Toxic effect of nonylphenol on Phaeodactylum triconutum and its mechanism

In order to explore the toxic effects of nonylphenol (NP) on marine microalgae, effects of NP on the growth of Phaeodactylumtriconutum were studied. The exposure concentrations of NP were 0, 0.2, 0.4, 0.6, 0.8, 1.0 and 2.0 mg·L-1. Growth, photosyntheticpigment contents, soluble protein contents, MDA contents and Fv/Fm, as well as 24h, 48h, 72h and 96h EC50 were measured during theexperimental period. The results showed that, the 96 h EC50 of NP for P. triconutum was 0.84 mg·L-1. When the exposure concentrationof NP was above 0.4 mg·L-1, the growth of P. triconutum was inhibited. And when it was more than 1.0 mg·L-1, there was mass mortalityof the algal cells. No growth of P. triconutum was observed as it came to 2.0 mg·L-1. The decreases of growth, photosynthetic pigmentcontents, soluble protein contents, MDA contents, Fv/Fm were more notable with the increasing exposure concentration of NP. After 24 hexposure treatment, MDA contents increased with the increase of concentration of NP, indicating that high NP concentration enhancedalgal cell membrane lipid peroxidation, and thus led to the structural damage and functional loss of cell membrane structure. NP hadobvious toxic effects on the growth of P. tricornutum, and antioxidant enzyme systems and photosynthetic system were damaged.