Abstract: Deicing salt was applied for clearing ice and snow on road in winter and entered into river with the surface runoff, so it affected the growth of aquatic organism and broke the equilibrium of aquatic ecosystem. In order to study the toxic effect of deicing salt on aquatic organisms, the effects of deicing salt on the growth, the content change of photosynthesis pigments, protein and polysaccharides of Chlorella vulgaris were analyzed. The results show that there is no significant effect for the growth of Chlorella vulgaris when the deicing salt concentration is 2 g·L^-1. However, there is a  significant inhibitory effect on the cell growth of Chlorella vulgaris when it is 4 g·L^-1, and the inhibitive effect of deicing salt significantly increases (P<0.01) with the increase of the concentrations. There is the significant stimulative effect on biosynthesis of chlorophyll (a) in a cell of Chlorella vulgaris when it is less than 4 g·L^-1, while the chlorophyll (a) contents decrease with further increase of deicing salt concentrations. Compared with the control, protein and polysaccharides contents decrease (P<0.01) significantly when it is more than 4 g·L^-1. It suggests that the growth and reproduction of Chlorella vulgaris will be inhibited and the cell will be destroyed when deicing salt concentration is more than 4 g·L^-1, and finally it will break the balance of aquatic ecosystem.

Key words: Deicing salts, Chlorella vulgaris, Growth, Chlorophyll (a), Protein, Polysaccharides