Abstract: The deep lakes in Plateau Canyon, because of their deep water and their dramatic water level change, are not conducive to the growth of aquatic plants, and thus, the ecological restoration techniques used for shallow lakes are difficult to be applied in deep lakes. In this study, various kinds of aquatic plants were planted on the floating island carrier in Youer Bay at the Lake Hongfeng, a typical plateau deep lake in Guizhou, and the chemical components (nitrogen, phosphorus, and heavy metals) in the roots, stems, and leaves of the plants were analyzed. The nitrogen content of the plants was Potamogeton crispus > Rumex > Silpniumper foliatum, the phosphorous content was P. crispus > Elodea muttallii > Rumex, and the effective plants for both nitrogen and phosphorus removal were P. crispus, E. muttallii, and Rumex. All test aquatic plants could accumulate the heavy metals Cu, Cd, Pb, Zn, and Hg. The cumulative concentration of the heavy metals in the plants was in the order of Zn > Pb > Cu >> Cd > Hg. In different parts of the plants, root had a higher bioaccumulation coefficient than stem and leaf. The Zn/Cd ratio was higher in leaves than in stems and roots. Overall, Lolium perenne, Rumex, and P. crispus had greater potential application prospect in water phytoremediation. There was a significant positive correlation between plant total nitrogen (TN) and total phosphorus (TP), but no obvious correlation between plant nutrients and heavy metals. The plant heavy metals were significantly positively correlated with each other. This study also showed that terrestrial plants could grow well on the floating island barrier, being available in the ecological remediation of the polluted water in deep lakes. In practice, both the water pollution and the plant absorption characteristics should be considered in selecting the best plant combinations.  

Key words: freeze-thaw processes, terrestrial ecosystem, nitrogen cycle, process, mechanism.