Abstract：Joint toxicity of cetyltrimethyl ammonium chloride (CTAC) together with fluoranthene (Flu) on Chlorella vulgaris was investigated by batch culture in laboratory. The joint toxicity of binary mixture of CTAC and Flu on Chlorella vulgaris changed from synergetic effect (0~22.50μg/L) to antagonetic effect (22.50~100.84μg/L) with increasing concentrations of Flu in the range of 0~100.84μg/L. The strongest synergetic effect (RI=2.01) was observed in the presence of 1.13μg/L Flu, and the percentage of inhibition of biomass increased from 37.5% to 80.9%, while the absorption of nitrogen and iron declined from 0.27mg to 0.083mg and from 9.18 μg to 2.14μg, respectively. At the same time, Zeta potential of algal cell increased from-10.0 mV to-8.3 mV, and chlorophyll-a and soluble protein content declined from 5.00mg/L to 2.57mg/L and from 80.65μg/mg to 50.36μg/mg, respectively. Above phenomena indicates that CTAC and Flu combined pollution system increased the Zeta potential of algal cell and thus inhibits the absorption of nitrogen and iron, which subsequently decreased the chlorophyll-a and protein content.
