[Effect of linolenic acid on bioavailability of cadmium in eutrophic water].

OBJECTIVE: To investigate the bioavailability of heavy metal cadmium on planktonic algae under the condition of containing linolenic acid.

METHODS: Using different concentrations of Cd~(2+)( 0. 10, 0. 20, 0. 30 and 0. 40 mg/L) alone, as well as different combinations of cadmium with 0. 01 mL/L linolenic acid that acted on Scenedesmus obliquus and Microcystis aeruginosa respectively, then the growth-inhibitory of S. obliquus and M. aeruginosa and the absorption of cadmium and adsorption of cadmium by S. obliquus and M. aeruginosa were detected.

RESULTS: Both cadmium alone and linolenic acid alone had certain inhibitory effects on M. aeruginosa and S. obliquus at the concentrations, and the inhibition was stronger on M. aeruginosa. The inhibition rates reached 42. 17% and 67. 42% of 0. 10 and 0. 40 mg/L Cd~(2+) at the 96 h, the inhibition rate of 0. 01 mL/L linolenic acid at the 96 h was 39. 33%, there were no changes with the inhibitory effects when linolenic acid and cadmium coexisted. But both the cadmium uptake and adsorption amount by M. aeruginosa and S. obliquus all decreased under the condition of containing linolenic acid( P < 0. 05).

CONCLUSION: The fatty acid carboxyl may have mild chelation to cadmium ions, which can reduce the heavy metal cadmium toxicity, and also reduce the uptake or absorption of cadmium by algae cells.