Ecological Toxicology Study Of Phthalate Esters To Marine Algae

The effects of phthalate esters (PAEs) on the growth of four species of marine algae including microalgae Dunaliella salina, Pavlova viridis, Phaeodactylum tricornutum and seaweed Gracilaria lemaneiformis were analyzed by a battery of experiments. Bio-accumulation of PAEs in the seaweed and the bio-magnification of PAEs in the food chain of seaweed-fish (Siganus oramin) were studied through the enclosure experiments. Results are summarized as the following:1) Exposure to 0. 1, 10, 40, 80 and 200 mg · L^-1 of Dimethyl phthalate (DMP) inhibited the growth of microalgae D. salina, P. viridis andP. tricornutum . The inhibitory rates of growth for D. salina, P. viridis and P. tricornutum were 22. 9—93. 1%, 42. 1—82. 2% and 61. 9—92. 2%, respectively. The 50% lethal concentrations (LC₅₀) of DMP for the three algae were 103. 4 44.0 and 0.12 mg · L^-1, respectively.2) Exposure to the mixture of DMP, Diethyl phthlate(DEP), Dibutyl phthlate(DBP) and Di(2-ethlhexyl) phthlate(DEHP) at the concentrations of 0. 05, 0. 10, 0. 20, 0. 40 mg · L^-1 affected the relative growth rate (RGR) and the chlorophyll a (Chl a) content of G. lemaneiformis. Toxic effects of PAEs on the seaweed increased with the concentrations of PAEs. Compared with the control, the treatment of G. lemaneiformis with 0.1—0.4 mg · L^-1 of PAEs decreased the RGR by 18. 4—21. 3% and Chi a content by 10. 4—15. 3%. The accumulations of the four PAEs in the seaweed were observed shown by gas chromatography (GC-ECD) detection. The amount of accumulated PAEs changed with the concentration of PAEs and the length of exposure time. The residues of DMP, DEP, DBP and DEHP were 0-0.14, 0.23-0.83, 0-1.32 and 0. 38-9. 72 mg · Kg^-1, respectively. Longer side-chain PAEs appeared to be accumulated more in the seaweed than the shorter ones, suggesting that the molecular structure of PAEs may affect its bio-accumulation.