Nitrogen and phosphorus removal and physiological response in Zizania latifolia and Sagittaria sagittifolia under different degree of eutrophic water

Two aquatic plants, Zizania latifolia and Sagittaria sagittifolia, were used to study the variation of physiological responses and the water qualities under mild, moderate and weighty eutrophic water in plastic pot scale experiments. The physiological characteristics of both plants were investigated, which included contents of leaf malondialdehyde (MDA) and proline, membrane permeability (MP), and activities of catalase (CAT) and peroxides (POD). The water qualities were analyzed correspondingly. The results showed remarkable effects of different degree of eutrophic water on physiological characteristics of the plants. Compared with mild eutrophic water, increasing degree of eutrophication significantly increased the contents of MDA and MP, decreased POD activity, especially in Zizania latifolia. The proline content increased more evidently in Sagittaria sagittifolia than that in Zizania latifolia, and the CAT activity showed no significant change in both plants. Removals of TN, NH4+-N and TP increased with increasing degree of eutrophication, reaching the highest value 96.5%, 97.2% and 92.7%, respectively, in Sagittaria sagittifolia under weighty eutrophic water. However, Zizania latifolia achieved its highest remove efficiency of TN and NH4+-N under moderate eutrophic water and that of TP under weighty eutrophic water. Besides, TN, NH4+-N and TP removals were higher in Zizania latifolia than those in Sagittaria sagittifolia under mild eutrophic water. These results suggested that Zizania latifolia and Sagittaria sagittifolia were the recommended aquatic plants in phytoremediation of mild and weighty eutrophicated water, respectively.