Comparison of the Aquatic Plants' Purification Effects on Eutrophic Water from Chaohu Lake Area

This research has examined the aquatic plants ability of removing N and P with the experiment materials of the aquatic plants in the river system in Chaohu Region. Results revealed that Ludwigia peploides subsp, Vallisneria spiralis, Water Hyacinth and Cyperus papyrus contribute to removing TN in water to the effect which correlates the growth rate of the plants. 1) Particularly, Water Hyacinth, which grows the fastest among the sample plants, effects with the highest efficiency in removing TN, with the removal ratio of about 77%, 6.8 times that of the control group; 2) 4 aquatic plants function with higher efficiency in removing NH3-N than TN, and the plants in Test 8d remove NH3-N up to the removing ratio of 65-92% or so; 3) 4 aquatic plants tend to degrade NO3--N at the ratio similar to TN, and the absorptive effect of Water Hyacinth tops among the 4 plants, while under the same conditions, the papyrus remains the lowest with the absorptive ratio of only 31.7%; 4) and the regulation that the experiment plants remove the TP in water differs from TP degradation, for, in the early stage of the experiment, plants in Test 20d remove phosphorus at the high rate; however, in the later stage of the experiment, the concentration of phosphorus in water remains stable. At the end of the experiment, the phosphorus removal ratio reached 47.2%, while the ratio that the papyrus removed the phosphorus was only 21.5%. These data suggest that the aquatic plants in Chaohu Region can exert efficient remediation effect upon the eutrophic water.