅藻的叶绿素荧光参数均有抑制作用，随暴露浓度的增大，微藻叶绿素a含量和光能转化效率逐渐降低，显示出明显的剂量-效应关系；Hg和DBP联合胁迫时表现出明显的对四尾栅藻的协同作用。研究成果可为污染物综合毒性监测提供理论依据。

 In environmental pollution monitoring at present, methods considering only the single index rather than the combined action of pollutants are mostly used which cannot reflect the comprehensive toxicity of pollutants. Taking chlorophyll-a content and optical energy conversion efficiency as indicators, we analyzed the toxicity of combined mercury (Hg) and DiButyl phthalate (DBP) on Scenedesmus quadricauda. Results showed that the chlorophyll fluorescence parameters of Scenedesmus quadricauda were inhibited either by Hg samples, DBP samples, or by joint samples of Hg and DBP. The chlorophyll-a content and optical energy conversion efficiency decreased with the increase of toxicant concentration, showing an obvious dose-response relationship. A conspicuous synergistic effect of Hg-DBP was found on Scenedesmus quadricauda. The results could provide a theoretical basis for monitoring the comprehensive toxicity of pollutants in water. 