Toxic Effects of Lanthanum, Cerium, Chromium and Zinc onPotamogeton Malaianus
摘要
The toxic effects of rare earth elements such as lanthanum, cerium and heavy metal elements such as chromium, zinc on Potamogeton malaianus Miq. were studied. The results show that the contentsof chlorophyll and soluble protein increase to a certain degree and then decrease under La^3+,Ce^3+, Zn^2+ stress, while a constantly dropping tendency appears under Cr^6+ stress. The four ions have different effects on protective enzyme systems of Potamogeton malaianus.They can induce rises of the activities of catalase (CAT) and peroxides (POD) at lower concentra-tion. however, with the increasing concentration,and the activities decline. The change of SOD activity is exactly opposite to that of CAT activity and POD activity, it falls at first and rises later. An increasing tendency of MDA content appears with the increasing concentration. The toxicities of La^3+, Zn^2+, Ce^3+ and Cr^6+ become more serious in the order. The lethal concentration of Cr^6+ to Potamogeton malaianusranges from 0.5 to 1 mg·L^-1, that of Ce^3+ and Zn^2+ ranges from 3 to 5 mg·L^-1, and that of La^3+ rangesfrom 7 to 10 mg·L^-1. The toxic mechanism of La^3+,Ce^3+ is similar to that of Cr^6+, Zn^2+.